ccache3.java

Java示例100

/**
 *  JDBC 2.0 Spec doesn't mandate that JDBC vendors implement a
 *  Connection Cache. However, we implemented a basic one with 2
 *  schemes as an Example.
 *
 *  There are 3 cache schemes: DYNAMIC_SCHEME (default)
 *                             FIXED_RETURN_NULL_SCHEME
 *                             FIXED_WAIT_SCHEME
 *
 *  A Sample demo to illustrate FIXED_WAIT_SCHEME of
 *  OracleConnectionCacheImpl.
 *  Fixed with Wait :  At no instance there will be no  more active
 *  connections than the  the Maximum limit. Request for new connections
 *  beyond the max limit will wait until other connections are relieved.
 *  Please compare with CCache1.java and CCache2.java
 *  Please use jdk1.2 or later version
 *
 *  usage: java CCache3
 *         java CCache3 <number of threads>
 */

import java.sql.*;
import oracle.jdbc.OracleStatement;
import oracle.jdbc.pool.*;
import java.util.Random;

public class CCache3 extends Thread
{
  // Default no of threads to 10
  private static int NUM_OF_THREADS = 10;

  int m_myId;

  static     int c_nextId = 1;
  static  Connection s_conn = null;
  static  boolean   share_connection = false;
  static  Random    rd = null;
  static  OracleConnectionPoolDataSource ocpds = null;
  static  OracleConnectionCacheImpl ods = null;

  synchronized static int getNextId()
  {
      return c_nextId++;
  }

  public static void main (String args [])
  {
    try  
    {  
      /* Load the JDBC driver */
      DriverManager.registerDriver(new oracle.jdbc.OracleDriver());

      String url = "jdbc:oracle:oci8:@";
      try {
        String url1 = System.getProperty("JDBC_URL");
        if (url1 != null)
          url = url1;
      } catch (Exception e) {
        // If there is any security exception, ignore it
        // and use the default
      }
 
      ods = new OracleConnectionCacheImpl();
      ods.setURL(url);
      ods.setUser("hr");
      ods.setPassword("hr");

      ods.setMaxLimit (3);
      ods.setCacheScheme (OracleConnectionCacheImpl.FIXED_WAIT_SCHEME);

      rd = new Random(12345);

      if (args.length > 1) {
        System.out.println("Usage: java CCache3 <no of Threads>\n       java CCache3");
        System.exit(0);
      }
      else if (args.length == 1)
      {
        NUM_OF_THREADS = Integer.parseInt (args[0]);
      }
  
      // Create the threads
      Thread[] threadList = new Thread[NUM_OF_THREADS];

      // spawn threads
      for (int i = 0; i < NUM_OF_THREADS; i++)
      {
          threadList[i] = new CCache3();
          threadList[i].start();
      }
    
      // Start everyone at the same time
      setGreenLight ();

      // wait for all threads to end
      for (int i = 0; i < NUM_OF_THREADS; i++)
      {
          threadList[i].join();
      }

    }
    catch (Exception e)
    {
       e.printStackTrace();
    }
  
  }  

  public CCache3()
  {
     super();
     // Assign an Id to the thread
     m_myId = getNextId();
  }

  public void run()
  {
    Connection conn = null;
    ResultSet     rs   = null;
    Statement  stmt = null;

    while (!getGreenLight())
      yield();
          
    try
    {    
 
      for (int i =0; i < 10; ++i)
      {
        System.out.println("Thread " + m_myId + " About to start " + i +
                            " th iteration");
        if (rd != null)
        {
          int sltp = (Math.abs(rd.nextInt())) % 30;
          System.out.println("Sleeping for " + sltp  + " secs.");
          sleep (sltp);
        }

      
        if (ods == null)
           System.out.println("ods is null");

        // Get the connection
        System.out.println("Thread " + m_myId + " Active Size is " +
                           ods.getActiveSize());
        System.out.println("Thread " + m_myId + " Cache Size is " +
                           ods.getCacheSize());
        System.out.println("Thread " + m_myId + " About to get Connection ");
        conn = ods.getConnection("hr","hr");
        System.out.println("Thread " + m_myId + " Got Connection ");
        stmt = conn.createStatement (); // Create a Statement

        // Yield to other threads
        yield();

        // Execute the Query
        rs = stmt.executeQuery ("select USER from dual");

        // Loop through the results
        while (rs.next())
        {
          System.out.println("Thread " + m_myId +
                             " User Name : " + rs.getString(1));
          yield();  // Yield To other threads
        }
          
        // Close all the resources
        
        rs.close();
        rs = null;
  
        // Yield to other threads
        yield();
        
        // Close the statement
        stmt.close();
        stmt = null;

        System.out.println("Thread " + m_myId + " Closing connection");
        conn.close();
        conn = null;

        System.out.println("Thread " + m_myId + " Done with " + i +
                            " th iteration");
      }
    }
    catch (Exception e)
    {
      System.out.println("Thread " + m_myId + " got Exception: " + e);
      e.printStackTrace();
      return;
    }
    System.out.println("Thread " + m_myId +  " is finished. ");
  }

  static boolean greenLight = false;
  static synchronized void setGreenLight () { greenLight = true; }
  synchronized boolean getGreenLight () { return greenLight; }

}