在J2EE項目的開發(fā)中，不管是對底層的數(shù)據(jù)庫操作過程，還是業(yè)務(wù)層的處理過程，還是控制層的處理過程，都不可避免會遇到各種可預(yù)知的、不可預(yù)知的異常需要處理。每個過程都單獨處理異常，系統(tǒng)的代碼耦合度高，工作量大且不好統(tǒng)一，維護的工作量也很大。 那么，能不能將所有類型的異常處理從各處理過程解耦出來，這樣既保證了相關(guān)處理過程的功能較單一，也實現(xiàn)了異常信息的統(tǒng)一處理和維護？答案是肯定的。下面將介紹使用Spring MVC統(tǒng)一處理異常的解決和實現(xiàn)過程

使用Spring MVC提供的SimpleMappingExceptionResolver

實現(xiàn)Spring的異常處理接口HandlerExceptionResolver 自定義自己的異常處理器

使用@ExceptionHandler注解實現(xiàn)異常處理

(一) SimpleMappingExceptionResolver

使用這種方式具有集成簡單、有良好的擴展性、對已有代碼沒有入侵性等優(yōu)點，但該方法僅能獲取到異常信息，若在出現(xiàn)異常時，對需要獲取除異常以外的數(shù)據(jù)的情況不適用。

@Configuration

@EnableWebMvc

@ComponentScan(basePackages = {"com.balbala.mvc.web"})

public class WebMVCConfig extends WebMvcConfigurerAdapter{

@Bean

public SimpleMappingExceptionResolver simpleMappingExceptionResolver()

{

SimpleMappingExceptionResolver b = new SimpleMappingExceptionResolver();

Properties mappings = new Properties();

mappings.put("org.springframework.web.servlet.PageNotFound", "page-404");

mappings.put("org.springframework.dao.DataAccessException", "data-access");

mappings.put("org.springframework.transaction.TransactionException", "transaction-Failure");

b.setExceptionMappings(mappings);

return b;

}

}

(二) HandlerExceptionResolver

相比第一種來說,HandlerExceptionResolver能準(zhǔn)確顯示定義的異常處理頁面,達(dá)到了統(tǒng)一異常處理的目標(biāo)

1.定義一個類實現(xiàn)HandlerExceptionResolver接口,這次貼一個自己以前的代碼

package com.athena.common.handler;

import com.athena.common.constants.ResponseCode;

import com.athena.common.exception.AthenaException;

import com.athena.common.http.RspMsg;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

import org.springframework.web.servlet.HandlerExceptionResolver;

import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.io.IOException;

import java.io.PrintWriter;

/**

* Created by sam on 15/4/14.

*/

public class GlobalHandlerExceptionResolver implements HandlerExceptionResolver {

private static final Logger LOG = LoggerFactory.getLogger(GlobalHandlerExceptionResolver.class);

/**

* 在這里處理所有得異常信息

*/

@Override

public ModelAndView resolveException(HttpServletRequest req, HttpServletResponse resp, Object o, Exception ex) {

ex.printStackTrace();

if (ex instanceof AthenaException) {

//AthenaException為一個自定義異常

ex.printStackTrace();

printWrite(ex.toString(), resp);

return new ModelAndView();

}

//RspMsg為一個自定義處理異常信息的類

//ResponseCode為一個自定義錯誤碼的接口

RspMsg unknownException = null;

if (ex instanceof NullPointerException) {

unknownException = new RspMsg(ResponseCode.CODE_UNKNOWN, "業(yè)務(wù)判空異常", null);

} else {

unknownException = new RspMsg(ResponseCode.CODE_UNKNOWN, ex.getMessage(), null); }

printWrite(unknownException.toString(), resp);

return new ModelAndView();

}

/**

* 將錯誤信息添加到response中

*

* @param msg

* @param response

* @throws IOException

*/

public static void printWrite(String msg, HttpServletResponse response) {

try {

PrintWriter pw = response.getWriter();

pw.write(msg);

pw.flush();

pw.close();

} catch (Exception e) {

e.printStackTrace();

}

}

}

2.加入spring的配置中,這里只貼出了相關(guān)部分

import com.athena.common.handler.GlobalHandlerExceptionResolver;

import org.springframework.context.annotation.Bean;

import com.athena.common.handler.GlobalHandlerExceptionResolver;

import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

/**

* Created by sam on 15/4/14.

*/

public class WebSpringMvcConfig extends WebMvcConfigurerAdapter {

@Bean

public GlobalHandlerExceptionResolver globalHandlerExceptionResolver() {

return new GlobalHandlerExceptionResolver();

}

}

(三)@ExceptionHandler

這是筆者現(xiàn)在項目的使用方式,這里也僅貼出了相關(guān)部分

1.首先定義一個父類,實現(xiàn)一些基礎(chǔ)的方法

package com.balabala.poet.base.spring;

import com.google.common.base.Throwables;

import com.raiyee.poet.base.exception.MessageException;

import com.raiyee.poet.base.utils.Ajax;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

import org.springframework.core.annotation.AnnotationUtils;

import org.springframework.http.HttpStatus;

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

import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.io.IOException;

import java.io.PrintWriter;

import java.util.Date;

public class BaseGlobalExceptionHandler {

protected static final Logger logger = null;

protected static final String DEFAULT_ERROR_MESSAGE = "系統(tǒng)忙，請稍后再試";

protected ModelAndView handleError(HttpServletRequest req, HttpServletResponse rsp, Exception e, String viewName, HttpStatus status) throws Exception {

if (AnnotationUtils.findAnnotation(e.getClass(), ResponseStatus.class) != null)

throw e;

String errorMsg = e instanceof MessageException ? e.getMessage() : DEFAULT_ERROR_MESSAGE;

String errorStack = Throwables.getStackTraceAsString(e);

getLogger().error("Request: {} raised {}", req.getRequestURI(), errorStack);

if (Ajax.isAjax(req)) {

return handleAjaxError(rsp, errorMsg, status);

}

return handleViewError(req.getRequestURL().toString(), errorStack, errorMsg, viewName);

}

protected ModelAndView handleViewError(String url, String errorStack, String errorMessage, String viewName) {

ModelAndView mav = new ModelAndView();

mav.addObject("exception", errorStack);

mav.addObject("url", url);

mav.addObject("message", errorMessage);

mav.addObject("timestamp", new Date());

mav.setViewName(viewName);

return mav;

}

protected ModelAndView handleAjaxError(HttpServletResponse rsp, String errorMessage, HttpStatus status) throws IOException {

rsp.setCharacterEncoding("UTF-8");

rsp.setStatus(status.value());

PrintWriter writer = rsp.getWriter();

writer.write(errorMessage);

writer.flush();

return null;

}

public Logger getLogger() {

return LoggerFactory.getLogger(BaseGlobalExceptionHandler.class);

}

}

2.針對你需要捕捉的異常實現(xiàn)相對應(yīng)的處理方式

package com.balabala.poet.base.spring;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

import org.springframework.http.HttpStatus;

import org.springframework.web.bind.annotation.ControllerAdvice;

import org.springframework.web.bind.annotation.ExceptionHandler;

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

import org.springframework.web.servlet.ModelAndView;

import org.springframework.web.servlet.NoHandlerFoundException;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

@ControllerAdvice

public class GlobalExceptionHandler extends BaseGlobalExceptionHandler {

//比如404的異常就會被這個方法捕獲

@ExceptionHandler(NoHandlerFoundException.class)

@ResponseStatus(HttpStatus.NOT_FOUND)

public ModelAndView handle404Error(HttpServletRequest req, HttpServletResponse rsp, Exception e) throws Exception {

return handleError(req, rsp, e, "error-front", HttpStatus.NOT_FOUND);

}

//500的異常會被這個方法捕獲

@ExceptionHandler(Exception.class)

@ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR)

public ModelAndView handleError(HttpServletRequest req, HttpServletResponse rsp, Exception e) throws Exception {

return handleError(req, rsp, e, "error-front", HttpStatus.INTERNAL_SERVER_ERROR);

}

//TODO 你也可以再寫一個方法來捕獲你的自定義異常

//TRY NOW!!!

@Override

public Logger getLogger() {

return LoggerFactory.getLogger(GlobalExceptionHandler.class);

}

}

以上就三種處理方式，希望對大家的學(xué)習(xí)有所幫助，也希望大家多多支持腳本之家。

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