Programming Tutorials

Configuring JDBC DataSources in Struts

By: Barbara in Struts Tutorials on 2008-12-10  

You can define any number of JDBC javax.sql.DataSource objects for the application in the configuration file under the element <data-sources>. Every data source is defined within the <data-sources> element using the <data-source> element. The <data-source> element defines a number of attributes, the most important of which are listed in Table below.

You supply any further configuration information using nested <set-property> tags. You can use these tags to set JavaBeans properties on the DataSource; they take property and value attributes to specify the property to set and the value to which to set it.

The default attribute values for <data-source> cause it to instantiate a GenericDataSource and give it the key. The GenericDataSource class wraps an ordinary JDBC Driver and turns it into a DataSource with a database connection pool. This class has a number of JavaBean properties to configure, the most important of which are listed in Table below.

The following excerpt illustrates how you'll use these attributes to define a DataSource for the pizza MySQL database:

<data-sources>
  <data-source key="pizza">
    <set-property property="driverClass"
                   value="com.mysql.jdbc.Driver" />
    <set-property property="url"
                   value="jdbc:mysql://localhost/pizza" />
  </data-source>
</data-sources>

The DataSource will be bound in the application context under the name pizza. You can use it in the JSTL <sql:query>, <sql:update>, and <sql:transaction> tags:

<sql:query var="myobject"
            dataSource="${applicationScope.pizza}">

You can also retrieve it from within a Struts action using the getDataSource() method:

DataSource ds = getDataSource(request, "pizza");
Connection con = ds.getConnection();