client.java

weblogic应用全实例

//声明本接口所在的包
package examples.rmi_iiop.ejb.rmi_iiop;
//声明本类引入的其他类
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;

/**
 * 这个客户端程序演示怎样调用一个无状态会话Bean，包括如下内容：
 * 
 * 创建一个远程对象Trader
 * 使用Trader买进一定数量的股票
 * 使用Trader卖出一定数量的股票
 * 删除Trader
 * 
 */

public class Client {
  //声明EJB的JNDI名
  private static final String JNDI_NAME = "rmi_iiop/TraderHome";
  //服务器地址
  private String url;
  //主接口
  private TraderHome home;
  //构造方法
  public Client(String url)
    throws NamingException
  {
    
    this.url       = url;
    //查找主接口
    home = lookupHome();
  }

  /**
   * 在命令行运行这个例程:
   * 
   * java examples.rmi_iiop.ejb.rmi_iiop.Client "iiop://localhost:7001"
   * 
   * @参数 url               URL such as "iiop://localhost:7001" of Server
   */
  public static void main(String[] args) throws Exception {
    //程序开始
    log("\nBeginning statelessSession.Client...\n");
    
    String url       = "iiop://localhost:7001";
    

    // 解析命令行参数
     if (args.length != 1) {
     //打印用法提示：
      System.out.println("Usage: java examples.rmi_iiop.ejb.rmi_iiop.Client t3://hostname:port");   
      return;
    } else {
      url = args[0];
    }

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

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

    log("\nEnd statelessSession.Client...\n");
  }

  /**
   * 运行这个实例
   */
  public void example()
    throws CreateException, RemoteException, RemoveException
  {
    
    // 创建Trader
    log("Creating a trader");
    Trader trader = (Trader) narrow(home.create(), Trader.class);

    String [] stocks = {"BEAS", "MSFT", "AMZN", "HWP" };

      // 执行买进操作
    for (int i=0; i<stocks.length; i++) {
      int shares = (i+1) * 100;
      log("Buying "+shares+" shares of "+stocks[i]+".");
      trader.buy(stocks[i], shares);
    }

    // 执行卖出操作
    for (int i=0; i<stocks.length; i++) {
      int shares = (i+1) * 100;
      log("Selling "+shares+" shares of "+stocks[i]+".");
      trader.sell(stocks[i], shares);
    }

    // 清除Trader
    log("Removing the trader");
    trader.remove();
  }

  /**
   * RMI/IIOP客户端应该使用这个narrow方法
   */
  private Object narrow(Object ref, Class c) {
    return PortableRemoteObject.narrow(ref, c);
  }

  /**
   * 在JNDI树中查找EJBs主接口
   */
  private TraderHome lookupHome()
    throws NamingException
  {
    // 查找JNDI上下文
    Context ctx = getInitialContext();
   
    try {
      //查找主接口实现类	
      Object home = ctx.lookup(JNDI_NAME);
      return (TraderHome) narrow(home, TraderHome.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;
    }
  }

  /**
   * 使用一个属性对象，创建上下文
   */
  private Context getInitialContext() throws NamingException {
    
    try {
      // 声明属性对象
      Properties h = new Properties();
      // 设置属性
      h.put(Context.INITIAL_CONTEXT_FACTORY,
        "com.sun.jndi.cosnaming.CNCtxFactory");
      h.put(Context.PROVIDER_URL, url);
      // 返回新的上下文对象
      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;
    }
  }

  /**
   * 也可以这样实现。
   * 这种实现方式依赖属性文件jndi.properties
   *
   */
//    private static Context getInitialContext()
//      throws NamingException
//    {
//      return new InitialContext();
//    }

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