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

• 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。