Java读取大文件的处理

publicclass ProgressMonitorTest {

      publicstaticvoid main(String[] args) {

             // 创建一个包含“Click me”的窗口

             final JFrame f =new JFrame("ProgressMonitor Sample");

             f.getContentPane().setLayout(new FlowLayout());

             JButton b = new JButton("Click me");

             f.getContentPane().add(b);

             f.pack();

 

             // 设置按钮的动作事件

             b.addActionListener(new ActionListener() {

                    publicvoid actionPerformed(ActionEvent e) {

                           // 这儿使用了新的线程处理按钮的动作事件，因为我们需要

                           // 主窗口的线程响应用户。这样你可以多次点击该按钮，

                           // 会启动多个读取文件的线程。主窗口也保持响应。

                           new Thread() {

                                  publicvoid run() {

                                         try {

                                                // 打开文件输出流，把InputStream包装在ProgressMonitorInputStream中。

                                                // 在当前目录中需要放置一个大文件，建议超过50M

                                                String fileName = "D:\\qincidong\\资料\\ext\\深入浅出Ext.JS.徐会生等.pdf";
                                               InputStream in = new FileInputStream(fileName);
                                               ProgressMonitorInputStream pm = new ProgressMonitorInputStream( f, "Reading a big file", in);
                                               ProgressMonitor pmr = pm.getProgressMonitor();
                                              // 读取文件，如果总耗时超过2秒，将会自动弹出一个进度监视窗口。
                                             // 显示已读取的百分比。
                                            int c;
                                             File file = new File(fileName);
                                             long total = file.length();
                                             long curr = 0;
                                             byte[] data = new byte[1024];
                           
                                             while ((c = pm.read(data)) != -1) {
                                                   curr += c;
                                                  // 处理代码
                                                 pmr.setNote("已完成" + (curr*100 / total) + "%");
                                                 // 感觉不够明显，这里每执行一次循环，暂停一下
                                                 Thread.sleep(1);
                                              }
                                              System.out.println("执行完毕。total:" + total + ",curr:" + curr);
                                                pm.close();

                                         } catch (Exception ex) {

                                                ex.printStackTrace();

                                         }

                                  }

                           }.start();

                    }

             });

 

             // 设置缺省的窗口关闭行为，并显示窗口。

             f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

             f.setVisible(true);

      }

}