Spring Boot之全局异常

• • 一、背景
  • 二、maven依赖
  • 三、自定义异常
  • • 3.1 异常信息类
    • 3.2 自定义异常类
  • 四、全局异常处理（核心）
  • 五、验证
  • • 5.1、配置文件
    • 5.2、测试类

  我们在实际项目开发中，在不同的硬件或者软件环境下会出现很多异常情况，如果每个地方都要去捕获各种异常，那么程序会很臃肿，如果服务端错误的信息直接暴露给用户，那样的体验会很糟糕，这些信息甚至被黑客用来攻击我们的服务，导致更大的事故，所以我们今天弄一个全局异常处理。

pom.xml

    4.0.0
    
        org.springframework.boot
        spring-boot-starter-parent
        2.5.2
        
    

    com.alian
    exception
    0.0.1-SNAPSHOT
    exception
    Spring Boot之全局异常

    
        1.8
    

    

        
            org.springframework.boot
            spring-boot-starter-web
            ${parent.version}
        

    

    
        
            
                org.springframework.boot
                spring-boot-maven-plugin
            
        
    

  先定义一个异常信息类，包括错误码和异常信息。

ErrorResponseEntity.java

package com.alian.exception.exceptions;

import java.io.Serializable;

public class ErrorResponseEntity implements Serializable {

    private static final long serialVersionUID = -4383509268106883368L;

    private int errorCode;

    private String errorMessage;

    public ErrorResponseEntity() {
        super();
    }

    public ErrorResponseEntity(int errorCode, String errorMessage) {
        this.errorCode = errorCode;
        this.errorMessage = errorMessage;
    }

    public int getErrorCode() {
        return errorCode;
    }

    public void setErrorCode(int errorCode) {
        this.errorCode = errorCode;
    }

    public String getErrorMessage() {
        return errorMessage;
    }

    public void setErrorMessage(String errorMessage) {
        this.errorMessage = errorMessage;
    }

}

  要实现自定义的异常，我编写的类可以继承RuntimeException，相当于我们的类也是一个运行时异常类。

CustomException.java

package com.alian.exception.exceptions;

public class CustomException extends RuntimeException {

    private static final long serialVersionUID = -8793729160842629256L;

    private int errorCode;

    public CustomException() {
        super();
    }

    public CustomException(int errorCode, String message) {
        super(message);
        this.setErrorCode(errorCode);
    }

    public int getErrorCode() {
        return errorCode;
    }

    public void setErrorCode(int errorCode) {
        this.errorCode = errorCode;
    }
}

  在spring 3.2中，新增了@ControllerAdvice，@RestControllerAdvice注解，可以用于定义@ExceptionHandler、@InitBinder、@ModelAttribute，并应用到所有@RequestMapping中，从源码中我们也知道@RestControllerAdvice就是@ControllerAdvice和@ResponseBody的合并，此注解通过对异常的拦截实现的统一异常返回处理，返回json格式的异常。

GlobalExceptionHandler.java

package com.alian.exception.exceptions;

import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.HttpRequestMethodNotSupportedException;
import org.springframework.web.bind.MethodArgumentNotValidException;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RestControllerAdvice;
import org.springframework.web.context.request.WebRequest;
import org.springframework.web.method.annotation.MethodArgumentTypeMismatchException;
import org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExceptionHandler;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


@RestControllerAdvice
public class GlobalExceptionHandler extends ResponseEntityExceptionHandler {

    
    @ExceptionHandler(RuntimeException.class)
    public ErrorResponseEntity runtimeExceptionHandler(HttpServletRequest request, final Exception ex, HttpServletResponse response) {
        response.setStatus(HttpStatus.BAD_REQUEST.value());
        RuntimeException exception = (RuntimeException) ex;
        return new ErrorResponseEntity(400, exception.getMessage());
    }

    
    @ExceptionHandler(CustomException.class)
    public ErrorResponseEntity customExceptionHandler(HttpServletRequest request, final Exception ex, HttpServletResponse response) {
        response.setStatus(HttpStatus.BAD_REQUEST.value());
        CustomException exception = (CustomException) ex;
        return new ErrorResponseEntity(exception.getErrorCode(), exception.getMessage());
    }

    
    @Override
    protected ResponseEntity