client.java

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//定义本类在包examples.cluster.ejb 中
package examples.cluster.ejb;
//本接口用到的其他类
import javax.ejb.*;
import javax.naming.*;
import java.rmi.*;
import java.util.Hashtable;

import examples.cluster.utils.*;
import examples.cluster.ejb.teller.*;
import examples.cluster.ejb.account.AccountResult;

/**
 * 这个类使用容器管理的JDBC实体EJB演示负载平衡.
 * 包括如下操作:
 * 
 * 启动一个循环，重复查看结算值，存入和提取业务。
 * 如果业务失败，检查这个业务是否确实被触发，如果没有，则触发这个业务。
 * 然后，显示每次调用的情况。
 * 
 */
public class Client {
  //静态变量
  //服务器url
  static String    url         = "t3://localhost:7001";
  //账号1
  static String    account1    = "10000";
  //账号2
  static String    account2    = "10005";
  //循环次数
  static int       ITERATIONS  = 5;
  //最大尝试数
  static final int MAXATTEMPTS = 5;
  //
  static final int SLEEP       = 1000; //time to sleep between invocations
  //窗口主接口
  static TellerHome   bank;
  //窗口
  static Teller       teller;
  //工具
  static ClusterUtils stats    = new ClusterUtils();
  
  static int          i; 
  //业务数
  static int          trans; 

  Client() {
  }

  /**
   * 用命令行运行这个例程。如:
   * java examples.cluster.ejb.Client "t3://localhost:7001"
   * 
   * @参数 url               URL 如 "t3://localhost:7001" 
   */
  public static void main(String[] args)
  {
    //实例开始	
    System.out.println("\nBeginning examples.cluster.ejb.Client...\n");
    //本类实例
    Client client = new Client();

    // 解析命令行参数
     if (args.length != 1) {
     //打印用法提示
      System.out.println("Usage: java examples.cluster.ejb.Client t3://hostname:port");   
      return;
    } else {
    //服务器url
      url = args[0];
    }
    //存入数量初始值
    double        depositAmount    = 0;
    //提取数量初始值
    double        withdrawalAmount = 0;
    //转账数量初始值
    double        transferAmount   = 0;

    try {
    //获取上下文
      Context ctx  = getInitialContext();

      // 获取TellerHome对象(bank), 从那我们创建Tellers
      bank = (TellerHome)ctx.lookup("examples.cluster.ejb.TellerHome");

      // 重复每个业务

      for (i = 0 ; i < ITERATIONS; i++) {
      	//业务开始
        System.out.println("Start of transaction set " + (i+1));

        // 数量
        depositAmount   = (100 * (i+1));
        transferAmount  = depositAmount/2;
        withdrawalAmount = transferAmount;
        //业务数
        trans = 0;
        //结算
        client.new Balance(account1).transaction();
        Thread.sleep(SLEEP);
        //存入
        client.new Deposit(account1, depositAmount).transaction();
        Thread.sleep(SLEEP);
        //提取
        client.new Withdrawal(account1, withdrawalAmount).transaction();
        Thread.sleep(SLEEP);
        //转账
        client.new Transfer(account1, account2, transferAmount).transaction();
        Thread.sleep(SLEEP);
        //业务结束
        System.out.println("End of transaction set " + (i+1) + "\n");
      }
    }
    catch (TellerException pe) {
    //异常处理
      System.out.println("Processing Error: " + pe);
    } 
    catch (Exception e) {
    //其它异常
      System.out.println(":::::::::::::: Error :::::::::::::::::");
      e.printStackTrace();
    }
    System.out.println("\nStatistics for different servers:\n");
    System.out.println(stats.processStatistics());

    System.out.println("\nEnd examples.cluster.ejb.Client...\n");
  }


  /**
   * 获取初始化上下文
   *
   * @返回                  Context
   * @异常               java.lang.Exception 如果通信错误
   */
  static public Context getInitialContext() throws Exception {
    //属性对象
    Hashtable h = new Hashtable();
    //设置属性
    h.put(Context.INITIAL_CONTEXT_FACTORY,
        "weblogic.jndi.WLInitialContextFactory");
    h.put(Context.PROVIDER_URL, url);
    //创建上下文实例
    return new InitialContext(h);
  }

  /**
   * 内部类用来调用会话beans.
   *
   */
  class Transaction{
    //结果
    TellerResult result;
    //服务器
    String tellerServer;
    //业务id
    String transId = getTransactionID();
    double amount;
    //账号1id
    String account1Id;
    //账号1服务器名
    String account1Server;
    //账号1结算值
    double account1Balance;
    //账号2id
    String account2Id;
    //账号2服务器名
    String account2Server;
    //账号2结算值
    double account2Balance;
    //窗口消息
    String tellerMessage;
    //动作消息
    String actionMessage;
    //账号1消息
    String account1Message;
    //账号2消息
    String account2Message;

    /**
     * 调用窗口TellerBean的业务方法
     * 它会捕获TellerBean的任何RemoteExceptions
     * 检查业务是否驱动，
     *
     * @异常               Exception if the transaction is not
     *                          completed in the MAXATTEMPTS
     * @异常               TellerException if there is
     *                          an error in performing the transaction
     * @异常               RemoteException if there is
     *                          a communications or systems failure
     * @异常               CreateException if there is
     *                          a problem creating a teller
     */
    void transaction() throws Exception, TellerException, RemoteException, CreateException {
      //业务计数加1	
      trans++;
      int attempts      = 0;
      int set           = i;
      boolean committed = false;
      boolean invoke    = true;
      //打印业务计数和业务id
      System.out.println("Transaction " + trans + " of set " + (set + 1) +
                         " (" + transId + ")");
      while (attempts < MAXATTEMPTS) {
        try {
          attempts++;
          System.out.println("  Attempt " + attempts);
          if (teller == null)
            //创建窗口对象
            teller = bank.create();
          if (invoke) {
            //触发业务
            invokeTransaction();
            //打印报告
            buildReport();
            printReport();
            //业务结束
            System.out.println("  End of transaction " + trans + 
                               " of set " + (set + 1));
            return;
          } else { // 检查业务
            //检查业务id是否触发
            committed = teller.checkTransactionId(transId);
            System.out.println("    Checked transaction " + transId + 
                               ": committed = " + committed);
            if (committed) {
              return;
            } else {
             //没触发
              System.out.println("    Attempting Transaction " + trans + " again");
              invoke = true;
            }
          }
        }
        catch (RemoteException re) {
          System.out.println("    Error: " + re);
          teller = null;
          invoke = false;
        }
      }
      throw new Exception("  Transaction " + trans + " of set " +
                          (set + 1) + " ended unsuccessfully");
    }