Introduction
- To access the database in Servlet, load the JDBC driver and return the Connection object.
- The Connection object is used to create Statement object. Before starting with database access through servlet, make sure that the proper JDBC connection with database has been setup.
Accessing a Database
Following files are required for accessing the database:i. welcome.html
ii. ServletDatabaseDemo.java
iii. web.xml
iv. ojdbc14.jar
Note: We are using Oracle database and type 4 (thin driver) to connect with Servlet application.
Example : Accessing the database and displaying the record
//welcome.html
<form action="show" method="post">
Enter Table Name : <input type="text" name="table">
<input type="submit" value="Show Records">
</form>
//ServletDatabaseDemo.java
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class ServletDatabaseDemo extends HttpServlet
{
protected void doPost(HttpServletRequest req, HttpServletResponse res)throws ServletException,IOException
{
PrintWriter pw = res.getWriter();
res.setContentType("text/html");
String tableName = req.getParameter("table");
try
{
Class.forName("oracle.jdbc.driver.OracleDriver");
Connection con = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:XE","scott","tiger");
Statement st=con.createStatement();
System.out.println ("connection established successfully...!!");
ResultSet rs = st.executeQuery("Select * from "+tableName);
pw.println("<table border=1>");
while(rs.next())
{
pw.println("<tr><td>"+rs.getInt(1)+"</td>
<td>"+rs.getString(2)+"</td>
<td>"+rs.getString(3)+"</td>
<td>"+rs.getString(4)+"</td></tr>");
}
pw.println("</table>");
pw.close();
rs.close();
con.close();
}
catch (Exception e)
{
e.printStackTrace();
}
}
}
//web.xml
<web-app>
<servlet>
<servlet-name>ServletDBConnection</servlet-name>
<servlet-class>ServletDatabaseDemo</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>ServletDBConnection</servlet-name>
<url-pattern>/showrecord</url-pattern>
</servlet-mapping>
</web-app>
