(1)面向切面编程(方面),利用 AOP 可以对业务逻辑的各个部分进行隔离,从而使得业务逻辑各部分之间的耦合度降低,提高程序的可重用性,同时提高了开发的效率。
(2)通俗描述:不通过修改源代码方式,在主干功能里面添加新功能
(3)使用登录例子说明 AOP
public interface UserDao {
public int add(int a, int b);
public String update(String id);
}
(2)创建接口实现类,实现方法
public class UserDaoImpl implements UserDao{
@Override
public int add(int a, int b) {
return a+b;
}
@Override
public String update(String id) {
return id;
}
}
(3)使用 Proxy 类创建接口代理对象
public class JDKProxy {
public static void main(String[] args) {
//创建接口实现类代理对象
Class[] interfaces = {UserDao.class};
// 使用匿名内部类
// Proxy.newProxyInstance(JDKProxy.class.getClassLoader(), interfaces, new InvocationHandler() {
// @Override
// public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
// return null;
// }
// });
UserDaoImpl userDao = new UserDaoImpl();
UserDao dao =(UserDao) Proxy.newProxyInstance(JDKProxy.class.getClassLoader(), interfaces, new UserDaoProxy(userDao));
int result = dao.add(1,2);
System.out.println("result:" + result);
}
}
//创建代理对象代码
class UserDaoProxy implements InvocationHandler{
//1 把创建的是谁的代理对象,把谁传递过来
//有参数构造传递
private Object obj;
public UserDaoProxy(Object obj){
this.obj=obj;
}
//增强的逻辑
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
//方法之前
System.out.println("方法之前执行...."+method.getName()+":传递的参数..."+ Arrays.toString(args));
//被增强的方法执行
Object res = method.invoke(obj, args);
//方法之后
System.out.println("方法之后执行..." + obj);
return res;
}
}
public class User {
public void add(){
System.out.println("add...");
}
}
//增强的类
public class UserProxy {
//前置通知
public void before(){
System.out.println("before.....");
}
}
<?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:context="http://www.springframework.org/schema/context"
xmlns:aop="http://www.springframework.org/schema/aop"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd">
<!--开启注解扫描-->
<context:component-scan base-package="com.gbx.spring5.aopanno"></context:component-scan>
</beans>
//增强的类
@Component
public class UserProxy {
//前置通知
public void before(){
System.out.println("before.....");
}
}
//被增强的类
@Component
public class User {
public void add(){
System.out.println("add...");
}
}
//增强的类
@Component
@Aspect //生成代理对象
public class UserProxy {
//前置通知
public void before(){
System.out.println("before.....");
}
}
<!--开启Aspect生成代理对象-->
<aop:aspectj-autoproxy></aop:aspectj-autoproxy>
//增强的类
@Component
@Aspect //生成代理对象
public class UserProxy {
//前置通知
//@Before注解表示作为前置通知
@Before(value="execution(* com.gbx.spring5.aopanno.User.add(..))")
public void before(){
System.out.println("before.....");
}
//后置通知(返回通知)
@AfterReturning(value = "execution(* com.gbx.spring5.aopanno.User.add(..))")
public void afterReturning(){
System.out.println("afterReturning...");
}
//异常通知
@AfterThrowing(value = "execution(* com.gbx.spring5.aopanno.User.add(..))")
public void afterThrowing(){
System.out.println("afterThrowing...");
}
//环绕通知
@Around(value = "execution(* com.gbx.spring5.aopanno.User.add(..))")
public void around(ProceedingJoinPoint proceedingJoinPoint) throws Throwable {
System.out.println("环绕之前...");
proceedingJoinPoint.proceed();
System.out.println("环绕之后...");
}
//最终通知
@After(value = "execution(* com.gbx.spring5.aopanno.User.add(..))")
public void after(){
System.out.println("after...");
}
}
//相同的切入点抽取
@Pointcut(value = "execution(* com.gbx.spring5.aopanno.User.add(..))")
public void pointdemo(){
}
//前置通知
//@Before注解表示作为前置通知
@Before(value="pointdemo()")
public void before(){
System.out.println("before.....");
}
@Component
@Aspect
@Order(1)
public class PersonProxy {
//后置通知(返回通知)
@Before(value = "execution(* com.gbx.spring5.aopanno.User.add(..))")
public void afterReturning(){
System.out.println("Person Before...");
}
}
@Configuration
@ComponentScan(basePackages = {"com.gbx"})
@EnableAspectJAutoProxy(proxyTargetClass = true)
public class ConfigAop {
}
public class Book {
public void buy(){
System.out.println("buy.....");
}
}
public class BookProxy {
public void before(){
System.out.println("before......");
}
}
<!--创建对象-->
<bean id="book" class="com.gbx.spring5.aopxml.Book"></bean>
<bean id="bookProxy" class="com.gbx.spring5.aopxml.BookProxy"></bean>
<!--配置aop增强-->
<aop:config>
<!--切入点-->
<aop:pointcut id="p" expression="execution(* com.gbx.spring5.aopxml.Book.buy(..))"/>
<!--配置切面-->
<aop:aspect ref="bookProxy">
<!--增强作用在具体的方法上-->
<aop:before method="before" pointcut-ref="p"/>
</aop:aspect>
</aop:config>