JsonView和统一封装返回结果的问题

[yangwenliang123]

项目里很多时候使用统一封装返回结果，例如net.dreamlu.mica.core.result.R类。

public class User {
public interface UserInfo{};
public interface UserDetail extends UserInfo{};

private String username;
private String password;
@JSONVIEW(UserInfo.class)
public String getUsername() {
return username;
}
@JSONVIEW(UserDetail.class)
public String getPassword() {
return password;
}
}

@RequestMapping("/user")
@JSONVIEW(User.UserInfo.class)
public User getUser(@RequestParam String username){
User user = new User();
user.setUsername("123");
user.setPassword("123");
return user;
}

@RequestMapping("/user")
@JSONVIEW(User.UserInfo.class)
public R getUser(@RequestParam String username){
User user = new User();
user.setUsername("123");
user.setPassword("123");
return R.success(user);
}

在第一个返回中 可以只给前端展示username属性

但是在第二个返回中 用R包装了User对象后，JsonView就失效了，在前端无法获取到User对象的数据。

[MessiCY1994]

亲，你的邮件我已经收到，谢谢

[ChunMengLu]

@yangwenliang123 这个是 chatgpt 的回答，你试试，可以微调，做的更加完美：

当响应统一包装为Result<User>时，@JsonView注解无法直接生效。这是因为@JsonView注解的作用对象是属性字段，而不是包装类。

为了使@JsonView注解生效，你可以通过下面方式来处理：

使用ResponseBodyAdvice：实现ResponseBodyAdvice接口，将@JsonView注解的配置应用到返回结果上。

@ControllerAdvice
public class JsonViewResponseBodyAdvice implements ResponseBodyAdvice<Object> {
    
    @Override
    public boolean supports(MethodParameter returnType, Class<? extends HttpMessageConverter<?>> converterType) {
        return true;
    }
    
    @Override
    public Object beforeBodyWrite(Object body, MethodParameter returnType, MediaType selectedContentType,
            Class<? extends HttpMessageConverter<?>> selectedConverterType, ServerHttpRequest request,
            ServerHttpResponse response) {

        if (body instanceof Result<?>) {
            R<?> result = (Result<?>) body;
            if (result.getData() != null && result.getData() instanceof User) {
                User user = (User) result.getData();
                MappingJacksonValue wrapper = new MappingJacksonValue(user);
                wrapper.setSerializationView(UserViews.Full.class);
                return new Result<>(result.getCode(), result.getMessage(), wrapper);
            }
        }
        
        return body;
    }
}

上面的代码中，JsonViewResponseBodyAdvice类实现了ResponseBodyAdvice接口，并在beforeBodyWrite方法中对返回结果进行处理。如果返回结果是Result<User>类型且包含非空的User对象，则将User对象进行包装，并设置视图为UserViews.Full.class。

[ChunMengLu]

@yangwenliang123 mica-lite 中已经添加支持，详见：https://github.com/lets-mica/mica/blob/master/mica-lite/src/main/java/net/dreamlu/mica/lite/jackson/JsonViewResultAdvice.java

另外需要配置 jackson：https://github.com/lets-mica/mica/blob/master/mica-lite/src/main/java/net/dreamlu/mica/lite/config/MicaLiteConfiguration.java#L40

周末会发版 2.7.x 和 3.1.x

[OHUHO]

我采用了自定义序列化器解决

/**

• @description: 自定义序列化器，处理JsonView对Result和IPage字段

• @author: Walker walker.top@qq.com

• @Date: 2024-12-14 15:14:14

• @Version: 1.0.0
  */
  public class ResultSerializer extends JsonSerializer<Result<?>> {

  private static final String RESULT_CODE = "code";
  private static final String RESULT_MESSAGE = "message";
  private static final String RESULT_DATA = "data";

  private static final String PAGE_TOTAL = "total";
  private static final String PAGE_SIZE = "size";
  private static final String PAGE_CURRENT = "current";
  private static final String PAGE_PAGES = "pages";
  private static final String PAGE_RECORDS = "records";

  @OverRide
  public void serialize(Result<?> result, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException {
  jsonGenerator.writeStartObject();
  jsonGenerator.writeNumberField(RESULT_CODE, result.getCode());
  jsonGenerator.writeStringField(RESULT_MESSAGE, result.getMessage());
  jsonGenerator.writeFieldName(RESULT_DATA);

   Object data = result.getData();
   Class<?> activeView = serializerProvider.getActiveView();
  
   if (data == null) {
       jsonGenerator.writeNull();
   } else {
       serializeData(data, jsonGenerator, serializerProvider, activeView);
   }
   jsonGenerator.writeEndObject();
  

  }

  /**

  • 序列化Result对象的Data属性
  • @param data data
  • @param jsonGenerator jsonGenerator
  • @param serializerProvider serializerProvider
  • @param activeView activeView
  • @throws IOException exception
    */
    private void serializeData(Object data, JsonGenerator jsonGenerator, SerializerProvider serializerProvider, Class activeView) throws IOException { if (activeView == null) { // 默认的序列化 serializerProvider.defaultSerializeField(RESULT_DATA, data, jsonGenerator); } else if (data instanceof IPage page) {
    // 序列化Mybatis的Page对象
    serializePage(page, jsonGenerator, activeView, serializerProvider);
    } else {
    // 序列化普通对象
    serializeObject(data, jsonGenerator, activeView, serializerProvider);
    }
    }

  /**

  • 序列化Mybatis的Page对象
  • @param page page
  • @param jsonGenerator jsonGenerator
  • @param activeView activeView
  • @param serializerProvider serializerProvider
  • @throws IOException exception
    */
    private void serializePage(IPage page, JsonGenerator jsonGenerator, Class activeView, SerializerProvider serializerProvider) throws IOException {
    jsonGenerator.writeStartObject();
    jsonGenerator.writeNumberField(PAGE_TOTAL, page.getTotal());
    jsonGenerator.writeNumberField(PAGE_SIZE, page.getSize());
    jsonGenerator.writeNumberField(PAGE_CURRENT, page.getCurrent());
    jsonGenerator.writeNumberField(PAGE_PAGES, page.getPages());
    jsonGenerator.writeFieldName(PAGE_RECORDS);
    serializeObject(page.getRecords(), jsonGenerator, activeView, serializerProvider);
    jsonGenerator.writeEndObject();
    }

  /**

  • 序列化普通对象
  • @param data data
  • @param jsonGenerator jsonGenerator
  • @param activeView activeView
  • @param serializerProvider serializerProvider
  • @throws IOException exception
    */
    private void serializeObject(Object data, JsonGenerator jsonGenerator, Class<?> activeView, SerializerProvider serializerProvider) throws IOException {
    ObjectMapper mapper = new ObjectMapper();
    mapper.setConfig(serializerProvider.getConfig());
    ObjectWriter writer = mapper.writerWithView(activeView);
    String serializedData = writer.writeValueAsString(data);
    jsonGenerator.writeRawValue(serializedData);
    }
    }