多线程与文件下载

1.文件下载:

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    public void download(String<!--more--> urlString,String filename,String savePath) throws IOException {
        //构造URL
        URL url = new URL(urlString);
        //打开链接
        URLConnection con = url.openConnection();
        //设置请求超时为5s
        con.setConnectTimeout(5*1000);
        //输入流
        InputStream is = con.getInputStream();
        //1k的缓冲数据
        byte[] bs = new byte[1024];
        //读取到的数据长度
        int len;
        File sf = new File(savePath);
        if (sf.exists()){
            sf.mkdirs();
        }
        OutputStream os = new FileOutputStream(sf.getPath()+"\\"+filename+".jpg");
        //开始读数
        while((len = is.read(bs)) != -1){
            os.write(bs,0,len);
        }
        os.close();
        is.close();
    }

2.多线程

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        //批量创建实例
        downpic[] arr = new downpic[threadNum];
        //批量创建多线程
        Thread[] thArr = new Thread[threadNum];
        //给示例赋值
        for (int i = 0; i < threadNum; i++) {
            arr[i] = new downpic(picNum/threadNum*i,picNum/threadNum);
        }
        //批量开始线程
        for (int i = 0; i < threadNum; i++) {
            thArr[i] = new Thread(arr[i]);
            thArr[i].start();
        }