On Tue, 25 Feb 2003, Venkatarman, Rajagopal wrote:
> Date: Tue, 25 Feb 2003 14:16:49 -0500
> From: "Venkatarman, Rajagopal" <[EMAIL PROTECTED]>
> Reply-To: Jakarta Commons Users List <[EMAIL PROTECTED]>
> To: "'[EMAIL PROTECTED]'" <[EMAIL PROTECTED]>
> Subject: [Digester] Attribute Mapping
>
> Im trying to use the Digester to map attribute key-value to a bean property.
> This is the format of my XML
>
> <Employee Name="Raj">
>
If you make a slight tweak to this and make it:
<Employee name="Raj"/>
instead, then Digester has a pretty easy way to deal with stuff like this.
Consider that you have a JavaBean called EmployeeBean that has the usual
property getter and setter methods:
public class EmployeeBean {
...
public String getName();
public void setName(String name);
...
}
Now, let's say you want to create an ArrayList of all the employees in
your XML document. One way to do that would be:
Digester digester = new Digester();
List list = new ArrayList();
digester.push(list);
digester.addObjectCreate("Employees/Employee",
"com.mycompany.mybeans.EmployeeBean");
digester.addSetProperties("Employees/Employee");
digester.addSetNext("Employees/Employee",
"add", "java.lang.Object");
InputStream stream = ...; // InputStream for your XML document
digester.parse(stream);
The three rules, in order, do this for each <Employee> element
* Create a new instance of EmployeeBean and push it on Digester's stack
* Call all the property setters that have property names matching
the attributes of this element (so you can populate as many
properties as you want with just this one rule)
* Pass the top object on the stack (the EmployeeBean you just
created and populated) to the "add" method of the next-to-top
object on the stack (the List we pushed at the beginning)
* Pop the EmployeeBean instance off the stack now that we're
done with it.
The key ease-of-use feature is that all the property names are matched up
dynamically -- but only if your attributes follow the JavaBeans convention
for the property names themselves (start with a lower case letter). If
you cannot do this, you're going to be stuck either with your XSLT
transformation, or using nested elements the way you did it, or with
creating a custom Rule implementation that can do whatever is needed.
There's lots more examples of this kind of thing in the Digester javadocs
-- especially the Package Description for the org.apache.commons.digester
package.
http://jakarta.apache.org/commons/digester/api/
Craig
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