springboot返回统一接口与统一异常处理

在做后端服务开发时，想要每次获取的数据和抛出的异常保持统一的返回结果，结构清晰，方便管理

1. 封装统一返回格式工具类ResultUtil

//引入Lombok依赖，不引入可以自己构建getter,setter
@Data
@Component
public class ResultUtil<T> {
    //三个主要参数，code码，消息体，数据体
    private Integer code;

    private String msg;

    private T data;
	//定义默认成功code码
    private static  final  Integer SUCCESS_CODE =10000;
	//定义默认成功msg
    private static final String SUCCESS_MSG = "SUCCESS";
    //全参构造函数
    public ResultUtil(Integer code, String msg, T data) {
        this.code = code;
        this.msg = msg;
        this.data = data;
    }
	//两参数构造函数
    public ResultUtil(Integer code, String msg) {
        this.code = code;
        this.msg = msg;
    }
    //无参构造函数
    public ResultUtil(){
        //在success()无参传入时调用
        this(SUCCESS_CODE,SUCCESS_MSG);
    }

    //默认成功返回，比如增加、删除、修改
    public static ResultUtil success(){
        //直接调用无参构造函数
         return  new ResultUtil();
    }
    //带参成功返回，比如查询
    public static<T>  ResultUtil<T> success(T data){
        ResultUtil<T> resultUtil = new ResultUtil<>();
        resultUtil.setData(data);
        return resultUtil;
    }
    //默认失败返回，需要传入code,msg，但是这样我们需要记录各类异常比较麻烦，可以直接引入异常枚举类，如下
    public static<T> ResultUtil<T> error(Integer code,String msg){
        return  new ResultUtil<>(code,msg);
    }

    //传入异常枚举类
    public static<T> ResultUtil<T> error(CodeMsgEnum ex){
        return  new ResultUtil<>(ex.getCode(),ex.getMsg());
    }
}

2. 自定义异常枚举类

public enum CodeMsgEnum {
    //各类错误信息，可以存储在这里
    COMMON_ERROR(10001,"通用错误"),
    USER_EXITS(10002,"用户已存在"),
    SYSTEM_ERROR(20000,"系统异常");

    private Integer code;

    private String msg;

	//构造函数，也可以使用lombok的 @AllArgsConstructor 全参构造器
     CodeMsgEnum(Integer code, String msg) {
         this.code = code;
         this.msg = msg;
    }

    //下面是getter,setter方法，也可以使用lombok的@Getter,@Setter
    public Integer getCode() {
        return code;
    }

    public String getMsg() {
        return msg;
    }

    public void setCode(Integer code) {
        this.code = code;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }
}

3. 测试

@RestController
public class UserController {

    @Autowired
    private UserService userService;

    @GetMapping("/get/user")
    public ResultUtil UserInfo(@RequestParam Integer id){
        return  ResultUtil.success();
        return  ResultUtil.success( userService.getUser(id));
        return  ResultUtil.error(CodeMsgEnum.COMMON_ERROR);
    }
}

4. 自定义异常类

@Data
public class CommonException extends Exception {
    private Integer code;

    private String msg;

    CommonException(Integer code,String msg){
        this.code = code;
        this.msg  = msg;
    }
    public CommonException(CodeMsgEnum ex){
        this(ex.getCode(),ex.getMsg());
    }
}

5. 统一异常处理

//ControllerAdvice是Controller增强器,可对controller中被 @RequestMapping注解的方法加一些逻辑处理
@ControllerAdvice
public class GlobalExceptionHandler {

    //处理系统异常
    @ExceptionHandler(value = Exception.class)
    @ResponseBody
    public ResultUtil  SystemHandle(Exception e) {
        return ResultUtil.error(CodeMsgEnum.SYSTEM_ERROR);
    }

    //处理自定义异常
    @ExceptionHandler(value = CommonException.class)
    @ResponseBody
    public ResultUtil  CommonHandle(CommonException e) {
        return ResultUtil.error(e.getCode(),e.getMsg());
    }
}

6. 测试异常

@RestController
public class UserController {

    @Autowired
    private UserService userService;

    @GetMapping("/get/user")
    public ResultUtil UserInfo(@RequestParam Integer id){
        //测试内部异常
        if(true){
		  throw new CommonException(CodeMsgEnum.USER_EXITS);
        }
        return  ResultUtil.success();
       //测试系统异常
        Integer a = 1;
        Integer b = 0;
        Integer c = a/b;
        return  ResultUtil.success();
    }
}