import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.lang.reflect.Method;
import java.util.Hashtable;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
public class DynamicHookupTest extends JFrame {
DynamicActionAdapter actionAdapter = new DynamicActionAdapter();
JLabel label = new JLabel("Ready...", JLabel.CENTER);
int count;
public DynamicHookupTest() {
JButton launchButton = new JButton("Launch!");
getContentPane().add(launchButton, "South");
getContentPane().add(label, "Center");
actionAdapter.hookup(launchButton, this, "launchTheMissiles");
}
public void launchTheMissiles() {
label.setText("Launched: " + count++);
}
public static void main(String[] args) {
JFrame f = new DynamicHookupTest();
f.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent we) {
System.exit(0);
}
});
f.setSize(150, 150);
f.setVisible(true);
}
}
class DynamicActionAdapter implements ActionListener {
Hashtable actions = new Hashtable();
public void hookup(Object sourceObject, Object targetObject, String targetMethod) {
actions.put(sourceObject, new Target(targetObject, targetMethod));
invokeReflectedMethod(sourceObject, "addActionListener", new Object[] { this },
new Class[] { ActionListener.class });
}
public void actionPerformed(ActionEvent e) {
Target target = (Target) actions.get(e.getSource());
if (target == null)
throw new RuntimeException("unknown source");
invokeReflectedMethod(target.object, target.methodName, null, null);
}
private void invokeReflectedMethod(Object target, String methodName, Object[] args,
Class[] argTypes) {
try {
Method method = target.getClass().getMethod(methodName, argTypes);
method.invoke(target, args);
} catch (Exception e) {
throw new RuntimeException("invocation problem: " + e);
}
}
class Target {
Object object;
String methodName;
Target(Object object, String methodName) {
this.object = object;
this.methodName = methodName;
}
}
}