Java动态代理的简单示例

1. 需要一个接口，用于定义被代理的行为。不使用接口不行。2. InvocationHandler接口的invoke方法有3个参数，分别是被代理对象、被执行的接口方法、方法参数3. Proxy.newInstance的参数分别是被代理对象的类加载器、接口、InvocationHandler实例

public class MyInvocationHandler implements InvocationHandler {

private Object target;

public MyInvocationHandler() {
super();
}

public MyInvocationHandler(Object target) {
super();
this.target = target;
}

@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
System.out.println("before...");
method.invoke(target, args);
System.out.println("after...");
return null;
}

public static void main(String[] args) {
TestService myopt = new MyOpt();
InvocationHandler handler = new MyInvocationHandler(myopt);
TestService opt = (TestService) Proxy.newProxyInstance(myopt.getClass().getClassLoader(),
myopt.getClass().getInterfaces(), handler);
opt.test();
}

public interface TestService {

default void test() {
System.out.println("接口");
}
}

public static class MyOpt implements TestService {

}
}