java 实现一个单线程的资源下载器

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package cn.lruihao.base; import java.awt.FlowLayout; import java.awt.Font; import java.awt.HeadlessException; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.io.FileOutputStream; import java.io.InputStream; import java.net.URL; import java.net.URLConnection; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JOptionPane; import javax.swing.JPanel; import javax.swing.JTextField; public class SingleThreadDown extends JFrame implements ActionListener { private final JPanel panel=new JPanel(); private final JLabel label1=new JLabel("网络资源的单线程下载："); private final JLabel label2=new JLabel("网络资源的网址："); JButton StartButton = new JButton("单击开始下载"); JButton resetButton = new JButton("清空"); JButton exitButton = new JButton("退出"); JTextField urlField = new JTextField(20); public SingleThreadDown() { panel.setLayout(new FlowLayout()); //布局管理器 label1.setFont(new Font("雅黑",Font.BOLD,15)); panel.add(label1); panel.add(label2); panel.add(urlField); panel.add(StartButton); panel.add(resetButton); panel.add(exitButton); setContentPane(panel); setSize(400,200); setLocation(400,400); setVisible(true); //面板可视化，也可以在 main 中通过 JFrame 子类对象调用方法设置 setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //默认关闭事件 StartButton.addActionListener(this);//添加点击事件，传入 ActionListener 对象，由于子类继承了 ActionListener 接口，所以 this resetButton.addActionListener(this); exitButton.addActionListener(this); } public void download(String address) throws Exception { URL url = new URL(address); URLConnection urlcon = url.openConnection(); urlcon.connect(); InputStream in=urlcon.getInputStream();//获取的字节流对象 String filePath = url.getFile(); int pos=filePath.lastIndexOf("/"); //"/"分割的最后一个串的下标 String fileName = filePath.substring(pos 1); FileOutputStream out = new FileOutputStream("C:\Users\李瑞豪、Desktop\" fileName); byte[] b = new byte[1024]; int len=0; while((len=in.read(b,0,1024))!=-1) { out.write(b,0,len); } out.close(); in.close(); JOptionPane.showMessageDialog(this, "下载完毕"); } @Override public void actionPerformed(ActionEvent e) { if(e.getSource()==StartButton) { if("".equals(urlField.getText())){ JOptionPane.showMessageDialog(this, "请输入资源地址"); } String url = urlField.getText(); try { download(url); } catch (Exception e1) { JOptionPane.showMessageDialog(this, "资源地址有误，请检查~"); e1.printStackTrace(); } }else if(e.getSource()==resetButton) { urlField.setText(""); }else { System.exit(0); } } public static void main(String[] args) { new SingleThreadDown(); } }