动态代理

来源：互联网发布：酒店诡异事件知乎编辑：程序博客网时间：2024/05/18 00:15
package com.bjsxt.proxy;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;public class Proxy {    public static Object newProxyInstance(Class infce, InvocationHandler h) throws Exception { //JDK6 Complier API, CGLib, ASM        String methodStr = "";        String rt = "\r\n";        Method[] methods = infce.getMethods();        /*        for(Method m : methods) {            methodStr += "@Override" + rt +                          "public void " + m.getName() + "() {" + rt +                            "   long start = System.currentTimeMillis();" + rt +                            "   System.out.println(\"starttime:\" + start);" + rt +                            "   t." + m.getName() + "();" + rt +                            "   long end = System.currentTimeMillis();" + rt +                            "   System.out.println(\"time:\" + (end-start));" + rt +                         "}";        }        */        for(Method m : methods) {            methodStr += "@Override" + rt +                          "public void " + m.getName() + "() {" + rt +                         "    try {" + rt +                         "    Method md = " + infce.getName() + ".class.getMethod(\"" + m.getName() + "\");" + rt +                         "    h.invoke(this, md);" + rt +                         "    }catch(Exception e) {e.printStackTrace();}" + rt +                         "}";        }        String src =             "package com.bjsxt.proxy;" +  rt +            "import java.lang.reflect.Method;" + rt +            "public class $Proxy1 implements " + infce.getName() + "{" + rt +            "    public $Proxy1(InvocationHandler h) {" + rt +            "        this.h = h;" + rt +            "    }" + rt +            "    com.bjsxt.proxy.InvocationHandler h;" + rt +            methodStr +            "}";        String fileName =             "d:/src/com/bjsxt/proxy/$Proxy1.java";        File f = new File(fileName);        FileWriter fw = new FileWriter(f);        fw.write(src);        fw.flush();        fw.close();        //compile        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();        //load into memory and create an instance        URL[] urls = new URL[] {new URL("file:/" + "d:/src/")};        URLClassLoader ul = new URLClassLoader(urls);        Class c = ul.loadClass("com.bjsxt.proxy.$Proxy1");        System.out.println(c);        Constructor ctr = c.getConstructor(InvocationHandler.class);        Object m = ctr.newInstance(h);        //m.move();        return m;    }}
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