cvs commit: jakarta-velocity/examples DBContext.java

[geirm]

geirm       01/01/02 21:42:57

  Added:       examples DBContext.java
  Log:
  Silly example of a Context implementaion that uses MySQL as the storage mechanism.
  
  Revision  Changes    Path
  1.1                  jakarta-velocity/examples/DBContext.java
  
  Index: DBContext.java
  ===================================================================
  
  import java.sql.*;
  import java.io.Serializable;
  import java.io.*;
  
  import org.apache.velocity.context.AbstractContext;
  import org.apache.velocity.context.Context;
  
  /**
   *   Example context impl that uses a database to store stuff :)
   *
   *   yes, this is silly
   *
   *   expects a mysql db test with table 
   * 
   *  CREATE TABLE contextstore (
   *    k varchar(100),
   *    val blob
   *  );
   *
   *  very fragile, crappy code.... just a demo!
   *
   * @author <a href="mailto:[EMAIL PROTECTED]">Geir Magnusson Jr.</a>
   * @version $Id: DBContext.java,v 1.1 2001/01/03 05:42:57 geirm Exp $
   */
  
  public class DBContext extends AbstractContext
  {
      Connection conn = null;
  
      public DBContext()
      {
          super();
          setup();
      }
  
      public DBContext( Context inner )
      {
          super( inner );
          setup();
      }
  
      public Object internalGet( String key )
      {
          try 
          {
              String data = null;
  
              String sql = "SELECT k, val FROM contextstore WHERE k ='"+key+"'";
              
              Statement s = conn.createStatement();
  
              ResultSet rs = s.executeQuery( sql );
  
              if(rs.next())
                 data = rs.getString("val");
              
              rs.close();
              s.close();
              
              ObjectInputStream in = new ObjectInputStream(  new ByteArrayInputStream( 
data.getBytes() ));
  
              Object o =  in.readObject();
  
              in.close();
  
              return o;
          }        
          catch(Exception e)
          {
              System.out.println("internalGet() : " + e );
          }
  
          return null;
      }
  
      public Object internalPut( String key, Object value )
      {
  
          try 
          {    
              ByteArrayOutputStream baos = new ByteArrayOutputStream();
              ObjectOutputStream out = new ObjectOutputStream( baos );
              
              out.writeObject( value );
              String data = baos.toString();
  
              out.close();
              baos.close();
            
              Statement s = conn.createStatement();
  
              s.executeUpdate( "DELETE FROM contextstore WHERE k = '" + key + "'" );
              s.executeUpdate( "INSERT INTO contextstore (k,val) values ('"+key+"','" 
+ data + "')" );
  
              s.close();            
          }        
          catch(Exception e)
          {
              System.out.println("internalGet() : " + e );
          }
  
          return null;
      }
  
      public  boolean internalContainsKey(Object key)
      {
          return false;
      }
  
      public  Object[] internalGetKeys()
      {
          return null;
      }
  
      public  Object internalRemove(Object key)
      {
          return null;
      }
  
  
      private void setup()
      {
          try
          {
              Class.forName("org.gjt.mm.mysql.Driver").newInstance();
              conn = 
DriverManager.getConnection("jdbc:mysql://localhost/test?user=root");
          }
          catch (Exception e) 
          {
              System. out.println(e);
          }
        
          return;
      }
  }