CORBA中传递对象 java语言

CORBA的IDL数据类型定义了一系列的基本数据类型，但是如果需要传递对象可能就有些问题了。虽然IDL文件中的interface其实就是传递对象的一种方法，我的理解就是把要传递的对象的属性分成基本数据类型传递过去，但是如果传递的对象结构变化了，还需要修改IDL文件。所以想找到一个直接传递对象的方法，研究了CORBA定义的数据类型，最好的办法就是像很多连接传输对象的方法一样，传递byte数组。

建一个目录，名为Hello（名字随意起），然后在这个目录中建两个子目录，分别为server，client

在两个目录中各建一个People.java文件,内容如下:

import java.io.*;
class People implements Serializable
{
private String name;
private int age;

public People()
{
name = "CY";
age = 27;
}

public People(String str, int i)
{
name = str;
age = i;
}

public String getName()
{
return name;
}

public int getAge()
{
return age;
}

}

在server目录建一个Hello.idl文件,内容如下:

module HelloApp
{
interface Hello
{
string sayHello();
oneway void shutdown();
};
};

同样在server目录建HelloServer.java文件,内容如下:

// A server for the Hello object

import HelloApp.*;
import org.omg.CosNaming.*;
import org.omg.CosNaming.NamingContextPackage.*;
import org.omg.CORBA.*;
import org.omg.PortableServer.*;
import org.omg.PortableServer.POA;
import java.util.Properties;

public class HelloServer {

public static void main(String args[]) {
try{
// create and initialize the ORB
ORB orb = ORB.init(args, null);

// get reference to rootpoa & activate the POAManager
POA rootpoa =
(POA)orb.resolve_initial_references("RootPOA");
rootpoa.the_POAManager().activate();

// create servant and register it with the ORB
HelloImpl helloImpl = new HelloImpl();
helloImpl.setORB(orb);

// get object reference from the servant
org.omg.CORBA.Object ref =
rootpoa.servant_to_reference(helloImpl);

// and cast the reference to a CORBA reference
Hello href = HelloHelper.narrow(ref);

// get the root naming context
// NameService invokes the transient name service
org.omg.CORBA.Object objRef =
orb.resolve_initial_references("NameService");
// Use NamingContextExt, which is part of the
// Interoperable Naming Service (INS) specification.
NamingContextExt ncRef =
NamingContextExtHelper.narrow(objRef);

// bind the Object Reference in Naming
String name = "Hello1";
NameComponent path[] = ncRef.to_name( name );
ncRef.rebind(path, href);

System.out.println
("HelloServer ready and waiting ...");

// wait for invocations from clients
orb.run();
}

catch (Exception e) {
System.err.println("ERROR: " + e);
e.printStackTrace(System.out);
}

System.out.println("HelloServer Exiting ...");

} //end main
} // end class

在server目录下建立HelloImpl.java文件,内容如下:

// The servant -- object implementation -- for the Hello
// example. Note that this is a subclass of HelloPOA, whose
// source file is generated from the compilation of
// Hello.idl using j2idl.

import HelloApp.*;
import org.omg.CosNaming.*;
import org.omg.CosNaming.NamingContextPackage.*;
import org.omg.CORBA.*;
import org.omg.PortableServer.*;
import org.omg.PortableServer.POA;

import java.util.Properties;
import java.io.*;

class HelloImpl extends HelloPOA //必须继承这个类，在helloApp目录中已自动生成
{
private ORB orb;
private byte[] bytes;
public void setORB(ORB orb_val)
{
orb = orb_val;
}

// implement sayHello() method
public byte[] sayHello()
{
return (ObjectToByte(new People("Chen Yi",27)));
}

// implement shutdown() method
public void shutdown()
{
orb.shutdown(false);
}
public byte[] ObjectToByte(java.lang.Object obj)
{

try {
//object to bytearray
ByteArrayOutputStream bo = new ByteArrayOutputStream();
ObjectOutputStream oo = new ObjectOutputStream(bo);
oo.writeObject(obj);

bytes = bo.toByteArray();

bo.close();
oo.close();

}
catch(Exception e) {
System.out.println("translation"+e.getMessage());
e.printStackTrace();
}
return(bytes);
}

} //end class

在client目录下建立HelloClient.java文件,内容如下:

// A sample Java IDL object client application.
import HelloApp.*;
import org.omg.CosNaming.*;
import org.omg.CosNaming.NamingContextPackage.*;
import org.omg.CORBA.*;
import java.io.*;

public class HelloClient
{
static Hello helloImpl;
String [] x=new String[6];
static People people;
static java.lang.Object obj;
public static void main(String args[]){
try{
// create and initialize the ORB
ORB orb = ORB.init(args, null);

System.out.println("ORB initialised/n");

// get the root naming context
org.omg.CORBA.Object objRef =
orb.resolve_initial_references("NameService");

// Use NamingContextExt instead of NamingContext,
// part of the Interoperable naming Service.
NamingContextExt ncRef =
NamingContextExtHelper.narrow(objRef);

// resolve the Object Reference in Naming
String name = "Hello1";
helloImpl =
HelloHelper.narrow(ncRef.resolve_str(name));

people = (People)(ByteToObject(helloImpl.sayHello()));

System.out.println
("Obtained a handle on server object: "
+ helloImpl);
System.out.println(people.getName());
helloImpl.shutdown();

}
catch (Exception e) {
System.out.println("ERROR : " + e) ;
e.printStackTrace(System.out);
}
} //end main

private static java.lang.Object ByteToObject(byte[] bytes){
try {
//bytearray to object
ByteArrayInputStream bi = new ByteArrayInputStream(bytes);
ObjectInputStream oi = new ObjectInputStream(bi);

obj = oi.readObject();

bi.close();
oi.close();
}
catch(Exception e) {
System.out.println("translation"+e.getMessage());
e.printStackTrace();
}
return obj;
}
} // end class

下面是单机版编译步骤

1. 编译server中IDL文件,在命令行执行 idlj -fall HelloApp.idl

2. 编译server中.java文件 javac *.java

3. 将server中编译IDL文件后产生的文件目录HelloApp复制到client目录中

4. 编译client中.java文件 javac *.java

5. 运行orbd start orbd -ORBInitialPort 1050

6. 运行server start java HelloServer -ORBInitialPort 1050 -ORBInitialHost localhost

7. 运行client java HelloClient -ORBInitialPort 1050 -ORBInitialHost localhost

运行结果,会在client命令行中看到打印出人名.如果需要进一步测试,可以在HelloImpl中修改new People(str,i)的参数也可以在client中调用People的其他方法.

多机版运行方法
编译方法同单机版
1. 运行orbd start orbd -ORBInitialPort 1050 -ORBInitialHost servermachinename

2. 运行server java HelloServer -ORBInitialPort 1050

3. 运行client java HelloClient -ORBInitialHost nameserverhost -ORBInitialPort 1050

注意 nameserverhost 是服务器的IP地址

另外idlj命令的参数也可以修改, -fall是生成server和client的映射, -fserver是生成server映射, -fclient是生成client映射.如果用后面两个参数需要将.idl文件分别放在两个目录中