Internet资源的断点续传实例

package com.web.test2;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;

public class TestDownLoad {

    private long start = 0;
    private long end = 0;

    public TestDownLoad(long start,long end){
        this.start = start;
        this.end = end;
    }

    public TestDownLoad(long start){
        this.start = start;
    }

    public TestDownLoad(){

    }

    public void down(){

        try {
            URL url = new URL("http://img05.tooopen.com/images/20140604/sy_62331342149.jpg");
            URLConnection conn = url.openConnection();
            /*设置请求参数*/
            conn.setRequestProperty("User-Agent", "NetFox");
            String sProperty = "bytes="+start+"-";
            if (end > 0) {
                sProperty = "bytes="+start+"-"+end;
            }

            conn.setRequestProperty("RANGE", sProperty);
            conn.connect();

            InputStream in = conn.getInputStream();
            String file = url.getFile();
            String name = file.substring(file.lastIndexOf("/")+1);
            System.out.println(name);
            //以追加的方式写文件
            FileOutputStream fos = new FileOutputStream("F://"+name,true);
            byte[] b = new byte[1024];
            int len = 0;
            while((len = in.read(b)) != -1){
                fos.write(b, 0, len);
            }
            fos.close();
            in.close();
            conn.connect();
        } catch (MalformedURLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            System.out.println("文件不存在");
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        TestDownLoad d1 = new TestDownLoad(0,2000);
        d1.down();
        /*执行完d1的方法，再执行d2的方法，同时执行会并发下载，发生冲突*/
//      TestDownLoad d2 = new TestDownLoad(2000);
//      d2.down();

    }
}