【JAVA】通过URLConnection/HttpURLConnection发送HTTP请求的方法（一）

Java原生的API可用于发送HTTP请求

 即java.net.URL、java.net.URLConnection，JDK自带的类；

 

 1.通过统一资源定位器（java.net.URL）获取连接器（java.net.URLConnection）

 2.设置请求的参数

 3.发送请求

 4.以输入流的形式获取返回内容

 5.关闭输入流

• 封装请求类
  

  

    1 package com.util;
    2 
    3 import java.io.BufferedReader;
    4 import java.io.IOException;
    5 import java.io.InputStream;
    6 import java.io.InputStreamReader;
    7 import java.io.OutputStream;
    8 import java.io.OutputStreamWriter;
    9 import java.net.HttpURLConnection;
   10 import java.net.MalformedURLException;
   11 import java.net.URL;
   12 import java.net.URLConnection;
   13 import java.util.Iterator;
   14 import java.util.Map;
   15 
   16 public class HttpConnectionUtil {
   17 
   18     // post请求
   19     public static final String HTTP_POST = "POST";
   20 
   21     // get请求
   22     public static final String HTTP_GET = "GET";
   23 
   24     // utf-8字符编码
   25     public static final String CHARSET_UTF_8 = "utf-8";
   26 
   27     // HTTP内容类型。如果未指定ContentType，默认为TEXT/HTML
   28     public static final String CONTENT_TYPE_TEXT_HTML = "text/xml";
   29 
   30     // HTTP内容类型。相当于form表单的形式，提交暑假
   31     public static final String CONTENT_TYPE_FORM_URL = "application/x-www-form-urlencoded";
   32 
   33     // 请求超时时间
   34     public static final int SEND_REQUEST_TIME_OUT = 50000;
   35 
   36     // 将读超时时间
   37     public static final int READ_TIME_OUT = 50000;
   38 
   39     /**
   40      * 
   41      * @param requestType
   42      *            请求类型
   43      * @param urlStr
   44      *            请求地址
   45      * @param body
   46      *            请求发送内容
   47      * @return 返回内容
   48      */
   49     public static String requestMethod(String requestType, String urlStr, String body) {
   50 
   51         // 是否有http正文提交
   52         boolean isDoInput = false;
   53         if (body != null && body.length() > 0)
   54             isDoInput = true;
   55         OutputStream outputStream = null;
   56         OutputStreamWriter outputStreamWriter = null;
   57         InputStream inputStream = null;
   58         InputStreamReader inputStreamReader = null;
   59         BufferedReader reader = null;
   60         StringBuffer resultBuffer = new StringBuffer();
   61         String tempLine = null;
   62         try {
   63             // 统一资源
   64             URL url = new URL(urlStr);
   65             // 连接类的父类，抽象类
   66             URLConnection urlConnection = url.openConnection();
   67             // http的连接类
   68             HttpURLConnection httpURLConnection = (HttpURLConnection) urlConnection;
   69 
   70             // 设置是否向httpUrlConnection输出，因为这个是post请求，参数要放在
   71             // http正文内，因此需要设为true, 默认情况下是false;
   72             if (isDoInput) {
   73                 httpURLConnection.setDoOutput(true);
   74                 httpURLConnection.setRequestProperty("Content-Length", String.valueOf(body.length()));
   75             }
   76             // 设置是否从httpUrlConnection读入，默认情况下是true;
   77             httpURLConnection.setDoInput(true);
   78             // 设置一个指定的超时值（以毫秒为单位）
   79             httpURLConnection.setConnectTimeout(SEND_REQUEST_TIME_OUT);
   80             // 将读超时设置为指定的超时，以毫秒为单位。
   81             httpURLConnection.setReadTimeout(READ_TIME_OUT);
   82             // Post 请求不能使用缓存
   83             httpURLConnection.setUseCaches(false);
   84             // 设置字符编码
   85             httpURLConnection.setRequestProperty("Accept-Charset", CHARSET_UTF_8);
   86             // 设置内容类型
   87             httpURLConnection.setRequestProperty("Content-Type", CONTENT_TYPE_FORM_URL);
   88             // 设定请求的方法，默认是GET
   89             httpURLConnection.setRequestMethod(requestType);
   90 
   91             // 打开到此 URL 引用的资源的通信链接（如果尚未建立这样的连接）。
   92             // 如果在已打开连接（此时 connected 字段的值为 true）的情况下调用 connect 方法，则忽略该调用。
   93             httpURLConnection.connect();
   94 
   95             if (isDoInput) {
   96                 outputStream = httpURLConnection.getOutputStream();
   97                 outputStreamWriter = new OutputStreamWriter(outputStream);
   98                 outputStreamWriter.write(body);
   99                 outputStreamWriter.flush();// 刷新
  100             }
  101             if (httpURLConnection.getResponseCode() >= 300) {
  102                 throw new Exception(
  103                         "HTTP Request is not success, Response code is " + httpURLConnection.getResponseCode());
  104             }
  105 
  106             if (httpURLConnection.getResponseCode() == HttpURLConnection.HTTP_OK) {
  107                 inputStream = httpURLConnection.getInputStream();
  108                 inputStreamReader = new InputStreamReader(inputStream);
  109                 reader = new BufferedReader(inputStreamReader);
  110 
  111                 while ((tempLine = reader.readLine()) != null) {
  112                     resultBuffer.append(tempLine);
  113                     resultBuffer.append("\n");
  114                 }
  115             }
  116 
  117         } catch (MalformedURLException e) {
  118             // TODO Auto-generated catch block
  119             e.printStackTrace();
  120         } catch (IOException e) {
  121             // TODO Auto-generated catch block
  122             e.printStackTrace();
  123         } catch (Exception e) {
  124             // TODO Auto-generated catch block
  125             e.printStackTrace();
  126         } finally {// 关闭流
  127 
  128             try {
  129                 if (outputStreamWriter != null) {
  130                     outputStreamWriter.close();
  131                 }
  132             } catch (Exception e) {
  133                 // TODO Auto-generated catch block
  134                 e.printStackTrace();
  135             }
  136             try {
  137                 if (outputStream != null) {
  138                     outputStream.close();
  139                 }
  140             } catch (Exception e) {
  141                 // TODO Auto-generated catch block
  142                 e.printStackTrace();
  143             }
  144             try {
  145                 if (reader != null) {
  146                     reader.close();
  147                 }
  148             } catch (Exception e) {
  149                 // TODO Auto-generated catch block
  150                 e.printStackTrace();
  151             }
  152             try {
  153                 if (inputStreamReader != null) {
  154                     inputStreamReader.close();
  155                 }
  156             } catch (Exception e) {
  157                 // TODO Auto-generated catch block
  158                 e.printStackTrace();
  159             }
  160             try {
  161                 if (inputStream != null) {
  162                     inputStream.close();
  163                 }
  164             } catch (Exception e) {
  165                 // TODO Auto-generated catch block
  166                 e.printStackTrace();
  167             }
  168         }
  169         return resultBuffer.toString();
  170     }
  171 
  172     /**
  173      * 将map集合的键值对转化成：key1=value1&key2=value2 的形式
  174      * 
  175      * @param parameterMap
  176      *            需要转化的键值对集合
  177      * @return 字符串
  178      */
  179     public static String convertStringParamter(Map parameterMap) {
  180         StringBuffer parameterBuffer = new StringBuffer();
  181         if (parameterMap != null) {
  182             Iterator iterator = parameterMap.keySet().iterator();
  183             String key = null;
  184             String value = null;
  185             while (iterator.hasNext()) {
  186                 key = (String) iterator.next();
  187                 if (parameterMap.get(key) != null) {
  188                     value = (String) parameterMap.get(key);
  189                 } else {
  190                     value = "";
  191                 }
  192                 parameterBuffer.append(key).append("=").append(value);
  193                 if (iterator.hasNext()) {
  194                     parameterBuffer.append("&");
  195                 }
  196             }
  197         }
  198         return parameterBuffer.toString();
  199     }
  200 
  201     public static void main(String[] args) throws MalformedURLException {
  202 
  203         System.out.println(requestMethod(HTTP_GET, "http://127.0.0.1:8080/test/TestHttpRequestServlet",
  204                 "username=123&password=我是谁"));
  205 
  206     }
  207 }

  

   

• 测试Servlet
  

  

   1 package com.servlet;
   2 
   3 import java.io.IOException;
   4 
   5 import javax.servlet.ServletException;
   6 import javax.servlet.http.HttpServlet;
   7 import javax.servlet.http.HttpServletRequest;
   8 import javax.servlet.http.HttpServletResponse;
   9 
  10 public class TestHttpRequestServelt extends HttpServlet {
  11 
  12 
  13     @Override
  14     protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  15 
  16         System.out.println("this is a TestHttpRequestServlet");
  17         request.setCharacterEncoding("utf-8");
  18         
  19         String username = request.getParameter("username");
  20         String password = request.getParameter("password");
  21         
  22         System.out.println(username);
  23         System.out.println(password);
  24         
  25         response.setContentType("text/plain; charset=UTF-8");
  26         response.setCharacterEncoding("UTF-8");
  27         response.getWriter().write("This is ok!");
  28         
  29     }
  30 }

  

     

• web.xml配置
  

  

   1 <?xml version="1.0" encoding="UTF-8"?>
   2 <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
   3   <display-name>test</display-name>
   4   
   5   <servlet>
   6       <servlet-name>TestHttpRequestServlet</servlet-name>
   7       <servlet-class>com.servlet.TestHttpRequestServelt</servlet-class>
   8   </servlet>
   9   
  10   <servlet-mapping>
  11       <servlet-name>TestHttpRequestServlet</servlet-name>
  12       <url-pattern>/TestHttpRequestServlet</url-pattern>
  13   </servlet-mapping>
  14   
  15   <welcome-file-list>
  16     <welcome-file>index.html</welcome-file>
  17     <welcome-file>index.htm</welcome-file>
  18     <welcome-file>index.jsp</welcome-file>
  19     <welcome-file>default.html</welcome-file>
  20     <welcome-file>default.htm</welcome-file>
  21     <welcome-file>default.jsp</welcome-file>
  22   </welcome-file-list>
  23 </web-app>