問題描述：

要求：

編寫實現連加、連減和加減混合等數學++/- -運算，並進行測試。

實現詳解：

1 編寫IDL介面counter.idl：

module CounterApp{  

    interface Counter{  

        readonly attribute long value;  

        void inc();  

        void dec();  

    };  

};

2編譯IDL介面：X:\corba>idlj –fall counter.idl

編譯結果生成CounterApp包，生成下述檔案

_CounterStub.java

Counter.java

CounterHelper.java

CounterHolder.java

CounterOperations.java

CounterPOA.java

3 編寫並編譯物件實現程式碼：CounterImpl.java

import CounterApp.*;

public class CounterImpl extends CounterPOA {

    private int count;  

    public CounterImpl(){  

        count = 0;  

    }  

    public void inc(){  

        count++;  

    }  

    public void dec(){  

        count - -;  

    }  

    public int value(){  

        return count;  

    }  

}

4 編寫並編譯服務端程式: Server.java

import CounterApp.*;  

import java.io.*;  

import org.omg.CosNaming.*;

import org.omg.CosNaming.NamingContextPackage.*;

import org.omg.CORBA.*;

import org.omg.CORBA.portable.*;

import org.omg.PortableServer.*;

public class Server {

public static void main(String[] args){

try{

ORB orb = ORB.init(args, null);

org.omg.CORBA.Object poaobj = orb.resolve_initial_references ("RootPOA");

org.omg.PortableServer.POA rootPOA = org.omg.PortableServer.POAHelper.narrow(poaobj);

org.omg.PortableServer.POAManager manager = rootPOA.the_POAManager();

CounterImpl c_impl = new CounterImpl();

Counter c = c_impl._this(orb);

NamingContext ncRef = NamingContextHelper.narrow(orb.resolve_initial_references("NameService"));

NameComponent nc = new NameComponent("Count", "");

NameComponent path[] = {nc};

ncRef.rebind(path, c);

FileOutputStream file = new FileOutputStream("Counter.ref");

PrintWriter writer = new PrintWriter(file);

String ref = orb.object_to_string(c);

writer.println(ref);

writer.flush();

file.close();

System.out.println("Server started."+" Stop:Ctrl-c");

rootPOA.the_POAManager().activate();

orb.run();

}catch(IOException ex){

System.out.println("File error:"+ex.getMessage());

System.exit(2);

}catch(Exception ex){

System.out.println("Exception: "+ex.getMessage());

System.exit(1);

}

}

}

5 編寫並編譯客戶端程式: Client.java

import CounterApp.*; 

import java.util.*;  

import java.io.*;  

import org.omg.CORBA.*;

import org.omg.CosNaming.*;

public class Client {  

public static void main(String[] args){  

try{  

ORB orb = ORB.init(args, null);

org.omg.CORBA.Object obj = orb.resolve_initial_references("NameService");

NamingContext ncRef = NamingContextHelper.narrow(obj);

NameComponent nc = new NameComponent("Count","");

NameComponent path[] = {nc};

String ref = null;

try{  

Scanner reader = new Scanner(new File("Counter.ref"));  

ref = reader.nextLine();  

}catch(IOException ex){  

System.out.println("File error: "+ex.getMessage());  

System.exit(2);  

}  

obj = orb.string_to_object(ref);  

if(obj == null){  

System.out.println("Invalid IOR");  

System.exit(4);  

}  

Counter c = null;  

try{  

c = CounterHelper.narrow(obj);  

}catch(BAD_PARAM ex){  

System.out.println("Narrowing failed");  

System.exit(3);  

}  

int inp = -1;  

do{  

System.out.print("Counter value: "+c.value()+"\nAction(+/-/e)?");  

System.out.flush();  

do{  

try{  

inp = System.in.read();  

}catch(IOException ioe){}  

}while(inp != '+' && inp != '-' && inp != 'e');  

if(inp == '+')  

c.inc();  

else if(inp == '-')  

c.dec();  

}while(inp != 'e');  

}catch(Exception ex){  

System.out.println("Exception: "+ex.getMessage());  

System.exit(1);  

}  

}  

}

實現步驟：

最終結果：

在這裡我運行了兩個客戶端，會發現他們操作的都是同一個數：

客戶端把計數器操作到-1：

客戶端2進行加加操作 會發現又變成了0：