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package com.xiaoxuzhu;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JTextField;
/**
* Description:
*
* @author xiaoxuzhu
* @version 1.0
*
* <pre>
* 修改记录:
* 修改后版本 修改人 修改日期 修改内容
* 2022/5/29.1 xiaoxuzhu 2022/5/29 Create
* </pre>
* @date 2022/5/29
*/
public class BreakPointSuperveneFrame extends JFrame {
private JTextField tf_totalLength;
private JTextField tf_residuaryLength;
private JTextField tf_readToPos;
private JTextField tf_address;
private JTextField tf_endPos;
private JTextField tf_startPos;
private String urlAddress = "";// 用于存储网络资源的地址
private long totalLength = 0;// 存储网络资源的大小，以字节为单位
private long readToPos = 0;// 存储上次读取到的位置
private long residuaryLength = 0;// 存储未读内容的大小
/**
* Launch the application
*
* @param args
*/
public static void main(String args[]) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
BreakPointSuperveneFrame frame = new BreakPointSuperveneFrame();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the frame
*/
public BreakPointSuperveneFrame() {
super();
getContentPane().setLayout(null);
setTitle("下载网络资源的断点续传");
setBounds(100, 100, 514, 238);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
tf_startPos = new JTextField();
tf_startPos.setBounds(80, 165, 113, 22);
getContentPane().add(tf_startPos);
final JLabel label = new JLabel();
label.setText("起始位置：");
label.setBounds(10, 167, 74, 18);
getContentPane().add(label);
final JLabel label_1 = new JLabel();
label_1.setText("结束位置：");
label_1.setBounds(199, 167, 74, 18);
getContentPane().add(label_1);
tf_endPos = new JTextField();
tf_endPos.setBounds(267, 165, 117, 22);
getContentPane().add(tf_endPos);
final JLabel label_2 = new JLabel();
label_2.setText("网络资源的地址：");
label_2.setBounds(10, 52, 113, 18);
getContentPane().add(label_2);
tf_address = new JTextField();
tf_address.addActionListener(new ActionListener() {
public void actionPerformed(final ActionEvent e) {
try {
urlAddress = tf_address.getText().trim();
URL url = new URL(urlAddress);// 获得网络资源的URL
HttpURLConnection connection = (HttpURLConnection) url
.openConnection();// 获得连接对象
connection.connect();// 连接网络资源
totalLength = connection.getContentLength();// 获得网络资源的长度
connection.disconnect();// 断开连接
tf_totalLength.setText(String.valueOf(totalLength));// 显示总长度
tf_readToPos.setText("0");// 显示上次读取到的位置
residuaryLength = totalLength;// 未读内容为文件总长度
tf_residuaryLength.setText(String.valueOf(residuaryLength));// 显示未读内容
} catch (MalformedURLException e1) {
e1.printStackTrace();
} catch (IOException e2) {
e2.printStackTrace();
}
}
});
tf_address.setBounds(119, 50, 365, 22);
getContentPane().add(tf_address);
final JLabel label_3 = new JLabel();
label_3.setForeground(new Color(0, 0, 255));
label_3.setFont(new Font("", Font.BOLD, 14));
label_3.setText("输入网络资源的地址并回车，可以获得网络资源的大小。");
label_3.setBounds(10, 10, 384, 22);
getContentPane().add(label_3);
final JLabel label_4 = new JLabel();
label_4.setForeground(new Color(128, 0, 0));
label_4.setText("网络资源的大小为");
label_4.setBounds(10, 76, 113, 38);
getContentPane().add(label_4);
final JLabel label_5 = new JLabel();
label_5.setText("上次读取到");
label_5.setBounds(10, 123, 74, 18);
getContentPane().add(label_5);
tf_readToPos = new JTextField();
tf_readToPos.setBounds(80, 121, 113, 22);
tf_readToPos.setEnabled(false);
getContentPane().add(tf_readToPos);
final JLabel label_6 = new JLabel();
label_6.setText("字节处，还剩");
label_6.setBounds(202, 123, 87, 18);
getContentPane().add(label_6);
tf_residuaryLength = new JTextField();
tf_residuaryLength.setBounds(285, 120, 117, 22);
tf_residuaryLength.setEnabled(false);
getContentPane().add(tf_residuaryLength);
final JLabel label_7 = new JLabel();
label_7.setText("字节未读。");
label_7.setBounds(404, 123, 80, 18);
getContentPane().add(label_7);
final JLabel label_4_1 = new JLabel();
label_4_1.setForeground(new Color(128, 0, 0));
label_4_1.setText("个字节。");
label_4_1.setBounds(404, 76, 80, 38);
getContentPane().add(label_4_1);
tf_totalLength = new JTextField();
tf_totalLength.setBounds(119, 84, 283, 22);
tf_totalLength.setEnabled(false);
getContentPane().add(tf_totalLength);
final JButton button = new JButton();
button.setBounds(395, 162, 89, 28);
getContentPane().add(button);
button.addActionListener(new ActionListener() {
public void actionPerformed(final ActionEvent e) {
if (totalLength == 0) {
JOptionPane.showMessageDialog(null,
"没有网络资源。\n\n请输入正确的网址，然后回车。");
return;
}
long startPos = 0;// 起始位置
long endPos = 0;// 结束位置
try {
startPos = Long.parseLong(tf_startPos.getText().trim());// 起始位置
endPos = Long.parseLong(tf_endPos.getText().trim());// 结束位置
} catch (Exception ex) {
JOptionPane.showMessageDialog(null, "输入的起始位置或结束位置不正确。");
return;
}
readToPos = endPos;// 记录读取到的位置
residuaryLength = totalLength - readToPos;// 记录未读内容的大小
tf_readToPos.setText(String.valueOf(readToPos));// 显示读取到的位置
tf_residuaryLength.setText(String.valueOf(residuaryLength));// 显示未读字节数
tf_startPos.setText(String.valueOf(readToPos));// 设置下一个读取点的开始位置
tf_endPos.setText(String.valueOf(totalLength));// 设置下一个读取点的结束位置
tf_endPos.requestFocus();// 使结束位置文本框获得焦点
tf_endPos.selectAll();// 选择结束位置文本框中的全部内容，方便输入结束位置值
download(startPos, endPos);// 调用方法进行下载
}
});
button.setText("开始下载");
}
public void download(long startPosition, long endPosition) {
try {
URL url = new URL(urlAddress);// 获得网络资源的URL
HttpURLConnection connection = (HttpURLConnection) url
.openConnection();// 获得连接对象
connection.setRequestProperty("User-Agent", "NetFox");// 设置请求属性
String rangeProperty = "bytes=" + startPosition + "-";// 定义请求范围属性
if (endPosition > 0) {
rangeProperty += endPosition;// 调整请求范围属性
}
connection.setRequestProperty("RANGE", rangeProperty);// 设置请求范围属性
connection.connect();// 连接网络资源
InputStream in = connection.getInputStream();// 获得输入流对象
String file = url.getFile();// 获得文件对象
String name = file.substring(file.lastIndexOf('/') + 1);// 获得文件名
FileOutputStream out = new FileOutputStream("d:/" + name, true);// 创建输出流对象,保存下载的资源
byte[] buff = new byte[2048];// 创建字节数组
int len = 0;// 定义存储读取内容长度的变量
len = in.read(buff);// 读取内容
while (len != -1) {
out.write(buff, 0, len);// 写入磁盘
len = in.read(buff);// 读取内容
}
out.close();// 关闭流
in.close();// 关闭流
connection.disconnect();// 断开连接
if (readToPos > 0 && readToPos == totalLength) {
JOptionPane.showMessageDialog(null, "完成网络资源的下载。\n单击“确定”按钮退出程序。");
System.exit(0);
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
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