技術標籤：javaexceptionspring

如何在controller層中優雅的攔截異常

目標

• 學習全域性異常攔截器處理controller所有異常的返回封裝
• 定義列舉異常碼，優雅的設計自定義異常

1.自定義一個列舉類，用於存放異常程式碼

public enum BizError {
    SYSTEM_ERROR("000","系統異常"),
    INVALID_ERROR("001","非法引數"),
    NOT_AUTHRIOZED("002","未授權");

    //異常碼
 

    private String errorCode;
    //異常資訊
    private String errorMessage;

    private BizError(String errorCode,String errorMessage){
        this.errorCode=errorCode;
        this.errorMessage=errorMessage;
    }

    public String getErrorCode() {
        return errorCode;
    }

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

    public String getErrorMessage() {
        return errorMessage;
    }

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

2.自定義一個異常類

public class MyException extends RuntimeException
 
{

    private BizError bizError;
    private String message;

    public MyException(BizError bizError){
        super(bizError.getErrorMessage());
        this.bizError = bizError;
    }

    public MyException(BizError bizError,String message){
        super(StringUtils.isEmpty(bizError)?message:bizError.getErrorMessage());
        this.bizError=bizError;
        this.message=message;
    }

    public BizError getBizError() {
        return bizError;
    }

    public void setBizError(BizError bizError) {
        this.bizError = bizError;
    }

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

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

3.自定義全域性異常攔截器

/**
 * 全域性異常攔截器
 */
public class GlobalExceptionInterceptor implements HandlerExceptionResolver {
    //日誌輸出
    private Logger log = LoggerFactory.getLogger(GlobalExceptionInterceptor.class);
    @Override
    public ModelAndView resolveException(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) {
        ModelAndView modelAndView = new ModelAndView();
        System.out.println("全域性異常攔截");
        try {
            if(e instanceof MyException){
                setJSONErrorResponse(httpServletResponse,((MyException) e).getBizError());
                log.error(((MyException) e).getBizError().getErrorCode()+"---->"+((MyException) e).getBizError().getErrorMessage(),e);
            }else {
                setJSONErrorResponse(httpServletResponse,BizError.SYSTEM_ERROR);
                e.printStackTrace();
            }
        } catch (IOException ioException) {
            ioException.printStackTrace();
        }
        //返回一個空的modelAndView
        return modelAndView;
    }

    private void setJSONErrorResponse(HttpServletResponse httpServletResponse, BizError bizError) throws IOException {
        httpServletResponse.setContentType("application/json;charset=UTF-8");
        httpServletResponse.setCharacterEncoding("UTF-8");
        //拼接json
        String retStr = "{\"errorCode\":\""+bizError.getErrorCode()+
                            "\",\"status\":\"filed\",\"errorMsg\":\""+bizError.getErrorMessage()+"\"}";
        httpServletResponse.getWriter().write(retStr);
    }

}

具體異常攔截邏輯，程式碼非常簡單，學習下這種設計思路，優雅減少專案樣板程式碼

1. 通過異常instanceof判斷出自定義異常，
2. 然後取出異常碼，通過json方式返回給前端

還要記得配置

<bean id="exceptionResolver" class="com.ssm.interceptor.GlobalExceptionInterceptor"></bean>

4.測試demo

1. controller

@Controller
public class HelloController {
    @Autowired
    UsersService usersService;
    
    @RequestMapping("/ex/{id}")
    public String testEX(@PathVariable("id") String id){
        usersService.doEX(id);
        return "OK";
    }
}

2. service

@Service
public class UsersServiceImpl implements UsersService {
    @Autowired
    UsersDao usersDao;

    @Override
    public void doEX(String id) {
        switch (id){
            case "1":
                throw new MyException(BizError.SYSTEM_ERROR);
            case "2":
                throw new MyException(BizError.INVALID_ERROR);
            case "3":
                throw new MyException(BizError.NOT_AUTHRIOZED);
        }
    }
}

測試結果