understandcacheattributes.java

数据库连接包括连接池。很有用的资料

/**
* @author  Rajat Gupta
* @version 1.0
*
* Development Environment        :  Oracle JDeveloper 10g
* Name of the Application        :  UnderstandCacheAttributes.java
* Creation/Modification History  :
*
*    Rajat       25-Aug-2004      Created
*
* Overview of Application        :  This is the main class of the sample application.
*                                   To understand all the various possibilities
*                                   of Connection Attributes, run this class with
*                                   appropriate parameters.
*
**/

package oracle.otnsamples.connectioncache.attributes;

// Import Packages
import java.sql.Statement;
import java.util.Properties;
import oracle.jdbc.driver.OracleConnection;
import oracle.jdbc.pool.OracleDataSource;

public class UnderstandCacheAttributes {

  /**
   * Initialize Oracle DataSource
   */
  OracleDataSource ods;

  /**
   * Empty Constructor
   */
  public UnderstandCacheAttributes(){
  }

  /**
   * This is the main method of the class. It invokes various
   * methods within this class based on the passed arguments.
   *
   * @param args Passed Arguments
   */
  public static void main(String[] args){
    // Instantiate Class
    UnderstandCacheAttributes cacheAttributes = new UnderstandCacheAttributes();
    try{
      // Instantiate Oracle DataSource
      cacheAttributes.ods = new OracleDataSource();

      if (args.length == 0)
      {
        // If no arguments are passed, then print the list of operations
        System.out.println("\nPlease run the class with an argument. ConnectionCache"
                + " will be set for all operations with default attributes.");
        System.out.println("\n1. To retrieve the connection with default "
                + "attributes, run with argument 'default'.");
        System.out.println("\n2. To retrieve the connection with new attributes,"
                + " run with argument 'new'.");
        System.out.println("\n3. To retrieve the connection with default"
                + " attributes and update it, run with argument 'update'.");
        System.out.println("\n4. To retrieve the connection with matching "
                + "attributes, run with argument 'matching'.");
        System.out.println("\n5. To clear the connection of all attributes, "
                + "run with argument 'clear'.");
      }else{
        // Read the parameter
        String runMethod = args[0];

        // Invoking various methods to demonstrate the features, functionality
        // and usage of Oracle Connection Cache Attributes

        if (runMethod.equalsIgnoreCase("default")){
          // Initialize the Connection Cache and its attributes
          cacheAttributes.setConnectionCacheAttributes();
          System.out.println();

          System.out.println("----> We will now retrieve this connection. The "
            + "following method does this");
          cacheAttributes.getConnectionWithDefaultSetAttributes();

          System.out.println();
          System.out.println("----> CONCLUSION : We have retrieved the same connection");
        }else if (runMethod.equalsIgnoreCase("new")){
          // Initialize the Connection Cache and its attributes
          cacheAttributes.setConnectionCacheAttributes();
          System.out.println();

          System.out.println("----> Lets try to retrieve the connection with a "
            + "new set of Attributes");
          cacheAttributes.getConnectionWithNewAttributes();

          System.out.println();
          System.out.println("----> CONCLUSION : There is not matching connection "
            + "in the cache. So, we have got a new connection.");

        }else if (runMethod.equalsIgnoreCase("update")){
          // Initialize the Connection Cache and its attributes
          cacheAttributes.setConnectionCacheAttributes();
          System.out.println();

          System.out.println("----> Let us now update the connection attributes "
            + "and use it");
          cacheAttributes.getConnectionAndUpdateAttributes();

        }else if (runMethod.equalsIgnoreCase("matching")){
          // Initialize the Connection Cache and its attributes
          cacheAttributes.setConnectionCacheAttributes();
          System.out.println();

          System.out.println("----> The following method tries to retrieve the "
            + "connection with a matching set of attributes");
          cacheAttributes.getConnectionWithMatchingAttributes();

          System.out.println();
          System.out.println("----> CONCLUSION : As there is no connection with "
            + "exact set of attributes in the cache, we have retrieved a matching "
            + "connection which in this case happens to be OTN_CONNECTION. If "
            + "there was a connection in the cache with an exact match, then "
            + "that connection would be retrieved.");

        }else if (runMethod.equalsIgnoreCase("clear")){
          // Initialize the Connection Cache and its attributes
          cacheAttributes.setConnectionCacheAttributes();
          System.out.println();

          System.out.println("----> The following method clears the connection "
            + "of all its attributes");
          cacheAttributes.clearConnectionAttributes();
          System.out.println();

          System.out.println("----> Lets see if the Connection Attributes have "
            + "been cleared");
          cacheAttributes.getConnectionWithDefaultSetAttributes();

          System.out.println();
          System.out.println("----> CONCLUSION : There is not matching connection in the cache");
        }else{
        }
      }
    }catch(Exception e){
      // Catch and print in case of an exception
      e.printStackTrace();
    }
  }

  /**
   * This method initializes the Oracle DataSource and Connection Cache.
   * The default connection attributes are also set within this method.
   *
   * @exception Exception In Case of an Exception
   */
  private void setConnectionCacheAttributes() throws Exception{
    System.out.println("\n------------- Invoking method "
       + "setConnectionCacheAttributes() ----------------");

    System.out.println("-- Set up a new Connection");

    // Set DataSource properties
    ods.setUser(ConnectionParams.userName);
    ods.setPassword(ConnectionParams.password);
    ods.setServerName(ConnectionParams.serverName);
    ods.setDatabaseName(ConnectionParams.sid);
    ods.setPortNumber(ConnectionParams.portNo);
    ods.setDriverType(ConnectionParams.driverType);

    // Enable Connection Cache
    ods.setConnectionCachingEnabled(true);

    // Enter a name for Connection Cache
    ods.setConnectionCacheName("MyCache");

    // This is a connection cache parameter. This specifies that if there
    // is not an exact match of the connection attributes, even then retrieve
    // a matching connection. This value, by default, is false.
    // For more information on this feature and attribute, please read the
    // accompanied Readme file with this sample application.
    Properties cacheProps  =  new Properties();
    cacheProps.put("ClosestConnectionMatch", "true");
    ods.setConnectionCacheProperties(cacheProps);

    // Get a Connection from the Oracle DataSource
    OracleConnection conn = (OracleConnection)ods.getConnection();

    System.out.println("-- Connection Retrieved. Executing Sample Query in "
      + "the database");

    // Execute a Sample Query in the database to demonstrate that the
    // connection is established
    this.executeQuery(conn);

    System.out.println();
    System.out.println("-- Initializing Connection Attributes. This set includes");
    System.out.println("-- CONNECTION_NAME = OTN_CONNECTION");
    System.out.println("-- NLS_LANG = AMERICAN_AMERICA.WE8ISO8859P1");
    System.out.println();
    System.out.println("----> We will call it Default Set Attributes");

    // Initialize default Connection Attributes
    java.util.Properties connAttr = new Properties();
    connAttr.setProperty("CONNECTION_NAME", "OTN_CONNECTION");
    connAttr.setProperty("NLS_LANG", "AMERICAN_AMERICA.WE8ISO8859P1");

    System.out.println();
    System.out.println("-- Setting these Attributes And Closing Connection");

    System.out.println();

    // Apply the attributes to the connection and release the connection back
    // to the MyCache
    conn.close(connAttr);
  }


  /**
   * This method retrieves the connection after passing default
   * attributes. The attributes are then listed on the console.
   *
   * @exception Exception In Case of an Exception
   */
  private void getConnectionWithDefaultSetAttributes() throws Exception{
    System.out.println("\n----- Invoking method "
      + "getConnectionWithDefaultSetAttributes() ---------------");

    System.out.println("-- Initializing Default Set Properties");

    // Initialize default Connection Attributes
    java.util.Properties connAttr = new Properties();
    connAttr.setProperty("CONNECTION_NAME", "OTN_CONNECTION");
    connAttr.setProperty("NLS_LANG", "AMERICAN_AMERICA.WE8ISO8859P1");

    System.out.println("-- Retrieving Connection with Default Set Attributes");

    // Get a Connection from the Oracle DataSource
    OracleConnection conn = (OracleConnection)ods.getConnection(connAttr);
    System.out.println();
    System.out.println("-- Connection Retrieved. Executing Sample Query in "
      + "the database");