Android入門：用HttpClient模擬HTTP的GET和POST請求

一、HttpClient介紹

HttpClient是用來模擬HTTP請求的，其實實質就是把HTTP請求模擬後發給Web服務器；Android已經集成了HttpClient，因此可以直接使用；

注：此處HttpClient代碼不只可以適用於Android，也可適用於一般的Java程序；

HTTP GET核心代碼：

(1)DefaultHttpClient client = new DefaultHttpClient();
(2)HttpGet get = new HttpGet(String url);//此處的URL為http://..../path?arg1=value&....argn=value
(3)HttpResponse response = client.execute(get); //模擬請求
(4)int code = response.getStatusLine().getStatusCode();//返回響應碼
(5)InputStream in = response.getEntity().getContent();//服務器返回的數據

HTTP POST核心代碼：

(1)DefaultHttpClient client = new DefaultHttpClient();
(2)BasicNameValuePair pair = new BasicNameValuePair(String name,String value);//創建一個請求頭的字段，比如content-type,text/plain
(3)UrlEncodedFormEntity entity = new UrlEncodedFormEntity(List<NameValuePair> list,String encoding);//對自定義請求頭進行URL編碼
(4)HttpPost post = new HttpPost(String url);//此處的URL為http://..../path
(5)post.setEntity(entity);
(6)HttpResponse response = client.execute(post);
(7)int code = response.getStatusLine().getStatusCode();
(8)InputStream in = response.getEntity().getContent();//服務器返回的數據

二、服務器端代碼

服務器端代碼和通過URLConnection發出請求的代碼不變：

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.         System.out.println("age="+age);  
23.         response.setCharacterEncoding("UTF-8");  
24.         OutputStream out = response.getOutputStream();//返回數據   
25.         out.write("GET請求成功!".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.         System.out.println("age="+age);  
36.         response.setCharacterEncoding("UTF-8");  
37.         OutputStream out = response.getOutputStream();  
38.         out.write("POST請求成功!".getBytes("UTF-8"));  
39.         out.close();  
40.           
41.     }  
42.   
43. }