HttpClient
HttpClient 是Apache Jakarta Common 下的子项目,可以用来提供高效的、最新的、功能丰富的支持 HTTP 协议的客户端编程工具包,并且它支持 HTTP 协议最新的版本和建议。
以下列出的是 HttpClient 提供的主要的功能,要知道更多详细的功能可以参见 HttpClient 的主页。
(1)实现了所有 HTTP 的方法(GET,POST,PUT,HEAD 等)
(2)支持自动转向
(3)支持 HTTPS 协议
(4)支持代理服务器等
使用HttpClient 实现get请求:
//创建一个默认的链接 CloseableHttpClient client = HttpClients.createDefault(); //创建一个请求 HttpGet httpGet=new HttpGet("https://kyfw.12306.cn/otn/leftTicket/queryZ?leftTicketDTO.train_date=2020-02-05&leftTicketDTO.from_station=BJP&leftTicketDTO.to_station=CQW&purpose_codes=ADULT"); //执行请求获取响应的结果 CloseableHttpResponse response = client.execute(httpGet); //获取响应的状态码 System.out.println("服务器返回状态码:"+response.getStatusLine().getStatusCode()); //服务器正常响应 if(response.getStatusLine().getStatusCode()==200){ //获取响应结果 System.out.println(EntityUtils.toString(response.getEntity(),"UTF-8")); } //关闭结果对象 response.close(); //关闭链接 client.close();
使用HttpClient 实现post请求:
做一个post请求的服务端:
package com.wish; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.IOException; @WebServlet("/HttpClientWeb") public class HttpClientWeb extends HttpServlet { @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { //获取数据 String userName =req.getParameter("userName"); System.out.println("接受的数据:"+userName); resp.setContentType("text/html;charset=utf-8"); resp.getWriter().write("服务器正确接收到数据"); } @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { doPost(req,resp); } }
使用post请求
//创建链接 CloseableHttpClient client = HttpClients.createDefault(); //创建请求 HttpPost post=new HttpPost("http://localhost:8080/HttpClientWeb"); //创建参数队列 List<NameValuePair> pairList=new ArrayList<>(); pairList.add(new BasicNameValuePair("userName","张三")); //创建请求体,封装参数 UrlEncodedFormEntity entity=new UrlEncodedFormEntity(pairList,"UTF-8"); //将请求体交给当前请求 post.setEntity(entity); //发送请求,接收结果 CloseableHttpResponse response = client.execute(post); System.out.println("接收到的结果为:"+ EntityUtils.toString(response.getEntity(),"UTF-8")); //关闭资源 response.close(); client.close();