java多线程下载

Posted 2021-02-14

package DownLoaderItem;

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

public class DownLoaderUI extends JFrame implements ActionListener{

private JLabel lburl;
private TextField tfurl;

private JLabel lblocation;
private TextField tfloacation;

private JLabel lbcount;
private TextField tfcount;

private JButton btnstar;

public JProgressBar bar;

public DownLoaderUI(){
    init();
    this.setVisible(true);
}

private void init() {
    this.setBounds(100,50,800,600);
    this.setLayout(null);

    lburl=new JLabel("url地址");
    lburl.setBounds(0,0,100,30);
    this.add(lburl);

    tfurl=new TextField("http://localhost:8080/zhao.txt");
    tfurl.setBounds(0,40,800,30);
    this.add(tfurl);

    lblocation=new JLabel("保存地址");
    lblocation.setBounds(0,80,100,30);
    this.add(lblocation);

    tfloacation=new TextField("e:\test\zhaouu.txt");
    tfloacation.setBounds(0,120,800,30);
    this.add(tfloacation);

    lbcount=new JLabel("线程数");
    lbcount.setBounds(0,160,100,30);
    this.add(lbcount);

    tfcount=new TextField("3");
    tfcount.setBounds(0,200,800,30);
    this.add(tfcount);

    btnstar=new JButton("开始");
    btnstar.setBounds(0,240,100,30);
    btnstar.addActionListener(this);
    this.add(btnstar);

    bar=new JProgressBar();
    bar.setBounds(0,280,750,30);
    this.add(bar);

    this.addWindowListener(new WindowAdapter() {
        @Override
        public void windowClosing(WindowEvent e) {
            System.exit(-1);
        }
    });
}

@Override
public void actionPerformed(ActionEvent e) {
    Object source = e.getSource();
    if(source==btnstar){
        String url=tfurl.getText();
        String location=tfloacation.getText();
        int count=Integer.parseInt(tfcount.getText());
        DownLoader d = new DownLoader(url,location,count,this);
        bar.setMaximum(d.getLength());
        d.startDownload();
    }
}
}

package DownLoaderItem;

public class Mainx {
        public static void main(String[] args) {
                new DownLoaderUI();
        }
}

package DownLoaderItem;

import java.net.HttpURLConnection;
import java.net.URL;

public class DownLoader {
        private String url;
        private String location;
        private int count;
        private DownLoaderUI ui;
        private int length;

        public String getUrl() {
                return url;
        }

        public void setUrl(String url) {
                this.url = url;
        }

        public String getLocation() {
                return location;
        }

        public void setLocation(String location) {
                this.location = location;
        }

        public int getCount() {
                return count;
        }

        public void setCount(int count) {
                this.count = count;
        }

        public DownLoaderUI getUi() {
                return ui;
        }

        public void setUi(DownLoaderUI ui) {
                this.ui = ui;
        }

        public int getLength() {
                return length;
        }

        public void setLength(int length) {
                this.length = length;
        }

        public DownLoader(String url, String location, int count, DownLoaderUI ui) {
                this.url = url;
                this.location = location;
                this.count = count;
                this.ui = ui;
                this.length=getContentLen();
        }

        private int getContentLen() {
                try {
                        URL u = new URL(this.url);
                        HttpURLConnection conn= (HttpURLConnection) u.openConnection();
                        int len = conn.getContentLength();
                        return len;
                }catch (Exception e){
                        e.printStackTrace();
                }
                return -1;
        }

        public void startDownload() {
                int blockSize=length/count;
                int startpos;
                int endpos;
                for(int i=0;i<count;i++){
        if(i==count-1){
            endpos=length-1;
        }else{
            endpos=(i+1)*blockSize-1;
        }
        new DownLoaderThread(url,location,i*blockSize,endpos,ui).start();
    }
}

}

package DownLoaderItem;

import java.io.InputStream;
import java.io.RandomAccessFile;
import java.net.HttpURLConnection;
import java.net.URL;

public class DownLoaderThread extends Thread {
        private String url;
        private String location;
        private int startpos;
        private int endpos;
        private DownLoaderUI ui;

        public DownLoaderThread(String url, String location, int startpos, int endpos, DownLoaderUI ui) {
                this.url = url;
                this.location = location;
                this.startpos = startpos;
                this.endpos = endpos;
                this.ui = ui;
        }

        @Override
        public void run() {
                try {
                        URL u = new URL(url);
                        HttpURLConnection conn= (HttpURLConnection) u.openConnection();
                        conn.setRequestProperty("Range","bytes="+startpos+"_"+endpos);
                        InputStream in = conn.getInputStream();
                        RandomAccessFile raf = new RandomAccessFile(location, "rw");
                        raf.seek(startpos);
                        byte[] buf=new byte[1024];
                        int len=0;
                        while((len=in.read(buf))!=-1){
                                raf.write(buf,0,len);
                                synchronized (ui.bar){
                                        ui.bar.setValue(ui.bar.getValue()+len);
                                }
                        }
                        raf.close();
                        in.close();
                }catch (Exception e){
                        e.printStackTrace();
                }
        }
}