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。

@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

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

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

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;

@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);

}

}

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。