目前Android 与服务器交互有两种方式：1.Socket 2. Http ；

但由于Http的封装性以及性能比socket要好，所以推荐使用http方式和服务器交互；

通过http访问服务器有三种方法：1.post  2. get  3.或者上传文件

例子如下：

protected JSONObject toWebService(String url, String method,
				List<NameValuePair> params) {
			try {
				Log.w("HealthCareAPI", "toWebService: url = " + url);
				HttpUriRequest request = null;
				if (HealthCareApi.GET_METHOD.equalsIgnoreCase(method)) {  //Get方法
					url = url + "?" + URLEncodedUtils.format(params, "UTF-8");
					Log.w("HealthCareApiCore", url);
					request = new HttpGet(url);
				} else if (HealthCareApi.POST_METHOD.equalsIgnoreCase(method)) {  //Post方法
					HttpPost postRequest = new HttpPost(url);
					UrlEncodedFormEntity entity = new UrlEncodedFormEntity(
							params, HTTP.UTF_8);
					postRequest.setHeader("Content-Type",
							"application/x-www-form-urlencoded; charset=utf-8");
					postRequest.setEntity(entity);
					request = postRequest;
				} else if (HealthCareApi.POST_METHOD_WITH_BIN    
						.equalsIgnoreCase(method)) {   //上传文件，这里指的是上传图片文件
					HttpPost postRequest = new HttpPost(url);
					MultipartEntity multipartContent = new MultipartEntity();
					for (NameValuePair nameValuePair : params) {
						if (nameValuePair.getName().equals("photo")
								|| nameValuePair.getName().equals("pic")
								|| nameValuePair.getName().equals("photo_url")) {
							File photoFile = new File(nameValuePair.getValue());
							if (photoFile.exists()) {
								String extensionName = HealthCareApi
										.getExtensionName(photoFile.getName());
								FileBody fileBody = new FileBody(photoFile,
										MimeTypeMap.getSingleton()
												.getMimeTypeFromExtension(
														new String(extensionName).toLowerCase()));
								multipartContent.addPart(
										nameValuePair.getName(), fileBody);
							}
						} else {
							multipartContent.addPart(nameValuePair.getName(),
									new StringBody(nameValuePair.getValue(),
											Charset.forName("UTF-8")));
						}
					}
					postRequest.setEntity(multipartContent);
					request = postRequest;
				}
				HttpParams httpParams = new BasicHttpParams();
				HttpConnectionParams
						.setConnectionTimeout(httpParams, 20 * 1000);
				HttpConnectionParams.setSoTimeout(httpParams, 20 * 1000);
				HttpResponse httpResponse = new DefaultHttpClient(httpParams)
						.execute(request);
				HttpEntity entity = httpResponse.getEntity();
				String res = EntityUtils.toString(entity, "UTF-8");
				Log.w("HealtCareApi", "res: " + res);
				JSONObject object = new JSONObject(res);
				return object;
			} catch (Exception e) {
				e.printStackTrace();
				mException = e;
			}
			return null;
		}