android的HttpClient实现简单的get和post请求

  /**   * Http工具类   */  public class HttpUtil {      // 创建HttpClient对象      public static HttpClient httpClient = new DefaultHttpClient();      public static final String BASE_URL = "";         /**       * get请求       *       * @param url       *            发送请求的URL       * @return 服务器响应字符串       * @throws Exception       */      public static String doGet(String url) throws Exception {          // 创建HttpGet对象。          HttpGet get = new HttpGet(url);          // 发送GET请求          HttpResponse httpResponse = httpClient.execute(get);          // 如果服务器成功地返回响应          if (httpResponse.getStatusLine().getStatusCode() == 200) {              // 获取服务器响应字符串              HttpEntity entity = httpResponse.getEntity();              InputStream content = entity.getContent();              return convertStreamToString(content);          }          return null;      }         /**       * post请求       *       * @param url       *            发送请求的URL       * @param params       *            请求参数       * @return 服务器响应字符串       * @throws Exception       */      public static String doPost(String url, Map<String, String> rawParams)              throws Exception {          // 创建HttpPost对象。          HttpPost post = new HttpPost(url);          // 如果传递参数个数比较多的话可以对传递的参数进行封装          List<NameValuePair> params = new ArrayList<NameValuePair>();          for (String key : rawParams.keySet()) {              // 封装请求参数              params.add(new BasicNameValuePair(key, rawParams.get(key)));          }          // 设置请求参数          post.setEntity(new UrlEncodedFormEntity(params, "utf-8"));          // 发送POST请求          HttpResponse httpResponse = httpClient.execute(post);          // 如果服务器成功地返回响应          if (httpResponse.getStatusLine().getStatusCode() == 200) {              // 获取服务器响应字符串              HttpEntity entity = httpResponse.getEntity();              InputStream content = entity.getContent();              return convertStreamToString(content);          }          return null;      }         /**       * 获取服务器的响应，转换为字符串       */      private static String convertStreamToString(InputStream is) {          BufferedReader reader = new BufferedReader(new InputStreamReader(is));          StringBuilder sb = new StringBuilder();          String line = null;          try {              while ((line = reader.readLine()) != null) {                  sb.append(line);              }          } catch (IOException e) {              e.printStackTrace();          } finally {              try {                  is.close();              } catch (IOException e) {                  e.printStackTrace();              }          }          return sb.toString();      }  }