AOP（面向方面）的思想，就是把項目共同的那部分功能分離開來，比如日志記錄，避免在業(yè)務(wù)邏輯里面夾雜著跟業(yè)務(wù)邏輯無關(guān)的代碼 id="cproIframe_u1892994_2" width="580" height="90" src="http://pos.baidu.com/acom?adn=3&at=231&aurl=&cad=1&ccd=24&cec=GBK&cfv=17&ch=0&col=zh-CN&conBW=0&conOP=1&cpa=1&dai=2&dis=0&ltr=https%3A%2F%2Fwww.baidu.com%2Flink%3Furl%3DZo87x2oY1aTIV7BqAJF2O_rS8vSjZfTOHAVsD7gTOIOVCfKUzurVEwTbWtwjhHQm%26wd%3Daop%25E7%25BC%2596%25E7%25A8%258B%2520java%2520interface%26issp%3D1%26f%3D3%26ie%3Dutf-8%26tn%3Dbaiduhome_pg%26inputT%3D1561%26oq%3DAOP%25E7%25BC%2596%25E7%25A8%258B%2520%26rsp%3D2&ltu=http%3A%2F%2Fwww.jb51.net%2Farticle%2F41733.htm&lu_161=0&lunum=6&n=jb51_cpr&pcs=1196x557&pis=10000x10000&ps=516x133&psr=1366x768&pss=1196x517&qn=339fe513a5488057&rad=&rsi0=580&rsi1=90&rsi5=4&rss0=%23FFFFFF&rss1=%23F7FCFF&rss2=%230000ff&rss3=%23444444&rss4=%23008000&rss5=&rss6=%23e10900&rss7=&scale=&skin=tabcloud_skin_3&stid=5&td_id=1892994&ti=java%E4%BD%BF%E7%94%A8%E5%8A%A8%E6%80%81%E4%BB%A3%E7%90%86%E6%9D%A5%E5%AE%9E%E7%8E%B0AOP(%E6%97%A5%E5%BF%97%E8%AE%B0%E5%BD%95)%E7%9A%84%E5%AE%9E%E4%BE%8B%E4%BB%A3%E7%A0%81_java_%E8%84%9A%E6%9C%AC%E4%B9%8B%E5%AE%B6&titFF=%E5%AE%8B%E4%BD%93&titFS=12&titTA=left&tn=text_default_580_90&tpr=1430969112016&ts=1&version=2.0&xuanting=0&dtm=BAIDU_DUP2_SETJSONADSLOT&dc=2&di=u1892994&tt=1430969111986.2132.2227.2228" align="center,center" marginwidth="0" marginheight="0" scrolling="no" frameborder="0" allowtransparency="true">

下面是一個AOP實現(xiàn)的簡單例子：

首先定義一些業(yè)務(wù)方法：

復(fù)制代碼代碼如下:
/**
?* Created with IntelliJ IDEA.
?* Author: wangjie? email:tiantian.china.2@gmail.com
?* Date: 13-9-23
?* Time: 下午3:49
?*/
public interface BussinessService {
??? public String login(String username, String password);
??? public String find();
}

public class BussinessServiceImpl implements BussinessService {
??? private Logger logger = Logger.getLogger(this.getClass().getSimpleName());

??? @Override
??? public String login(String username, String password) {
??????? return "login success";
??? }

??? @Override
??? public String find() {
??????? return "find success";
??? }

}

復(fù)制代碼代碼如下:
/**
?* Created with IntelliJ IDEA.
?* Author: wangjie? email:tiantian.china.2@gmail.com
?* Date: 13-9-24
?* Time: 上午10:27
?*/
public interface WorkService {
??? public String work();
??? public String sleep();
}

public class WorkServiceImpl implements WorkService{
??? @Override
??? public String work() {
??????? return "work success";
??? }

??? @Override
??? public String sleep() {
??????? return "sleep success";
??? }
}

實現(xiàn)InvocationHandler接口，使用map來存儲不同的InvocationHandler對象，避免生成過多。

復(fù)制代碼代碼如下:
package com.wangjie.aoptest2.invohandler;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.Arrays;
import java.util.HashMap;
import java.util.logging.Logger;

/**
?* Created with IntelliJ IDEA.
?* Author: wangjie? email:tiantian.china.2@gmail.com
?* Date: 13-9-23
?* Time: 下午3:47
?*/
public class LogInvoHandler implements InvocationHandler{
??? private Logger logger = Logger.getLogger(this.getClass().getSimpleName());

??? private Object target; // 代理目標(biāo)
??? private Object proxy; // 代理對象

??? private static HashMap<Class<?>, LogInvoHandler> invoHandlers = new HashMap<Class<?>, LogInvoHandler>();

??? private LogInvoHandler() {
??? }

??? /**
???? * 通過Class來生成動態(tài)代理對象Proxy
???? * @param clazz
???? * @return
???? */
??? public synchronized static<T> T getProxyInstance(Class<T> clazz){
??????? LogInvoHandler invoHandler = invoHandlers.get(clazz);

??????? if(null == invoHandler){
??????????? invoHandler = new LogInvoHandler();
??????????? try {
??????????????? T tar = clazz.newInstance();
??????????????? invoHandler.setTarget(tar);
??????????????? invoHandler.setProxy(Proxy.newProxyInstance(tar.getClass().getClassLoader(),
??????????????????????? tar.getClass().getInterfaces(), invoHandler));
??????????? } catch (Exception e) {
??????????????? e.printStackTrace();
??????????? }
??????????? invoHandlers.put(clazz, invoHandler);

??????? }

??????? return (T)invoHandler.getProxy();
??? }

??? @Override
??? public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {

??????? Object result = method.invoke(target, args); // 執(zhí)行業(yè)務(wù)處理

??????? // 打印日志
??????? logger.info("____invoke method: " + method.getName()
??????????????????? + "; args: " + (null == args ? "null" : Arrays.asList(args).toString())
??????????????????? + "; return: " + result);

??????? return result;
??? }

??? public Object getTarget() {
??????? return target;
??? }

??? public void setTarget(Object target) {
??????? this.target = target;
??? }

??? public Object getProxy() {
??????? return proxy;
??? }

??? public void setProxy(Object proxy) {
??????? this.proxy = proxy;
??? }
}

然后編寫一個Test類測試：

復(fù)制代碼代碼如下:
/**
?* Created with IntelliJ IDEA.
?* Author: wangjie? email:tiantian.china.2@gmail.com
?* Date: 13-9-24
?* Time: 上午9:54
?*/
public class Test {
??? public static Logger logger = Logger.getLogger(Test.class.getSimpleName());
??? public static void main(String[] args) {

??????? BussinessService bs = LogInvoHandler.getProxyInstance(BussinessServiceImpl.class);
??????? bs.login("zhangsan", "123456");
??????? bs.find();

??????? logger.info("--------------------------------------");

??????? WorkService ws = LogInvoHandler.getProxyInstance(WorkServiceImpl.class);
??????? ws.work();
??????? ws.sleep();

??????? logger.info("--------------------------------------");

??????? BussinessService bss = LogInvoHandler.getProxyInstance(BussinessServiceImpl.class);
??????? bss.login("lisi", "654321");
??????? bss.find();

??? }
}

以后需要添加新的業(yè)務(wù)邏輯XXXService，只需要調(diào)用

XXXService xs = LogInvoHandler.getProxyInstance(XXXServiceImpl.class);

即可。

也可以模仿Spring等框架的配置，把bean的類名配置在xml文件中，如：

<bean id="bussinessService" class="com.wangjie.aoptest2.service.impl.BussinessServiceImpl">

然后在java代碼中解析xml，通過Class.forName("com.wangjie.aoptest2.service.impl.BussinessServiceImpl");獲得Class對象

然后通過LogInvoHandler.getProxyInstance(Class.forName("com.wangjie.aoptest2.service.impl.BussinessServiceImpl"));獲得代理對象Proxy

再使用反射去調(diào)用代理對象的方法。

?

運行結(jié)果如下：

九月 24, 2013 11:08:03 上午 com.wangjie.aoptest2.invohandler.LogInvoHandler invoke
INFO: ____invoke method: login; args: [zhangsan, 123456]; return: login success
九月 24, 2013 11:08:03 上午 com.wangjie.aoptest2.invohandler.LogInvoHandler invoke
INFO: ____invoke method: find; args: null; return: find success
九月 24, 2013 11:08:03 上午 com.wangjie.aoptest2.Test main
INFO: --------------------------------------
九月 24, 2013 11:08:03 上午 com.wangjie.aoptest2.invohandler.LogInvoHandler invoke
INFO: ____invoke method: work; args: null; return: work success
九月 24, 2013 11:08:03 上午 com.wangjie.aoptest2.invohandler.LogInvoHandler invoke
INFO: ____invoke method: sleep; args: null; return: sleep success
九月 24, 2013 11:08:03 上午 com.wangjie.aoptest2.Test main
INFO: --------------------------------------
九月 24, 2013 11:08:03 上午 com.wangjie.aoptest2.invohandler.LogInvoHandler invoke
INFO: ____invoke method: login; args: [lisi, 654321]; return: login success
九月 24, 2013 11:08:03 上午 com.wangjie.aoptest2.invohandler.LogInvoHandler invoke
INFO: ____invoke method: find; args: null; return: find success

總結(jié)

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