概述 本文来实现一个简易的RPC通信框架，大致的核心流程：
实现客户端 代理类处理逻辑 ：InvocationHandler
扫描被代理接口，生成代理类，注入 Spring 容器
根据调用的接口，找到指定的实现类，并完成调用。
扫描组件 启动类：
@SpringBootApplication //自定义扫描 @EnableNettyRpcClient(basePackages = {"com.nettyRpc"}) public class NettyRpcSpringBootApplication {
public static void main(String[] args) {
SpringApplication.run(NettyRpcSpringBootApplication.class);
}
} 自定义扫描注解 EnableNettyRpcClient ：
@Retention(RetentionPolicy.RUNTIME) @Target(ElementType.TYPE) @Documented @Import(NettyRpcClientRegistrar.class) public @interface EnableNettyRpcClient {
//扫描的包名，如果为空，则根据启动类所在的包名扫描
String[] basePackages() default {};
//扫描的字节码类型，可根据字节码类型获取对应的包路径
Class<?>[] basePackageClasses() default {};
} 扫描实现类 NettyRpcClientRegistrar：
public class NettyRpcClientRegistrar implements ImportBeanDefinitionRegistrar, BeanClassLoaderAware {
private ClassLoader classLoader;
@Override
public void setBeanClassLoader(ClassLoader classLoader) {
this.classLoader = classLoader;
}
@Override
public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
ClassPathScanningCandidateComponentProvider scan = getScanner();
//指定注解，类似于Feign注解
scan.addIncludeFilter(new AnnotationTypeFilter(NettyRpcClient.class));
Set<BeanDefinition> candidateComponents = new HashSet<>();
for (String basePackage : getBasePackages(importingClassMetadata)) {
candidateComponents.addAll(scan.findCandidateComponents(basePackage));
}
candidateComponents.stream().forEach(beanDefinition -> {
if (!registry.containsBeanDefinition(beanDefinition.getBeanClassName())) {
if (beanDefinition instanceof AnnotatedBeanDefinition) {
AnnotatedBeanDefinition annotatedBeanDefinition = (AnnotatedBeanDefinition) beanDefinition;
AnnotationMetadata annotationMetadata = annotatedBeanDefinition.getMetadata();
Assert.isTrue(annotationMetadata.isInterface(), "@NettyRpcClient can only be specified on an interface");
Map<String, Object> attributes = annotationMetadata.getAnnotationAttributes(NettyRpcClient.class.getCanonicalName());
this.registerNettyRpcClient(registry, annotationMetadata,attributes);
}
}
});
}
private void registerNettyRpcClient(BeanDefinitionRegistry registry,
AnnotationMetadata annotationMetadata, Map<String, Object> attributes) {
String className = annotationMetadata.getClassName();
BeanDefinitionBuilder definition = BeanDefinitionBuilder
.genericBeanDefinition(NettyRpcClientFactoryBean.class);
definition.setAutowireMode(AbstractBeanDefinition.AUTOWIRE_BY_TYPE);
definition.addPropertyValue("type", className);
String name = attributes.get("name") == null ? "" :(String)(attributes.get("name"));
String alias = name + "NettyRpcClient";
AbstractBeanDefinition beanDefinition = definition.getBeanDefinition();
beanDefinition.setPrimary(true);
BeanDefinitionHolder holder = new BeanDefinitionHolder(beanDefinition, className,
new String[] { alias });
BeanDefinitionReaderUtils.registerBeanDefinition(holder, registry);
}
protected ClassPathScanningCandidateComponentProvider getScanner() {
return new ClassPathScanningCandidateComponentProvider(false) {
@Override
protected boolean isCandidateComponent(
AnnotatedBeanDefinition beanDefinition) {
if (beanDefinition.getMetadata().isIndependent()) {
// 判断接口是否继承了 Annotation注解
if (beanDefinition.getMetadata().isInterface() && beanDefinition.getMetadata()
.getInterfaceNames().length == 1 && Annotation.class.getName().equals(beanDefinition.getMetadata().getInterfaceNames()[0])) {
try {
Class<?> target = ClassUtils.forName(beanDefinition.getMetadata().getClassName(),
NettyRpcClientRegistrar.this.classLoader);
return !target.isAnnotation();
} catch (Exception ex) {
this.logger.error(
"Could not load target class: " + beanDefinition.getMetadata().getClassName(), ex);
}
}
return true;
}
return false;
}
};
}
protected Set<String> getBasePackages(AnnotationMetadata importingClassMetadata) {
Map<String, Object> attributes = importingClassMetadata
.getAnnotationAttributes(EnableNettyRpcClient.class.getCanonicalName());
Set<String> basePackages = new HashSet<>();
for (String pkg : (String[]) attributes.get("basePackages")) {
if (StringUtils.hasText(pkg)) {
basePackages.add(pkg);
}
}
for (Class<?> clazz : (Class[]) attributes.get("basePackageClasses")) {
basePackages.add(ClassUtils.getPackageName(clazz));
}
if (basePackages.isEmpty()) {
basePackages.add(
ClassUtils.getPackageName(importingClassMetadata.getClassName()));
}
return basePackages;
}
} 扫描代理工厂类：NettyRpcClientFactoryBean
@Data @EqualsAndHashCode(callSuper = false) public class NettyRpcClientFactoryBean implements FactoryBean{
private Class<?> type;
@Override
public Object getObject() throws Exception {
return Proxy.newProxyInstance(type.getClassLoader(), new Class[]{type}, new NettyRpcInvocationHandler(type));
}
@Override
public Class<?> getObjectType() {
return this.type;
}
} 请求拦截实现类：NettyRpcInvocationHandler
public class NettyRpcInvocationHandler implements InvocationHandler {
private Class<?> type;
public NettyRpcInvocationHandler(Class<?> type){
this.type = type;
}
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
//构造调用信息
RpcInfo rpcInfo = new RpcInfo();
rpcInfo.setClassName(type.getName());
rpcInfo.setMethodName(method.getName());
rpcInfo.setParamTypes(method.getParameterTypes());
rpcInfo.setParams(args);
//使用netty发送调用信息给服务提供方
NioEventLoopGroup group = new NioEventLoopGroup();
Bootstrap bootstrap = new Bootstrap();
RPCClientHandler rpcClientHandler = new RPCClientHandler();
try {
bootstrap.group(group)
.channel(NioSocketChannel.class)
.option(ChannelOption.SO_KEEPALIVE, true)
.option(ChannelOption.TCP_NODELAY, true)
.handler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ch.pipeline().addLast(new ObjectEncoder());
//反序列化对象时指定类解析器，null表示使用默认的类加载器
ch.pipeline().addLast(new ObjectDecoder(1024 * 64, ClassResolvers.cacheDisabled(null)));
ch.pipeline().addLast(rpcClientHandler);
}
});
//connect是异步的，但调用其future的sync则是同步等待连接成功
ChannelFuture future = bootstrap.connect("127.0.0.1", 80).sync();
//同步等待调用信息发送成功
future.channel().writeAndFlush(rpcInfo).sync();
//同步等待RPCClientHandler的channelRead被触发后（意味着收到了调用结果）
future.channel().closeFuture().sync();
} catch (Exception e) {
e.printStackTrace();
} finally {
group.shutdownGracefully();
}
//返回调用结果
return rpcClientHandler.getRpcResult();
}
} 客户端 Netty 客户端 ChannelHandler：：RPCClientHandler
public class RPCClientHandler extends ChannelHandlerAdapter {
/**
* RPC调用返回的结果
*/
private Object rpcResult;
public Object getRpcResult() {
return rpcResult;
}
public void setRpcResult(Object rpcResult) {
this.rpcResult = rpcResult;
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
setRpcResult(msg);
ctx.close();
}
} 请求实体 RpcInfo：
@Data public class RpcInfo implements Serializable {
/**
* 调用服务的接口名
*/
private String className;
/**
* 调用服务的方法名
*/
private String methodName;
/**
* 调用方法的参数列表类型
*/
private Class[] paramTypes;
/**
* 调用服务传参
*/
private Object[] params;
} 服务端 NettyServer：
public class NettyRpcServer {
public static void main(String[] args){
NioEventLoopGroup boss = new NioEventLoopGroup();
NioEventLoopGroup worker = new NioEventLoopGroup();
ServerBootstrap bootstrap = new ServerBootstrap();
try {
bootstrap.group(boss, worker)
.channel(NioServerSocketChannel.class)
.option(ChannelOption.SO_BACKLOG, 128)
.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ch.pipeline().addLast(new ObjectEncoder());
ch.pipeline().addLast(new ObjectDecoder(1024 * 64, ClassResolvers.cacheDisabled(null)));
ch.pipeline().addLast(new NettyRpcServerHandler());
}
});
//bind初始化端口是异步的，但调用sync则会同步阻塞等待端口绑定成功
ChannelFuture future = bootstrap.bind(80).sync();
future.channel().closeFuture().sync();
} catch (Exception e) {
e.printStackTrace();
}finally {
boss.shutdownGracefully();
worker.shutdownGracefully();
}
}
} Netty 服务端 ChannelHandler：
public class NettyRpcServerHandler extends ChannelHandlerAdapter {
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
//获取调用信息，寻找服务实现类
RpcInfo rpcInfo = (RpcInfo) msg;
String implName = getImplClassName(rpcInfo.getClassName());
Class<?> clazz = Class.forName(implName);
Method method = clazz.getMethod(rpcInfo.getMethodName(), rpcInfo.getParamTypes());
Object result = method.invoke(clazz.newInstance(), rpcInfo.getParams());
ctx.writeAndFlush(result);
}
private String getImplClassName(String interfaceName) throws ClassNotFoundException {
Class interClass = Class.forName(interfaceName);
String servicePath = "com.nettyRpc.server";
Reflections reflections = new Reflections(servicePath);
Set<Class> implClasses = reflections.getSubTypesOf(interClass);
if (implClasses.isEmpty()) {
System.err.println("impl class is not found!");
} else if (implClasses.size() > 1) {
System.err.println("there are many impl classes, not sure invoke which");
} else {
Class[] classes = implClasses.toArray(new Class[1]);
return classes[0].getName();
}
return null;
}
} 请求示例 代理客户端：
@NettyRpcClient public interface UserService { String callRpc(String param); } 服务端具体实现类：
public class UserServiceImpl implements UserService {
@Override
public String callRpc(String param) {
System.out.println(param);
return param;
}
} 远程调用：
@RestController public class UserController {
@Autowired
UserService userService;
@RequestMapping(value = "/callRpc")
public String callRpcTest(){
userService.callRpc("callRpc execute......");
return "ok";
}
}
