Java Reference
In-Depth Information
Now that you have created and understand the ConnectionPoolServlet , you can put it to use
with another example. This example is based on your TitleListServlet , except that you will
do a generic query with no request parameters. There are two important changes to this servlet.
The first is how it gets a connection and the second is how it releases that connection.
The TitleListGlobalPooledServlet gets a Connection object by calling the
ServletContext.getAttribute() method, passing it the key “CONNECTION_POOL” , which
returns a reference to the ConnectionPool object. It can then call the
ConnectionPool.getConnection() method to get a JDBC connection:
// Get a reference to the ConnectionPool from the Global
// ServletContext
pool =(ConnectionPool)
// Get a connection from the ConnectionPool
con = pool.getConnection();
When the servlet finishes with the connection, it must release it. This is done by calling the
ConnectionPool 's releaseConnection() method:
// Release the connection
That is all there is to it. After you are finished with the ConnectionPool , it still resides in the
ServletContext waiting on future requests. You'll find the entire source for the
TitleListGlobalPooledServlet in Listing 7.11.
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
import java.sql.*;
import ConnectionPool.*;
public class TitleListGlobalPooledServlet extends HttpServlet {
public void init(ServletConfig config)
throws ServletException {
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