动态代理 AOP底层实现：有接口自动应用的就是JDK动态代理
（1）.JDK 在运行时运行时注入
本质：在内存中构建出接口的实现类
特点：被代理对象，必须有接口
实例：
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
public class Test {
public static void main(String[] args) {
final SomeService service = new SomeServiceImpl();
SomeService proxy =(SomeService)Proxy.newProxyInstance(service.getClass().getClassLoader(),
service.getClass().getInterfaces(), new InvocationHandler() {
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
System.out.println("before=======");
method.invoke(service,args);
System.out.println("after========");
return null;
}
});
proxy.doSome();
}
}
Cglib 底层，注入，编译期已经注入了
本质：在内存中生成被代理类（目标类）的【子类】
特点：可以在没有接口的情况下代理
对于不使用接口的业务类，无法使用JDK动态代理，cglib采用非常底层的字节码技术，
可以为一个类创建子类
import cn.SomeServiceImpl;
import org.springframework.cglib.proxy.Enhancer;
import org.springframework.cglib.proxy.MethodInterceptor;
import org.springframework.cglib.proxy.MethodProxy;
import java.lang.reflect.Method;
public class Test {
public static void main(String[] args) {
final SomeServiceImpl someService = new SomeServiceImpl();
Enhancer enhancer = new Enhancer();
enhancer.setSuperclass(someService.getClass());
enhancer.setCallback(new MethodInterceptor() {
public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {
System.out.println("=======before");
methodProxy.invoke(someService,objects);
return null;
}
});
SomeServiceImpl proxy = (SomeServiceImpl) enhancer.create();
proxy.doSome();
}
}
接下来是四种增强
前置增强 MethodBeforeAdvice
import org.springframework.aop.AfterReturningAdvice;
import java.lang.reflect.Method;
public class AfterAdvice implements AfterReturningAdvice {
public void afterReturning(Object o, Method method, Object[] objects, Object o1) throws Throwable {
System.out.println("after========");
}
}
<bean id="service" class="cn.SomeServiceImpl"></bean>
<bean id="beforeAdvice" class="cn.BeforeAdvice"></bean> <bean id="proxyService" class="org.springframework.aop.framework.ProxyFactoryBean"> <property name="target" ref="service"></property> <property name="interceptorNames" value="beforeAdvice"></property> </bean>
后置增强 AfterReturingAdvice
import org.springframework.aop.AfterReturningAdvice;
import java.lang.reflect.Method;
public class AfterAdvice implements AfterReturningAdvice {
public void afterReturning(Object o, Method method, Object[] objects, Object o1) throws Throwable {
System.out.println("after========");
}
}
xml文件内容
<bean id="service" class="cn.SomeServiceImpl"></bean>
<bean id="afterAdvice" class="cn.AfterAdvice"></bean>
<bean id="proxyService" class="org.springframework.aop.framework.ProxyFactoryBean">
<property name="target" ref="service"></property>
<property name="interceptorNames" value="afterAdvice"></property>
</bean>
3.环绕增强
import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;
public class HrAdvice implements MethodInterceptor {
public Object invoke(MethodInvocation methodInvocation) throws Throwable {
System.out.println("before====");
methodInvocation.proceed();
System.out.println("after====");
return null;
}
}
xml文件
<bean id="service" class="cn.SomeServiceImpl"></bean>
<bean id="hrAdvice" class="cn.HrAdvice"></bean>
<bean id="proxyService" class="org.springframework.aop.framework.ProxyFactoryBean">
<property name="target" ref="service"></property>
<property name="interceptorNames" value="hrAdvice"></property>
</bean>
异常增强
public class MyThrowsAdvice implements ThrowsAdvice {
public void afterThrowing(Exception e){
System.out.println("网络异常......");
}
}
<bean id="service" class="cn.SomeServiceImpl"></bean>
<bean id="throwsAdvice" class="cn.MyThrowsAdvice"></bean>
<bean id="proxyService" class="org.springframework.aop.framework.ProxyFactoryBean">
<property name="target" ref="service"></property>
<property name="interceptorNames" value="throwsAdvice"></property>
</bean>
