【Java入门提高篇】Day12 Java代理——Cglib动态代理

public class Programmer {

    private String name;
    
    public void setName(String name) {
　　　　 System.out.println("Setting Name.");
        this.name = name;
    }public void code(){
        System.out.println(name + " is writing bugs.");
    }
}

public class ProgrammerProxy implements MethodInterceptor {

    /**
     * 内部持有委托类对象的引用
     */
    private Object target;

    /**
     * 创建代理类对象
     */
    public Programmer createProxy(Programmer object){
        target = object;
        //创建Enhancer对象
        Enhancer enhancer = new Enhancer();
        //设置要代理的目标类，以扩展功能
        enhancer.setSuperclass(this.target.getClass());
        //设置单一回调对象，在回调中拦截对目标方法的调用
        enhancer.setCallback(this);
        //设置类加载器
        enhancer.setClassLoader(object.getClass().getClassLoader());
        //创建代理对象
        return (Programmer)enhancer.create();
    }

    /**
     * 回调方法:在代理实例上拦截并处理目标方法的调用，返回结果
     * @param proxy  代理类
     * @param method 被代理的方法
     * @param params 该方法的参数数组
     * @param methodProxy
     */
    @Override
    public Object intercept(Object proxy, Method method, Object[] params, MethodProxy methodProxy) throws Throwable {
        //调用之前处理
        doBefore();

        //调用原方法
        method.invoke(target,params);

        //调用之后处理
        doAfter();

        return null;
    }

    private void doAfter() {
        System.out.println("do after.");
    }

    private void doBefore() {
        System.out.println("do before.");
    }

}

public class ProxyTest {

    @Test
    public void testCglibProxy(){
        //创建一个Programmer对象
        Programmer programmerA = new Programmer();
        programmerA.setName("Frank");

        //创建代理对象
        Programmer programmerProxyA = new ProgrammerProxy().createProxy(programmerA);
        programmerProxyA.code();

        //修改代理对象
        programmerProxyA.setName("Wang");
        programmerProxyA.code();

        //修改委托类对象
        programmerA.setName("Song");
        programmerProxyA.code();
    }
}

Setting Name.
do before.
Frank is writing bugs.
do after.
do before.
Setting Name.
do after.
do before.
Wang is writing bugs.
do after.
Setting Name.
do before.
Song is writing bugs.
do after.