java - 使用 GZIP、JSON 响应和 JQuery

Question

但是，我想尽可能使用 GZIP 压缩我的回复。我尝试使用 Compression filter code可在 headfirst 站点免费下载。它适用于 html、图像、css 和 javascript。

我接下来发布过滤器。它检查 GZIP 是否是可接受的编码，并将 gzip 添加为内容编码。请参阅:wrappedResp.setHeader("Content-Encoding", "gzip");

public class CompressionFilter implements Filter {

  private ServletContext ctx;
  private FilterConfig cfg;

    /**
     * The init method saves the config object and a quick reference to the
     * servlet context object (for logging purposes).
     */
  public void init(FilterConfig cfg) 
     throws ServletException {
    this.cfg = cfg;
    ctx = cfg.getServletContext();
    //ctx.log(cfg.getFilterName() + " initialized.");
  }

        /**
         * The heart of this filter wraps the response object with a Decorator
         * that wraps the output stream with a compression I/O stream.
         * Compression of the output stream is only performed if and only if
         * the client includes an Accept-Encoding header (specifically, for gzip).
         */
      public void doFilter(ServletRequest req,
                   ServletResponse resp,
                   FilterChain fc)
         throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) resp;

        // Dose the client accept GZIP compression?
        String valid_encodings = request.getHeader("Accept-Encoding");
        if ( (valid_encodings != null) && (valid_encodings.indexOf("gzip") > -1) ) {

          // Then wrap the response object with a compression wrapper
          // We'll look at this class in a minute.
          CompressionResponseWrapper wrappedResp = new CompressionResponseWrapper(response);

          // Declare that the response content is being GZIP encoded.
          wrappedResp.setHeader("Content-Encoding", "gzip");

          // Chain to the next component (thus processing the request)
          fc.doFilter(request, wrappedResp);

          // A GZIP compression stream must be "finished" which also
          // flushes the GZIP stream buffer which sends all of its
          // data to the original response stream.
          GZIPOutputStream gzos = wrappedResp.getGZIPOutputStream();
          gzos.finish();
          // The container handles the rest of the work.

          //ctx.log(cfg.getFilterName() + ": finished the request.");

        } else {
          fc.doFilter(request, response);
          //ctx.log(cfg.getFilterName() + ": no encoding performed.");
        }   
      }

      public void destroy() {
          // nulling out my instance variables
          cfg = null;
          ctx = null;
      }
    }

我正在使用下一个代码在 Struts 网络应用程序中发送 JSON 响应。

public ActionForward get(ActionMapping mapping,
    ActionForm     form,
    HttpServletRequest request,
    HttpServletResponse response) {
       JSONObject json = // Do some logic here
       RequestUtils.populateWithJSON(response, json);
       return null;         
}

public static void populateWithJSON(HttpServletResponse response,JSONObject json) {
    if(json!=null) {
        response.setContentType("text/x-json;charset=UTF-8");       
        response.setHeader("Cache-Control", "no-cache");
        try {
             response.getWriter().write(json.toString());
        } catch (IOException e) {
            throw new ApplicationException("IOException in populateWithJSON", e);
        }               
    }
 }

它在没有压缩的情况下工作正常，但如果我压缩 JSON 响应，我就再也看不到我的 JSON 对象了。我使用 JQuery 处理 JSON Ajax 调用，代码片段如下:

    $.post(url,parameters, function(json) {
    // Do some DOM manipulation with the data contained in the JSON Object
}, "json");

如果我看到带有 Firebug 的响应是空的。

我是否应该折射我的压缩过滤器以跳过 JSON 响应中的压缩？还是有解决方法？

对我来说，JQuery 似乎无法将响应识别为 JSON，因为我正在添加 Gzip 压缩。

Answer 1

If I see the response with Firebug it is empty.

这是您的线索 - 这不是 JQuery 问题，而是服务器端问题。 (除了建议您停止查看客户端之外，恐怕我无法帮助您)

用 gzip 压缩 ajax 响应没有问题 - 如果您在 Firebug 中看不到响应，那么 JQuery 也看不到它。