httpclient 简单介绍使用方法





 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 params=new HashMap();
		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 params){
		CloseableHttpClient httpClient=HttpClients.createDefault();
		//httpClient.e
		HttpPost post=new HttpPost(url);
		 List formparams = new ArrayList();  
		 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);
	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		this.doPost(req, resp);
	}
	
	public static int serversRunFlag=0;
	@Override
	protected 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：

1

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