Spring的注解@RestControllerAdvice,抛出异常后统一返回处理

看@RestControllerAdvice源码可以知道，它就是@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

demo:创建一个自定义BaseException 异常，可以根据需要自定义各种异常

package com.ruoyi.common.exception;

import com.ruoyi.common.utils.MessageUtils;
import com.ruoyi.common.utils.StringUtils;

/**
 * 基础异常
 * 
 * @author ruoyi
 */
public class BaseException extends RuntimeException
{
    private static final long serialVersionUID = 1L;

    /**
     * 所属模块
     */
    private String module;

    /**
     * 错误码
     */
    private String code;

    /**
     * 错误码对应的参数
     */
    private Object[] args;

    /**
     * 错误消息
     */
    private String defaultMessage;

    public BaseException(String module, String code, Object[] args, String defaultMessage)
    {
        this.module = module;
        this.code = code;
        this.args = args;
        this.defaultMessage = defaultMessage;
    }

    public BaseException(String module, String code, Object[] args)
    {
        this(module, code, args, null);
    }

    public BaseException(String module, String defaultMessage)
    {
        this(module, null, null, defaultMessage);
    }

    public BaseException(String code, Object[] args)
    {
        this(null, code, args, null);
    }

    public BaseException(String defaultMessage)
    {
        this(null, null, null, defaultMessage);
    }

    @Override
    public String getMessage()
    {
        String message = null;
        if (!StringUtils.isEmpty(code))
        {
            message = MessageUtils.message(code, args);
        }
        if (message == null)
        {
            message = defaultMessage;
        }
        return message;
    }

    public String getModule()
    {
        return module;
    }

    public String getCode()
    {
        return code;
    }

    public Object[] getArgs()
    {
        return args;
    }

    public String getDefaultMessage()
    {
        return defaultMessage;
    }
}

新建一个全局异常处理类：加上@RestControllerAdvice注解，每个异常方法需要加上@ExceptionHandler(BaseException.class)注解

package com.ruoyi.framework.web.exception;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.security.access.AccessDeniedException;
import org.springframework.security.authentication.AccountExpiredException;
import org.springframework.security.core.userdetails.UsernameNotFoundException;
import org.springframework.validation.BindException;
import org.springframework.web.bind.MethodArgumentNotValidException;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RestControllerAdvice;
import org.springframework.web.servlet.NoHandlerFoundException;
import com.ruoyi.common.constant.HttpStatus;
import com.ruoyi.common.exception.BaseException;
import com.ruoyi.common.exception.CustomException;
import com.ruoyi.common.exception.DemoModeException;
import com.ruoyi.common.utils.StringUtils;
import com.ruoyi.framework.web.domain.AjaxResult;

/**
 * 全局异常处理器
 * 
 * @author 
 */
@RestControllerAdvice
public class GlobalExceptionHandler
{
    private static final Logger log = LoggerFactory.getLogger(GlobalExceptionHandler.class);

    /**
     * 基础异常
     */
    @ExceptionHandler(BaseException.class)
    public AjaxResult baseException(BaseException e)
    {
        return AjaxResult.error(e.getMessage());
    }

    /**
     * 业务异常
     */
    @ExceptionHandler(CustomException.class)
    public AjaxResult businessException(CustomException e)
    {
        if (StringUtils.isNull(e.getCode()))
        {
            return AjaxResult.error(e.getMessage());
        }
        return AjaxResult.error(e.getCode(), e.getMessage());
    }

    @ExceptionHandler(NoHandlerFoundException.class)
    public AjaxResult handlerNoFoundException(Exception e)
    {
        log.error(e.getMessage(), e);
        return AjaxResult.error(HttpStatus.NOT_FOUND, "路径不存在，请检查路径是否正确");
    }

    @ExceptionHandler(AccessDeniedException.class)
    public AjaxResult handleAuthorizationException(AccessDeniedException e)
    {
        log.error(e.getMessage());
        return AjaxResult.error(HttpStatus.FORBIDDEN, "没有权限，请联系管理员授权");
    }

    @ExceptionHandler(AccountExpiredException.class)
    public AjaxResult handleAccountExpiredException(AccountExpiredException e)
    {
        log.error(e.getMessage(), e);
        return AjaxResult.error(e.getMessage());
    }

    @ExceptionHandler(UsernameNotFoundException.class)
    public AjaxResult handleUsernameNotFoundException(UsernameNotFoundException e)
    {
        log.error(e.getMessage(), e);
        return AjaxResult.error(e.getMessage());
    }

    @ExceptionHandler(Exception.class)
    public AjaxResult handleException(Exception e)
    {
        log.error(e.getMessage(), e);
        return AjaxResult.error(e.getMessage());
    }

    /**
     * 自定义验证异常
     */
    @ExceptionHandler(BindException.class)
    public AjaxResult validatedBindException(BindException e)
    {
        log.error(e.getMessage(), e);
        String message = e.getAllErrors().get(0).getDefaultMessage();
        return AjaxResult.error(message);
    }

    /**
     * 自定义验证异常
     */
    @ExceptionHandler(MethodArgumentNotValidException.class)
    public Object validExceptionHandler(MethodArgumentNotValidException e)
    {
        log.error(e.getMessage(), e);
        String message = e.getBindingResult().getFieldError().getDefaultMessage();
        return AjaxResult.error(message);
    }

    /**
     * 演示模式异常
     */
    @ExceptionHandler(DemoModeException.class)
    public AjaxResult demoModeException(DemoModeException e)
    {
        return AjaxResult.error("演示模式，不允许操作");
    }
}

在业务方法抛出异常：

 @Override
    public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException
    {
        SysUser user = userService.selectUserByUserName(username);
        if (StringUtils.isNull(user))
        {
            log.info("登录用户：{} 不存在.", username);
            throw new UsernameNotFoundException("登录用户：" + username + " 不存在");
        }
        else if (UserStatus.DELETED.getCode().equals(user.getDelFlag()))
        {
            log.info("登录用户：{} 已被删除.", username);
            throw new BaseException("对不起，您的账号：" + username + " 已被删除");
        }
        else if (UserStatus.DISABLE.getCode().equals(user.getStatus()))
        {
            log.info("登录用户：{} 已被停用.", username);
            throw new BaseException("对不起，您的账号：" + username + " 已停用");
        }

        return createLoginUser(user);
    }

AjaxResult的构造方法

 /**
     * 返回错误消息
     * 
     * @param msg 返回内容
     * @return 警告消息
     */
    public static AjaxResult error(String msg)
    {
        return AjaxResult.error(msg, null);
    }
/**
    
     * 返回错误消息
     * 
     * @param msg 返回内容
     * @param data 数据对象
     * @return 警告消息
     */
    public static AjaxResult error(String msg, Object data)
    {
        return new AjaxResult(HttpStatus.ERROR, msg, data);
    }

这样我们就可以自定义各种异常，在业务代码中不进行处理便可抛出异常进行中止程序，统一返回自定义的异常json格式