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：