優(yōu)雅地在Java應(yīng)用中實(shí)現(xiàn)全局枚舉處理的方法

// 靜態(tài)方法方式
public enum GenderEnum {

  // 代碼略
 
  public static GenderEnum get(int value) {
   for (GenderEnum item : GenderEnum.values()) {
   if (value == item.getValue()) {
     return item;
    }
   }
   return null;
  }
}
// 工具類方式
public class EnumUtil {

 public static <E extends Enumerable> E of(@Nonnull Class<E> classType, int value) {
  for (E enumConstant : classType.getEnumConstants()) {
   if (value == enumConstant.getValue()) {
    return enumConstant;
   }
  }
  return null;
 }

}

GenderEnum gender = EnumUtil.of(GenderEnum.class,1);

public interface Enumerable<E extends Enumerable> {

 /**
  * 獲取在i18n文件中對應(yīng)的 key
  * @return key
  */
 @Nonnull
 String getKey();

 /**
  * 獲取最終保存到數(shù)據(jù)庫的值
  * @return 值
  */
 @Nonnull
 int getValue();

 /**
  * 獲取 key 對應(yīng)的文本信息
  * @return 文本信息
  */
 @Nonnull
 default String getText() {
  return I18nMessageUtil.getMessage(this.getKey(), null);
 }
}
public enum GenderEnum implements Enumerable {

 /** 男 */
 MALE(1, "male"),

 /** 女 */
 FEMALE(2, "female");

 private int value;

 private String key;

 GenderEnum(int value, String key) {
  this.value = value;
  this.key = key;
 }

 @Override
 public String getKey() {
  return this.key;
 }

 @Override
 public int getValue() {
  return this.value;
 }
}

@Configuration
public class MvcConfiguration implements WebMvcConfigurer, WebBindingInitializer {

 /**
  * [get]請求中，將int值轉(zhuǎn)換成枚舉類
  * @param registry
  */
 @Override
 public void addFormatters(FormatterRegistry registry) {
  registry.addConverterFactory(new EnumConverterFactory());
 }
}

public class EnumConverterFactory implements ConverterFactory<String, Enumerable> {

 private final Map<Class, Converter> converterCache = new WeakHashMap<>();

 @Override
 @SuppressWarnings({"rawtypes", "unchecked"})
 public <T extends Enumerable> Converter<String, T> getConverter(@Nonnull Class<T> targetType) {
  return converterCache.computeIfAbsent(targetType,
    k -> converterCache.put(k, new EnumConverter(k))
  );
 }

 protected class EnumConverter<T extends Enumerable> implements Converter<Integer, T> {

  private final Class<T> enumType;

  public EnumConverter(@Nonnull Class<T> enumType) {
   this.enumType = enumType;
  }

  @Override
  public T convert(@Nonnull Integer value) {
   return EnumUtil.of(this.enumType, value);
  }
 }
}

@Configuration
@Slf4j
public class JacksonConfiguration {

 /**
  * Jackson的轉(zhuǎn)換器
  * @return
  */
 @Bean
 @Primary
 @SuppressWarnings({"rawtypes", "unchecked"})
 public MappingJackson2HttpMessageConverter mappingJacksonHttpMessageConverter() {
  final MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
  ObjectMapper objectMapper = converter.getObjectMapper();
  // Include.NON_EMPTY 屬性為 空（""） 或者為 NULL 都不序列化，則返回的json是沒有這個(gè)字段的。這樣對移動端會更省流量
  objectMapper.setSerializationInclusion(JsonInclude.Include.NON_EMPTY);
  // 反序列化時(shí)候，遇到多余的字段不失敗，忽略
  objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
  // 允許出現(xiàn)特殊字符和轉(zhuǎn)義符
  objectMapper.configure(JsonParser.Feature.ALLOW_UNQUOTED_CONTROL_CHARS, true);
  // 允許出現(xiàn)單引號
  objectMapper.configure(JsonParser.Feature.ALLOW_SINGLE_QUOTES, true);
  SimpleModule customerModule = new SimpleModule();
  customerModule.addDeserializer(String.class, new StringTrimDeserializer(String.class));
  customerModule.addDeserializer(Enumerable.class, new EnumDeserializer(Enumerable.class));
  customerModule.addSerializer(Enumerable.class, new EnumSerializer(Enumerable.class));
  objectMapper.registerModule(customerModule);
  converter.setSupportedMediaTypes(ImmutableList.of(MediaType.TEXT_HTML, MediaType.APPLICATION_JSON));
  return converter;
 }

}
public class EnumDeserializer<E extends Enumerable> extends StdDeserializer<E> {

 private Class<E> enumType;

 public EnumDeserializer(@Nonnull Class<E> enumType) {
  super(enumType);
  this.enumType = enumType;
 }

 @Override
 public E deserialize(JsonParser jsonParser, DeserializationContext deserializationContext) throws IOException {
  return EnumUtil.of(this.enumType, jsonParser.getIntValue());
 }

}

// 注冊枚舉類序列化處理類
customerModule.addSerializer(Enumerable.class, new EnumSerializer(Enumerable.class));

public class EnumSerializer extends StdSerializer<Enumerable> {

 public EnumSerializer(@Nonnull Class<Enumerable> type) {
  super(type);
 }

 @Override
 public void serialize(Enumerable enumerable, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException {
  jsonGenerator.writeStartObject();
  jsonGenerator.writeNumberField("value", enumerable.getValue());
  jsonGenerator.writeStringField("text", enumerable.getText());
  jsonGenerator.writeEndObject();
 }
}

application.yml
--
mybatis:
 configuration:
  default-enum-type-handler: github.shiyajian.pretty.config.enums.EnumTypeHandler

public class EnumTypeHandler<E extends Enumerable> extends BaseTypeHandler<E> {

  private Class<E> enumType;

  public EnumTypeHandler() { /* instance */ }


  public EnumTypeHandler(@Nonnull Class<E> enumType) {
    this.enumType = enumType;
  }

  @Override
  public void setNonNullParameter(PreparedStatement preparedStatement, int i, E e, JdbcType jdbcType) throws SQLException {
    preparedStatement.setInt(i, e.getValue());
  }

  @Override
  public E getNullableResult(ResultSet rs, String columnName) throws SQLException {
    int value = rs.getInt(columnName);
    return rs.wasNull() ? null : EnumUtil.of(this.enumType, value);
  }

  @Override
  public E getNullableResult(ResultSet rs, int columnIndex) throws SQLException {
    int value = rs.getInt(columnIndex);
    return rs.wasNull() ? null : EnumUtil.of(this.enumType, value);
  }

  @Override
  public E getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {
    int value = cs.getInt(columnIndex);
    return cs.wasNull() ? null : EnumUtil.of(this.enumType, value);
  }

}