代碼使用了common-io，需要其jar

1 接口

Java代碼??

public?interface?Pruduct?{??

????void?selling();??

}??

?2 書籍類

Java代碼??

public?class?Book?implements?Pruduct?{??

????@Override??

????public?void?selling()?{??

????????try?{??

????????????Thread.sleep(1000);??

????????????System.out.println("books?selling.....");??

????????}?catch?(InterruptedException?e)?{??

????????????e.printStackTrace();??

????????}??

????}??

}??

?3 定義日志類

Java代碼??

public?class?LogTranService{??

??

????public?static?void?before(){??

???????????

????????System.out.println("begin?log...");??

????}??

??

????public?static?void?after(){??

????????System.out.println("finish?log...");??

????}??

??

}??

?4 定義時間類

Java代碼??

public?class?TimeTranService?{??

????static?long?bgn;??

??

????public?static?void?before(){??

????????bgn?=?System.currentTimeMillis();??

????????System.out.println("begin?time...??"?+?bgn);??

????}??

????public?static?void?after(){??

????????long?end?=?System.currentTimeMillis();??

????????System.out.println("end?time...??"?+?(end-bgn));??

????}??

??

}??

?5 定義InvocationHander?

Java代碼??

import?java.lang.reflect.Method;??

??

public?interface?InvocationHander?{??

????public?void?invoke(Object?o,Method?m);??

}??

?

Java代碼??

import?java.lang.reflect.Method;??

public?class?ProxyHander?implements?InvocationHander?{??

??

????private?Object?target;??

????public?ProxyHander(Object?target)?{??

????????this.target?=?target;??

????}??

????@Override??

????public?void?invoke(Object?o,?Method?m)?{??

????????try?{??

????????????TimeTranService.before();??

????????????LogTranService.before();??

????????????m.invoke(target);??

????????????LogTranService.after();??

????????????TimeTranService.after();??

????????}?catch?(Exception?e)?{??

????????????e.printStackTrace();??

????????}???

????}??

}??

?6 代理類

Java代碼??

import?java.io.File;??

import?java.io.IOException;??

import?java.lang.reflect.Constructor;??

import?java.lang.reflect.Method;??

??

import?javax.tools.JavaCompiler;??

import?javax.tools.JavaCompiler.CompilationTask;??

import?javax.tools.StandardJavaFileManager;??

import?javax.tools.ToolProvider;??

??

import?org.apache.commons.io.FileUtils;??

public?class?Proxy?{??

????/*?

?????*?空的構造函數?

?????*/??

????private?Proxy(){??

????}??

????/*?

?????*?返回代理類?

?????*/??

????public?static?Object?newProxyInstance(Class?inter,InvocationHander?h){??

????????String?proxyClassName?=?"$Proxy3";??

????????String?packageName??=?inter.getPackage().getName();??

????????String?InHanderPackage?=?h.getClass().getPackage().getName();??

????????String?rt?=?"\r\n";//?換行??

????????String?methodCode?=?"";??

????????for?(Method?method:inter.getMethods())?{??

????????????methodCode+="???@Override"+rt+??

??????????????

????????????"???public?void?"+?method.getName()+"()?{"+rt+??

????????????"???????try{"+rt+??

????????????"???????????Method?method??=?"+inter.getName()+".class.getMethod(\""???

????????????+???????????method.getName()+???"\");"+rt+??

????????????"???????????h.invoke(this,method);??????"+rt+??

????????????"???????}catch(Exception?e?){"?+rt+??

????????????"???????????e.printStackTrace();"?+rt+??

????????????"???????}"+rt+??

????????????"???}";??

????????}??

????????/*?

?????????*?總的java代碼?

?????????*/??

????????String?javaCode=????

????????"package??"+packageName+";"+rt+??

????????"import?"+InHanderPackage+".InvocationHander;"+rt+??

??????????

????????"import?java.lang.reflect.Method;"+rt+??

????????"public?class?"+proxyClassName+"?implements?"+inter.getName()+"?{"+rt+??

????????"???public?"+proxyClassName+"("+InHanderPackage+".InvocationHander?h)?{"+rt+??

????????"???????super();"+rt+??

????????"???????this.h?=?h;"+rt+??

????????"???}"+rt+??

????????"???private?"+InHanderPackage+".InvocationHander?h;"+rt+??

????????methodCode+rt+??

????????"}";??

????????/*?

?????????*??生成java文件?

?????????*/??

????????//?生成文件路徑??

????????String?filename?=??System.getProperty("user.dir")+"/bin/"+packageName+"/"+proxyClassName+".java";??

????????File?file?=?new?File(filename);??

????????try?{??

????????????System.out.println(filename);??

????????????FileUtils.writeStringToFile(file,?javaCode);//?commons-io這個框架可以放很方便的操作文件??

????????}?catch?(IOException?e)?{??

????????????e.printStackTrace();??

????????}??

??????????

??????????

????????//?編譯??拿到編譯器??

????????JavaCompiler?compiler?=?ToolProvider.getSystemJavaCompiler();??

????????//?文件管理??

????????StandardJavaFileManager?fileMgr?=?compiler.getStandardFileManager(null,?null,?null);??

????????//獲取文件??

????????Iterable?units?=?fileMgr.getJavaFileObjects(filename);??

??????????

????????//?編譯任務??

????????CompilationTask?t??=?compiler.getTask(null,?fileMgr,?null,?null,?null,?units);??

????????//?call進行編譯??

????????t.call();??

????????try?{??

????????????fileMgr.close();??

????????}?catch?(IOException?e)?{??

????????????e.printStackTrace();??

????????}??

??????????

????????//?load到內存??

????????ClassLoader?cl?=?ClassLoader.getSystemClassLoader();??

????????try?{??

????????????Class?c?=?cl.loadClass(packageName+"."+proxyClassName);??

????????????Constructor?ctr?=?c.getConstructor(InvocationHander.class);??

????????????System.out.println("代理類的名字為："+c.getName()+"===========");??

????????????return?ctr.newInstance(h);??

????????}?catch?(Exception?e)?{??

????????????e.printStackTrace();??

????????}??

????????return?null;??

????}??

}??

?7 測試

Java代碼??

public?class?Client?{??

????public?static?void?main(String[]?args)?{??

????????Book?book?=?new?Book();??

????????InvocationHander?h?=?new?ProxyHander(book);??

????????Pruduct?m?=?(Pruduct)Proxy.newProxyInstance(Pruduct.class,h);??

????????m.selling();??

????}??

} ?

?

?

=============僅供參考============

轉載于:https://www.cnblogs.com/xm1-ybtk/p/5099325.html

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