滚动条在iframe中不起作用

Question

我正在尝试在java swing中创建自定义查看器，我已经设法在我的iFrame上显示文本数据，但问题在于文本卷是; arge因为滚动条出现在框架上但不起作用....请让我知道可以做什么......代码......

公共类DocumentViewer扩展了JFrame {

static JEditorPane je = new JEditorPane();
static JTextArea textArea = new JTextArea();
StringBuffer outputBuff = new StringBuffer();

private JPanel contentPane;

/**
 * Launch the application.
 */
public static void main(String[] args) {

    EventQueue.invokeLater(new Runnable() {
        public void run() {
            try {
                DocumentViewer frame = new DocumentViewer();
                JInternalFrame iFrame = new JInternalFrame("Document",false, true, false, false);

                JScrollPane scrollPane = new JScrollPane(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
                    JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
                iFrame.getContentPane().add(textArea, BorderLayout.CENTER);
                iFrame.setVisible(true);
                iFrame.validate();
                frame.getContentPane().add(iFrame, BorderLayout.CENTER);
                frame.setVisible(true);
                frame.validate();



            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
}

/**
 * Create the frame.
 */
public DocumentViewer() {

    outputBuff = readFile();
    System.out.println("::::output" + outputBuff);
    textArea.setText(outputBuff.toString());
    textArea.requestFocus();
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setBounds(100, 100, 350, 350);
    contentPane = new JPanel();
    contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
    contentPane.setLayout(new BorderLayout(0, 0));
    setContentPane(contentPane);
}

public StringBuffer readFile(){

    StringBuffer sb = new StringBuffer();
try{
    //text[start]

    BufferedReader buf = new BufferedReader(new FileReader("C:\\Users\\azhar.memon\\Desktop\\test.txt"));
    String readLine = buf.readLine();
     while(readLine != null){

         sb.append(readLine + " ").append(System.getProperty("line.separator"));
         readLine = buf.readLine();  
     }
     buf.close();
     System.out.println(":::" + sb);

    //text[end]

}catch(Exception e){
    e.printStackTrace();
}
    return sb;
}

}