HTTP 获取网页内容 HttpURLConnection与HttpClient

最新推荐文章于 2024-05-12 18:04:11 发布

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最新推荐文章于 2024-05-12 18:04:11 发布

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分类专栏： http 文章标签： exception null string url

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本文对比了使用java.net.HttpURLConnection和Apache HttpClient两种方法获取网页内容的实现方式、优势及区别，详细阐述了如何利用这些类进行HTTP请求，并解析响应内容。

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HTTP 获取网页内容可用以下两个类实现

java.net.HttpURLConnection;

核心代码如下：

String urlString ="http://www.baidu.com/s?wd=1&rsv_bp=0&rsv_spt=3&inputT=280";

   StringBuffer stringBuffer = new StringBuffer();
                     try {
                            URL url = newURL(urlString);
                            HttpURLConnectionurlConnection = (HttpURLConnection) url.openConnection();
                            urlConnection.setConnectTimeout(Constant.TIME_OUT_INTERVAL);
                            urlConnection.connect();

                            StringcontentEncodingString = getEncoding(urlConnection);
                            InputStreamReaderinputStreamReader = null;
                            if(contentEncodingString != null)
                            {
                                   inputStreamReader= new InputStreamReader(urlConnection.getInputStream(), contentEncodingString);
                            }else{
                                   inputStreamReader= new InputStreamReader(urlConnection.getInputStream());
                            }

                            BufferedReaderbufReader = new BufferedReader(inputStreamReader);

                            StringinputLine = null;
                            int len = 0;
                            while((inputLine= bufReader.readLine()) != null)
                            {
                                   stringBuffer.append(inputLine);
                                   stringBuffer.append("\n");
                            }

                            showContentLen(stringBuffer.length());
                            showContent(stringBuffer.toString());

                            bufReader.close();
                            urlConnection.disconnect();

                     } catch (Exception e){
                            // TODO:handle exception
                            e.printStackTrace();
                            displayError(e.getMessage());
                            return ;
                     }

org.apache.http.client.HttpClient;

String urlString ="http://www.baidu.com/s?wd=1&rsv_bp=0&rsv_spt=3&inputT=280";

   try {
                            HttpGethttpGet = new HttpGet(urlString);
                            HttpClienthttpClient = new DefaultHttpClient();

                            HttpResponsehttpResponse = httpClient.execute(httpGet);

                            HttpEntityentity = httpResponse.getEntity();
                           String charsetString = getContentCharSet(entity);
                           Log.i("", "charsetString = " + charsetString);

                            int responseCode= httpResponse.getStatusLine().getStatusCode();
                            if(responseCode == HttpStatus.SC_OK)
                            {
                                   StringresultData = EntityUtils.toString(httpResponse.getEntity());
                                   showContentLen(resultData.length());
                                   showContent(resultData);
                            }else{
                                   displayError("Getdata error!");
                            }
                     } catch (Exception e){
                            // TODO:handle exception
                            e.printStackTrace();
                            displayError(e.getMessage());
                            return ;
                     }

区别：

虽然java.net这个包中提供了HttpURLConnection，通过HTTP获取资源的基本功能，但是它不能够充分地满足很多应用在灵活性或功能上的要求。Jakarta工程的HttpClient组件则填补了这一空白，提供一种高效的、最新的，且功能丰富的套件的客户端，并且实现最新的HTTP标准和建议。

同时HttpClient在获取网页的时候会自动解析其编码，而HttpURLConnection则需要自己解析，如下：

publicString getEncoding(HttpURLConnection urlConnection)

     {
         if (urlConnection == null)
         {
              return null;
         }

         Map<String,List<String>> map = urlConnection.getHeaderFields();
         Set<String> keys =map.keySet();
       Iterator<String>iterator = keys.iterator();

   // 遍历,查找字符编码
   String key = null;
   String tmp = null;

        while(iterator.hasNext()) {
          key = iterator.next();
          tmp = map.get(key).toString().toLowerCase();
          // 获取content-type charset
          if (key != null && key.equals("Content-Type")) {
           int m = tmp.indexOf("charset=");
           if (m != -1) {
           return tmp.substring(m + 8).replace("]","");
           }
          }
        }

         return null;

     }