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;
}
}
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(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();
}
}
}
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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();
}
}
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(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 );
}
}
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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;
@ControllerAdvice
public 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 );
}
}
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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#