java 综合示例代码
package javaenhance.src.cn.itcast.day3;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.ArrayList;
import java.util.Collection;
public class ProxyTest {
/**
* @param args
*/
public static void main(String[] args) throws Exception{
// TODO Auto-generated method stub
//接收两个参数，一个是后边参数的字节码的加载器，一个是所要实现代理的接口的字节码
Class clazzProxy1 = Proxy.getProxyClass(Collection.class.getClassLoader(), Collection.class);
System.out.println(clazzProxy1.getName());//打印代理的名字 $Proxy0
System.out.println("----------begin constructors list----------");
/*想打印出如下格式：
* $Proxy0()
$Proxy0(InvocationHandler,int)*/
Constructor[] constructors = clazzProxy1.getConstructors();//获取代理的构造函数
for(Constructor constructor : constructors){
String name = constructor.getName();//获取代理的构造函数的name
StringBuilder sBuilder = new StringBuilder(name);
sBuilder.append('(');
Class[] clazzParams = constructor.getParameterTypes();//获取代理的构造函数的参数
for(Class clazzParam : clazzParams){
sBuilder.append(clazzParam.getName()).append(',');
}
if(clazzParams!=null && clazzParams.length != 0)//稳妥的判断是否是一个参数，不是就删掉最后的，
sBuilder.deleteCharAt(sBuilder.length()-1);
sBuilder.append(')');
System.out.println(sBuilder.toString()); //$Proxy0(java.lang.reflect.InvocationHandler)
}
System.out.println("----------begin methods list----------");
/*$Proxy0()
$Proxy0(InvocationHandler,int)*/
Method[] methods = clazzProxy1.getMethods();//获取代理身上的方法
for(Method method : methods){
String name = method.getName();
StringBuilder sBuilder = new StringBuilder(name);
sBuilder.append('(');
Class[] clazzParams = method.getParameterTypes();
for(Class clazzParam : clazzParams){
sBuilder.append(clazzParam.getName()).append(',');
}
if(clazzParams!=null && clazzParams.length != 0)
sBuilder.deleteCharAt(sBuilder.length()-1);
sBuilder.append(')');
System.out.println(sBuilder.toString());
}
System.out.println("----------begin create instance object----------");
//Object obj = clazzProxy1.newInstance();
//方式一：通过接口的子类创建对象
Constructor constructor =
clazzProxy1.getConstructor(InvocationHandler.class);
//获取代理身上的构造函数
//创建内部类MyInvocationHandler1，目的是传递给代理的构造器
class MyInvocationHandler1 implements InvocationHandler{
public Object invoke(Object proxy, Method method, Object[] args)
throws Throwable {
// TODO Auto-generated method stub
return null;
}
}
//方式二：匿名内部类
Collection proxy1 = (Collection)constructor.newInstance(new MyInvocationHandler1());
System.out.println(proxy1);//没有错误
proxy1.clear();//没有错误
//proxy1.size();报错，因为，代理调用size方法，其实是调用了MyInvocationHandler1中的invoke，他的返回值是null
//System.out.println("111111111111111");//调试用的
//用了匿名内部类的方法实现
Collection proxy2 = (Collection)constructor.newInstance(new InvocationHandler(){
public Object invoke(Object proxy, Method method, Object[] args)
throws Throwable {
return null;
}
});
/*下边这部分代码非常重要和精辟*/
final ArrayList target = new ArrayList();
Collection proxy3 = (Collection)getProxy(target,new MyAdvice());
proxy3.add("zxx");
proxy3.add("lhm");
proxy3.add("bxd");
System.out.println(proxy3.size());
System.out.println(proxy3.getClass().getName());
}
private static Object getProxy(final Object target,final Advice advice) {
//方式三，newProxyInstance这个方法需要三个参数，可以直接创建target的代理对象
Object proxy3 = Proxy.newProxyInstance(
target.getClass().getClassLoader(),
/*new Class[]{Collection.class},*/
//获取target上的接口
target.getClass().getInterfaces(),
new InvocationHandler(){
public Object invoke(Object proxy, Method method, Object[] args)
throws Throwable {
/*long beginTime = System.currentTimeMillis();
Object retVal = method.invoke(target, args);
long endTime = System.currentTimeMillis();
System.out.println(method.getName() + " running time of " + (endTime - beginTime));
return retVal;*/
//把上边的代码封装到一个类中，让后调用该类的方法，就实现了方法的封装
advice.beforeMethod(method);
Object retVal = method.invoke(target, args);
advice.afterMethod(method);
return retVal;
}
}
);
return proxy3;
}
}
/*$Proxy0
----------begin constructors list----------
$Proxy0(java.lang.reflect.InvocationHandler)
----------begin methods list----------
hashCode()
equals(java.lang.Object)
toString()
add(java.lang.Object)
contains(java.lang.Object)
isEmpty()
size()
toArray()
toArray([Ljava.lang.Object;)
addAll(java.util.Collection)
iterator()
remove(java.lang.Object)
clear()
containsAll(java.util.Collection)
removeAll(java.util.Collection)
retainAll(java.util.Collection)
getProxyClass(java.lang.ClassLoader,[Ljava.lang.Class;)
newProxyInstance(java.lang.ClassLoader,[Ljava.lang.Class;,java.lang.reflect.InvocationHandler)
isProxyClass(java.lang.Class)
getInvocationHandler(java.lang.Object)
getClass()
notify()
notifyAll()
wait(long)
wait(long,int)
wait()
----------begin create instance object----------
null
到传智播客来学习啦！
从传智播客毕业上班啦！
add running time of 0
到传智播客来学习啦！
从传智播客毕业上班啦！
add running time of 0
到传智播客来学习啦！
从传智播客毕业上班啦！
add running time of 0
到传智播客来学习啦！
从传智播客毕业上班啦！
size running time of 0
3
$Proxy1*/
---------------------------------------------
import java.lang.reflect.Method;
public interface Advice {
void beforeMethod(Method method);
void afterMethod(Method method);
}
---------------------------------------------
package javaenhance.src.cn.itcast.day3;
import java.lang.reflect.Method;
//创建实现Advice接口的子类
public class MyAdvice implements Advice {
long beginTime = 0;
public void afterMethod(Method method) {
// TODO Auto-generated method stub
System.out.println("从传智播客毕业上班啦！");
long endTime = System.currentTimeMillis();
System.out.println(method.getName() + " running time of " + (endTime - beginTime));
}
public void beforeMethod(Method method) {
// TODO Auto-generated method stub
System.out.println("到传智播客来学习啦！");
beginTime = System.currentTimeMillis();
}
}
