平台做网站点击,恒华大厦做网站公司,大连网页建站模板,在线做爰a视频网站在J2EE项目的开发中#xff0c;不管是对底层的数据库操作过程#xff0c;还是业务层的处理过程#xff0c;还是控制层的处理过程#xff0c;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#xff0c;系统的代码耦合度高#xff0c;工作…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。ConfigurationEnableWebMvcComponentScan(basePackages {com.balbala.mvc.web})public class WebMVCConfig extends WebMvcConfigurerAdapter{Beanpublic 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*/Overridepublic 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 {Beanpublic 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!!!Overridepublic 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脚本之家。
