package udp;
import java.net.* ;
import javax.swing.* ;
import java.awt.event.*;
import java.io.* ;
public class Download
{
  public static void main(String[]args)
  {
     JFrame jf=new JFrame("XiaoWei DownLoad Software") ;
     jf.addWindowListener(new   WindowAdapter()
                          {
                         public  void windowClosing(WindowEvent e)
                           {
                             System.exit(0);   //退出程序
                           }
                          });
      jf.setSize(600,400);
      jf.setLocation(200,300);
      JPanel p=new JPanel() ;   //面板默认是FlowLayout布局管理器
      final JTextField j=new  JTextField("Please Input DownLoad Address In This Area",40) ;
      JLabel l=new JLabel("请输入下载地址:") ;
      p.add(l);
      p.add(j);
      jf.getContentPane().add(p,"North");
      final   JTextArea t1=new JTextArea() ;
      jf.getContentPane().add(t1,"Center");
      JButton b=new JButton("DownLoad") ;
      jf.getContentPane().add(b,"South") ;
      b.addActionListener(new ActionListener()
                          {
                            public void actionPerformed(ActionEvent e)
                            {
                               String s=j.getText();  //如果要在内部类中使用局部变量的话 要把局部变量设置为final类型 最终类型
                               try
                               {
                                 String line=System.getProperty("line.separator") ;//获得与平台无关的换行
                                 URL url=new URL(s);
                                  URLConnection u=url.openConnection() ;   //打开连接 获得URLConnection类的对象
                                 t1.append("目标主机:" +url.getHost());
                                 t1.append(line);
                                 t1.append("主机缺省端口:"+url.getDefaultPort());
                                 t1.append(line);
                                 t1.append("目标类型:"+u.getContentType()) ;
                                 t1.append(line);
                                 t1.append("对象大小"+u.getContentLength());
                                 InputStream in=u.getInputStream() ;//打开 输入流
                                 InputStreamReader r=new InputStreamReader(in);  //字节流到字符流转换的桥梁
                                 BufferedReader br=new BufferedReader(r) ;  //连接到bufferreader提供读取一行数据的功能
                                 FileOutputStream fos=new FileOutputStream("D:\\1.html") ;  //假如我们下载网页文件
                                 String str ;   //用String的好处是  读取到多少个字符 就会开辟多少的空间

                                   while ((str=br.readLine())!=null) {
                                     fos.write(str.getBytes()); //因为读取一行文本会忽略换行回车 那么实际读取的文件会小 所以应该加上 我们应该使用与系统无关的回车换行
                                       fos.write(line.getBytes()); //最后写的文件比 实际文件大2个字节 是因为 我们在最后一次多写入了 回车 换行 2个字节
                                   }

                                 fos.close(); //关闭文件流
                                 br.close();
                                 r.close();
                                 in.close(); //使用完流要关闭
                               }
                               catch(Exception xe)
                               {
                                 xe.printStackTrace();
                               }

                            }
                          });
      jf.show();

 

  }

}