Java&CORBA编程实例2

Java&CORBA编程实例2

 要熟练掌握CORBA也并不容易。本文再提供一个Java与CORBA编程的例子，以进一步加深对CORBA的认识。

 

一、编写IDL文件

counter.idl源码：

 

module CounterApp{
    interface Counter{
        readonly attribute long value;
        void inc();
        void dec();
    };
};

 

二、用idlj生成需要的文件

命令：idlj -fall counter.idl

生成的文件如下图所示：

 

三、编写服务器端文件

1）编写Server.java

Server.java源码：

package server;
import CounterApp.*;

import java.util.Properties;
import org.omg.CORBA.*;
import org.omg.PortableServer.POA;
import org.omg.PortableServer.POAHelper;
import java.io.*;
import static java.lang.System.*;

public class Server {
    public static void main(String[] args){
        try{
            Properties props = getProperties();
            ORB orb = ORB.init(args, props);
            org.omg.CORBA.Object obj = null;
            POA rootPOA = null;
            try{
                obj = orb.resolve_initial_references("RootPOA");
                rootPOA = POAHelper.narrow(obj);
            }catch(org.omg.CORBA.ORBPackage.InvalidName e){

            }
            CounterImpl c_impl = new CounterImpl();
            Counter c = c_impl._this(orb);
            try{
                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();
                out.println("Server started."+" Stop: Ctrl-c");
            }catch(IOException ex){
                out.println("File error: "+ex.getMessage());
                exit(2);
            }
            rootPOA.the_POAManager().activate();
            orb.run();
        }catch(Exception ex){
            out.println("Exception: "+ex.getMessage());
            exit(1);
        }
    }
}

2）编写CounterImpl.java

CounterImpl.java源码：

package server;
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;
    }
}

 

四、编写客户端文件

Client.java源码：

package client;
import CounterApp.*;

import java.util.*;
import java.io.*;
import org.omg.CORBA.*;
import static java.lang.System.*;
public class Client {
    public static void main(String[] args){
        try{
            Properties props = getProperties();
            ORB orb = ORB.init(args, props);
            String ref = null;
            org.omg.CORBA.Object obj = null;
            try{
                Scanner reader = new Scanner(new File("Counter.ref"));
                ref = reader.nextLine();
            }catch(IOException ex){
                out.println("File error: "+ex.getMessage());
                exit(2);
            }
            obj = orb.string_to_object(ref);
            if(obj == null){
                out.println("Invalid IOR");
                exit(4);
            }
            Counter c = null;
            try{
                c = CounterHelper.narrow(obj);
            }catch(BAD_PARAM ex){
                out.println("Narrowing failed");
                exit(3);
            }
            int inp = -1;
            do{
                out.print("Counter value: "+c.value()+"/nAction(+/-/e)?");
                out.flush();
                do{
                    try{
                        inp = 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){
            out.println("Exception: "+ex.getMessage());
            exit(1);
        }
    }
}

 

五、整个项目结构图

如图所示：

 

六、运行程序：

1）启动orbd
start orbd -ORBInitialPort 1050 -ORBInitialHost localhost

 

2）开始Server服务器
java server/Server -ORBInitialPort 1050 -ORBInitialHost localhost

注：如在同一台主机上运行，可省略-ORBInitialHost localhost

3）运行客户端应用程序
java client/Client -ORBInitialPort 1050 -ORBInitialHost localhost

 

七、运行结果截图：

服务器端截图：

 

 客户端截图：