httpclient 简单介绍使用方法

来源：互联网发布：windows消息机制linux 编辑：程序博客网时间：2024/05/22 17:22

客户端使用HttpClient发送请求。

1. 创建HttpClient。

2. 创建请求实例，指定URL。发送GET请求，创建HttpGet对象；发送POST请求，创建HttpPost对象。

3. 传递请求参数，可调用HttpGet、HttpPost共同的setParams(HetpParams params)方法添加请求参数；对于HttpPost，也可调用setEntity(HttpEntity entity)方法来设置请求参数。

4. 调用HttpClient对象的execute(HttpUriRequest request)发送请求，返回一个HttpResponse。

5. 调用HttpResponse的getAllHeaders()、getHeaders(String name)等方法可获取服务器的响应头；调用HttpResponse的getEntity()方法可获取HttpEntity对象，该对象包装了服务器返回的信息。

6. 释放连接。

客户端代码

public static void main(String[] args) {HttpClient http=new HttpClient();Map<String,String> params=new HashMap<String, String>();params.put("dateUpdateFlag","1");params.put("dateUpdateV","2");params.put("serversRunFlag","3");http.sendMsg("http://127.0.0.1:8008/updataclient/Service", params);}public String sendMsg(String url,Map<String,String> params){CloseableHttpClient httpClient=HttpClients.createDefault();//httpClient.eHttpPost post=new HttpPost(url); List<NameValuePair> formparams = new ArrayList<NameValuePair>();   for (String nameValuePair : params.keySet()) { formparams.add(new BasicNameValuePair(nameValuePair, params.get(nameValuePair)));  } UrlEncodedFormEntity uefEntity=null;  CloseableHttpResponse response=null; try {uefEntity=new UrlEncodedFormEntity(formparams,"utf-8");post.setEntity(uefEntity); response=httpClient.execute(post);HttpEntity entity =response.getEntity();System.out.println(EntityUtils.toString(entity, "UTF-8"));} catch (UnsupportedEncodingException e) {e.printStackTrace();} catch (ClientProtocolException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}finally{try {if(response!=null)response.close();if(httpClient!=null)httpClient.close();} catch (IOException e) {e.printStackTrace();}} return null;}

服务器端代码

public class Services extends HttpServlet {public static Logger logger = Logger.getLogger(Services.class);@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {this.doPost(req, resp);}public static int serversRunFlag=0;@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {String dateUpdateFlag=(String) req.getAttribute("dateUpdateFlag");System.out.println(req.getParameter("dateUpdateFlag"));String dateUpdateV=(String)req.getAttribute("dateUpdateV");System.out.println(req.getParameter("dateUpdateV"));String serversRunFlag=(String)req.getAttribute("serversRunFlag");System.out.println(req.getParameter("serversRunFlag");printToJson("设置成功！", resp);       }/** *  */protected void printToJson(String jsonStr,HttpServletResponse response) {response.setCharacterEncoding("UTF-8");response.setContentType("text/json");response.setDateHeader("Expires", 0);PrintWriter out = null;try {out = response.getWriter();out.println(jsonStr);} catch (IOException e) {//e.printStackTrace();}finally {if (null != out) {out.flush();out.close();}}}}

运行客户端main方法结果：

客户端运行结果输出：

设置成功！

服务器端运行结果输出：

0 0