一、静态代理
- 实现方法:代理对象与目标对象实现统一的接口或者继承统一的父类。
- demo:
public interface IService {
public void method(String argument);
}
public class ServiceImpl implements IService{
@Override
public void method(String argument) {
System.out.println("argument = [" + argument + "]");
}
}
public class ServiceProxy implements IService {
private IService target;
public ServiceProxy(IService target) {
this.target = target;
}
@Override
public void method(String argument) {
System.out.println("执行前");
target.method(argument);
System.out.println("执行后");
}
}
public class Main {
public static void main(String[] args) {
IService target = new ServiceImpl();
ServiceProxy proxy = new ServiceProxy(target);
proxy.method("hello");
}
}
二、JDK代理
- 实现方法:目标对象实现接口,代理对象具有获取代理方法。
- demo:
public class ProxyFactory{
private Object target;
public ProxyFactory(Object target) {
this.target = target;
}
public Object getProxyInstance() {
return Proxy.newProxyInstance(
target.getClass().getClassLoader(),
target.getClass().getInterfaces(),
(proxy, method, args) -> {
System.out.println("执行前");
Object res = method.invoke(target, args);
System.out.println("执行后");
return res;
}
);
}
}
public class Main {
public static void main(String[] args) {
IService target = new ServiceImpl();
IService proxyInstance = (IService) new ProxyFactory(target).getProxyInstance();
proxyInstance.method("hello");
}
}
三、cglib代理:
- 实现方法:引入cglib的jar包
- demo:
public class CglibProxyFactory implements MethodInterceptor {
private Object target;
public CglibProxyFactory(Object target) {
this.target = target;
}
public Object getProxyInstance() {
Enhancer en = new Enhancer();
en.setSuperclass(target.getClass());
en.setCallback(this);
return en.create();
}
@Override
public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {
System.out.println("执行前");
Object res = method.invoke(target, objects);
System.out.println("执行后");
return res;
}
}
public class Main {
public static void main(String[] args) {
IService target = new ServiceImpl();
IService proxyInstance = (IService) new CglibProxyFactory(target).getProxyInstance();
proxyInstance.method("hello");
}
}
3.在Spring的AOP中,如果加入容器的目标对象有实现接口,会用JDK代理,否则用cglib代理。
4.目标对象中被static、final修饰的方法不会被拦截,因此不会执行额外的业务。