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  • 封装 HttpURLConnection

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

    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.   
    96. }  
    [java] view plaincopy
    1. package com.sw.servlet;  
    2. import java.io.BufferedReader;  
    3. import java.io.IOException;  
    4. import java.io.InputStreamReader;  
    5. import java.io.OutputStream;  
    6. import javax.servlet.ServletException;  
    7. import javax.servlet.ServletInputStream;  
    8. import javax.servlet.http.HttpServlet;  
    9. import javax.servlet.http.HttpServletRequest;  
    10. import javax.servlet.http.HttpServletResponse;  
    11. /** 
    12.  * Servlet implementation class ReceiveDataServlet 
    13.  */  
    14. public class ReceiveDataServlet extends HttpServlet {  
    15.     private static final long serialVersionUID = 1L;  
    16.          
    17.     /** 
    18.      * @see HttpServlet#HttpServlet() 
    19.      */  
    20.     public ReceiveDataServlet() {  
    21.         super();  
    22.         // TODO Auto-generated constructor stub  
    23.     }  
    24.     /** 
    25.      * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) 
    26.      */  
    27.     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {  
    28.         System.out.println("----------get--------------");        
    29.         String username = new String(request.getParameter("username").getBytes("iso-8859-1"),"utf-8");  
    30.         String password = new String(request.getParameter("password").getBytes("iso-8859-1"),"utf-8");  
    31.         System.out.println(username);  
    32.         System.out.println(password);  
    33.         OutputStream os = response.getOutputStream();  
    34.         os.write("get".getBytes("utf-8"));  
    35.     }  
    36.     /** 
    37.      * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) 
    38.      */  
    39.     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {  
    40.         System.out.println("----------post--------------");  
    41.         BufferedReader br = new BufferedReader(new InputStreamReader((ServletInputStream)request.getInputStream()));  
    42.         String line = null;  
    43.         StringBuilder sb = new StringBuilder();  
    44.         while((line = br.readLine())!=null){  
    45.             sb.append(line);  
    46.         }         
    47.         System.out.println(sb.toString());  
    48.         br.close();  
    49. /*      String username = new String(request.getParameter("username").getBytes("iso-8859-1"),"utf-8"); 
    50.         String password = new String(request.getParameter("password").getBytes("iso-8859-1"),"utf-8"); 
    51.         System.out.println(username); 
    52.         System.out.println(password); 
    53. */      OutputStream os = response.getOutputStream();  
    54.         os.write("post".getBytes("utf-8"));  
    55.     }  
    56.       
    57.     @Override  
    58.     protected void doDelete(HttpServletRequest request, HttpServletResponse response)  
    59.             throws ServletException, IOException {  
    60.         System.out.println("----------delete--------------");  
    61.         String username = new String(request.getParameter("username").getBytes("iso-8859-1"),"utf-8");  
    62.         String password = new String(request.getParameter("password").getBytes("iso-8859-1"),"utf-8");  
    63.         System.out.println(username);  
    64.         System.out.println(password);  
    65.         OutputStream os = response.getOutputStream();  
    66.         os.write("delete".getBytes("utf-8"));             
    67.     }  
    68.       
    69.     @Override  
    70.     protected void doPut(HttpServletRequest request, HttpServletResponse response)  
    71.             throws ServletException, IOException {  
    72.         System.out.println("----------put--------------");  
    73.           
    74.     /*  BufferedReader br = new BufferedReader(new InputStreamReader((ServletInputStream)request.getInputStream())); 
    75.         String line = null; 
    76.         StringBuilder sb = new StringBuilder(); 
    77.         while((line = br.readLine())!=null){ 
    78.             sb.append(line); 
    79.         }        
    80.         System.out.println(sb.toString()); 
    81.         br.close();*/  
    82.           
    83.         String username = new String(request.getParameter("username").getBytes("iso-8859-1"),"utf-8");  
    84.         String password = new String(request.getParameter("password").getBytes("iso-8859-1"),"utf-8");  
    85.         System.out.println(username);  
    86.         System.out.println(password);  
    87.         OutputStream os = response.getOutputStream();  
    88.         os.write("put".getBytes("utf-8"));    
    89.     }  
    90. }  

    程序中对于request.getInputStream和getParameter的获取方式可能说明的会多少有些问题，我也是通过几组测试后得出的结论。肯定有我没有测试到得。如果有问题，请指出，我会再看到评论后进行测试，修改。

    另外，Apache的HttpClient非常好。封装的详细。在我的工作中也用到过，在以后会对于HttpClient进行有些单独的程序笔记。

    这里HttpUrlConnection是同事在别的项目中用到的，用法比较简单，我大体给他简单讲解了一下，简明扼要，功能完备，还是很方便，

    所以在这里记下来，留个笔记吧。

    btw,最近工作比较忙，有2个月没有写些东西了，在工作中确实还遇到了不少有意思的问题，最近刚好快闲下来了，慢慢整理一下。
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  • 原文地址：https://www.cnblogs.com/greywolf/p/2645179.html
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