client.java

weblogic应用全实例

//定义本类在包examples.ejb20.homeMethods 中
package examples.ejb20.homeMethods;
//本接口用到的其他类
import java.rmi.RemoteException;
import java.util.Enumeration;
import java.util.Properties;
import java.util.Vector;

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

/**
 * 这个类演示了如何调用一个实体EJB。
 * 这个例子同时演示了怎样在JNDI树查找EJB主接口。
 */

public class Client {
//声明变量
  private String m_url;
  
  private AccountHome m_home;
//构造方法
  public Client(String url)
    throws NamingException
  {
    m_url = url;
    //找找主接口，lookupHome是本例自定义方法。
    m_home = lookupHome();
  }

  /**
   * 在命令行运行这个实例：
   * java examples.ejb20.homeMethods.Client "t3://localhost:7001"
   * 参数是可选的
   * @参数 url               URL such as "t3://localhost:7001" 
   */
  public static void main(String[] args) throws NamingException {
    System.out.println("\nBeginning ejb20.examples.homeMethods.Client...\n");

    String url       = "t3://localhost:7001";
    
     
    // 解析命令行参数
     if (args.length != 1) {
      System.out.println("Usage: java examples.ejb20.homeMethods.Client t3://hostname:port");   
      return;
    } else {
      url = args[0];
    }

    
    Client client = null;

    try {
    	//本类实例
      client = new Client(url);
    } catch (NamingException ne) {
    	//异常处理
      ne.printStackTrace();
      log("Unable to look up the beans home: " + ne.getMessage());
      System.exit(1);
    }

    try {
    	//调用例程
      client.example();

} catch (Exception e) {
	//异常处理
      log("There was an exception while creating and using the Accounts.");
      log("This indicates that there was a problem communicating with the server: "+e);
    } 

    System.out.println("\nEnd ejb20.examples.homeMethods.Client...\n");
  }
     
  //例程方法
  public void example() throws RemoteException, NamingException {
    //主方法
    String message = m_home.homyMethod();
    System.out.println("\n\n  Here is the message from the remote invocation of the Home Method homyMethod: '"+
		       message+"'\n\n");
  }

  /**
   * 使用JNDI查找bean主接口。
   */
  private AccountHome lookupHome()
    throws NamingException
  {
  //上下文
    Context ctx = getInitialContext();
   
    try {
    	//查找主接口
      Object home = ctx.lookup("homeMethods.AccountHome");
      return (AccountHome) PortableRemoteObject.narrow(home, AccountHome.class);

	} catch (NamingException ne) {
	//异常处理
      log("The client was unable to lookup the EJBHome.  Please make sure " +
      "that you have deployed the ejb with the JNDI name " + 
      "homeMethods.AccountHome on the WebLogic server at "+m_url);

      throw ne;
    }
  }

  /**
   * 从JNDI树中获取初始化上下文
   *
   * 可以使用jndi.properties属性文件，设置
   * INITIAL_CONTEXT_FACTORY和PROVIDER_URL属性
   *  private Context getInitialContext() throws NamingException {
   *    return new InitialContext();
   *  }
   * 
   */
  private Context getInitialContext() throws NamingException {
    
    try {
      // 属性文件
      Properties h = new Properties();
      h.put(Context.INITIAL_CONTEXT_FACTORY,
        "weblogic.jndi.WLInitialContextFactory");
      h.put(Context.PROVIDER_URL, m_url);
      return new InitialContext(h);
    } catch (NamingException ne) {
    //异常处理
      log("We were unable to get a connection to the WebLogic server at "+m_url);
      log("Please make sure that the server is running.");
      throw ne;
    }
  }

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