- 当 15 秒内没有任何消息时，发送一个**保活 `ping` 注释**，以防某些代理关闭连接，正如 [HTML 规范：Server-Sent Events](https://html.spec.whatwg.org/multipage/server-sent-events.html#authoring-notes) 中建议的那样。
- 设置 `Cache-Control: no-cache` 响应头，**防止缓存**流。
- 设置特殊响应头 `X-Accel-Buffering: no`，以**防止**某些代理（如 Nginx）**缓冲**。

- ストリームの**キャッシュを防止**するため、`Cache-Control: no-cache` ヘッダーを設定します。
- Nginx など一部のプロキシでの**バッファリングを防ぐ**ため、特別なヘッダー `X-Accel-Buffering: no` を設定します。

        response.setCharacterEncoding("UTF-8");
        response.setHeader("Cache-Control", "no-cache");
        response.setHeader("Connection", "keep-alive");
        response.setHeader("X-Accel-Buffering", "no"); // Disable nginx buffering

        try (final PrintWriter writer = response.getWriter()) {
            final String userId = getUserId(request);

            // Set LLM type name as Access Type for search log

     * <p>
     * Continues an MD4 message digest operation, by filling the buffer,
     * transform(ing) data in 512-bit message block(s), updating the variables
     * context and count, and leaving (buffering) the remaining bytes in buffer
     * for the next update or finish.
     *
     * @param    input    input block
     * @param    offset    start of meaningful bytes in input

    assert response.status_code == 200
    assert response.headers["content-type"] == "text/event-stream; charset=utf-8"
    assert response.headers["cache-control"] == "no-cache"
    assert response.headers["x-accel-buffering"] == "no"

    lines = response.text.strip().split("\n")
    data_lines = [line for line in lines if line.startswith("data: ")]
    assert len(data_lines) == 3

 * @since 1.0
 */
@J2ktIncompatible
@GwtIncompatible
public final class CharStreams {

  // 2K chars (4K bytes)
  private static final int DEFAULT_BUF_SIZE = 0x800;

  /** Creates a new {@code CharBuffer} for buffering reads or writes. */
  static CharBuffer createBuffer() {
    return CharBuffer.allocate(DEFAULT_BUF_SIZE);
  }

  private CharStreams() {}

  /**

				PutByteBuffer(payload)
				if err != nil {
					r := RemoteErr(err.Error())
					return &r
				}
			}

			var inT chan Req
			if h.InCapacity > 0 {
				// Don't add extra buffering
				inT = make(chan Req)
				go func() {
					defer xioutil.SafeClose(inT)
					for {
						select {
						case <-ctx.Done():
							return
						case v, ok := <-in:
							if !ok {

- Configurar el header `Cache-Control: no-cache` para **evitar el almacenamiento en caché** del stream.
- Configurar un header especial `X-Accel-Buffering: no` para **evitar el buffering** en algunos proxies como Nginx.

- Den Header `Cache-Control: no-cache` setzen, um **Caching** des Streams zu verhindern.
- Einen speziellen Header `X-Accel-Buffering: no` setzen, um **Buffering** in einigen Proxys wie Nginx zu verhindern.

- Definir o cabeçalho `Cache-Control: no-cache` para evitar o cache do stream.
- Definir o cabeçalho especial `X-Accel-Buffering: no` para evitar buffering em alguns proxies como o Nginx.