add charset specific for easy call of HttpClientDownloader

webmagic-core/src/main/java/us/codecraft/webmagic/downloader/HttpClientDownloader.java

@@ -46,6 +46,17 @@ public class HttpClientDownloader implements Downloader {
         return (Html) page.getHtml();
     }
 
+    /**
+     * A simple method to download a url.
+     *
+     * @param url
+     * @return html
+     */
+    public Html download(String url,String charset) {
+        Page page = download(new Request(url), Site.me().setCharset(charset).toTask());
+        return (Html) page.getHtml();
+    }
+
     @Override
     public Page download(Request request, Task task) {
         Site site = null;
@@ -87,13 +98,12 @@ public class HttpClientDownloader implements Downloader {
             } while (retry);
             int statusCode = httpResponse.getStatusLine().getStatusCode();
             if (acceptStatCode.contains(statusCode)) {
+                handleGzip(httpResponse);
                 //charset
                 if (charset == null) {
                     String value = httpResponse.getEntity().getContentType().getValue();
                     charset = UrlUtils.getCharset(value);
                 }
-                //
-                handleGzip(httpResponse);
                 return handleResponse(request, charset, httpResponse, task);
             } else {
                 logger.warn("code error " + statusCode + "\t" + request.getUrl());