Recipe 23.8 Using A SQL JSTL Tag Without a DataSource Configuration

Problem

You want to specify the DataSource for the JSTL SQL tags inside a JSP.

Solution

Use the sql:setDataSource tag to establish a DataSource for the other SQL tags, such as sql:query.

Discussion

You can explicitly set the DataSource for the JSTL SQL tags in a JSP using sql:setDataSource and its dataSource attribute. Example 23-9 creates the same DataSource as Recipe 23.6 and stores it in a variable named dSource. The sql:query tag then specifies this DataSource with its own dataSource attribute. The code otherwise accomplishes the same task as Example 23-8: the JSP sends a SELECT SQL statement to the database system, then displays the results.

Example 23-9. Using the sql:setDataSource tag

<%@ taglib uri="http://java.sun.com/jstl/core" prefix="c" %>
<%@ taglib uri="http://java.sun.com/jstl/sql" prefix="sql" %>

<html>
<head><title>Database Query</title></head>
<body>
<h2>Querying a database from a JSTL tag</h2>

<sql:setDataSource dataSource=
"jdbc:oracle:thin:@192.168.0.2:1521:ORCL,oracle.jdbc.driver.OracleDriver,scott,tiger" 
var="dSource" scope="application"/>

<sql:query var="athletes" dataSource="dSource">
SELECT * FROM athlete
</sql:query>

<table border="1">

<c:forEach var="row" items="${athletes.rows}">

<tr>
<th>user_id</th>
<th>name</th>
<th>birthdate</th>
<th>passwrd</th>
<th>gender</th></tr>

<tr>
<td><c:out value="${row.user_id}"/></td>
<td><c:out value="${row.name}"/></td>
<td><c:out value="${row.birthdate}"/></td>
<td><c:out value="${row.passwrd}"/></td>
<td><c:out value="${row.gender}"/></td>
</tr>

</c:forEach>
</table>

</body>
</html>

The code stores the DataSource in an application-scoped variable, so that another JSP can access the DataSource this way:

<sql:query var="athletes" dataSource="${dSource}">
SELECT * FROM athlete
</sql:query>

The only difference between this sql:query usage and Example 23-9 is that the value of the dataSource attribute has to be resolved using the EL; the tag has to find and get the value of an application-scoped variable (a servlet context attribute) named "dSource."

You can also specify a DataSource in the JSTL SQL tags as a Java Naming and Directory Interface (JNDI) string, but we will reserve discussion of that topic for Chapter 21, which covers using databases with servlets and JSPs.

Recipe 23.8 Using A SQL JSTL Tag Without a DataSource Configuration

Problem

Solution

Discussion

Example 23-9. Using the sql:setDataSource tag

See Also