在J2EE项目的开发中，不管是对底层的数据库操作过程，还是业务层的处理过程，还是控制层的处理过程，都不可避免会遇到各种可预知的、不可预知的异常需要处理。每个过程都单独处理异常，系统的代码耦合度高，工作量大且不好统一，维护的工作量也很大。 那么，能不能将所有类型的异常处理从各处理过程解耦出来，这样既保证了相关处理过程的功能较单一，也实现了异常信息的统一处理和维护？答案是肯定的。下面将介绍使用Spring MVC统一处理异常的解决和实现过程
- 使用Spring MVC提供的SimpleMappingExceptionResolver
- 实现Spring的异常处理接口HandlerExceptionResolver 自定义自己的异常处理器
- 使用@ExceptionHandler注解实现异常处理
(一) SimpleMappingExceptionResolver
使用这种方式具有集成简单、有良好的扩展性、对已有代码没有入侵性等优点，但该方法仅能获取到异常信息，若在出现异常时，对需要获取除异常以外的数据的情况不适用。
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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
相比第一种来说,HandlerExceptionResolver能准确显示定义的异常处理页面,达到了统一异常处理的目标
1.定义一个类实现HandlerExceptionResolver接口,这次贴一个自己以前的代码
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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); /** * 在这里处理所有得异常信息 */ @Override public ModelAndView resolveException(HttpServletRequest req, HttpServletResponse resp, Object o, Exception ex) { ex.printStackTrace(); if (ex instanceof AthenaException) { //AthenaException为一个自定义异常 ex.printStackTrace(); printWrite(ex.toString(), resp); return new ModelAndView(); } //RspMsg为一个自定义处理异常信息的类 //ResponseCode为一个自定义错误码的接口 RspMsg unknownException = null; if (ex instanceof NullPointerException) { unknownException = new RspMsg(ResponseCode.CODE_UNKNOWN, "业务判空异常", null); } else { unknownException = new RspMsg(ResponseCode.CODE_UNKNOWN, ex.getMessage(), null); } printWrite(unknownException.toString(), resp); return new ModelAndView(); } /** * 将错误信息添加到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,这里只贴出了相关部分
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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
这是笔者现在项目的使用方式,这里也仅贴出了相关部分
1.首先定义一个父类,实现一些基础的方法
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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 = "系统忙，请稍后再试"; 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.针对你需要捕捉的异常实现相对应的处理方式
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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的异常就会被这个方法捕获 @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的异常会被这个方法捕获 @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 你也可以再写一个方法来捕获你的自定义异常 //TRY NOW!!! @Override public Logger getLogger() { return LoggerFactory.getLogger(GlobalExceptionHandler.class); } } |
以上就三种处理方式，希望对大家的学习有所帮助，也希望大家多多支持服务器之家。
原文链接：http://www.jianshu.com/p/f968b8dcf95a#
