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：