@ControllerAdvice和@ExceptionHandler

1. 使用 @ControllerAdvice和@ExceptionHandler处理全局异常

1. 新建异常信息实体类

非必要的类，主要用于包装异常信息。

 package com.test.exception.myexception;

 public class ErrorResponse {
     private String message;
     private String errorTypeName;

     public ErrorResponse(Exception e) {
         this(e.getClass().getName(), e.getMessage());
     }

     public ErrorResponse(String errorTypeName, String message) {
         this.errorTypeName = errorTypeName;
         this.message = message;
     }

     public String getMessage() {
         return message;
     }

     public void setMessage(String message) {
         this.message = message;
     }

     public String getErrorTypeName() {
         return errorTypeName;
     }

     public void setErrorTypeName(String errorTypeName) {
         this.errorTypeName = errorTypeName;
     }
 }

2. 自定义异常类型

package com.test.exception.myexception;

public class ReourceNotFoundException extends RuntimeException {
    private String message;

    public ReourceNotFoundException() {
        super();
    }

    public ReourceNotFoundException(String message) {
        super(message);
        this.message = message;
    }

    @Override
    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }
}

3. 新建异常处理类

我们只需要在类上加上@ControllerAdvice注解这个类就成为了全局异常处理类，当然你也可以通过 assignableTypes指定特定的 Controller类，让异常处理类只处理特定类抛出的异常。

 package com.test.exception.handler;

 import com.test.exception.myexception.ErrorResponse;
 import com.test.exception.myexception.ReourceNotFoundException;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.ControllerAdvice;
 import org.springframework.web.bind.annotation.ExceptionHandler;
 import org.springframework.web.bind.annotation.ResponseBody;
 import org.springframework.web.server.ResponseStatusException;

 @ControllerAdvice(assignableTypes = {com.test.exception.controller.ExceptionController.class})
 @ResponseBody
 public class GlobalExceptionHandler {
     ErrorResponse illegalArgumentResponse = new ErrorResponse(new IllegalArgumentException("参数错误!"));
     ErrorResponse resourseNotFoundResponse = new ErrorResponse(new com.test.exception.myexception.ReourceNotFoundException("Sorry, the resourse not found!"));

     @ExceptionHandler(value = Exception.class)// 拦截所有异常, 这里只是为了演示，一般情况下一个方法特定处理一种异常
     public ResponseEntity<ErrorResponse> exceptionHandler(Exception e) {

         if (e instanceof IllegalArgumentException) {
             return ResponseEntity.status(400).body(illegalArgumentResponse);
         } else if (e instanceof ReourceNotFoundException) {
             return ResponseEntity.status(404).body(resourseNotFoundResponse);
         }else if(e instanceof ResponseStatusException){
             return ResponseEntity.status(502).body(resourseNotFoundResponse);
         }
         return null;
     }
 }

4. controller模拟抛出异常

 package com.test.exception.controller;

 import com.test.exception.myexception.ReourceNotFoundException;
 import org.springframework.http.HttpStatus;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.RestController;
 import org.springframework.web.server.ResponseStatusException;

 @RestController
 public class ExceptionController {

     @GetMapping("/illegalArgumentException")
     public void throwException() {
         throw new IllegalArgumentException();
     }

     @GetMapping("/resourceNotFoundException")
     public void throwException2() {
         throw new ReourceNotFoundException();

     }

     @GetMapping("/resourceNotFoundException2")
     public void throwException3() {
         throw new ResponseStatusException(HttpStatus.BAD_GATEWAY,"The resource not found",new ReourceNotFoundException());
     }
 }

使用 Get 请求: http://localhost:8080/resourceNotFoundException

{"message":"Sorry, the resourse not found!","errorTypeName":"com.test.exception.myexception.ReourceNotFoundException"}

---

3. ResponseStatusException

研究 ResponseStatusException 我们先来看看，通过 ResponseStatus注解简单处理异常的方法（将异常映射为状态码）。

package com.test.exception.myexception;

import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.ResponseStatus;

@ResponseStatus(code = HttpStatus.BAD_GATEWAY)
public class ReourceNotFoundException2 extends RuntimeException {
    public ReourceNotFoundException2() {
    }

    public ReourceNotFoundException2(String message) {
        super(message);
    }
}

这种通过 ResponseStatus注解简单处理异常的方法是的好处是比较简单，但是一般我们不会这样做，通过ResponseStatusException会更加方便,可以避免我们额外的异常类。

    @GetMapping("/resourceNotFoundException2")
    public void throwException3() {
        throw new ResponseStatusException(HttpStatus.BAD_GATEWAY,"The resource not found",new ReourceNotFoundException());
    }

ResponseStatusException 提供了三个构造方法：

    public ResponseStatusException(HttpStatus status) {
        this(status, null, null);
    }

    public ResponseStatusException(HttpStatus status, @Nullable String reason) {
        this(status, reason, null);
    }

    public ResponseStatusException(HttpStatus status, @Nullable String reason, @Nullable Throwable cause) {
        super(null, cause);
        Assert.notNull(status, "HttpStatus is required");
        this.status = status;
        this.reason = reason;
    }

构造函数中的参数解释如下：

• status ： http status
• reason ：response 的消息内容
• cause ： 抛出的异常