1.JDK动态代理
jdk动态代理必须要借助接口才能代理对象,所以先定义接口并实现定义接口 代码如下
package com.day1.com.test1;
/**
* Created by leewihong on 2018/6/14.
*/
public interface test1_helloworldInterface {
public void sayHelloWorld();
}
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接口实现代码
package com.day1.com.test1;
/**
* Created by leewihong on 2018/6/14.
*/
public class test1_helloworldImpl implements test1_helloworldInterface {
@Override
public void sayHelloWorld() {
System.out.println("sayhelloworld");
}
}
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建立代理对象与真实服务对象之间的关系,然后在实现代理逻辑,因此先创建一个代理对象,这个代理对象是需要去实现import java.lang.reflect.InvocationHandler接口,他里面定义了一个invoke方法,并提供接口数组用于下挂代理对象,这一步相当关键,代码如下
package com.day1.com.test1;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
/**
* Created by leewihong on 2018/6/14.
*/
public class jdkexampleProxy implements InvocationHandler {
private Object targetImpl = null;
public Object bind(Object targetImpl){
this.targetImpl = targetImpl;
// 建立代理对象和真实对象之间的关系
return Proxy.newProxyInstance(targetImpl.getClass().getClassLoader(),targetImpl.getClass
().getInterfaces(),this);
}
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
System.out.println("进入代理逻辑方法");
System.out.println("在调度真实对象之前的服务");
// invoke相当于是调度了真实的方法
Object result = method.invoke(targetImpl,args);
System.out.println("在调度真实对象之后的服务");
return result;
}
}
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动态代理测试方法
package com.day1.com.test1;
/**
* Created by leewihong on 2018/6/14.
*/
public class test1 {
public static void main(String [] args){
// 1.test1
jdkexampleProxy jdkexampleProxy = new jdkexampleProxy();
test1_helloworldInterface proxy = (test1_helloworldInterface) jdkexampleProxy.bind(new test1_helloworldImpl());
proxy.sayHelloWorld();
}
}
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动态代理测试结果
进入代理逻辑方法
在调度真实对象之前的服务
sayhelloworld
在调度真实对象之后的服务
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验证args参数是否传过去新建另外一个接口
package com.day1.com.test1;
/**
* Created by leewihong on 2018/6/14.
*/
public interface test1_hellowordinterface2 {
public void sayhelloword2(String name);
}
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实现类如下
package com.day1.com.test1;
/**
* Created by leewihong on 2018/6/14.
*/
public class test1_hellowordimpl2 implements test1_hellowordinterface2{
@Override
public void sayhelloword2(String name) {
System.out.println(name);
}
}
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测试代码
package com.day1.com.test1;
/**
* Created by leewihong on 2018/6/14.
*/
public class test1 {
public static void main(String [] args){
// 1.test1
jdkexampleProxy jdkexampleProxy = new jdkexampleProxy();
test1_helloworldInterface proxy = (test1_helloworldInterface) jdkexampleProxy.bind(new test1_helloworldImpl());
proxy.sayHelloWorld();
// 2.test2
test1_hellowordinterface2 proxy2 = (test1_hellowordinterface2) jdkexampleProxy.bind(new test1_hellowordimpl2
());
proxy2.sayhelloword2("weihong");
}
}
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输出结果
进入代理逻辑方法
在调度真实对象之前的服务
sayhelloworld
在调度真实对象之后的服务
进入代理逻辑方法
在调度真实对象之前的服务
weihong
在调度真实对象之后的服务
Process finished with exit code 0
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2.拦截器
拦截器所做的一个目的其实就是需要暴漏一个接口给外部,然后将代理和接口给绑定起来,外部只需要关注接口怎么定义和实现即可
定义拦截器接口
public interface test2_interceptor {
public boolean before(Object proxy, Object target, Method method, Object [] args);
public void around(Object proxy, Object target, Method method, Object [] args);
public void after(Object proxy, Object target, Method method, Object [] args);
}
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实现拦截器接口
package com.day1.com.test1.com.test2;
import java.lang.reflect.Method;
/**
* Created by leewihong on 2018/6/14.
*/
public class test2_myinterceptor implements test2_interceptor {
@Override
public boolean before(Object proxy, Object target, Method method, Object[] args) {
System.out.println("反射方法前逻辑");
return false;
}
@Override
public void around(Object proxy, Object target, Method method, Object[] args) {
System.out.println("取代了了被代理对象的方法");
}
@Override
public void after(Object proxy, Object target, Method method, Object[] args) {
System.out.println("反射方法后逻辑");
}
}
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在代理中绑定拦截接口
package com.day1.com.test1.com.test2;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
/**
* Created by leewihong on 2018/6/14.
*/
public class test2_interceptorJDKProxy implements InvocationHandler {
private Object target = null;
private String interceptorclass = null;
public test2_interceptorJDKProxy(Object target,String interceptorclass){
this.target = target;
this.interceptorclass = interceptorclass;
}
public static Object bind(Object target,String interceptorclass){
return Proxy.newProxyInstance(target.getClass().getClassLoader(),target.getClass()
.getInterfaces(),new test2_interceptorJDKProxy(target,interceptorclass));
}
@Override
public Object invoke(Object proxy,Method method, Object[] args) throws
Throwable {
if (interceptorclass == null){
// 没有拦截器直接反射原有方法
return method.invoke(target,args);
}
Object result = null;
// 通过反射生成拦截器
test2_interceptor test2_interceptor =(test2_interceptor) Class.forName(interceptorclass).newInstance();
if (test2_interceptor.before(proxy,target,method,args))
{
// 反射原有对象方法
result = method.invoke(target,args);
}
else {
test2_interceptor.around(proxy,target,method,args);
}
test2_interceptor.after(proxy,target,method,args);
return result;
}
}
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测试动态代理拦截器
package com.day1.com.test1.com.test2;
import com.day1.com.test1.test1_helloworldImpl;
/**
* Created by leewihong on 2018/6/14.
*/
public class test2 {
public static void main(String [] args){
test2_helloword proxy = (test2_helloword) test2_interceptorJDKProxy.bind(new
test2_hellowordImp(),"com.day1.com.test1.com.test2.test2_myinterceptor");
proxy.sayhelloword();
}
}
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得到结果
反射方法前逻辑
取代了了被代理对象的方法
反射方法后逻辑
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