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@Builderpublic 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")@Slf4jpublic 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")@Slf4jpublic 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@Builderpublic 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")@Slf4jpublic 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@ApiModelpublic 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")@Slf4jpublic 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...