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关于spring:springboot2之优雅处理返回值

jiezi

前言

最近项目组有个老我的项目要进行前后端拆散革新，应前端同学的要求，其后端提供的返回值格局需形如

{
  "status": 0,
  "message": "success",
  "data": {}}

不便前端数据处理。要实现前端同学这个需要，其实也挺简略的，仅需做如下革新，新增一个返回对象，形如

@Data
@AllArgsConstructor
@NoArgsConstructor
@Builder
public class Result<T> {
    public static final int success = 0;
    public static final int fail = 1;
    private int status = success;
    private String message = "success";
    private T data;


}

而后 controller 革新成如下


@RestController
@RequestMapping("/user")
@Slf4j
public class UserController {


  @Autowired
  private UserService userService;

  @PostMapping(value="/add")
  public Result<UserDTO> addUser(@Valid UserDTO userDTO, BindingResult bindingResult){Result<UserDTO> result = new Result<>();
    if (bindingResult.hasErrors()){return getUserFailResult(bindingResult, result);
    }
    saveUser(userDTO, result);

    return result;

  }
}

仅仅须要这么革新就能够满足前端同学的述求。但这边存在一个问题就是，这个我的项目后端接口的 contoller 之前都是间接返回业务 bean 对象，形如下

@RestController
@Api(tags = "用户治理")
@Slf4j
public class UserController {

    @Autowired
    private UserService userService;

    @GetMapping(value="/get/{id}")
    @ApiOperation("依据用户 ID 查找用户")
    @ApiImplicitParam(value = "用户 id",name = "id",required = true,paramType = "path")
    public UserDTO getUserById(@PathVariable("id") Long id){UserDTO dto = userService.getUserById(id);
        log.info("{}",dto);
        return dto;

    }
    }

如果按下面的思路

把 UserDTO 革新成 Result<UserDTO>

尽管能够满足需要，但问题是后端这样的接口有好几十个，按这种改法很显著工作量比拟大，更重要的不合乎开闭准则 –对扩大凋谢，对批改敞开。那有没有优雅一点的解决形式呢？答案是有的，利用
@RestControllerAdvice+ResponseBodyAdvice 就能够满足咱们的需要

革新

1、在革新前，先简略介绍一下 @RestControllerAdvice 和 ResponseBodyAdvice

@RestControllerAdvice

@RestControllerAdvice 这个注解是 spring 4.3 版本之后新增的注解。用于定义 @ExceptionHandler、@InitBinder、@ModelAttribute，并利用到所有 @RequestMapping。利用他能够来做 异样对立解决 。如果应用的 spring 低于 4.3，那能够应用 @ControllerAdvice+@ResponseBody。@ControllerAdvice 是 spring 3.2 版本后就提供的注解，其实现的性能和 @RestControllerAdvice 相似。
其具体的参考文档，能够查看链接 @RestControllerAdvice 文档以及 @ControllerAdvice 文档

ResponseBodyAdvice

这个是 spring4.1 版本之后，新增的接口。其作用是 容许在执行 @ResponseBody 或 ResponseEntity 控制器办法之后但在应用 HttpMessageConverter 编写注释之前自定义响应。能够间接在 RequestMappingHandlerAdapter 和 ExceptionHandlerExceptionResolver 中注册实现，也能够在 @ControllerAdvice 或者 @RestControllerAdvice 中注解。其具体参考文档能够查看链接 ResponseBodyAdvice 文档

2、编写一个通用的响应实体

@Data
@AllArgsConstructor
@NoArgsConstructor
@Builder
public class Result<T> {
    public static final int success = 0;
    public static final int fail = 1;
    private int status = success;
    private String message = "success";
    private T data;


}

3、编写一个类上加上 @RestControllerAdvice 并实现 ResponseBodyAdvice 接口。用来对立解决响应值

@RestControllerAdvice(basePackages = "com.github.lybgeek")
@Slf4j
public class ResponseAdvice implements ResponseBodyAdvice {
    @Override
    public boolean supports(MethodParameter methodParameter, Class aClass) {return true;}

    @Override
    public Object beforeBodyWrite(Object o, MethodParameter methodParameter, MediaType mediaType, Class aClass, ServerHttpRequest serverHttpRequest, ServerHttpResponse serverHttpResponse) {if(Objects.isNull(o)){return Result.builder().message("success").build();}

        if(o instanceof Result){return o;}

        return Result.builder().message("success").data(o).build();}

    @ExceptionHandler(Exception.class)
    @ResponseStatus(code = HttpStatus.INTERNAL_SERVER_ERROR)
    public Result<?> exceptionHandler(HttpServletRequest request, Exception e) {log.error(e.getMessage(), e);
        return Result.builder().message(e.getMessage()).status(Result.fail).build();}

    /**
     * 针对业务异样对立解决
     * @param request
     * @param bizException
     * @return
     */
    @ExceptionHandler(BizException.class)
    @ResponseStatus(code = HttpStatus.EXPECTATION_FAILED)
    public Result<?> bizExceptionHandler(HttpServletRequest request, BizException bizException) {int errorCode = bizException.getCode();
            log.error("catch bizException {}", errorCode);
            return Result.builder().message(bizException.getMessage()).status(errorCode).build();}


    /**
     * 针对 Validate 校验异样对立解决
     * @param request
     * @param methodArgumentNotValidException
     * @return
     */
    @ExceptionHandler(MethodArgumentNotValidException.class)
    @ResponseStatus(code = HttpStatus.BAD_REQUEST)
    public Result<?> methodArgumentNotValidExceptionExceptionHandler(HttpServletRequest request, MethodArgumentNotValidException methodArgumentNotValidException) {Result result = new Result();
        log.error("catch methodArgumentNotValidException :" + methodArgumentNotValidException.getMessage(), methodArgumentNotValidException);
        return ResultUtils.INSTANCE.getFailResult(methodArgumentNotValidException.getBindingResult(),result);
    }

    /**
     * 针对 Assert 断言异样对立解决
     * @param request
     * @param illegalArgumentExceptionException
     * @return
     */
    @ExceptionHandler(IllegalArgumentException.class)
    @ResponseStatus(code = HttpStatus.EXPECTATION_FAILED)
    public Result<?> illegalArgumentExceptionHandler(HttpServletRequest request, IllegalArgumentException illegalArgumentExceptionException) {log.error("illegalArgumentExceptionException:"+illegalArgumentExceptionException.getMessage(), illegalArgumentExceptionException);
        return Result.builder().message(illegalArgumentExceptionException.getMessage()).status(Result.fail).build();}

测试验证

1、编写业务 DTO

@Data
@AllArgsConstructor
@NoArgsConstructor
@Builder
@ApiModel
public class UserDTO implements Serializable {@NotNull(message = "编号不能为空",groups = {Update.class, Delete.class})
  @ApiModelProperty(value = "编号",name = "id",example = "1")
  private Long id;

  @NotBlank(message = "用户名不能为空",groups = {Add.class})
  @ApiModelProperty(value = "用户名",name = "userName",example = "zhangsan")
  private String userName;

  @NotBlank(message = "姓名不能为空",groups = {Add.class})
  @ApiModelProperty(value = "姓名",name = "realName",example = "张三")
  private String realName;

  @NotBlank(message = "明码不能为空",groups = {Add.class})
  @Size(max=32,min=6,message = "明码长度要在 6 -32 之间",groups = {Add.class})
  @ApiModelProperty(value = "明码",name = "password",example = "123456")
  private String password;

  @NotNull(message = "性别不能为空",groups = {Add.class})
  @ApiModelProperty(value = "性别",name = "gender",example = "1")
  @EnumValid(target = Gender.class, message = "性别取值必须为 0 或者 1",groups = {Add.class,Update.class})
  private Integer gender;

  @ApiModelProperty(value = "邮箱",name = "email",example = "zhangsan@qq.com")
  @Pattern(regexp = "^[a-zA-Z0-9_.-]+@[a-zA-Z0-9-]+(\\.[a-zA-Z0-9-]+)*\\.[a-zA-Z0-9]{2,6}$",message = "不满足邮箱正则表达式",groups = {Add.class,Update.class})
  private String email;



}

2、编写业务 controller

@RestController
@Api(tags = "用户治理")
@Slf4j
public class UserController {

    @Autowired
    private UserService userService;

    @GetMapping(value="/get/{id}")
    @ApiOperation("依据用户 ID 查找用户")
    @ApiImplicitParam(value = "用户 id",name = "id",required = true,paramType = "path")
    public UserDTO getUserById(@PathVariable("id") Long id){UserDTO dto = userService.getUserById(id);
        log.info("{}",dto);
        return dto;

    }

    @PostMapping(value="/add")
    @ApiOperation("增加用户")
    public UserDTO add(@RequestBody @Validated({Add.class}) UserDTO userDTO){log.info("{}",userDTO);
        return userService.save(userDTO);
    }

    @PostMapping(value="/update")
    @ApiOperation("更新用户")
    public UserDTO update(@RequestBody @Validated({Update.class}) UserDTO userDTO){log.info("{}",userDTO);
        return userService.save(userDTO);
    }

    @DeleteMapping(value="/detele")
    @ApiOperation("删除用户")
    public boolean delete(@Validated({Delete.class}) UserDTO userDTO){log.info("id：{}",userDTO.getId());
        return userService.delete(userDTO.getId());
    }
}

注： 业务 service 就不贴了和文章内容关系不大。如果感兴趣的敌人，能够从文末提供的链接进行查看

3、利用 swagger 在线接口文档进行测试

a：失常响应时，返回值形如下

{
  "status": 0,
  "message": "success",
  "data": {
    "id": 1,
    "userName": "zhangsan",
    "realName": "张三",
    "password": "123456",
    "gender": 1,
    "email": "zhangsan@qq.com"
  }
}

b：当数据校验异样时，返回值形如下

{
  "status": 1,
  "message": "姓名不能为空;",
  "data": null
}

c: 当业务异样时，返回值形如下

{
  "status": 1,
  "message": "user is not found by id :3",
  "data": null
}

总结

本文次要介绍了如何利用 @RestControllerAdvice 和 ResponseBodyAdvice 来对立解决返回值。本文代码示例还实现了分组校验，自定义校验，利用 mdc traceId 日志埋点，如果对这些内容感兴趣的敌人，能够查看文末我的项目链接

demo 链接

https://github.com/lyb-geek/s…

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