JavaServer Pages, 3rd Edition

Using a Generic Database Bean

Some consider using the JSTL database access actions in JSP pages a bad idea because so much business logic ends up in the presentation layer (the View). For a very simple application, it’s no big deal, but for a more complex application it’s better to move the SQL statements to some other component type. You have basically two options: move it to a Controller servlet (or an action class that the servlet delegates to), as in the Chapter 19 example, or encapsulate it in a custom action. In both cases it makes sense to add yet another abstraction layer in the form of a bean that encapsulates the SQL statements and let the servlet or tag handler access the data in a purer form. One example of such a bean is the EmployeeRegistryBean used in Chapter 19 for authentication as well as for retrieving and saving information about an employee.

When you develop this type of database access components, you can of course use the JDBC API directly. I find it handy to use a generic JDBC bean, such as the com.ora.jsp.beans.sql.SQLCommandBean described in this section. Besides taking care of a lot of the grunt work, it also converts a query result into an instance of the same class that the JSTL <sql:query> action uses to expose the result. This makes it easy to use in a JSP page that renders the result.

The SQLCommandBean has three write-only properties. Example 24-4 shows the beginning of the class file with the setter methods.

Example 24-4. SQLCommandBean property ...