Android入门：用HttpClient模拟HTTP的GET和POST请求

一、HttpClient介绍

HttpClient是用来模拟HTTP请求的，其实实质就是把HTTP请求模拟后发给Web服务器；Android已经集成了HttpClient，因此可以直接使用；

注：此处HttpClient代码不只可以适用于Android，也可适用于一般的Java程序；

HTTP GET核心代码：

(1)DefaultHttpClient client = new DefaultHttpClient();
(2)HttpGet get = new HttpGet(String url);//此处的URL为http://..../path?arg1=value&....argn=value
(3)HttpResponse response = client.execute(get); //模拟请求
(4)int code = response.getStatusLine().getStatusCode();//返回响应码
(5)InputStream in = response.getEntity().getContent();//服务器返回的数据

HTTP POST核心代码：

(1)DefaultHttpClient client = new DefaultHttpClient();
(2)BasicNameValuePair pair = new BasicNameValuePair(String name,String value);//创建一个请求头的字段，比如content-type,text/plain
(3)UrlEncodedFormEntity entity = new UrlEncodedFormEntity(List<NameValuePair> list,String encoding);//对自定义请求头进行URL编码
(4)HttpPost post = new HttpPost(String url);//此处的URL为http://..../path
(5)post.setEntity(entity);
(6)HttpResponse response = client.execute(post);
(7)int code = response.getStatusLine().getStatusCode();
(8)InputStream in = response.getEntity().getContent();//服务器返回的数据

二、服务器端代码

服务器端代码和通过URLConnection发出请求的代码不变：

1. package org.xiazdong.servlet;  
2.   
3. import java.io.IOException;  
4. import java.io.OutputStream;  
5.   
6. import javax.servlet.ServletException;  
7. import javax.servlet.annotation.WebServlet;  
8. import javax.servlet.http.HttpServlet;  
9. import javax.servlet.http.HttpServletRequest;  
10. import javax.servlet.http.HttpServletResponse;  
11.   
12. @WebServlet("/Servlet1")  
13. public class Servlet1 extends HttpServlet {  
14.   
15.     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {  
16.         String nameParameter = request.getParameter("name");  
17.         String ageParameter = request.getParameter("age");  
18.         String name = new String(nameParameter.getBytes("ISO-8859-1"),"UTF-8");  
19.         String age = new String(ageParameter.getBytes("ISO-8859-1"),"UTF-8");  
20.         System.out.println("GET");  
21.         System.out.println("name="+name);  
22. "age="+age);  
23.         response.setCharacterEncoding("UTF-8");  
24.         OutputStream out = response.getOutputStream();//返回数据   
25.         out.write("GET请求成功!".getBytes("UTF-8"));  
26.         out.close();  
27.     }  
28.   
29.     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {  
30.         request.setCharacterEncoding("UTF-8");  
31.         String name = request.getParameter("name");  
32.         String age  = request.getParameter("age");  
33.         System.out.println("POST");  
34.         System.out.println("name="+name);  
35. "age="+age);  
36.         response.setCharacterEncoding("UTF-8");  
37.         OutputStream out = response.getOutputStream();  
38.         out.write("POST请求成功!".getBytes("UTF-8"));  
39.         out.close();  
40.           
41.     }  
42.   
43. }