Adding a DataSource

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The first component that we configure is a DataSource. As we discussed in Chapter 11, "Integrating the Jakarta Commons Database Connection Pool (DBCP)," there are two methods for configuring a DataSource. With the first method, which is not applicable to this discussion, you directly manipulating a DataSource instance using one of your own components. The second method, which we demonstrate in this section, involves modifying the struts-config.xml file. This method leaves management of the DataSource in the capable hands of the Controller, allowing you, the developer, to focus on project-specific efforts.

When describing DataSource instances, you must use the <data-sources> element. This element contains n-number of <data-source> sub-elements, which describe each DataSource instance. The syntax of the <data-sources> element, containing a single <data-source> sub-element, is shown in the following code snippet:

 <data-sources>   <data-source     type="org.apache.commons.dbcp.BasicDataSource">     <set-property property="driverClassName"       value="com.mysql.jdbc.Driver" />     <set-property property="url"       value="jdbc:mysql://localhost/stocks" />     <set-property property="username"       value="YOUR USERNAME" />     <set-property property="password"       value="YOUR PASSWORD" />   </data-source> </data-sources> 

As you can see, the <data-source> sub-element is described completely using <set-property> sub-elements. Each one of the properties listed in the <set-property> elements maps to a single <data-source> attribute. Table 15.3 describes the attributes of a <data-source> entry.

Table 15.3: The Attributes of a <data-source> Entry

Attribute	Description
type	The fully qualified class name of the DataSource object being used in this <data-source> definition. This class must extend javax.sql.DataSource, and it must be completely configurable using <set-property> sub-elements (all configurable data members must satisfy the JavaBean specification). (optional)
className	The fully qualified classname of the configuration object for the instance of this DataSource. The implementation of this object must extend org.apache.struts.config.DataSourceConfig. (optional)
key	A unique key identifying a DataSource instance stored in the ServletContext. If this property is not used, then the key is defaulted to Action.DATA_SOURCE_KEY. If you intend to use more than one DataSource in your application, you must include a key for each one. (optional)

As we stated earlier, the actual attributes used by a specific DataSource are dependent on that DataSource's implementation. Therefore, the contents of your particular <set-property> sub-elements also depend on your specific implementation.

This code snippet shows an example that uses the <data-source> sub-element:

 <data-sources>   <data-source     type="org.apache.commons.dbcp.BasicDataSource">     <set-property property="driverClassName"       value="com.mysql.jdbc.Driver" />     <set-property property="url"       value="jdbc:mysql://localhost/stocks" />     <set-property property="username"       value="YOUR USERNAME" />     <set-property property="password"       value="YOUR PASSWORD" />   </data-source> </data-sources> 

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