为什么80%的码农都做不了架构师?>>>
AOP 的重要概念
1 切面
切面编程(事务, 日志, 安全) 编程实现 在实际应用中通常是存放切面的普通java 类 需要通过配置<bean>标识指定
2 通知
通知是切面的具体表现,亿ro目标作为参照点,根据位置的不同,又分为 (前置通知, 后置通知 , 异常通知, 环绕通知)调用时 需要指定具体位置。
3 切入点
切入点用于定义通知到什么连接点去。
4 目标对象
目标对象指定的是织入切面的对象
5 代理对象
通过目标对象应用之后,被动态创建的对象, 代理对象的功能相当与目标对象中核心业务逻辑功能加上方面代码实现的功能
6 织入
织入是将切面应用到目标对象 ,从而创建一个新的代理对象的过程。
代码实现
基于代理类ProxyFactoryBean实现AOP
package com.sun.dao;
public interface UserDao {
//添加用户
//删除用户
public void delUser(int id);
public void addUser(String username, String password);
}
package com.sun.dao;
public class UserDaoImpl implements UserDao {
public void addUser(String username, String password) {
// TODO Auto-generated method stub
System.out.println("添加用户"+username+"成功");
}
public void delUser(int id) {
// TODO Auto-generated method stub
System.out.println("删除"+id+"成功");
}
}
package com.sun.biz;
public interface UserBiz {
public void addUser(String username,String password);
//删除用户
public void delUser(int id);
}
package com.sun.biz;
import com.sun.dao.UserDao;
public class UserBizImpl implements UserBiz {
UserDao userdao;
public UserDao getUserdao() {
return userdao;
}
public void setUserdao(UserDao userdao) {
this.userdao = userdao;
}
public void addUser(String username, String password) {
// TODO Auto-generated method stub
userdao.addUser(username, password);
}
public void delUser(int id) {
// TODO Auto-generated method stub
userdao.delUser(id);
}
}
package com.sun.aop;
import java.lang.reflect.Method;
import org.apache.log4j.Logger;
import org.springframework.aop.MethodBeforeAdvice;
public class LoggerAdvice implements MethodBeforeAdvice {
private Logger logger = Logger.getLogger(LoggerAdvice.class);
public void before(Method method, Object[] args, Object target)
throws Throwable {
// TODO Auto-generated method stub
String targetClassName = target.getClass().getName();
//h获取被调用的方法名
String targetMethodName=method.getName();
//日志格式字符串
String loginInfoText = "前置通知"+targetClassName+"类的"+targetMethodName+"方法开始执行";
logger.info(loginInfoText);
}
创建log4j.properties
log4j.rootLogger=info,stdout,info,debug,error
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=[%-5p] [%d{HH:mm:ss}] %c - %m%n
log4j.logger.info=info
log4j.appender.info=org.apache.log4j.DailyRollingFileAppender
log4j.appender.info.layout=org.apache.log4j.PatternLayout
log4j.appender.info.layout.ConversionPattern=[%-5p] [%d{HH:mm:ss}] %c - %m%n
log4j.appender.info.datePattern='.'yyyy-MM-dd
log4j.appender.info.Threshold = INFO
log4j.appender.info.append=true
log4j.appender.info.File=${webApp.root}/WEB-INF/logs/info.log
log4j.logger.debug=debug
log4j.appender.debug=org.apache.log4j.DailyRollingFileAppender
log4j.appender.debug.layout=org.apache.log4j.PatternLayout
log4j.appender.debug.layout.ConversionPattern=[%-5p] [%d{HH:mm:ss}] %c - %m%n
log4j.appender.debug.datePattern='.'yyyy-MM-dd
log4j.appender.debug.Threshold = DEBUG
log4j.appender.debug.append=true
log4j.appender.debug.File=${webApp.root}/WEB-INF/logs/debug.log
log4j.logger.error=error
log4j.appender.error=org.apache.log4j.DailyRollingFileAppender
log4j.appender.error.layout=org.apache.log4j.PatternLayout
log4j.appender.error.layout.ConversionPattern=[%-5p] [%d{HH:mm:ss}] %c - %m%n
log4j.appender.error.datePattern='.'yyyy-MM-dd
log4j.appender.error.Threshold = ERROR
log4j.appender.error.append=true
log4j.appender.error.File=${webApp.root}/WEB-INF/logs/error.log
将业务逻辑代码 和 方面代码 组装到代理类中
是用Spring 配置文件来实现ApllicationContext.xml 文件中来
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">
<!-- 配置创建UserDAOImpl的实例 -->
<bean id="userDAO" class="com.sun.dao.UserDaoImpl">
</bean>
<!-- 配置创建UserBizImpl的实例 -->
<bean id="userBiz" class="com.sun.biz.UserBizImpl">
<!-- 依赖注入数据访问层组件 -->
<property name="userdao" ref="userDAO" />
</bean>
<!-- 定义前置通知 -->
<bean id="logAdvice" class="com.sun.aop.LoggerAdvice"></bean>
<!-- 定义代理类,名 称为ub,将通过ub访问业务类中的方法 -->
<bean id="ub" class="org.springframework.aop.framework.ProxyFactoryBean">
<property name="proxyInterfaces">
<value>com.sun.biz.UserBiz</value>
</property>
<property name="interceptorNames">
<list>
<value>logAdvice</value>
</list>
</property>
<property name="target" ref="userBiz"></property>
</bean>
</beans>
编制测试类
package com.sun.test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.sun.biz.UserBiz;
public class Test {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
//装配UserbIZimpl事例化
UserBiz userbiz = (UserBiz) context.getBean("ub");
userbiz.addUser("wangming", "485487");
userbiz.delUser(1);
}
}
结果显示
[INFO ] [16:11:10] org.springframework.context.support.ClassPathXmlApplicationContext - Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@1060478: display name [org.springframework.context.support.ClassPathXmlApplicationContext@1060478]; startup date [Mon Sep 17 16:11:10 CST 2012]; root of context hierarchy
[INFO ] [16:11:10] org.springframework.beans.factory.xml.XmlBeanDefinitionReader - Loading XML bean definitions from class path resource [applicationContext.xml]
[INFO ] [16:11:10] org.springframework.context.support.ClassPathXmlApplicationContext - Bean factory for application context [org.springframework.context.support.ClassPathXmlApplicationContext@1060478]: org.springframework.beans.factory.support.DefaultListableBeanFactory@11daa0e
[INFO ] [16:11:10] org.springframework.beans.factory.support.DefaultListableBeanFactory - Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@11daa0e: defining beans [userDAO,userBiz,logAdvice,ub]; root of factory hierarchy
[INFO ] [16:11:10] com.sun.aop.LoggerAdvice - 前置通知com.sun.biz.UserBizImpl类的addUser方法开始执行
添加用户wangming成功
[INFO ] [16:11:10] com.sun.aop.LoggerAdvice - 前置通知com.sun.biz.UserBizImpl类的delUser方法开始执行
删除1成功
成功