proxy -----3 模拟类似JDK 的PROXY

首先准备工作:
package com.wjj.myproxy;

import java.lang.reflect.Method;

public interface InvocationHandler {
public void invoke(Object o,Method m);
}





===================
package com.wjj.myproxy;

import java.lang.reflect.Method;

public class LogIH implements InvocationHandler {

@Override
public void invoke(Object o, Method m) {

try {
System.out.println("invocate log start--------->");
m.invoke(o, new Object[]{});
System.out.println("invocate log stop--------->");
} catch (Exception e) {
e.printStackTrace();
}
}

}


============================


package com.wjj.myproxy;

import java.io.File;
import java.io.FileWriter;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.net.URL;
import java.net.URLClassLoader;

import javax.tools.JavaCompiler;
import javax.tools.StandardJavaFileManager;
import javax.tools.ToolProvider;
import javax.tools.JavaCompiler.CompilationTask;

import com.wjj.proxy.Car;


public class Proxya {
public static Object getProxy(Class proxyinterface,InvocationHandler h)throws Exception{

Method[] methods = proxyinterface.getMethods();
String methodStr = "";

for(Method m : methods){
methodStr += "@Override\r\n";
methodStr +="public void " + m.getName() + "(){\r\n" +
"try{"+
"Method md = " + proxyinterface.getName() + ".class.getMethod(\"" + m.getName() + "\");\r\n"+
"h.invoke(this,md);\r\n" +
"System.out.println(this.getName());"+
"}catch(Exception e){e.printStackTrace();\r\n}"+

"}";
}


String src = "package com.wjj.myproxy;\r\n"+
"import java.lang.reflect.Method;"+

"public class CarTimeProxy implements "+proxyinterface.getName()+" {"+

"com.wjj.myproxy.InvocationHandler h = null;"+


"public CarTimeProxy(InvocationHandler car) {"+
"super();"+
"this.h = car;"+
"}"+methodStr+

"}";

String fileName = System.getProperty("user.dir") +"/src/com/wjj/myproxy/CarTimeProxy.java";

File file = new File(fileName);
FileWriter writer = new FileWriter(file);
writer.write(src);
writer.flush();
writer.close();

JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
StandardJavaFileManager fileMgr = compiler.getStandardFileManager(null, null, null);
Iterable units = fileMgr.getJavaFileObjects(fileName);
CompilationTask t = compiler.getTask(null, fileMgr, null, null, null, units);
t.call();
fileMgr.close();


URL[] urls = new URL[]{new URL("file:/" + System.getProperty("user.dir")+"/src")};
URLClassLoader ul = new URLClassLoader(urls);
Class clazz = ul.loadClass("com.wjj.myproxy.CarTimeProxy");
System.out.println(clazz);


Constructor cos = clazz.getConstructor(InvocationHandler.class);
return cos.newInstance(h);
}
}

===========
到以上代码，可以对任何一个对象， 生成任意一个方法的代理，其代理内容可自已new invocationhandler 自己实现，然后将自己的实现传进去就可以了。