我想知道怎样才能得到多行文本框的光标位置

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

public class T extends JFrame {
JTextArea t = new JTextArea(
"随便用鼠标单击改变光标位置，然后看效果asdsbarweqrwehgdfbfqwerqwehasdrqwerewq");
{
t.addMouseListener(new MouseAdapter() {
public void mouseClicked(MouseEvent e) {
showPositon(e);
}
});
t.setLineWrap(true);
add(t);
setSize(200, 300);
setLocation(300, 300);
setVisible(true);
}

public static void main(String[] args) {
new T();
}

protected void showPositon(MouseEvent e) {
int start = t.getCaretPosition();
int len = t.getText().length();
int end = start + 5 < len ? start + 5 : len;
t.setSelectionStart(start);
t.setSelectionEnd(end);
String c = start < t.