public PMInputStreamFixed()
{
f = new JFrame("ProgressMonitorInputStream Example");
Container contentPane = f.getContentPane();
textarea = new JTextArea();
JScrollPane scrollPane = new JScrollPane(textarea);
scrollPane.setPreferredSize(new Dimension(350,350));
JButton b = new JButton("读取文件");
b.addActionListener(this);
label = new JLabel(" ",JLabel.CENTER);