HttpURLConnection简单用法

转http://fhd001.iteye.com/blog/732729

HttpURLConnection为javaAPI提供的一种Rest访问的方式。其支持对Post,Delete,Get,Put等方式的访问。

以下为对于HttpURLConnection对Post等方式访问的一段代码。

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   1. package com.sw.study.urlConnection;  
   2.   
   3. import java.io.BufferedReader;  
   4. import java.io.InputStreamReader;  
   5. import java.io.OutputStream;  
   6. import java.net.HttpURLConnection;  
   7. import java.net.URL;  
   8. import java.net.URLConnection;  
   9. import java.util.HashMap;  
  10. import java.util.Map;  
  11.   
  12. public class URLConnectionUtil {  
  13.       
  14.     private static final String SERVLET_POST = "POST" ;  
  15.     private static final String SERVLET_GET = "GET" ;  
  16.     private static final String SERVLET_DELETE = "DELETE" ;  
  17.     private static final String SERVLET_PUT = "PUT" ;  
  18.       
  19.     private static String prepareParam(Map<String,Object> paramMap){  
  20.         StringBuffer sb = new StringBuffer();  
  21.         if(paramMap.isEmpty()){  
  22.             return "" ;  
  23.         }else{  
  24.             for(String key: paramMap.keySet()){  
  25.                 String value = (String)paramMap.get(key);  
  26.                 if(sb.length()<1){  
  27.                     sb.append(key).append("=").append(value);  
  28.                 }else{  
  29.                     sb.append("&").append(key).append("=").append(value);  
  30.                 }  
  31.             }  
  32.             return sb.toString();  
  33.         }  
  34.     }  
  35.       
  36.     public static void  doPost(String urlStr,Map<String,Object> paramMap ) throws Exception{  
  37.         URL url = new URL(urlStr);  
  38.         HttpURLConnection conn = (HttpURLConnection)url.openConnection();  
  39.         conn.setRequestMethod(SERVLET_POST);  
  40.         String paramStr = prepareParam(paramMap);  
  41.         conn.setDoInput(true);  
  42.         conn.setDoOutput(true);  
  43.         OutputStream os = conn.getOutputStream();       
  44.         os.write(paramStr.toString().getBytes("utf-8"));       
  45.         os.close();           
  46.           
  47.         BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));  
  48.         String line ;  
  49.         String result ="";  
  50.         while( (line =br.readLine()) != null ){  
  51.             result += "\n"+line;  
  52.         }  
  53.         System.out.println(result);  
  54.         br.close();  
  55.           
  56.     }  
  57.       
  58.     public static void  doGet(String urlStr,Map<String,Object> paramMap ) throws Exception{  
  59.         String paramStr = prepareParam(paramMap);  
  60.         if(paramStr == null || paramStr.trim().length()<1){  
  61.               
  62.         }else{  
  63.             urlStr +="?"+paramStr;  
  64.         }  
  65.         System.out.println(urlStr);  
  66.         URL url = new URL(urlStr);  
  67.         HttpURLConnection conn = (HttpURLConnection)url.openConnection();  
  68.         conn.setRequestMethod(SERVLET_PUT);  
  69.         conn.setRequestProperty("Content-Type","text/html; charset=UTF-8");  
  70.           
  71.         conn.connect();  
  72.         BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));  
  73.         String line ;  
  74.         String result ="";  
  75.         while( (line =br.readLine()) != null ){  
  76.             result += "\n"+line;  
  77.         }  
  78.         System.out.println(result);  
  79.         br.close();  
  80.     }  
  81.       
  82.     public static void doPut(String urlStr,Map<String,Object> paramMap) throws Exception{  
  83.         URL url = new URL(urlStr);  
  84.         HttpURLConnection conn = (HttpURLConnection)url.openConnection();  
  85.         conn.setRequestMethod(SERVLET_PUT);  
  86.         String paramStr = prepareParam(paramMap);  
  87.         conn.setDoInput(true);  
  88.         conn.setDoOutput(true);  
  89.         OutputStream os = conn.getOutputStream();       
  90.         os.write(paramStr.toString().getBytes("utf-8"));       
  91.         os.close();           
  92.           
  93.         BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));  
  94.         String line ;  
  95.         String result ="";  
  96.         while( (line =br.readLine()) != null ){  
  97.             result += "\n"+line;  
  98.         }  
  99.         System.out.println(result);  
 100.         br.close();  
 101.                   
 102.     }  
 103.       
 104.     public static void doDelete(String urlStr,Map<String,Object> paramMap) throws Exception{  
 105.         String paramStr = prepareParam(paramMap);  
 106.         if(paramStr == null || paramStr.trim().length()<1){  
 107.               
 108.         }else{  
 109.             urlStr +="?"+paramStr;  
 110.         }     
 111.         System.out.println(urlStr);  
 112.         URL url = new URL(urlStr);  
 113.         HttpURLConnection conn = (HttpURLConnection)url.openConnection();  
 114.         conn.setDoOutput(true);  
 115.         conn.setRequestMethod(SERVLET_DELETE);  
 116.         //屏蔽掉的代码是错误的，java.net.ProtocolException: HTTP method DELETE doesn't support output  
 117. /*      OutputStream os = conn.getOutputStream();      
 118.         os.write(paramStr.toString().getBytes("utf-8"));      
 119.         os.close();  */   
 120.           
 121.         if(conn.getResponseCode() ==200){  
 122.             System.out.println("成功");  
 123.         }else{  
 124.             System.out.println(conn.getResponseCode());  
 125.         }  
 126.     }  
 127.       
 128.     public static void main(String[] args) throws Exception{  
 129.         String urlStr = "http://localhost:8080/SwTest/ReceiveDataServlet";  
 130.         Map<String,Object> map = new HashMap<String,Object>();  
 131.         map.put("username","张三");  
 132.         map.put("password","88888");  
 133. //      URLConnectionUtil.doGet(urlStr, map);  
 134. //      URLConnectionUtil.doPost(urlStr, map);  
 135. //      URLConnectionUtil.doPut(urlStr, map);  
 136.         URLConnectionUtil.doDelete(urlStr, map);  
 137.           
 138.     }  
 139.       
 140.       
 141. } 

方法中是存在重复的。有些方法是可以通过参数的改变来达到统一，但是那样的做法对于程序的扩展性会有很大的局限性。

还是对于每一种方式提供一个单独的方法进行访问比较好。

在Servlet端，获取参数可以通过

request.getInputStream,及request.getParamter来进行。

其中，当Rest访问传入参数是通过conn的outputStream来进行的，可以通过request.getInputStream来进行参数获取（Post方式可通用）；

当以url?key=value方法传递参数时，可以通过request.getParamter来进行参数获取。（Post方式可通用）

其中request.getInputStream和request.getParamter两种方式不能同时出现。当request.getParamter运行的过程，也是输入流的读取过程。当输入流读取完成后，再次调用时无效的。

附上Servlet端程序

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   1. package com.sw.servlet;  
   2.   
   3. import java.io.BufferedReader;  
   4. import java.io.IOException;  
   5. import java.io.InputStreamReader;  
   6. import java.io.OutputStream;  
   7.   
   8. import javax.servlet.ServletException;  
   9. import javax.servlet.ServletInputStream;  
  10. import javax.servlet.http.HttpServlet;  
  11. import javax.servlet.http.HttpServletRequest;  
  12. import javax.servlet.http.HttpServletResponse;  
  13.   
  14. /** 
  15.  * Servlet implementation class ReceiveDataServlet 
  16.  */  
  17. public class ReceiveDataServlet extends HttpServlet {  
  18.     private static final long serialVersionUID = 1L;  
  19.          
  20.     /** 
  21.      * @see HttpServlet#HttpServlet() 
  22.      */  
  23.     public ReceiveDataServlet() {  
  24.         super();  
  25.         // TODO Auto-generated constructor stub  
  26.     }  
  27.   
  28.     /** 
  29.      * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) 
  30.      */  
  31.     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {  
  32.         System.out.println("----------get--------------");        
  33.         String username = new String(request.getParameter("username").getBytes("iso-8859-1"),"utf-8");  
  34.         String password = new String(request.getParameter("password").getBytes("iso-8859-1"),"utf-8");  
  35.         System.out.println(username);  
  36.         System.out.println(password);  
  37.         OutputStream os = response.getOutputStream();  
  38.         os.write("get".getBytes("utf-8"));  
  39.     }  
  40.   
  41.     /** 
  42.      * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) 
  43.      */  
  44.     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {  
  45.         System.out.println("----------post--------------");  
  46.         BufferedReader br = new BufferedReader(new InputStreamReader((ServletInputStream)request.getInputStream()));  
  47.         String line = null;  
  48.         StringBuilder sb = new StringBuilder();  
  49.         while((line = br.readLine())!=null){  
  50.             sb.append(line);  
  51.         }         
  52.         System.out.println(sb.toString());  
  53.         br.close();  
  54. /*      String username = new String(request.getParameter("username").getBytes("iso-8859-1"),"utf-8"); 
  55.         String password = new String(request.getParameter("password").getBytes("iso-8859-1"),"utf-8"); 
  56.         System.out.println(username); 
  57.         System.out.println(password); 
  58. */      OutputStream os = response.getOutputStream();  
  59.         os.write("post".getBytes("utf-8"));  
  60.     }  
  61.       
  62.     @Override  
  63.     protected void doDelete(HttpServletRequest request, HttpServletResponse response)  
  64.             throws ServletException, IOException {  
  65.         System.out.println("----------delete--------------");  
  66.         String username = new String(request.getParameter("username").getBytes("iso-8859-1"),"utf-8");  
  67.         String password = new String(request.getParameter("password").getBytes("iso-8859-1"),"utf-8");  
  68.         System.out.println(username);  
  69.         System.out.println(password);  
  70.         OutputStream os = response.getOutputStream();  
  71.         os.write("delete".getBytes("utf-8"));             
  72.     }  
  73.       
  74.     @Override  
  75.     protected void doPut(HttpServletRequest request, HttpServletResponse response)  
  76.             throws ServletException, IOException {  
  77.         System.out.println("----------put--------------");  
  78.           
  79.     /*  BufferedReader br = new BufferedReader(new InputStreamReader((ServletInputStream)request.getInputStream())); 
  80.         String line = null; 
  81.         StringBuilder sb = new StringBuilder(); 
  82.         while((line = br.readLine())!=null){ 
  83.             sb.append(line); 
  84.         }        
  85.         System.out.println(sb.toString()); 
  86.         br.close();*/  
  87.           
  88.         String username = new String(request.getParameter("username").getBytes("iso-8859-1"),"utf-8");  
  89.         String password = new String(request.getParameter("password").getBytes("iso-8859-1"),"utf-8");  
  90.         System.out.println(username);  
  91.         System.out.println(password);  
  92.         OutputStream os = response.getOutputStream();  
  93.         os.write("put".getBytes("utf-8"));    
  94.     }  
  95.