client.java

weblogic应用全实例

//声明本类定义在包examples.ejb.subclass中
package examples.ejb.subclass;
//声明本类引入的其它类或包
import java.rmi.RemoteException;
import java.util.Properties;

import javax.ejb.CreateException;
import javax.ejb.RemoveException;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.rmi.PortableRemoteObject;

/**
 * 这个类演示怎样使用一个EJBean，它是另一个bean的子类：

 * 创建ChildBean的一个实例
 * 调用ChildBean重载的方法
 * 调用继承ParentBean的方法
 * 调用ChildBean中的方法
 * 清除ChildBean实例
 * 
 */
public class Client {
  //声明jndi名
  private static final String JNDI_NAME = "SubClass.ChildHome";
  //声明服务器url
  private String url;
  //声明主接口
  private ChildHome home;
  //构造方法
  public Client(String url)
    throws NamingException
  {

    this.url       = url;
    //查找主接口
    home = lookupHome();
  }

  /**
   * 在命令行运行本类，如:
   * java examples.ejb.subclass.Client "t3://localhost:7001"
   * 
   * @参数 url               URL 例如： "t3://localhost:7001" 
   */
  public static void main(String[] args) {
    System.out.println("\nBegin subclass.Client...\n");

    String url       = "t3://localhost:7001";
         
    // 解析命令行参数
     if (args.length != 1) {
      System.out.println("Usage: java examples.ejb.subclass.Client t3://hostname:port");   
      return;
    } else {
      url = args[0];
    }

    Client client = null;

    try {
     //本类实例
      client = new Client(url);
    } catch (NamingException ne) {
      System.exit(1);
    }

    try {
    //本例方法	
      client.example();
    } catch (Exception e) {
      log("There was an exception while creating and using the ChildBean.");
      log("This indicates that there was a problem communicating with the server: "+e);
    } 

    System.out.println("\nEnd subclass.Client...\n");
  }

  /**
   * 运行这例程
   */
  public void example()
    throws CreateException, RemoteException, RemoveException
  {
    System.out.println("Creating ChildBean...\n");
    //创建远程对象
    Child child = (Child) narrow(home.create(), Child.class);

    log("Calling method overloaded by ChildBean class");
    //调用远程方法，重载的方法
    String message = child.sayHello();
    log(message);
    
    log("Calling method inherited by ChildBean class");
    //调用远程方法，继承的方法
    message = child.nonOverloadedMethod();
    log(message);

    log("Calling method that only exists in ChildBean class");
    //调用远程方法，子类定义的方法
    message = child.childOnlyMethod();
    log(message);
    
    System.out.println("Removing ChildBean...\n");
    child.remove();
  }



  /**
   * RMI/IIOP 客户端必须使用PortableRemoteObject.narrow()方法
   */
  private Object narrow(Object ref, Class c) {
    return PortableRemoteObject.narrow(ref, c);
  }

  //查找主接口
  private ChildHome lookupHome()
    throws NamingException
  {
    // 使用JNDI查找beans
    Context ctx = getInitialContext();
   
    try {
      //查找主接口对象
      Object home = ctx.lookup(JNDI_NAME);

      return (ChildHome) narrow(home, ChildHome.class);

    } catch (NamingException ne) {
      log("The client was unable to lookup the EJBHome.  Please make sure ");
      log("that you have deployed the ejb with the JNDI name "+JNDI_NAME+" on the WebLogic server at "+url);
      throw ne;
    }
  }

  /**
   * 另一个版本，必须使用属性文件jndi.properties定义了
   * INITIAL_CONTEXT_FACTORY和PROVIDER_URL属性。
   */
//    private Context getInitialContext() throws NamingException {
//      return new InitialContext();
//    }

  /**
   * 使用属性对象，创建上下文
   */
  private Context getInitialContext() throws NamingException {
    
    try {
      // 获取初始化上下文
      Properties h = new Properties();
      h.put(Context.INITIAL_CONTEXT_FACTORY,
        "weblogic.jndi.WLInitialContextFactory");
      h.put(Context.PROVIDER_URL, url);
      return new InitialContext(h);
    } catch (NamingException ne) {
      log("We were unable to get a connection to the WebLogic server at "+url);
      log("Please make sure that the server is running.");
      throw ne;
    }
  }

  private static void log(String s) {
    System.out.println(s);
  }

}