Swing Hacks

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Chapter 11, Native Integration and Packaging

#83 Control iTunes Under Windows

HACK

Working with COM

The Component Object Model (COM) is a standard way for Windows com-

ponents to expose functionality that other programs can call at runtime.

com4j (https://com4j.dev.java.net/) is an open source library that creates

connections from Java programs to COM objects. com4j has two parts: a

command-line program to create the Java interfaces that your program will

call, and a native library that binds your program to the COM object at run-

time.

com4j uses class annotations to do its magic, so you can only

use it with Java 5.0 or greater.

To get started, download the com4j package at https://com4j.dev.java.net/

servlets/ProjectDocumentList. With the com4j stubber and the iTunes exe-

cutable in your current directory, you can generate the interfaces like this:

java -jar tlbimp.jar -o jtunes -p test.jtunes iTunes.exe

This command will load the iTunes executable and look for COM defini-

tions. Once they are located,

tlbimp will generate a bunch of Java interfaces

in the

test.jtunes package and put the .java files into the jtunes directory. If

you look at the generated Java interfaces, you will see a whole slew of meth-

ods and objects for playing, querying tracks, and dealing with virtually every

other feature of iTunes. com4j will also pull out any embedded documenta-

tion and insert the documentation as JavaDoc comments in the generated

interfaces.

This process is pretty quick, so you may find it useful to call

it from Ant as part of your compile process.

Once you have the interface stubs, you can create a program to control

iTunes quite easily. You can use the same program that you did when con-

trolling iTunes on the Mac

[Hack #82]. Just replace the action listener with the

class in Example 11-6.

Example 11-6. A listener to control iTunes on Windows

import test.jtunes.*;

public class WinItunes {

public void actionPerformed(ActionEvent evt) {

try {