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Table of Contents
Connecting to the database through JSP
There are two distinct methods for connecting to the database using JSP. The JSP will be compiled into a servlet, and that happens automatically each time you change the code. The first method makes database connections in the .jsp page itself, while the second one sets up the database connection in a separate class (called a bean in Java server programming).
Connecting within JSP page
Here is an example for connecting to the Oracle database through JSP. This approach mixes the presentation and logic. Using a bean allows separating those.
This is very similar to accessing the database through a java application, except that it is not run by the user who writes the code. As a result, the classpath settings are different. As long as you use the directory structure discussed below, you should not have problems with the class path.
This method is not recommended as it may expose your username and password if you are using a shared environment such as the department lab. This is because the public_html directory cannot be read protected and still serve its purpose. Using a bean eliminates this problem and is much more commonly used in real-world/business situations.
<html>
<head>
</head>
<body>
<%@ page import="java.sql.*" %>
<%@ page import="java.io.*" %>
<%
//
Class.forName("oracle.jdbc.driver.OracleDriver");
// Initialize connection to database
// Remember to change username and password
Connection conn = DriverManager.getConnection("jdbc:oracle:thin:@db1.chpc.ndsu.nodak.edu:1521:cs", "username", "password");
// Create a statement and a query, execute the query
Statement stmt = conn.createStatement();
String query = ""; //Remember to change this to match your database
ResultSet rset = stmt.executeQuery(query);
// Iterate through all result rows
while(rset.next())
{
// Print the first item of the result
out.println(rset.getString(1));
// Print a line break
out.println("<br/>");
}
// Clean up
stmt.close();
rset.close();
conn.close();
%>
</body>
</html>
Connecting using a Bean
If you want to split presentation and database access to make a 3-tier application (presentation, logic, database), you will need two pieces:
- A class (called a 'bean') to handle all of the database access
- A JSP page to call functions of the class and display query results
The logic layer (database queries and other logic) will be implemented in a class, the presentation layer (your JSP/HTML) will call functions of the class, and the class will do the work of getting data from the database.