分批下载

最新推荐文章于 2023-10-11 17:40:21 发布

原创最新推荐文章于 2023-10-11 17:40:21 发布 · 344 阅读

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CC 4.0 BY-SA版权

本文介绍了一种分批下载大文件的策略，通过使用HTTP Range请求头，将文件分为多个部分进行下载，有效降低了网络延迟对下载速度的影响，提高了下载效率。

分批下载

思路 1. 第一次请求获取文件的总长度
-------2. 将文件分为若干份
-------3.用Range请求头做标记
-------4.随机流进行操作(完成分批下载)

private void downFile(String url, final String path) {
    Log.i("---", "downFile: 进入分批下载的方法");
    final Request request = new Request.Builder()
            .url(url)
            .get()
            .header("Range","bytes=0-"+number)
            .build();
    client.newCall(request).enqueue(new Callback() {
        @Override
        public void onFailure(Call call, IOException e) {
        }

        @Override
        public void onResponse(Call call, Response response) throws IOException {
            InputStream inputStream = response.body().byteStream();
            Buffer buffer = new Buffer();
            int len = 0;
            byte[] bys = new byte[1024];
            RandomAccessFile rw = new RandomAccessFile(path, "rw");
            rw.seek(0);
            while ((len = inputStream.read(bys))!= -1){
                rw.write(bys,0,len);
            }
        }
    });

    Request request1 = new Request.Builder()
            .url(url)
            .get()
            .header("Range", "types=" + number + "-" + number * 2)
            .build();
    client.newCall(request1).enqueue(new Callback() {
        @Override
        public void onFailure(Call call, IOException e) {
        }
        @Override
        public void onResponse(Call call, Response response) throws IOException {
            InputStream inputStream = response.body().byteStream();
            byte[] bys = new byte[1024];
            int len = 0;
            RandomAccessFile rw = new RandomAccessFile(path, "rw");
            rw.seek(number);
            while ((len = inputStream.read(bys,0,len))!=-1){
                count +=len;
                progress = (int) (len*100/length);

                rw.write(bys,0,len);
            }
        }
    });


    Request request2 = new Request.Builder()
            .url(url)
            .get()
            .header("Range", "types=" + number * 2 + "-" + length)
            .build();

    client.newCall(request2).enqueue(new Callback() {
        @Override
        public void onFailure(Call call, IOException e) {
        }
        @Override
        public void onResponse(Call call, Response response) throws IOException {
            InputStream inputStream = response.body().byteStream();
            byte[] bys = new byte[1024];
            int len = 0;
            RandomAccessFile rw = new RandomAccessFile(path, "rw");
            rw.seek(number*2);
            while ((len = inputStream.read(bys))!=-1){
                rw.write(bys,0,len);
            }
        }
    });
}