Java-JDK与CGLIB动态代理的实现

public interface SayService {
    void say(String name);
}
public class SayServiceImpl implements SayService {
    @Override
    public void say(String name) {
        System.out.println(name);
    }
}
public class DynamicProxy implements InvocationHandler {

    private Object target;

    public DynamicProxy(Object target) {
        this.target = target;
    }

	//生成代理对象
    public <T> T getProxy(){
        return (T) Proxy.newProxyInstance(
                target.getClass().getClassLoader(),
                target.getClass().getInterfaces(),
                this);
    }

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {

        System.out.println("代理前");
        //这里用的target而非方法参数的proxy
        Object obj = method.invoke(target, args);
        System.out.println("代理后");
        return obj;
    }
}

public class JDKProxyTest {

    public static void main(String[] args) {

        SayService sayService = new SayServiceImpl();

        SayService proxy = new DynamicProxy(sayService).getProxy();

        proxy.say("changjie");

        //将jdk中生成代理类输出到本地.Class文件，之后可以通过反编译软件打开查看
        createProxyClassFile("SayService",sayService.getClass().getInterfaces());
    }


    private static void createProxyClassFile(String name, Class<?> [] interfaces){
        //该方法为jdk中生成代理类的核心方法
        byte[] data = ProxyGenerator.generateProxyClass(name,interfaces);
        FileOutputStream out =null;
        try {
            out = new FileOutputStream(name+".class");
            System.out.println((new File(name)).getAbsolutePath());
            out.write(data);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            if(null!=out){
                try {
                    out.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

代理前
changjie
代理后
/Users/admin/IdeaProjects/spring-note/SayService

public final class SayService extends Proxy implements me.changjie.aop.proxy.SayService {
    private static Method m1;
    private static Method m2;
    private static Method m3;
    private static Method m0;

    public SayService(InvocationHandler var1) throws  {
        super(var1);
    }

    public final boolean equals(Object var1) throws  {
        try {
            return (Boolean)super.h.invoke(this, m1, new Object[]{var1});
        } catch (RuntimeException | Error var3) {
            throw var3;
        } catch (Throwable var4) {
            throw new UndeclaredThrowableException(var4);
        }
    }

    public final String toString() throws  {
        try {
            return (String)super.h.invoke(this, m2, (Object[])null);
        } catch (RuntimeException | Error var2) {
            throw var2;
        } catch (Throwable var3) {
            throw new UndeclaredThrowableException(var3);
        }
    }

    public final void say(String var1) throws  {
        try {
            //调用父类Proxy持有的InvocationHandle对象的invoke方法
            super.h.invoke(this, m3, new Object[]{var1});
        } catch (RuntimeException | Error var3) {
            throw var3;
        } catch (Throwable var4) {
            throw new UndeclaredThrowableException(var4);
        }
    }

    public final int hashCode() throws  {
        try {
            return (Integer)super.h.invoke(this, m0, (Object[])null);
        } catch (RuntimeException | Error var2) {
            throw var2;
        } catch (Throwable var3) {
            throw new UndeclaredThrowableException(var3);
        }
    }

    static {
        try {
            m1 = Class.forName("java.lang.Object").getMethod("equals", Class.forName("java.lang.Object"));
            m2 = Class.forName("java.lang.Object").getMethod("toString");
            m3 = Class.forName("me.changjie.aop.proxy.SayService").getMethod("say", Class.forName("java.lang.String"));
            m0 = Class.forName("java.lang.Object").getMethod("hashCode");
        } catch (NoSuchMethodException var2) {
            throw new NoSuchMethodError(var2.getMessage());
        } catch (ClassNotFoundException var3) {
            throw new NoClassDefFoundError(var3.getMessage());
        }
    }
}

public class CglibProxyTest {

    public static void main(String[] args) {
        Enhancer enhancer = new Enhancer();
        ////设置增强类的父类
        enhancer.setSuperclass(SayServiceImpl.class);
        //设置拦截器，拦截对父类所有非final方法的调用
        enhancer.setCallback(new MethodInterceptor() {
            @Override
            public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {
                System.out.println(o.getClass().getName());
                System.out.println("cglib动态代理before");
                //调用父类方法
                Object object = methodProxy.invokeSuper(o, objects);
                System.out.println("cglib动态代理after");
                return object;
            }
        });

        //创建动态代理对象
        SayService sayService = (SayService) enhancer.create();
        System.out.println(sayService.getClass().getName());

        sayService.say("changjie");
    }
}