Java Server Pages

Using a Generic Database Bean

All the database custom action tag handler classes described later in this chapter are based on a generic database bean named com.ora.jsp.sql.SQLCommandBean . This bean uses a number of other classes. Figure 17.3 shows the relationship between all these classes.

Figure 17-3. The SQLCommandBean and related classes

The SQLCommandBean takes care of setting all values in a JDBC java.sql.PreparedStatement and executing the statement. For SELECT statements, it also processes the result by creating com.ora.jsp.sql.Row objects containing a com.ora.jsp.sql.Column object for each column in the result. The rows returned by the SELECT statement are returned to the caller as a java.util.Vector with Row objects. The EmployeeRegistryBean described in Chapter 15 is one example of how to use this bean, and other examples follow in this chapter. Let’s look at each class in detail, starting with the SQLCommandBean itself.

The SQLCommandBean and Value Classes

The SQLCommandBean has three write-only properties. Example 17.3 shows the beginning of the class file with the setter methods.

Example 17-3. SQLCommandBean Property Setter Methods

package com.ora.jsp.sql; import java.util.*; import java.sql.*; import com.ora.jsp.sql.value.*; public class SQLCommandBean { private Connection conn; private String sqlValue; private Vector values; private boolean isExceptionThrown = false; ...