Android中使用gzip传递数据

HTTP协议上的GZIP编码是一种用来改进WEB应用程序性能的技术。大流量的WEB站点常常使用GZIP压缩技术来减少文件大小，减少文件大小有两个明显的好处，一是可以减少存储空间，二是通过网络传输文件时，可以减少传输的时间。作者在写这篇博客时经过测试，4.4MB的文本数据经过Gzip传输到客户端之后变为392KB，压缩效率极高。

一.服务端

服务端有2种方式去压缩，一种可以自己压缩，但是更推荐第二种方式，用PrintWriter作为输出流，工具类代码如下

/** * 判断浏览器是否支持 gzip 压缩 * @param req * @return boolean 值 */public static boolean isGzipSupport(HttpServletRequest req) {String headEncoding = req.getHeader("accept-encoding");if (headEncoding == null || (headEncoding.indexOf("gzip") == -1)) { // 客户端 不支持 gzipreturn false;} else { // 支持 gzip 压缩return true;}}/** * 创建 以 gzip 格式 输出的 PrintWriter 对象，如果浏览器不支持 gzip 格式，则创建普通的 PrintWriter 对象， * @param req * @param resp * @return * @throws IOException */public static PrintWriter createGzipPw(HttpServletRequest req, HttpServletResponse resp) throws IOException {PrintWriter pw = null;if (isGzipSupport(req)) { // 支持 gzip 压缩pw = new PrintWriter(new GZIPOutputStream(resp.getOutputStream()));// 在 header 中设置返回类型为 gzipresp.setHeader("content-encoding", "gzip");} else { // // 客户端 不支持 gzippw = resp.getWriter();}return pw;}

servlet代码如下：

public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setCharacterEncoding("utf-8");response.setHeader("Content-Encoding", "gzip");String ret = "{\"ContentLayer\":{\"title\":\"内容层\"},\"PageLink\":{\"title\":\"页面跳转\"},\"WebBrowser\":{\"title\":\"浏览器\"},"+ "\"InlinePage\":{\"title\":\"内嵌页面\"},\"VideoComp\":{\"title\":\"视频\"},"+ "\"PopButton\":{\"title\":\"内容开关\"},\"ZoomingPic\":{\"title\":\"缩放大图\"},"+ "\"Rotate360\":{\"title\":\"360度旋转\"}}";PrintWriter pw = new PrintWriter(new GZIPOutputStream(response.getOutputStream()));pw.write(ret);pw.close();}public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {this.doPost(request, response);}

在代理软件中跟踪到的数据如下：

‹«VrÎÏ+IÍ+ñI¬L-R²ªV*É,ÉIU²R:rëÄÝM•ju”ÓS}2ó²‘e/m>üì̏ë«@òá©INEùåŨúŸ¬?pàØw¼g^Nf^*ÈTóo™R–™’šïœŸ[€¬àÔåc[ÁÖç8•–”äç¡»nÿª7@¢òós3óÒ2“‘Uœþºýè–Ïg÷€Tå—$–¤› +r·¸ðä‡Zh¤†ˆ

实际数据如下：

{"ContentLayer":{"title":"内容层"},"PageLink":{"title":"页面跳转"},"WebBrowser":{"title":"浏览器"},"InlinePage":{"title":"内嵌页面"},"VideoComp":{"title":"视频"},"PopButton":{"title":"内容开关"},"ZoomingPic":{"title":"缩放大图"},"Rotate360":{"title":"360度旋转"}}

二.Android客户端

得到HttpClient代码：

private static DefaultHttpClient getHttpClient() {DefaultHttpClient httpClient = new DefaultHttpClient();// 设置 连接超时时间httpClient.getParams().setParameter(HttpConnectionParams.CONNECTION_TIMEOUT, TIMEOUT_CONNECTION);// 设置 读数据超时时间httpClient.getParams().setParameter(HttpConnectionParams.SO_TIMEOUT,TIMEOUT_SOCKET);// 设置 字符集httpClient.getParams().setParameter("http.protocol.content-charset",UTF_8);return httpClient;}

得到HttpPost：

private static HttpPost getHttpPost(String url) {HttpPost httpPost = new HttpPost(url);// 设置 请求超时时间httpPost.getParams().setParameter(HttpConnectionParams.SO_TIMEOUT,TIMEOUT_SOCKET);httpPost.setHeader("Connection", "Keep-Alive");httpPost.addHeader("Accept-Encoding", "gzip");return httpPost;}

访问网络代码：

public static InputStream http_post_return_byte(String url,Map<String, String> params) throws AppException {DefaultHttpClient httpclient = null;HttpPost post = null;HttpResponse response = null;StringBuilder sb = null;StringEntity stringEntity = null;try {httpclient = getHttpClient();post = getHttpPost(url);sb = new StringBuilder();if (params != null && !params.isEmpty()) {Logger.d("In http_post the url is get here");for (Entry<String, String> entry : params.entrySet()) {sb.append(entry.getKey()).append("=").append(URLEncoder.encode(entry.getValue(),HTTP.UTF_8)).append("&");}sb.deleteCharAt(sb.lastIndexOf("&"));Logger.d("In http_post the url is " + url + " and params is "+ sb.toString());stringEntity = new StringEntity(sb.toString());stringEntity.setContentType("application/x-www-form-urlencoded");post.setEntity(stringEntity);}response = httpclient.execute(post);int statusCode = response.getStatusLine().getStatusCode();Logger.d("statusCode is " + statusCode);if (statusCode != HttpStatus.SC_OK) {throw AppException.http(statusCode);}InputStream is = response.getEntity().getContent();Header contentEncoding = response.getFirstHeader("Content-Encoding");if (contentEncoding != null&& contentEncoding.getValue().equalsIgnoreCase("gzip")) {is = new GZIPInputStream(new BufferedInputStream(is));}return is;} catch (ClientProtocolException e) {e.printStackTrace();throw AppException.http(e);} catch (IOException e) {e.printStackTrace();throw AppException.network(e);} finally {/* * if (!post.isAborted()) { *  * post.abort(); } httpclient = null; */}}

 

 

 

 

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