Keymap的使用

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.InputEvent;
import java.awt.event.KeyEvent;
import java.util.Hashtable;

import javax.swing.Action;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.KeyStroke;
import javax.swing.text.BadLocationException;
import javax.swing.text.DefaultEditorKit;
import javax.swing.text.Document;
import javax.swing.text.JTextComponent;
import javax.swing.text.Keymap;
import javax.swing.text.TextAction;

public class KeyListener {
      public static void main(String[] args) {
            JTextArea area = new JTextArea(6, 32);
            Keymap parent = area.getKeymap();
            Keymap newmap = JTextComponent.addKeymap("KeymapExampleMap", parent);  //将一个新 keymap 添加到 keymap 层次结构。

            KeyStroke u = KeyStroke.getKeyStroke(KeyEvent.VK_U,InputEvent.CTRL_MASK);   //建立一个快捷键
            Action actionU = new UpWord();
            newmap.addActionForKeyStroke(u, actionU);  //向 keymap 添加绑定。

            Action actionList[] = area.getActions();   //文本域中有很多个Action
            Hashtable lookup = new Hashtable();
            for (int j = 0; j < actionList.length; j += 1)
              lookup.put(actionList[j].getValue(Action.NAME), actionList[j]);  //将每一个Action与它的名字关联，并存到哈希表中

            KeyStroke L = KeyStroke.getKeyStroke(KeyEvent.VK_L,InputEvent.CTRL_MASK);
            Action actionL = (Action) lookup.get(DefaultEditorKit.selectLineAction);
            newmap.addActionForKeyStroke(L, actionL);

            KeyStroke W = KeyStroke.getKeyStroke(KeyEvent.VK_W,InputEvent.CTRL_MASK);
            Action actionW = (Action) lookup.get(DefaultEditorKit.selectWordAction);
            newmap.addActionForKeyStroke(W, actionW);

            area.setKeymap(newmap);

            JFrame f = new JFrame("KeymapExample");
            f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            f.getContentPane().add(new JScrollPane(area), BorderLayout.CENTER);
            area.setText("This is a test.");
            f.pack();
            f.setVisible(true);
      }


}
//创建一个行为，该行为是使选定文本都变成大写的
class UpWord extends TextAction {
      public UpWord() {
        super("uppercase-word-action");
      }

      public void actionPerformed(ActionEvent e) {
            JTextComponent comp = getTextComponent(e);  //得到源组件
            if (comp == null)
              return;
            Document doc = comp.getDocument();
            int start = comp.getSelectionStart();  //选定文本的起始位置
            int end = comp.getSelectionEnd();
            try {
                  int left = javax.swing.text.Utilities.getWordStart(comp, start); //光标在start位置的单词的起始位置
                  int right = javax.swing.text.Utilities.getWordEnd(comp, end);    //这样将选定的文本扩充了它的开始和结尾
                  String word = doc.getText(left, right - left);  //得到选定的文本
                  doc.remove(left, right - left);
                  doc.insertString(left, word.toUpperCase(), null);
                  comp.setSelectionStart(start);
                  comp.setSelectionEnd(end);
            } catch (BadLocationException ble) {
                  return;
            }
      }
}