Jakarta Commons Cookbook

3.19. Getting and Setting Properties as Strings

Problem

You need to persist a bean to a text file, or populate a bean’s properties from a String.

Solution

Use BeanUtils to get and set bean properties with strings. This utility contains many of the same functions as PropertyUtils with one major exception; instead of returning the Object value of the property, BeanUtils returns and expects a string representation of a value. The following code uses BeanUtils to populate a bean that is dependent on user input:

import java.util.*;
import org.apache.commons.beanutils.*;

Person person = new Person( );
person.setAge( new Integer( 45 ) );
person.setName( "Donald" );
person.setOccupation( "Salesman" );

// Get the Age as a String
               String ageString = BeanUtils.getProperty( person, "age" );

               // Set the Age from a String
               BeanUtils.setProperty( person, "age", "50" );

Discussion

BeanUtils come in handy when a bean is populated from a user-supplied input like standard input or the parameters of an HTTP request. In fact, BeanUtils started as the mechanism used to populate a Struts ActionForm from the contents of an HTTP request. When the Struts ActionServlet receives a request that is mapped to an Action, the ActionServlet calls a method in RequestUtils, which examines the request and sets any properties on the relevant ActionForm. Because the inner workings of Struts are outside the scope of this book, Example 3-7 takes a String input from System.in and sets the age property of Person.

Example 3-7. Using ...