详解Spring全局异常处理的三种方式
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SpringMVC统一处理异常的解决和实现过程
- 使用SpringMVC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。
@Configuration
@EnableWebMvc
@ComponentScan(basePackages={"com.balbala.mvc.web"})
publicclassWebMVCConfigextendsWebMvcConfigurerAdapter{
@Bean
publicSimpleMappingExceptionResolversimpleMappingExceptionResolver()
{
SimpleMappingExceptionResolverb=newSimpleMappingExceptionResolver();
Propertiesmappings=newProperties();
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);
returnb;
}
}
(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
packagecom.athena.common.handler;
importcom.athena.common.constants.ResponseCode;
importcom.athena.common.exception.AthenaException;
importcom.athena.common.http.RspMsg;
importorg.slf4j.Logger;
importorg.slf4j.LoggerFactory;
importorg.springframework.web.servlet.HandlerExceptionResolver;
importorg.springframework.web.servlet.ModelAndView;
importjavax.servlet.http.HttpServletRequest;
importjavax.servlet.http.HttpServletResponse;
importjava.io.IOException;
importjava.io.PrintWriter;
/**
*Createdbysamon15/4/14.
*/
publicclassGlobalHandlerExceptionResolverimplementsHandlerExceptionResolver{
privatestaticfinalLoggerLOG=LoggerFactory.getLogger(GlobalHandlerExceptionResolver.class);
/**
*在这里处理所有得异常信息
*/
@Override
publicModelAndViewresolveException(HttpServletRequestreq,HttpServletResponseresp,Objecto,Exceptionex){
ex.printStackTrace();
if(exinstanceofAthenaException){
//AthenaException为一个自定义异常
ex.printStackTrace();
printWrite(ex.toString(),resp);
returnnewModelAndView();
}
//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
RspMsgunknownException=null;
if(exinstanceofNullPointerException){
unknownException=newRspMsg(ResponseCode.CODE_UNKNOWN,"业务判空异常",null);
}else{
unknownException=newRspMsg(ResponseCode.CODE_UNKNOWN,ex.getMessage(),null);}
printWrite(unknownException.toString(),resp);
returnnewModelAndView();
}
/**
*将错误信息添加到response中
*
*@parammsg
*@paramresponse
*@throwsIOException
*/
publicstaticvoidprintWrite(Stringmsg,HttpServletResponseresponse){
try{
PrintWriterpw=response.getWriter();
pw.write(msg);
pw.flush();
pw.close();
}catch(Exceptione){
e.printStackTrace();
}
}
}
2.加入spring的配置中,这里只贴出了相关部分
importcom.athena.common.handler.GlobalHandlerExceptionResolver;
importorg.springframework.context.annotation.Bean;
importcom.athena.common.handler.GlobalHandlerExceptionResolver;
importorg.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
/**
*Createdbysamon15/4/14.
*/
publicclassWebSpringMvcConfigextendsWebMvcConfigurerAdapter{
@Bean
publicGlobalHandlerExceptionResolverglobalHandlerExceptionResolver(){
returnnewGlobalHandlerExceptionResolver();
}
}
(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
packagecom.balabala.poet.base.spring;
importcom.google.common.base.Throwables;
importcom.raiyee.poet.base.exception.MessageException;
importcom.raiyee.poet.base.utils.Ajax;
importorg.slf4j.Logger;
importorg.slf4j.LoggerFactory;
importorg.springframework.core.annotation.AnnotationUtils;
importorg.springframework.http.HttpStatus;
importorg.springframework.web.bind.annotation.ResponseStatus;
importorg.springframework.web.servlet.ModelAndView;
importjavax.servlet.http.HttpServletRequest;
importjavax.servlet.http.HttpServletResponse;
importjava.io.IOException;
importjava.io.PrintWriter;
importjava.util.Date;
publicclassBaseGlobalExceptionHandler{
protectedstaticfinalLoggerlogger=null;
protectedstaticfinalStringDEFAULT_ERROR_MESSAGE="系统忙，请稍后再试";
protectedModelAndViewhandleError(HttpServletRequestreq,HttpServletResponsersp,Exceptione,StringviewName,HttpStatusstatus)throwsException{
if(AnnotationUtils.findAnnotation(e.getClass(),ResponseStatus.class)!=null)
throwe;
StringerrorMsg=einstanceofMessageException?e.getMessage():DEFAULT_ERROR_MESSAGE;
StringerrorStack=Throwables.getStackTraceAsString(e);
getLogger().error("Request:{}raised{}",req.getRequestURI(),errorStack);
if(Ajax.isAjax(req)){
returnhandleAjaxError(rsp,errorMsg,status);
}
returnhandleViewError(req.getRequestURL().toString(),errorStack,errorMsg,viewName);
}
protectedModelAndViewhandleViewError(Stringurl,StringerrorStack,StringerrorMessage,StringviewName){
ModelAndViewmav=newModelAndView();
mav.addObject("exception",errorStack);
mav.addObject("url",url);
mav.addObject("message",errorMessage);
mav.addObject("timestamp",newDate());
mav.setViewName(viewName);
returnmav;
}
protectedModelAndViewhandleAjaxError(HttpServletResponsersp,StringerrorMessage,HttpStatusstatus)throwsIOException{
rsp.setCharacterEncoding("UTF-8");
rsp.setStatus(status.value());
PrintWriterwriter=rsp.getWriter();
writer.write(errorMessage);
writer.flush();
returnnull;
}
publicLoggergetLogger(){
returnLoggerFactory.getLogger(BaseGlobalExceptionHandler.class);
}
}
2.针对你需要捕捉的异常实现相对应的处理方式
packagecom.balabala.poet.base.spring;
importorg.slf4j.Logger;
importorg.slf4j.LoggerFactory;
importorg.springframework.http.HttpStatus;
importorg.springframework.web.bind.annotation.ControllerAdvice;
importorg.springframework.web.bind.annotation.ExceptionHandler;
importorg.springframework.web.bind.annotation.ResponseStatus;
importorg.springframework.web.servlet.ModelAndView;
importorg.springframework.web.servlet.NoHandlerFoundException;
importjavax.servlet.http.HttpServletRequest;
importjavax.servlet.http.HttpServletResponse;
@ControllerAdvice
publicclassGlobalExceptionHandlerextendsBaseGlobalExceptionHandler{
//比如404的异常就会被这个方法捕获
@ExceptionHandler(NoHandlerFoundException.class)
@ResponseStatus(HttpStatus.NOT_FOUND)
publicModelAndViewhandle404Error(HttpServletRequestreq,HttpServletResponsersp,Exceptione)throwsException{
returnhandleError(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)
publicModelAndViewhandleError(HttpServletRequestreq,HttpServletResponsersp,Exceptione)throwsException{
returnhandleError(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
//TRYNOW!!!
@Override
publicLoggergetLogger(){
returnLoggerFactory.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毛票票。