android中的Protobuf简介以及使用

protobuf是一种用于序列化结构数据的工具，实现数据的存储与交换，与编程语言和开发平台无关，性能高效果，速度快，体积小。

定义proto文件：

package space;
option optimize_for = SPEED;

message course{
  optional string name = 1;
  optional int32 score = 2;

}
message student{
  optional string name = 1;
  optional  int32 age = 2;
  repeated course mCourse = 3;

}

我们需要将proto文件转换成对应的java文件，此时需要protoc.exe文件(官网可以下载)

项目build.gradle也要依赖

最后再加上一个脚本可以方便生成：

下面就是生成的类：

// Generated by the protocol buffer compiler.  DO NOT EDIT!
// source: pb_teacher.proto

package space;

public final class PbTeacher {
  private PbTeacher() {}
  public static void registerAllExtensions(
      com.google.protobuf.ExtensionRegistry registry) {
  }
  public interface courseOrBuilder
      extends com.google.protobuf.MessageOrBuilder {

    // optional string name = 1;
    /**
     * <code>optional string name = 1;</code>
     */
    boolean hasName();
    /**
     * <code>optional string name = 1;</code>
     */
    java.lang.String getName();
    /**
     * <code>optional string name = 1;</code>
     */
    com.google.protobuf.ByteString
        getNameBytes();

    // optional int32 score = 2;
    /**
     * <code>optional int32 score = 2;</code>
     */
    boolean hasScore();
    /**
     * <code>optional int32 score = 2;</code>
     */
    int getScore();
  }
  /**
   * Protobuf type {@code space.course}
   */
  public static final class course extends
      com.google.protobuf.GeneratedMessage
      implements courseOrBuilder {
    // Use course.newBuilder() to construct.
    private course(com.google.protobuf.GeneratedMessage.Builder<?> builder) {
      super(builder);
      this.unknownFields = builder.getUnknownFields();
    }
    private course(boolean noInit) { this.unknownFields = com.google.protobuf.UnknownFieldSet.getDefaultInstance(); }

    private static final course defaultInstance;
    public static course getDefaultInstance() {
      return defaultInstance;
    }

    public course getDefaultInstanceForType() {
      return defaultInstance;
    }

    private final com.google.protobuf.UnknownFieldSet unknownFields;
    @java.lang.Override
    public final com.google.protobuf.UnknownFieldSet
        getUnknownFields() {
      return this.unknownFields;
    }
    private course(
        com.google.protobuf.CodedInputStream input,
        com.google.protobuf.ExtensionRegistryLite extensionRegistry)
        throws com.google.protobuf.InvalidProtocolBufferException {
      initFields();
      int mutable_bitField0_ = 0;
      com.google.protobuf.UnknownFieldSet.Builder unknownFields =
          com.google.protobuf.UnknownFieldSet.newBuilder();
      try {
        boolean done = false;
        while (!done) {
          int tag = input.readTag();
          switch (tag) {
            case 0:
              done = true;
              break;
            default: {
              if (!parseUnknownField(input, unknownFields,
                                     extensionRegistry, tag)) {
                done = true;
              }
              break;
            }
            case 10: {
              bitField0_ |= 0x00000001;
              name_ = input.readBytes();
              break;
            }
            case 16: {
              bitField0_ |= 0x00000002;
              score_ = input.readInt32();
              break;
            }
          }
        }
      } catch (com.google.protobuf.InvalidProtocolBufferException e) {
        throw e.setUnfinishedMessage(this);
      } catch (java.io.IOException e) {
        throw new com.google.protobuf.InvalidProtocolBufferException(
            e.getMessage()).setUnfinishedMessage(this);
      } finally {
        this.unknownFields = unknownFields.build();
        makeExtensionsImmutable();
      }
    }
    public static final com.google.protobuf.Descriptors.Descriptor
        getDescriptor() {
      return space.PbTeacher.internal_static_space_course_descriptor;
    }

    protected com.google.protobuf.GeneratedMessage.FieldAccessorTable
        internalGetFieldAccessorTable() {
      return space.PbTeacher.internal_static_space_course_fieldAccessorTable
          .ensureFieldAccessorsInitialized(
              space.PbTeacher.course.class, space.PbTeacher.course.Builder.class);
    }

    public static com.google.protobuf.Parser<course> PARSER =
        new com.google.protobuf.AbstractParser<course>() {
      public course parsePartialFrom(
          com.google.protobuf.CodedInputStream input,
          com.google.protobuf.ExtensionRegistryLite extensionRegistry)
          throws com.google.protobuf.InvalidProtocolBufferException {
        return new course(input, extensionRegistry);
      }
    };

    @java.lang.Override
    public com.google.protobuf.Parser<course> getParserForType() {
      return PARSER;
    }

    private int bitField0_;
    // optional string name = 1;
    public static final int NAME_FIELD_NUMBER = 1;
    private java.lang.Object name_;
    /**
     * <code>optional string name = 1;</code>
     */
    public boolean hasName() {
      return ((bitField0_ & 0x00000001) == 0x00000001);
    }
    /**
     * <code>optional string name = 1;</code>
     */
    public java.lang.String getName() {
      java.lang.Object ref = name_;
      if (ref instanceof java.lang.String) {
        return (java.lang.String) ref;
      } else {
        com.google.protobuf.ByteString bs = 
            (com.google.protobuf.ByteString) ref;
        java.lang.String s = bs.toStringUtf8();
        if (bs.isValidUtf8()) {
          name_ = s;
        }
        return s;
      }
    }
    /**
     * <code>optional string name = 1;</code>
     */
    public com.google.protobuf.ByteString
        getNameBytes() {
      java.lang.Object ref = name_;
      if (ref instanceof java.lang.String) {
        com.google.protobuf.ByteString b = 
            com.google.protobuf.ByteString.copyFromUtf8(
                (java.lang.String) ref);
        name_ = b;
        return b;
      } else {
        return (com.google.protobuf.ByteString) ref;
      }
    }

    // optional int32 score = 2;
    public static final int SCORE_FIELD_NUMBER = 2;
    private int score_;
    /**
     * <code>optional int32 score = 2;</code>
     */
    public boolean hasScore() {
      return ((bitField0_ & 0x00000002) == 0x00000002);
    }
    /**
     * <code>optional int32 score = 2;</code>
     */
    public int getScore() {
      return score_;
    }

    private void initFields() {
      name_ = "";
      score_ = 0;
    }
    private byte memoizedIsInitialized = -1;
    public final boolean isInitialized() {
      byte isInitialized = memoizedIsInitialized;
      if (isInitialized != -1) return isInitialized == 1;

      memoizedIsInitialized = 1;
      return true;
    }

    public void writeTo(com.google.protobuf.CodedOutputStream output)
                        throws java.io.IOException {
      getSerializedSize();
      if (((bitField0_ & 0x00000001) == 0x00000001)) {
        output.writeBytes(1, getNameBytes());
      }
      if (((bitField0_ & 0x00000002) == 0x00000002)) {
        output.writeInt32(2, score_);
      }
      getUnknownFields().writeTo(output);
    }

    private int memoizedSerializedSize = -1;
    public int getSerializedSize() {
      int size = memoizedSerializedSize;
      if (size != -1) return size;

      size = 0;
      if (((bitField0_ & 0x00000001) == 0x00000001)) {
        size += com.google.protobuf.CodedOutputStream
          .computeBytesSize(1, getNameBytes());
      }
      if (((bitField0_ & 0x00000002) == 0x00000002)) {
        size += com.google.protobuf.CodedOutputStream
          .computeInt32Size(2, score_);
      }
      size += getUnknownFields().getSerializedSize();
      memoizedSerializedSize = size;
      return size;
    }

    private static final long serialVersionUID = 0L;
    @java.lang.Override
    protected java.lang.Object writeReplace()
        throws java.io.ObjectStreamException {
      return super.writeReplace();
    }

    public static space.PbTeacher.course parseFrom(
        com.google.protobuf.ByteString data)
        throws com.google.protobuf.InvalidProtocolBufferException {
      return PARSER.parseFrom(data);
    }
    public static space.PbTeacher.course parseFrom(
        com.google.protobuf.ByteString data,
        com.google.protobuf.ExtensionRegistryLite extensionRegistry)
        throws com.google.protobuf.InvalidProtocolBufferException {
      return PARSER.parseFrom(data, extensionRegistry);
    }
    public static space.PbTeacher.course parseFrom(byte[] data)
        throws com.google.protobuf.InvalidProtocolBufferException {
      return PARSER.parseFrom(data);
    }
    public static space.PbTeacher.course parseFrom(
        byte[] data,
        com.google.protobuf.ExtensionRegistryLite extensionRegistry)
        throws com.google.protobuf.InvalidProtocolBufferException {
      return PARSER.parseFrom(data, extensionRegistry);
    }
    public static space.PbTeacher.course parseFrom(java.io.InputStream input)
        throws java.io.IOException {
      return PARSER.parseFrom(input);
    }
    public static space.PbTeacher.course parseFrom(
        java.io.InputStream input,
        com.google.protobuf.ExtensionRegistryLite extensionRegistry)
        throws java.io.IOException {
      return PARSER.parseFrom(input, extensionRegistry);
    }
    public static space.PbTeacher.course parseDelimitedFrom(java.io.InputStream input)
        throws java.io.IOException {
      return PARSER.parseDelimitedFrom(input);
    }
    public static space.PbTeacher.course parseDelimitedFrom(
        java.io.InputStream input,
        com.google.protobuf.ExtensionRegistryLite extensionRegistry)
        throws java.io.IOException {
      return PARSER.parseDelimitedFrom(input, extensionRegistry);
    }
    public static space.PbTeacher.course parseFrom(
        com.google.protobuf.CodedInputStream input)
        throws java.io.IOException {
      return PARSER.parseFrom(input);
    }
    public static space.PbTeacher.course parseFrom(
        com.google.protobuf.CodedInputStream input,
        com.google.protobuf.ExtensionRegistryLite extensionRegistry)
        throws java.io.IOException {
      return PARSER.parseFrom(input, extensionRegistry);
    }

    public static Builder newBuilder() { return Builder.create(); }
    public Builder newBuilderForType() { return newBuilder(); }
    public static Builder newBuilder(space.PbTeacher.course prototype) {
      return newBuilder().mergeFrom(prototype);
    }
    public Builder toBuilder() { return newBuilder(this); }

    @java.lang.Override
    protected Builder newBuilderForType(
        com.google.protobuf.GeneratedMessage.BuilderParent parent) {
      Builder builder = new Builder(parent);
      return builder;
    }
    /**
     * Protobuf type {@code space.course}
     */
    public static final class Builder extends
        com.google.protobuf.GeneratedMessage.Builder<Builder>
       implements space.PbTeacher.courseOrBuilder {
      public static final com.google.protobuf.Descriptors.Descriptor
          getDescriptor() {
        return space.PbTeacher.internal_static_space_course_descriptor;
      }

      protected com.google.protobuf.GeneratedMessage.FieldAccessorTable
          internalGetFieldAccessorTable() {
        return space.PbTeacher.internal_static_space_course_fieldAccessorTable
            .ensureFieldAccessorsInitialized(
                space.PbTeacher.course.class, space.PbTeacher.course.Builder.class);
      }

      // Construct using space.PbTeacher.course.newBuilder()
      private Builder() {
        maybeForceBuilderInitialization();
      }

      private Builder(
          com.google.protobuf.GeneratedMessage.BuilderParent parent) {
        super(parent);
        maybeForceBuilderInitialization();
      }
      private void maybeForceBuilderInitialization() {
        if (com.google.protobuf.GeneratedMessage.alwaysUseFieldBuilders) {
        }
      }
      private static Builder create() {
        return new Builder();
      }

      public Builder clear() {
        super.clear();
        name_ = "";
        bitField0_ = (bitField0_ & ~0x00000001);
        score_ = 0;
        bitField0_ = (bitField0_ & ~0x00000002);
        return this;
      }

      public Builder clone() {
        return create().mergeFrom(buildPartial());
      }

      public com.google.protobuf.Descriptors.Descriptor
          getDescriptorForType() {
        return space.PbTeacher.internal_static_space_course_descriptor;
      }

      public space.PbTeacher.course getDefaultInstanceForType() {
        return space.PbTeacher.course.getDefaultInstance();
      }

      public space.PbTeacher.course build() {
        space.PbTeacher.course result = buildPartial();
        if (!result.isInitialized()) {
          throw newUninitializedMessageException(result);
        }
        return result;
      }

      public space.PbTeacher.course buildPartial() {
        space.PbTeacher.course result = new space.PbTeacher.course(this);
        int from_bitField0_ = bitField0_;
        int to_bitField0_ = 0;
        if (((from_bitField0_ & 0x00000001) == 0x00000001)) {
          to_bitField0_ |= 0x00000001;
        }
        result.name_ = name_;
        if (((from_bitField0_ & 0x00000002) == 0x00000002)) {
          to_bitField0_ |= 0x00000002;
        }
        result.score_ = score_;
        result.bitField0_ = to_bitField0_;
        onBuilt();
        return result;
      }

      public Builder mergeFrom(com.google.protobuf.Message other) {
        if (other instanceof space.PbTeacher.course) {
          return mergeFrom((space.PbTeacher.course)other);
        } else {
          super.mergeFrom(other);
          return this;
        }
      }

      public Builder mergeFrom(space.PbTeacher.course other) {
        if (other == space.PbTeacher.course.getDefaultInstance()) return this;
        if (other.hasName()) {
          bitField0_ |= 0x00000001;
          name_ = other.name_;
          onChanged();
        }
        if (other.hasScore()) {
          setScore(other.getScore());
        }
        this.mergeUnknownFields(other.getUnknownFields());
        return this;
      }

      public final boolean isInitialized() {
        return true;
      }

      public Builder mergeFrom(
          com.google.protobuf.CodedInputStream input,
          com.google.protobuf.ExtensionRegistryLite extensionRegistry)
          throws java.io.IOException {
        space.PbTeacher.course parsedMessage = null;
        try {
          parsedMessage = PARSER.parsePartialFrom(input, extensionRegistry);
        } catch (com.google.protobuf.InvalidProtocolBufferException e) {
          parsedMessage = (space.PbTeacher.course) e.getUnfinishedMessage();
          throw e;
        } finally {
          if (parsedMessage != null) {
            mergeFrom(parsedMessage);
          }
        }
        return this;
      }
      private int bitField0_;

      // optional string name = 1;
      private java.lang.Object name_ = "";
      /**
       * <code>optional string name = 1;</code>
       */
      public boolean hasName() {
        return ((bitField0_ & 0x00000001) == 0x00000001);
      }
      /**
       * <code>optional string name = 1;</code>
       */
      public java.lang.String getName() {
        java.lang.Object ref = name_;
        if (!(ref instanceof java.lang.String)) {
          java.lang.String s = ((com.google.protobuf.ByteString) ref)
              .toStringUtf8();
          name_ = s;
          return s;
        } else {
          return (java.lang.String) ref;
        }
      }
      /**
       * <code>optional string name = 1;</code>
       */
      public com.google.protobuf.ByteString
          getNameBytes() {
        java.lang.Object ref = name_;
        if (ref instanceof String) {
          com.google.protobuf.ByteString b = 
              com.google.protobuf.ByteString.copyFromUtf8(
                  (java.lang.String) ref);
          name_ = b;
          return b;
        } else {
          return (com.google.protobuf.ByteString) ref;
        }
      }
      /**
       * <code>optional string name = 1;</code>
       */
      public Builder setName(
          java.lang.String value) {
        if (value == null) {
    throw new NullPointerException();
  }
  bitField0_ |= 0x00000001;
        name_ = value;
        onChanged();
        return this;
      }
      /**
       * <code>optional string name = 1;</code>
       */
      public Builder clearName() {
        bitField0_ = (bitField0_ & ~0x00000001);
        name_ = getDefaultInstance().getName();
        onChanged();
        return this;
      }
      /**
       * <code>optional string name = 1;</code>
       */
      public Builder setNameBytes(
          com.google.protobuf.ByteString value) {
        if (value == null) {
    throw new NullPointerException();
  }
  bitField0_ |= 0x00000001;
        name_ = value;
        onChanged();
        return this;
      }

      // optional int32 score = 2;
      private int score_ ;
      /**
       * <code>optional int32 score = 2;</code>
       */
      public boolean hasScore() {
        return ((bitField0_ & 0x00000002) == 0x00000002);
      }
      /**
       * <code>optional int32 score = 2;</code>
       */
      public int getScore() {
        return score_;
      }
      /**
       * <code>optional int32 score = 2;</code>
       */
      public Builder setScore(int value) {
        bitField0_ |= 0x00000002;
        score_ = value;
        onChanged();
        return this;
      }
      /**
       * <code>optional int32 score = 2;</code>
       */
      public Builder clearScore() {
        bitField0_ = (bitField0_ & ~0x00000002);
        score_ = 0;
        onChanged();
        return this;
      }

      // @@protoc_insertion_point(builder_scope:space.course)
    }

    static {
      defaultInstance = new course(true);
      defaultInstance.initFields();
    }

    // @@protoc_insertion_point(class_scope:space.course)
  }

  public interface studentOrBuilder
      extends com.google.protobuf.MessageOrBuilder {

    // optional string name = 1;
    /**
     * <code>optional string name = 1;</code>
     */
    boolean hasName();
    /**
     * <code>optional string name = 1;</code>
     */
    java.lang.String getName();
    /**
     * <code>optional string name = 1;</code>
     */
    com.google.protobuf.ByteString
        getNameBytes();

    // optional int32 age = 2;
    /**
     * <code>optional int32 age = 2;</code>
     */
    boolean hasAge();
    /**
     * <code>optional int32 age = 2;</code>
     */
    int getAge();

    // repeated .space.course mCourse = 3;
    /**
     * <code>repeated .space.course mCourse = 3;</code>
     */
    java.util.List<space.PbTeacher.course> 
        getMCourseList();
    /**
     * <code>repeated .space.course mCourse = 3;</code>
     */
    space.PbTeacher.course getMCourse(int index);
    /**
     * <code>repeated .space.course mCourse = 3;</code>
     */
    int getMCourseCount();
    /**
     * <code>repeated .space.course mCourse = 3;</code>
     */
    java.util.List<? extends space.PbTeacher.courseOrBuilder> 
        getMCourseOrBuilderList();
    /**
     * <code>repeated .space.course mCourse = 3;</code>
     */
    space.PbTeacher.courseOrBuilder getMCourseOrBuilder(
        int index);
  }
  /**
   * Protobuf type {@code space.student}
   */
  public static final class student extends
      com.google.protobuf.GeneratedMessage
      implements studentOrBuilder {
    // Use student.newBuilder() to construct.
    private student(com.google.protobuf.GeneratedMessage.Builder<?> builder) {
      super(builder);
      this.unknownFields = builder.getUnknownFields();
    }
    private student(boolean noInit) { this.unknownFields = com.google.protobuf.UnknownFieldSet.getDefaultInstance(); }

    private static final student defaultInstance;
    public static student getDefaultInstance() {
      return defaultInstance;
    }

    public student getDefaultInstanceForType() {
      return defaultInstance;
    }

    private final com.google.protobuf.UnknownFieldSet unknownFields;
    @java.lang.Override
    public final com.google.protobuf.UnknownFieldSet
        getUnknownFields() {
      return this.unknownFields;
    }
    private student(
        com.google.protobuf.CodedInputStream input,
        com.google.protobuf.ExtensionRegistryLite extensionRegistry)
        throws com.google.protobuf.InvalidProtocolBufferException {
      initFields();
      int mutable_bitField0_ = 0;
      com.google.protobuf.UnknownFieldSet.Builder unknownFields =
          com.google.protobuf.UnknownFieldSet.newBuilder();
      try {
        boolean done = false;
        while (!done) {
          int tag = input.readTag();
          switch (tag) {
            case 0:
              done = true;
              break;
            default: {
              if (!parseUnknownField(input, unknownFields,
                                     extensionRegistry, tag)) {
                done = true;
              }
              break;
            }
            case 10: {
              bitField0_ |= 0x00000001;
              name_ = input.readBytes();
              break;
            }
            case 16: {
              bitField0_ |= 0x00000002;
              age_ = input.readInt32();
              break;
            }
            case 26: {
              if (!((mutable_bitField0_ & 0x00000004) == 0x00000004)) {
                mCourse_ = new java.util.ArrayList<space.PbTeacher.course>();
                mutable_bitField0_ |= 0x00000004;
              }
              mCourse_.add(input.readMessage(space.PbTeacher.course.PARSER, extensionRegistry));
              break;
            }
          }
        }
      } catch (com.google.protobuf.InvalidProtocolBufferException e) {
        throw e.setUnfinishedMessage(this);
      } catch (java.io.IOException e) {
        throw new com.google.protobuf.InvalidProtocolBufferException(
            e.getMessage()).setUnfinishedMessage(this);
      } finally {
        if (((mutable_bitField0_ & 0x00000004) == 0x00000004)) {
          mCourse_ = java.util.Collections.unmodifiableList(mCourse_);
        }
        this.unknownFields = unknownFields.build();
        makeExtensionsImmutable();
      }
    }
    public static final com.google.protobuf.Descriptors.Descriptor
        getDescriptor() {
      return space.PbTeacher.internal_static_space_student_descriptor;
    }

    protected com.google.protobuf.GeneratedMessage.FieldAccessorTable
        internalGetFieldAccessorTable() {
      return space.PbTeacher.internal_static_space_student_fieldAccessorTable
          .ensureFieldAccessorsInitialized(
              space.PbTeacher.student.class, space.PbTeacher.student.Builder.class);
    }

    public static com.google.protobuf.Parser<student> PARSER =
        new com.google.protobuf.AbstractParser<student>() {
      public student parsePartialFrom(
          com.google.protobuf.CodedInputStream input,
          com.google.protobuf.ExtensionRegistryLite extensionRegistry)
          throws com.google.protobuf.InvalidProtocolBufferException {
        return new student(input, extensionRegistry);
      }
    };

    @java.lang.Override
    public com.google.protobuf.Parser<student> getParserForType() {
      return PARSER;
    }

    private int bitField0_;
    // optional string name = 1;
    public static final int NAME_FIELD_NUMBER = 1;
    private java.lang.Object name_;
    /**
     * <code>optional string name = 1;</code>
     */
    public boolean hasName() {
      return ((bitField0_ & 0x00000001) == 0x00000001);
    }
    /**
     * <code>optional string name = 1;</code>
     */
    public java.lang.String getName() {
      java.lang.Object ref = name_;
      if (ref instanceof java.lang.String) {
        return (java.lang.String) ref;
      } else {
        com.google.protobuf.ByteString bs = 
            (com.google.protobuf.ByteString) ref;
        java.lang.String s = bs.toStringUtf8();
        if (bs.isValidUtf8()) {
          name_ = s;
        }
        return s;
      }
    }
    /**
     * <code>optional string name = 1;</code>
     */
    public com.google.protobuf.ByteString
        getNameBytes() {
      java.lang.Object ref = name_;
      if (ref instanceof java.lang.String) {
        com.google.protobuf.ByteString b = 
            com.google.protobuf.ByteString.copyFromUtf8(
                (java.lang.String) ref);
        name_ = b;
        return b;
      } else {
        return (com.google.protobuf.ByteString) ref;
      }
    }

    // optional int32 age = 2;
    public static final int AGE_FIELD_NUMBER = 2;
    private int age_;
    /**
     * <code>optional int32 age = 2;</code>
     */
    public boolean hasAge() {
      return ((bitField0_ & 0x00000002) == 0x00000002);
    }
    /**
     * <code>optional int32 age = 2;</code>
     */
    public int getAge() {
      return age_;
    }

    // repeated .space.course mCourse = 3;
    public static final int MCOURSE_FIELD_NUMBER = 3;
    private java.util.List<space.PbTeacher.course> mCourse_;
    /**
     * <code>repeated .space.course mCourse = 3;</code>
     */
    public java.util.List<space.PbTeacher.course> getMCourseList() {
      return mCourse_;
    }
    /**
     * <code>repeated .space.course mCourse = 3;</code>
     */
    public java.util.List<? extends space.PbTeacher.courseOrBuilder> 
        getMCourseOrBuilderList() {
      return mCourse_;
    }
    /**
     * <code>repeated .space.course mCourse = 3;</code>
     */
    public int getMCourseCount() {
      return mCourse_.size();
    }
    /**
     * <code>repeated .space.course mCourse = 3;</code>
     */
    public space.PbTeacher.course getMCourse(int index) {
      return mCourse_.get(index);
    }
    /**
     * <code>repeated .space.course mCourse = 3;</code>
     */
    public space.PbTeacher.courseOrBuilder getMCourseOrBuilder(
        int index) {
      return mCourse_.get(index);
    }

    private void initFields() {
      name_ = "";
      age_ = 0;
      mCourse_ = java.util.Collections.emptyList();
    }
    private byte memoizedIsInitialized = -1;
    public final boolean isInitialized() {
      byte isInitialized = memoizedIsInitialized;
      if (isInitialized != -1) return isInitialized == 1;

      memoizedIsInitialized = 1;
      return true;
    }

    public void writeTo(com.google.protobuf.CodedOutputStream output)
                        throws java.io.IOException {
      getSerializedSize();
      if (((bitField0_ & 0x00000001) == 0x00000001)) {
        output.writeBytes(1, getNameBytes());
      }
      if (((bitField0_ & 0x00000002) == 0x00000002)) {
        output.writeInt32(2, age_);
      }
      for (int i = 0; i < mCourse_.size(); i++) {
        output.writeMessage(3, mCourse_.get(i));
      }
      getUnknownFields().writeTo(output);
    }

    private int memoizedSerializedSize = -1;
    public int getSerializedSize() {
      int size = memoizedSerializedSize;
      if (size != -1) return size;

      size = 0;
      if (((bitField0_ & 0x00000001) == 0x00000001)) {
        size += com.google.protobuf.CodedOutputStream
          .computeBytesSize(1, getNameBytes());
      }
      if (((bitField0_ & 0x00000002) == 0x00000002)) {
        size += com.google.protobuf.CodedOutputStream
          .computeInt32Size(2, age_);
      }
      for (int i = 0; i < mCourse_.size(); i++) {
        size += com.google.protobuf.CodedOutputStream
          .computeMessageSize(3, mCourse_.get(i));
      }
      size += getUnknownFields().getSerializedSize();
      memoizedSerializedSize = size;
      return size;
    }

    private static final long serialVersionUID = 0L;
    @java.lang.Override
    protected java.lang.Object writeReplace()
        throws java.io.ObjectStreamException {
      return super.writeReplace();
    }

    public static space.PbTeacher.student parseFrom(
        com.google.protobuf.ByteString data)
        throws com.google.protobuf.InvalidProtocolBufferException {
      return PARSER.parseFrom(data);
    }
    public static space.PbTeacher.student parseFrom(
        com.google.protobuf.ByteString data,
        com.google.protobuf.ExtensionRegistryLite extensionRegistry)
        throws com.google.protobuf.InvalidProtocolBufferException {
      return PARSER.parseFrom(data, extensionRegistry);
    }
    public static space.PbTeacher.student parseFrom(byte[] data)
        throws com.google.protobuf.InvalidProtocolBufferException {
      return PARSER.parseFrom(data);
    }
    public static space.PbTeacher.student parseFrom(
        byte[] data,
        com.google.protobuf.ExtensionRegistryLite extensionRegistry)
        throws com.google.protobuf.InvalidProtocolBufferException {
      return PARSER.parseFrom(data, extensionRegistry);
    }
    public static space.PbTeacher.student parseFrom(java.io.InputStream input)
        throws java.io.IOException {
      return PARSER.parseFrom(input);
    }
    public static space.PbTeacher.student parseFrom(
        java.io.InputStream input,
        com.google.protobuf.ExtensionRegistryLite extensionRegistry)
        throws java.io.IOException {
      return PARSER.parseFrom(input, extensionRegistry);
    }
    public static space.PbTeacher.student parseDelimitedFrom(java.io.InputStream input)
        throws java.io.IOException {
      return PARSER.parseDelimitedFrom(input);
    }
    public static space.PbTeacher.student parseDelimitedFrom(
        java.io.InputStream input,
        com.google.protobuf.ExtensionRegistryLite extensionRegistry)
        throws java.io.IOException {
      return PARSER.parseDelimitedFrom(input, extensionRegistry);
    }
    public static space.PbTeacher.student parseFrom(
        com.google.protobuf.CodedInputStream input)
        throws java.io.IOException {
      return PARSER.parseFrom(input);
    }
    public static space.PbTeacher.student parseFrom(
        com.google.protobuf.CodedInputStream input,
        com.google.protobuf.ExtensionRegistryLite extensionRegistry)
        throws java.io.IOException {
      return PARSER.parseFrom(input, extensionRegistry);
    }

    public static Builder newBuilder() { return Builder.create(); }
    public Builder newBuilderForType() { return newBuilder(); }
    public static Builder newBuilder(space.PbTeacher.student prototype) {
      return newBuilder().mergeFrom(prototype);
    }
    public Builder toBuilder() { return newBuilder(this); }

    @java.lang.Override
    protected Builder newBuilderForType(
        com.google.protobuf.GeneratedMessage.BuilderParent parent) {
      Builder builder = new Builder(parent);
      return builder;
    }
    /**
     * Protobuf type {@code space.student}
     */
    public static final class Builder extends
        com.google.protobuf.GeneratedMessage.Builder<Builder>
       implements space.PbTeacher.studentOrBuilder {
      public static final com.google.protobuf.Descriptors.Descriptor
          getDescriptor() {
        return space.PbTeacher.internal_static_space_student_descriptor;
      }

      protected com.google.protobuf.GeneratedMessage.FieldAccessorTable
          internalGetFieldAccessorTable() {
        return space.PbTeacher.internal_static_space_student_fieldAccessorTable
            .ensureFieldAccessorsInitialized(
                space.PbTeacher.student.class, space.PbTeacher.student.Builder.class);
      }

      // Construct using space.PbTeacher.student.newBuilder()
      private Builder() {
        maybeForceBuilderInitialization();
      }

      private Builder(
          com.google.protobuf.GeneratedMessage.BuilderParent parent) {
        super(parent);
        maybeForceBuilderInitialization();
      }
      private void maybeForceBuilderInitialization() {
        if (com.google.protobuf.GeneratedMessage.alwaysUseFieldBuilders) {
          getMCourseFieldBuilder();
        }
      }
      private static Builder create() {
        return new Builder();
      }

      public Builder clear() {
        super.clear();
        name_ = "";
        bitField0_ = (bitField0_ & ~0x00000001);
        age_ = 0;
        bitField0_ = (bitField0_ & ~0x00000002);
        if (mCourseBuilder_ == null) {
          mCourse_ = java.util.Collections.emptyList();
          bitField0_ = (bitField0_ & ~0x00000004);
        } else {
          mCourseBuilder_.clear();
        }
        return this;
      }

      public Builder clone() {
        return create().mergeFrom(buildPartial());
      }

      public com.google.protobuf.Descriptors.Descriptor
          getDescriptorForType() {
        return space.PbTeacher.internal_static_space_student_descriptor;
      }

      public space.PbTeacher.student getDefaultInstanceForType() {
        return space.PbTeacher.student.getDefaultInstance();
      }

      public space.PbTeacher.student build() {
        space.PbTeacher.student result = buildPartial();
        if (!result.isInitialized()) {
          throw newUninitializedMessageException(result);
        }
        return result;
      }

      public space.PbTeacher.student buildPartial() {
        space.PbTeacher.student result = new space.PbTeacher.student(this);
        int from_bitField0_ = bitField0_;
        int to_bitField0_ = 0;
        if (((from_bitField0_ & 0x00000001) == 0x00000001)) {
          to_bitField0_ |= 0x00000001;
        }
        result.name_ = name_;
        if (((from_bitField0_ & 0x00000002) == 0x00000002)) {
          to_bitField0_ |= 0x00000002;
        }
        result.age_ = age_;
        if (mCourseBuilder_ == null) {
          if (((bitField0_ & 0x00000004) == 0x00000004)) {
            mCourse_ = java.util.Collections.unmodifiableList(mCourse_);
            bitField0_ = (bitField0_ & ~0x00000004);
          }
          result.mCourse_ = mCourse_;
        } else {
          result.mCourse_ = mCourseBuilder_.build();
        }
        result.bitField0_ = to_bitField0_;
        onBuilt();
        return result;
      }

      public Builder mergeFrom(com.google.protobuf.Message other) {
        if (other instanceof space.PbTeacher.student) {
          return mergeFrom((space.PbTeacher.student)other);
        } else {
          super.mergeFrom(other);
          return this;
        }
      }

      public Builder mergeFrom(space.PbTeacher.student other) {
        if (other == space.PbTeacher.student.getDefaultInstance()) return this;
        if (other.hasName()) {
          bitField0_ |= 0x00000001;
          name_ = other.name_;
          onChanged();
        }
        if (other.hasAge()) {
          setAge(other.getAge());
        }
        if (mCourseBuilder_ == null) {
          if (!other.mCourse_.isEmpty()) {
            if (mCourse_.isEmpty()) {
              mCourse_ = other.mCourse_;
              bitField0_ = (bitField0_ & ~0x00000004);
            } else {
              ensureMCourseIsMutable();
              mCourse_.addAll(other.mCourse_);
            }
            onChanged();
          }
        } else {
          if (!other.mCourse_.isEmpty()) {
            if (mCourseBuilder_.isEmpty()) {
              mCourseBuilder_.dispose();
              mCourseBuilder_ = null;
              mCourse_ = other.mCourse_;
              bitField0_ = (bitField0_ & ~0x00000004);
              mCourseBuilder_ = 
                com.google.protobuf.GeneratedMessage.alwaysUseFieldBuilders ?
                   getMCourseFieldBuilder() : null;
            } else {
              mCourseBuilder_.addAllMessages(other.mCourse_);
            }
          }
        }
        this.mergeUnknownFields(other.getUnknownFields());
        return this;
      }

      public final boolean isInitialized() {
        return true;
      }

      public Builder mergeFrom(
          com.google.protobuf.CodedInputStream input,
          com.google.protobuf.ExtensionRegistryLite extensionRegistry)
          throws java.io.IOException {
        space.PbTeacher.student parsedMessage = null;
        try {
          parsedMessage = PARSER.parsePartialFrom(input, extensionRegistry);
        } catch (com.google.protobuf.InvalidProtocolBufferException e) {
          parsedMessage = (space.PbTeacher.student) e.getUnfinishedMessage();
          throw e;
        } finally {
          if (parsedMessage != null) {
            mergeFrom(parsedMessage);
          }
        }
        return this;
      }
      private int bitField0_;

      // optional string name = 1;
      private java.lang.Object name_ = "";
      /**
       * <code>optional string name = 1;</code>
       */
      public boolean hasName() {
        return ((bitField0_ & 0x00000001) == 0x00000001);
      }
      /**
       * <code>optional string name = 1;</code>
       */
      public java.lang.String getName() {
        java.lang.Object ref = name_;
        if (!(ref instanceof java.lang.String)) {
          java.lang.String s = ((com.google.protobuf.ByteString) ref)
              .toStringUtf8();
          name_ = s;
          return s;
        } else {
          return (java.lang.String) ref;
        }
      }
      /**
       * <code>optional string name = 1;</code>
       */
      public com.google.protobuf.ByteString
          getNameBytes() {
        java.lang.Object ref = name_;
        if (ref instanceof String) {
          com.google.protobuf.ByteString b = 
              com.google.protobuf.ByteString.copyFromUtf8(
                  (java.lang.String) ref);
          name_ = b;
          return b;
        } else {
          return (com.google.protobuf.ByteString) ref;
        }
      }
      /**
       * <code>optional string name = 1;</code>
       */
      public Builder setName(
          java.lang.String value) {
        if (value == null) {
    throw new NullPointerException();
  }
  bitField0_ |= 0x00000001;
        name_ = value;
        onChanged();
        return this;
      }
      /**
       * <code>optional string name = 1;</code>
       */
      public Builder clearName() {
        bitField0_ = (bitField0_ & ~0x00000001);
        name_ = getDefaultInstance().getName();
        onChanged();
        return this;
      }
      /**
       * <code>optional string name = 1;</code>
       */
      public Builder setNameBytes(
          com.google.protobuf.ByteString value) {
        if (value == null) {
    throw new NullPointerException();
  }
  bitField0_ |= 0x00000001;
        name_ = value;
        onChanged();
        return this;
      }

      // optional int32 age = 2;
      private int age_ ;
      /**
       * <code>optional int32 age = 2;</code>
       */
      public boolean hasAge() {
        return ((bitField0_ & 0x00000002) == 0x00000002);
      }
      /**
       * <code>optional int32 age = 2;</code>
       */
      public int getAge() {
        return age_;
      }
      /**
       * <code>optional int32 age = 2;</code>
       */
      public Builder setAge(int value) {
        bitField0_ |= 0x00000002;
        age_ = value;
        onChanged();
        return this;
      }
      /**
       * <code>optional int32 age = 2;</code>
       */
      public Builder clearAge() {
        bitField0_ = (bitField0_ & ~0x00000002);
        age_ = 0;
        onChanged();
        return this;
      }

      // repeated .space.course mCourse = 3;
      private java.util.List<space.PbTeacher.course> mCourse_ =
        java.util.Collections.emptyList();
      private void ensureMCourseIsMutable() {
        if (!((bitField0_ & 0x00000004) == 0x00000004)) {
          mCourse_ = new java.util.ArrayList<space.PbTeacher.course>(mCourse_);
          bitField0_ |= 0x00000004;
         }
      }

      private com.google.protobuf.RepeatedFieldBuilder<
          space.PbTeacher.course, space.PbTeacher.course.Builder, space.PbTeacher.courseOrBuilder> mCourseBuilder_;

      /**
       * <code>repeated .space.course mCourse = 3;</code>
       */
      public java.util.List<space.PbTeacher.course> getMCourseList() {
        if (mCourseBuilder_ == null) {
          return java.util.Collections.unmodifiableList(mCourse_);
        } else {
          return mCourseBuilder_.getMessageList();
        }
      }
      /**
       * <code>repeated .space.course mCourse = 3;</code>
       */
      public int getMCourseCount() {
        if (mCourseBuilder_ == null) {
          return mCourse_.size();
        } else {
          return mCourseBuilder_.getCount();
        }
      }
      /**
       * <code>repeated .space.course mCourse = 3;</code>
       */
      public space.PbTeacher.course getMCourse(int index) {
        if (mCourseBuilder_ == null) {
          return mCourse_.get(index);
        } else {
          return mCourseBuilder_.getMessage(index);
        }
      }
      /**
       * <code>repeated .space.course mCourse = 3;</code>
       */
      public Builder setMCourse(
          int index, space.PbTeacher.course value) {
        if (mCourseBuilder_ == null) {
          if (value == null) {
            throw new NullPointerException();
          }
          ensureMCourseIsMutable();
          mCourse_.set(index, value);
          onChanged();
        } else {
          mCourseBuilder_.setMessage(index, value);
        }
        return this;
      }
      /**
       * <code>repeated .space.course mCourse = 3;</code>
       */
      public Builder setMCourse(
          int index, space.PbTeacher.course.Builder builderForValue) {
        if (mCourseBuilder_ == null) {
          ensureMCourseIsMutable();
          mCourse_.set(index, builderForValue.build());
          onChanged();
        } else {
          mCourseBuilder_.setMessage(index, builderForValue.build());
        }
        return this;
      }
      /**
       * <code>repeated .space.course mCourse = 3;</code>
       */
      public Builder addMCourse(space.PbTeacher.course value) {
        if (mCourseBuilder_ == null) {
          if (value == null) {
            throw new NullPointerException();
          }
          ensureMCourseIsMutable();
          mCourse_.add(value);
          onChanged();
        } else {
          mCourseBuilder_.addMessage(value);
        }
        return this;
      }
      /**
       * <code>repeated .space.course mCourse = 3;</code>
       */
      public Builder addMCourse(
          int index, space.PbTeacher.course value) {
        if (mCourseBuilder_ == null) {
          if (value == null) {
            throw new NullPointerException();
          }
          ensureMCourseIsMutable();
          mCourse_.add(index, value);
          onChanged();
        } else {
          mCourseBuilder_.addMessage(index, value);
        }
        return this;
      }
      /**
       * <code>repeated .space.course mCourse = 3;</code>
       */
      public Builder addMCourse(
          space.PbTeacher.course.Builder builderForValue) {
        if (mCourseBuilder_ == null) {
          ensureMCourseIsMutable();
          mCourse_.add(builderForValue.build());
          onChanged();
        } else {
          mCourseBuilder_.addMessage(builderForValue.build());
        }
        return this;
      }
      /**
       * <code>repeated .space.course mCourse = 3;</code>
       */
      public Builder addMCourse(
          int index, space.PbTeacher.course.Builder builderForValue) {
        if (mCourseBuilder_ == null) {
          ensureMCourseIsMutable();
          mCourse_.add(index, builderForValue.build());
          onChanged();
        } else {
          mCourseBuilder_.addMessage(index, builderForValue.build());
        }
        return this;
      }
      /**
       * <code>repeated .space.course mCourse = 3;</code>
       */
      public Builder addAllMCourse(
          java.lang.Iterable<? extends space.PbTeacher.course> values) {
        if (mCourseBuilder_ == null) {
          ensureMCourseIsMutable();
          super.addAll(values, mCourse_);
          onChanged();
        } else {
          mCourseBuilder_.addAllMessages(values);
        }
        return this;
      }
      /**
       * <code>repeated .space.course mCourse = 3;</code>
       */
      public Builder clearMCourse() {
        if (mCourseBuilder_ == null) {
          mCourse_ = java.util.Collections.emptyList();
          bitField0_ = (bitField0_ & ~0x00000004);
          onChanged();
        } else {
          mCourseBuilder_.clear();
        }
        return this;
      }
      /**
       * <code>repeated .space.course mCourse = 3;</code>
       */
      public Builder removeMCourse(int index) {
        if (mCourseBuilder_ == null) {
          ensureMCourseIsMutable();
          mCourse_.remove(index);
          onChanged();
        } else {
          mCourseBuilder_.remove(index);
        }
        return this;
      }
      /**
       * <code>repeated .space.course mCourse = 3;</code>
       */
      public space.PbTeacher.course.Builder getMCourseBuilder(
          int index) {
        return getMCourseFieldBuilder().getBuilder(index);
      }
      /**
       * <code>repeated .space.course mCourse = 3;</code>
       */
      public space.PbTeacher.courseOrBuilder getMCourseOrBuilder(
          int index) {
        if (mCourseBuilder_ == null) {
          return mCourse_.get(index);  } else {
          return mCourseBuilder_.getMessageOrBuilder(index);
        }
      }
      /**
       * <code>repeated .space.course mCourse = 3;</code>
       */
      public java.util.List<? extends space.PbTeacher.courseOrBuilder> 
           getMCourseOrBuilderList() {
        if (mCourseBuilder_ != null) {
          return mCourseBuilder_.getMessageOrBuilderList();
        } else {
          return java.util.Collections.unmodifiableList(mCourse_);
        }
      }
      /**
       * <code>repeated .space.course mCourse = 3;</code>
       */
      public space.PbTeacher.course.Builder addMCourseBuilder() {
        return getMCourseFieldBuilder().addBuilder(
            space.PbTeacher.course.getDefaultInstance());
      }
      /**
       * <code>repeated .space.course mCourse = 3;</code>
       */
      public space.PbTeacher.course.Builder addMCourseBuilder(
          int index) {
        return getMCourseFieldBuilder().addBuilder(
            index, space.PbTeacher.course.getDefaultInstance());
      }
      /**
       * <code>repeated .space.course mCourse = 3;</code>
       */
      public java.util.List<space.PbTeacher.course.Builder> 
           getMCourseBuilderList() {
        return getMCourseFieldBuilder().getBuilderList();
      }
      private com.google.protobuf.RepeatedFieldBuilder<
          space.PbTeacher.course, space.PbTeacher.course.Builder, space.PbTeacher.courseOrBuilder> 
          getMCourseFieldBuilder() {
        if (mCourseBuilder_ == null) {
          mCourseBuilder_ = new com.google.protobuf.RepeatedFieldBuilder<
              space.PbTeacher.course, space.PbTeacher.course.Builder, space.PbTeacher.courseOrBuilder>(
                  mCourse_,
                  ((bitField0_ & 0x00000004) == 0x00000004),
                  getParentForChildren(),
                  isClean());
          mCourse_ = null;
        }
        return mCourseBuilder_;
      }

      // @@protoc_insertion_point(builder_scope:space.student)
    }

    static {
      defaultInstance = new student(true);
      defaultInstance.initFields();
    }

    // @@protoc_insertion_point(class_scope:space.student)
  }

  private static com.google.protobuf.Descriptors.Descriptor
    internal_static_space_course_descriptor;
  private static
    com.google.protobuf.GeneratedMessage.FieldAccessorTable
      internal_static_space_course_fieldAccessorTable;
  private static com.google.protobuf.Descriptors.Descriptor
    internal_static_space_student_descriptor;
  private static
    com.google.protobuf.GeneratedMessage.FieldAccessorTable
      internal_static_space_student_fieldAccessorTable;

  public static com.google.protobuf.Descriptors.FileDescriptor
      getDescriptor() {
    return descriptor;
  }
  private static com.google.protobuf.Descriptors.FileDescriptor
      descriptor;
  static {
    java.lang.String[] descriptorData = {
      "\n\020pb_teacher.proto\022\005space"%\n\006course\022\014\n\004n" +
      "ame\030\001 \001(\t\022\r\n\005score\030\002 \001(\005"D\n\007student\022\014\n\004n" +
      "ame\030\001 \001(\t\022\013\n\003age\030\002 \001(\005\022\036\n\007mCourse\030\003 \003(\0132" +
      "\r.space.courseB\002H\001"
    };
    com.google.protobuf.Descriptors.FileDescriptor.InternalDescriptorAssigner assigner =
      new com.google.protobuf.Descriptors.FileDescriptor.InternalDescriptorAssigner() {
        public com.google.protobuf.ExtensionRegistry assignDescriptors(
            com.google.protobuf.Descriptors.FileDescriptor root) {
          descriptor = root;
          internal_static_space_course_descriptor =
            getDescriptor().getMessageTypes().get(0);
          internal_static_space_course_fieldAccessorTable = new
            com.google.protobuf.GeneratedMessage.FieldAccessorTable(
              internal_static_space_course_descriptor,
              new java.lang.String[] { "Name", "Score", });
          internal_static_space_student_descriptor =
            getDescriptor().getMessageTypes().get(1);
          internal_static_space_student_fieldAccessorTable = new
            com.google.protobuf.GeneratedMessage.FieldAccessorTable(
              internal_static_space_student_descriptor,
              new java.lang.String[] { "Name", "Age", "MCourse", });
          return null;
        }
      };
    com.google.protobuf.Descriptors.FileDescriptor
      .internalBuildGeneratedFileFrom(descriptorData,
        new com.google.protobuf.Descriptors.FileDescriptor[] {
        }, assigner);
  }

  // @@protoc_insertion_point(outer_class_scope)
}

然后再写个数据解析类：

package space

import android.os.Parcelable
import android.util.Log
import kotlinx.android.parcel.Parcelize

@Parcelize
data class Student(
    var name: String?, var age: Int?, var courseList: List<Course>
) : Parcelable {
    companion object {
        private const val TAG = "Student"
        fun parse(pb: PbTeacher.student?): Student? {
            if (pb?.mCourseList?.isEmpty() == true) {
                Log.w(TAG, "fromPb: pb.PbTeacher mCourseList is empty")
                return null
            }
            val list = mutableListOf<Course>()
            pb?.mCourseList?.forEach {
                list.add(Course.parse(it))
            }
            return Student(
                pb?.name, pb?.age, list
            ).also {
                Log.i(TAG, "[parse] Student: $it")
            }
        }
    }
}

@Parcelize
data class Course(
    val name: String,
    val score: Int,
) : Parcelable {
    companion object {
        const val TAG = "Course"
        fun parse(pb: PbTeacher.course): Course {
            return Course(
                pb.name, pb.score
            ).also {
                Log.i(TAG, "fromPb: Course: $it")
            }
        }
    }
}

在实际项目中使用：