文章来源:http://www.blogjava.net/amigoxie/archive/2007/07/24/132142.html
Tags: springspring | AOPAOP
2007-7-26 0:19:36 | 编辑
用spring的AOP实现异常拦截
最近用到spring的AOP来实现异常拦截，用到了spring的ThrowsAdvice。ThrowsAdvice是一个标示接口，我们可以在类中定义一个或多个，来捕获定义异常通知的bean抛出的异常，并在抛出异常前执行相应的方法。
我想大家可能都在项目中有过这样的需求，想在某种异常抛出时进行一些记录操作，例如记录错误日志到数据库或日志文件中，但把这些代码分布到项目各处不但难于管理，并且代码量巨大，用Spring的AOP来实现拦截不失为一个比较好的方法。
下面，让我们来感受一下它的魅力吧。
1. 操作类TestBean
/** *//**
* Copyright 2007 GuangZhou Cotel Co. Ltd. * All right reserved. * 测试异常拦截的bean * @author <a href="mailto:xiexingxing1121@126.com">AmigoXie</a> * @version 1.0 * Creation date: 2007-7-24 - 下午08:00:37
*/public class TestBean 
{
public void method1() throws Exception { throw new Exception("Exception happened!");
} /** *//** * 将字符串转换为整数. * @param number 需转换的字符串 * @return 转换成的字符串 * @throws NumberFormatException * @author <a href="mailto:xiexingxing1121@126.com">AmigoXie</a> * Creation date: 2007-7-24 - 下午08:05:41 */ public int changeToNumber(String number) throws NumberFormatException { //当number为空或非数字时，将抛出NumberFormatException int num = Integer.parseInt(number); return num; }}
2. 错误日志拦截类ExceptionAdvisor
import org.springframework.aop.ThrowsAdvice;import org.springframework.aop.framework.ProxyFactory;import java.lang.reflect.Method;/** *//** * Copyright 2007 GuangZhou Cotel Co. Ltd. * All right reserved. * 异常拦截类. * @author <a href="mailto:xiexingxing1121@126.com">AmigoXie</a> * @version 1.0 * Creation date: 2007-7-24 - 下午08:12:25 */public class ExceptionAdvisor implements ThrowsAdvice { public static void main(String[] args) { TestBean bean = new TestBean(); ProxyFactory pf = new ProxyFactory(); pf.setTarget(bean); pf.addAdvice(new ExceptionAdvisor()); TestBean proxy = (TestBean) pf.getProxy(); try { proxy.method1(); } catch (Exception ignore) { } try { proxy.changeToNumber("amigo"); } catch (Exception ignore) { } } /** *//** * 对未知异常的处理. * @param method * @param args * @param target * @param ex * @throws Throwable * @author <a href="mailto:xiexingxing1121@126.com">AmigoXie</a> * Creation date: 2007-7-24 - 下午03:35:02 */ public void afterThrowing(Method method, Object[] args, Object target, Exception ex) throws Throwable { System.out.println("*************************************"); System.out.println("Error happened in class: " + target.getClass().getName()); System.out.println("Error happened in method: " + method.getName()); for (int i = 0; i < args.length; i++) { System.out.println("arg[" + i + "]: " + args[i]); } System.out.println("Exception class: " + ex.getClass().getName()); System.out.println("*************************************"); } /** *//** * 对NullPointerException异常的处理 * @param method * @param args * @param target * @param ex * @throws Throwable * @author <a href="mailto:xiexingxing1121@126.com">AmigoXie</a> * Creation date: 2007-7-24 - 下午01:17:35 */ public void afterThrowing(Method method, Object[] args, Object target, NullPointerException ex) throws Throwable { System.out.println("*************************************"); System.out.println("Error happened in class: " + target.getClass().getName()); System.out.println("Error happened in method: " + method.getName()); for (int i = 0; i < args.length; i++) { System.out.println("args[" + i + "]: " + args[i]); } System.out.println("Exception class: " + ex.getClass().getName()); System.out.println("*************************************"); }} 运行ExceptionAdvisor类后，结果如下：
************************************
Error happened in class: TestBean
Error happened in method: method1
Exception class: java.lang.Exception
*************************************
*************************************
Error happened in class: TestBean
Error happened in method: changeToNumber
arg[0]: amigo
Exception class: java.lang.NumberFormatException
*************************************
在工程中，可将ExceptionAdvisor类作为bean定义，并指定要纳入其进行异常拦截的类。
