java - `setBufferedSize()`方法有什么作用？

Question

我不知道setBufferSize()方法的作用。谁能解释一下它的作用吗？如果我将 setBufferSize(4 * 1024) 更改为 setBufferSize(5) 会发生什么？当我这样做时，我没有看到任何变化!谁能解释一下吗？谢谢。

public class Test {

    public static void main(String[] args) {
        try {
            String url = "DOWNLOAD_LINK";
            HttpGet request = new HttpGet(url);
            ConnectionConfig connectionConfig = ConnectionConfig.custom()
                    .setBufferSize(4 * 1024).build();

            HttpClientBuilder builder = HttpClientBuilder.create();
            builder.setDefaultConnectionConfig(connectionConfig);

            HttpClient client = builder.build();

            HttpResponse response = client.execute(request);

            HttpEntity entity = response.getEntity();

            InputStream inputStream = entity.getContent();
            int len = 0;
            byte[] buffer = new byte[4098];
            while ((len = inputStream.read(buffer)) != -1) {
                System.out.println("len: " + len);
                //write into file , etc.
            }
            inputStream.close();
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (UnsupportedOperationException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

Answer 1

这里引用了 SetBufferedSize 的文档，相当完整:

Sets the preferred buffer size for the body of the response. The servlet container will use a buffer at least as large as the size requested. The actual buffer size used can be found using getBufferSize.

A larger buffer allows more content to be written before anything is actually sent, thus providing the servlet with more time to set appropriate status codes and headers. A smaller buffer decreases server memory load and allows the client to start receiving data more quickly.

Source

Apache's documentation