在J2EE項目的開發中，不管是對底層的數據庫操作過程，還是業務層的處理過程，還是控制層的處理過程，都不可避免會遇到各種可預知的、不可預知的異常需要處理。每個過程都單獨處理異常，系統的代碼耦合度高，工作量大且不好統一，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，這樣既保證了相關處理過程的功能較單一，也實現了異常信息的統一處理和維護？答案是肯定的。下面將介紹使用Spring MVC統一處理異常的解決和實現過程
- 使用Spring MVC提供的SimpleMappingExceptionResolver
- 實現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點，但該方法僅能獲取到異常信息，若在出現異常時，對需要獲取除異常以外的數據的情況不適用。
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@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能準確顯示定義的異常處理頁面,達到了統一異常處理的目標
1.定義一個類實現HandlerExceptionResolver接口,這次貼一個自己以前的代碼
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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, "業務判空異常", 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,這里只貼出了相關部分
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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
這是筆者現在項目的使用方式,這里也僅貼出了相關部分
1.首先定義一個父類,實現一些基礎的方法
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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相對應的處理方式
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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;@ControllerAdvicepublic 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，希望對大家的學習有所幫助，也希望大家多多支持服務器之家。
原文鏈接：http://www.jianshu.com/p/f968b8dcf95a#
