java中的動態代理----自己手動實現

代碼使用了common-io，需要其jar

1 接口

public?interface?Pruduct?{??
????void?selling();??
}??

?2 書籍類

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

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

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?

import?java.lang.reflect.Method;??
??
public?interface?InvocationHander?{??
????public?void?invoke(Object?o,Method?m);??
}??

?

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

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

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();??
????}??
} ?