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Spring MVC统一处理异常的解决和实现过程
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- 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创新互联。
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