但是，我想尽可能用 GZIP 压缩我的回复。我尝试使用可在 headfirst 站点免费下载的压缩过滤器代码。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 Content-Encoding。看：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 Web 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 Firebug 的响应，它是空的。
我应该折射我的压缩过滤器以跳过 JSON 响应中的压缩吗？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。