package component;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.text.*;

public class TextAreaFrame extends JFrame {
  JPanel contentPane = new JPanel();
  JTextArea jTextArea1 = new JTextArea
      ("文本框的創建語法：（1）new JTextArea()，創建空的文本框；" + 
          "（2）new JTextArea(String text)，創建帶有文字的文本框。");
  //創建文檔類
  Document document;
  //創建4個按鈕
  JButton jButton1 = new JButton();
  JButton jButton2 = new JButton();
  JButton jButton3 = new JButton();
  JButton jButton4 = new JButton();

  public TextAreaFrame() {
    try {
      //窗口關閉時清空內存
      setDefaultCloseOperation(EXIT_ON_CLOSE);
      jbInit();
    }
    catch (Exception e) {}
  }

  public static void main(String[] args) {
    TextAreaFrame frame = new TextAreaFrame();
    Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
    Dimension frameSize = frame.getSize();
    //居中對齊
    frame.setLocation((screenSize.width - frameSize.width) / 2,
        (screenSize.height - frameSize.height) / 2);
    frame.setVisible(true);
  }
  
  private void jbInit() throws Exception {
    contentPane = (JPanel)this.getContentPane();
    setTitle("文本框示例");
    setSize(new Dimension(412, 330));
    contentPane.setLayout(null);
    //設置文本框的位置與大小
    jTextArea1.setBounds(new Rectangle(21, 30, 363, 159));
    //使文本框自動換行
    jTextArea1.setLineWrap(true);
    jTextArea1.setWrapStyleWord(true);
    //取得文本框的Document類
    document = jTextArea1.getDocument();
    //分別設置按鈕的標題、位置、大小與加入動作接收器
    jButton1.setText("定義文本框鼠標位置");
    jButton1.setBounds(new Rectangle(22, 213, 159, 30));
    jButton1.addActionListener(new java.awt.event.ActionListener() {
      public void actionPerformed(ActionEvent e) {
        jButton1_actionPerformed(e);
      }
    });
    jButton2.setText("字符總數與指定范圍字符串");
    jButton2.setBounds(new Rectangle(186, 213, 198, 30));
    jButton2.addActionListener(new java.awt.event.ActionListener() {
      public void actionPerformed(ActionEvent e) {
        jButton2_actionPerformed(e);
      }
    });
    jButton3.setText("增加文本框的內容");
    jButton3.setBounds(new Rectangle(22, 255, 158, 30));
    jButton3.addActionListener(new java.awt.event.ActionListener() {
      public void actionPerformed(ActionEvent e) {
        jButton3_actionPerformed(e);
      }
    });
    jButton4.setText("在指定的位置插入字符");
    jButton4.setBounds(new Rectangle(186, 255, 198, 30));
    jButton4.addActionListener(new java.awt.event.ActionListener() {
      public void actionPerformed(ActionEvent e) {
        jButton4_actionPerformed(e);
      }
    });
    //加入各個控件
    contentPane.add(jTextArea1, null);
    contentPane.add(jButton1, null);
    contentPane.add(jButton2, null);
    contentPane.add(jButton3, null);
    contentPane.add(jButton4, null);
  }
  //定義文本框鼠標位置的方法
  void jButton1_actionPerformed(ActionEvent e) {
    try {
      int pos = Integer.parseInt(
          JOptionPane.showInputDialog("請輸入文本框鼠標的位置"));
      //定義文本框的光標位置
      jTextArea1.setCaretPosition(pos);
    }
    catch (Exception e1) {}
    //使文本框獲得焦點
    jTextArea1.requestFocus();
  }
  //顯示文本框的文字總數與指定位置的字符串的方法
  void jButton2_actionPerformed(ActionEvent e) {
    try {
      JOptionPane.showMessageDialog(null, "文本框的字符總數是" +
                                    String.valueOf(document.getLength()) + "\n"
                                    + "第1至9個字符是" + document.getText(0, 8) +
                                    "\n");
    }
    catch (Exception e1) {}
  }
  //在文本框中增加字符
  void jButton3_actionPerformed(ActionEvent e) {
    jTextArea1.append("\n這是新增加的內容");
  }
  //在文本框中插入字符
  void jButton4_actionPerformed(ActionEvent e) {
    jTextArea1.insert("這是新插入的內容",
                      jTextArea1.getCaretPosition());
  }
}