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  • 【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("
");
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 }
      HttpConnectionUtil
    • 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 }
      TestHttpRequestServelt

         

    • 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>
      web.xml
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  • 原文地址：https://www.cnblogs.com/h--d/p/5495524.html
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