Add XPath to JavaBeans

 

Request addressbook [1] to a JavaBean. state. code is a common way to interact with ans, but you can use more powerful XPath specifications.

The purpose of creating XPath is to access and modify XML data. However, a new project of Apache Jakarta allows you to apply powerful XPath specifications to normal JavaBeans.

As an example, we use a JavaBean with the following structure:

Person. name is a String
Person. age is an integer.
Person. birthtown is a Town object
Person. address is an array of Address objects.
Town. name is a string
Address. number is a string
Address. street is a string
Address. town is a Town object

(For simplicity, no source code is provided)

For a given Person object, you can use "name" to get the object name. You can use "birthtown/name" to get the name of the origin, you can also use "address [number = 21]/town/name" to get the name of the town associated with the address (for example, 21.

Apart from being more powerful, the main difference between XPath and the common bean symbols is that elements are separated by backslash (/) rather than periods (.). Once you get used to this feature, it will become very simple.

The following code demonstrates how easy it is to apply the XPath symbol to our JavaBean structure using JXPath:

Import org. apache. commons. jxpath. JXPathContext;
....
Person person = ....;
JXPathContext context = JXPathContext. newContext (person );
System. out. println (context. getValue ("name "));
System. out. println (context. getValue ("age "));
System. out. println (context. getValue ("birthtown/name "));
System. out. println (context. getValue ("address [number = 21]/street "));
System. out. println (context. getValue ("address [number = 21]/town/name "));
....
XPath can be used to set values or create beans. Of course, it can also read values. For more information about XPath and its JXPath implementation, see the JXPath site.