开发中，大量的枚举定义风格不一致。统一接口
public interface BaseEnum {
String getCode();
String getTitle();
String getName();
}
import BaseEnum;
public enum StatusEnum implements BaseEnum {
normal("1", "正常"), delete("0", "删除"), disabled("2", "不可用");
private String index;
private String title;
// 构造方法
private StatusEnum(String index, String title) {
this.title = title;
this.index = index;
}
//getter,setter
}
Mybatis 类型处理器添加
import java.sql.CallableStatement;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import org.apache.ibatis.type.BaseTypeHandler;
import org.apache.ibatis.type.EnumTypeHandler;
import org.apache.ibatis.type.JdbcType;
import BaseEnum;
public class DefaultEnumTypeHandler<E extends Enum<E>> extends BaseTypeHandler<E> {
private BaseTypeHandler<E> typeHandler = null;
public DefaultEnumTypeHandler(Class<E> type) {
if (type == null) {
throw new IllegalArgumentException("Type argument cannot be null");
}
if (BaseEnum.class.isAssignableFrom(type)) {
typeHandler = new EnumCodeTypeHandler(type);
} else {
typeHandler = new EnumTypeHandler<>(type);
}
}
@Override
public void setNonNullParameter(PreparedStatement ps, int i, E parameter, JdbcType jdbcType) throws SQLException {
typeHandler.setNonNullParameter(ps, i, parameter, jdbcType);
}
@Override
public E getNullableResult(ResultSet rs, String columnName) throws SQLException {
return (E) typeHandler.getNullableResult(rs, columnName);
}
@Override
public E getNullableResult(ResultSet rs, int columnIndex) throws SQLException {
return (E) typeHandler.getNullableResult(rs, columnIndex);
}
@Override
public E getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {
return (E) typeHandler.getNullableResult(cs, columnIndex);
}
}
import java.sql.CallableStatement;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import org.apache.ibatis.type.BaseTypeHandler;
import org.apache.ibatis.type.JdbcType;
import BaseEnum;
public class EnumCodeTypeHandler<E extends Enum<E> & BaseEnum> extends BaseTypeHandler<E> {
private final Class<E> type;
public EnumCodeTypeHandler(Class<E> type) {
if (type == null) {
throw new IllegalArgumentException("Type argument cannot be null");
}
this.type = type;
}
@Override
public void setNonNullParameter(PreparedStatement ps, int i, E parameter, JdbcType jdbcType) throws SQLException {
ps.setString(i, parameter.getCode());
}
@Override
public E getNullableResult(ResultSet rs, String columnName) throws SQLException {
String code = rs.getString(columnName);
return rs.wasNull() ? null : codeOf(this.type, code);
}
@Override
public E getNullableResult(ResultSet rs, int columnIndex) throws SQLException {
String code = rs.getString(columnIndex);
return rs.wasNull() ? null : codeOf(this.type, code);
}
@Override
public E getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {
String code = cs.getString(columnIndex);
return cs.wasNull() ? null : codeOf(this.type, code);
}
public static <T extends Enum<?> & BaseEnum> T codeOf(Class<T> enumClass, String code) {
T[] enumConstants = enumClass.getEnumConstants();
for (T t : enumConstants) {
if (t.getCode()
.equals(code)) {
return t;
}
}
return null;
}
}
注册到Mybatis配置类
//MyBatis configuration
Configuration configuration = new Configuration();
//...
configuration.getTypeHandlerRegistry()
.setDefaultEnumTypeHandler(DefaultEnumTypeHandler.class);
结合Spring Boot使用，参数自动转枚举。转换器是否生效，取决你的配置是否正确
import org.apache.commons.lang3.StringUtils;
import org.springframework.core.convert.converter.Converter;
import BaseEnum;
public class EnumConverter<T extends BaseEnum> implements Converter<String, T> {
private final Class<T> enumType;
public EnumConverter(Class<T> enumType) {
this.enumType = enumType;
}
@Override
public T convert(String source) {
if (StringUtils.isNotBlank(source)) {
// 得到枚举的所有值
T[] enums = this.enumType.getEnumConstants();
for (T e : enums) {
if (e.getCode().equals(source)) {
return e;
}
}
}
throw new IllegalArgumentException("No element matches " + source);
}
}
import java.util.Map;
import java.util.WeakHashMap;
import org.springframework.core.convert.converter.Converter;
import org.springframework.core.convert.converter.ConverterFactory;
import BaseEnum;
import EnumConverter;
public class BaseEnumConverterFactory implements ConverterFactory<String, BaseEnum> {
private static final Map<Class, Converter> converterMap = new WeakHashMap<>();
@Override
public <T extends BaseEnum> Converter<String, T> getConverter(Class<T> targetType) {
Converter result = converterMap.get(targetType);
if (result == null) {
result = new EnumConverter<T>(targetType);
converterMap.put(targetType, result);
}
return result;
}
}
public class DefaultMvcConfig extends WebMvcConfigurationSupport {
@Autowired
ServletContext servletContext;
@Override
protected void addInterceptors(InterceptorRegistry registry) {
super.addInterceptors(registry);
}
@Override
protected void addFormatters(FormatterRegistry registry) {
registry.addConverter(new DateConverter());
registry.addConverterFactory(new BaseEnumConverterFactory());
}
//...
}
结合fastjson,web接口参数时接收枚举参数，其他json库类似
public enum StatusEnum implements BaseEnum {
@JSONField(name = "1")
normal("1", "正常"),
@JSONField(name = "0")
delete("0", "删除"),
@JSONField(name = "1")
disabled("1", "不可用");
// ...
}
配上通用的工具类
import BaseEnum;
import java.util.*;
public class EnumUtils {
private static final String key_code = "code";
private static final String key_title = "title";
private static final String key_name = "name";
public static List<Map<String, Object>> nameTitleMaps(BaseEnum... baseEnums) {
List<Map<String, Object>> maps = new ArrayList<Map<String, Object>>();
for (BaseEnum baseEnum : baseEnums) {
Map<String, Object> map = new HashMap<String, Object>();
map.put(key_title, baseEnum.getTitle());
map.put(key_name, baseEnum.getName());
maps.add(map);
}
return maps;
}
public static List<Map<String, Object>> nameMaps(BaseEnum... baseEnums) {
List<Map<String, Object>> maps = new ArrayList<Map<String, Object>>();
for (BaseEnum baseEnum : baseEnums) {
Map<String, Object> map = new HashMap<String, Object>();
map.put(key_name, baseEnum.getName());
maps.add(map);
}
return maps;
}
public static List<Map<String, Object>> titleMaps(BaseEnum... baseEnums) {
List<Map<String, Object>> maps = new ArrayList<Map<String, Object>>();
for (BaseEnum baseEnum : baseEnums) {
Map<String, Object> map = new HashMap<String, Object>();
map.put(key_title, baseEnum.getTitle());
maps.add(map);
}
return maps;
}
public static List<Map<String, Object>> maps(BaseEnum... baseEnums) {
List<Map<String, Object>> maps = new ArrayList<Map<String, Object>>();
for (BaseEnum baseEnum : baseEnums) {
Map<String, Object> map = new HashMap<String, Object>();
map.put(key_code, baseEnum.getCode());
map.put(key_title, baseEnum.getTitle());
map.put(key_name, baseEnum.getName());
maps.add(map);
}
return maps;
}
public static <T extends BaseEnum> List<Map<String, Object>> nameMaps(Class<T> clazz) {
if (!clazz.isEnum()) {
return null;
}
List<Map<String, Object>> maps = new ArrayList<Map<String, Object>>();
T[] ts = (T[]) clazz.getEnumConstants();
for (T t : ts) {
Map<String, Object> map = new HashMap<String, Object>();
map.put(key_name, t.getName());
maps.add(map);
}
return maps;
}
public static <T extends BaseEnum> List<Map<String, Object>> titleMaps(Class<T> clazz) {
if (!clazz.isEnum()) {
return null;
}
List<Map<String, Object>> maps = new ArrayList<Map<String, Object>>();
T[] ts = (T[]) clazz.getEnumConstants();
for (T t : ts) {
Map<String, Object> map = new HashMap<String, Object>();
map.put(key_title, t.getTitle());
maps.add(map);
}
return maps;
}
public static <T extends BaseEnum> List<Map<String, Object>> nameTitleMaps(Class<T> clazz) {
if (!clazz.isEnum()) {
return null;
}
List<Map<String, Object>> maps = new ArrayList<Map<String, Object>>();
T[] ts = (T[]) clazz.getEnumConstants();
for (T t : ts) {
Map<String, Object> map = new HashMap<String, Object>();
map.put(key_title, t.getTitle());
map.put(key_name, t.getName());
maps.add(map);
}
return maps;
}
public static <T extends BaseEnum> List<Map<String, Object>> maps(Class<T> clazz) {
if (!clazz.isEnum()) {
return null;
}
List<Map<String, Object>> maps = new ArrayList<Map<String, Object>>();
T[] ts = (T[]) clazz.getEnumConstants();
for (T t : ts) {
Map<String, Object> map = new HashMap<String, Object>();
map.put(key_code, t.getCode());
map.put(key_title, t.getTitle());
map.put(key_name, t.getName());
maps.add(map);
}
return maps;
}
public static <T extends BaseEnum> List<T> toList(Class<T> clazz, String... codes) {
if (codes == null || codes.length == 0 || !clazz.isEnum()) {
return Collections.emptyList();
}
List<T> list = new ArrayList<>(codes.length);
T[] ts = (T[]) clazz.getEnumConstants();
for (T t : ts) {
for (String code : codes) {
if (t.getCode().equals(code)) {
list.add(t);
}
}
}
return list;
}
}
