【JAVA】經過URLConnection/HttpURLConnection發送HTTP請求的方法（一）

時間 2019-11-06

標籤 JAVA 經過 urlconnection httpurlconnection 發送 http 請求方法欄目 Java 简体版

原文原文鏈接

Java原生的API可用於發送HTTP請求html

即java.net.URL、java.net.URLConnection，JDK自帶的類；java

1.經過統一資源定位器（java.net.URL）獲取鏈接器（java.net.URLConnection）web

2.設置請求的參數緩存

3.發送請求app

4.以輸入流的形式獲取返回內容jsp

5.關閉輸入流ide

封裝請求類

  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請求
 19     public static final String HTTP_POST = "POST";
 20 
 21     // get請求
 22     public static final String HTTP_GET = "GET";
 23 
 24     // utf-8字符編碼
 25     public static final String CHARSET_UTF_8 = "utf-8";
 26 
 27     // HTTP內容類型。若是未指定ContentType，默認爲TEXT/HTML
 28     public static final String CONTENT_TYPE_TEXT_HTML = "text/xml";
 29 
 30     // HTTP內容類型。至關於form表單的形式，提交暑假
 31     public static final String CONTENT_TYPE_FORM_URL = "application/x-www-form-urlencoded";
 32 
 33     // 請求超時時間
 34     public static final int SEND_REQUEST_TIME_OUT = 50000;
 35 
 36     // 將讀超時時間
 37     public static final int READ_TIME_OUT = 50000;
 38 
 39     /**
 40      * 
 41      * @param requestType
 42      *            請求類型
 43      * @param urlStr
 44      *            請求地址
 45      * @param body
 46      *            請求發送內容
 47      * @return 返回內容
 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             // 統一資源
 64             URL url = new URL(urlStr);
 65             // 鏈接類的父類，抽象類
 66             URLConnection urlConnection = url.openConnection();
 67             // http的鏈接類
 68             HttpURLConnection httpURLConnection = (HttpURLConnection) urlConnection;
 69 
 70             // 設置是否向httpUrlConnection輸出，由於這個是post請求，參數要放在
 71             // http正文內，所以須要設爲true, 默認狀況下是false;
 72             if (isDoInput) {
 73                 httpURLConnection.setDoOutput(true);
 74                 httpURLConnection.setRequestProperty("Content-Length", String.valueOf(body.length()));
 75             }
 76             // 設置是否從httpUrlConnection讀入，默認狀況下是true;
 77             httpURLConnection.setDoInput(true);
 78             // 設置一個指定的超時值（以毫秒爲單位）
 79             httpURLConnection.setConnectTimeout(SEND_REQUEST_TIME_OUT);
 80             // 將讀超時設置爲指定的超時，以毫秒爲單位。
 81             httpURLConnection.setReadTimeout(READ_TIME_OUT);
 82             // Post 請求不能使用緩存
 83             httpURLConnection.setUseCaches(false);
 84             // 設置字符編碼
 85             httpURLConnection.setRequestProperty("Accept-Charset", CHARSET_UTF_8);
 86             // 設置內容類型
 87             httpURLConnection.setRequestProperty("Content-Type", CONTENT_TYPE_FORM_URL);
 88             // 設定請求的方法，默認是GET
 89             httpURLConnection.setRequestMethod(requestType);
 90 
 91             // 打開到此 URL 引用的資源的通訊連接（若是還沒有創建這樣的鏈接）。
 92             // 若是在已打開鏈接（此時 connected 字段的值爲 true）的狀況下調用 connect 方法，則忽略該調用。
 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 {// 關閉流
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      * 將map集合的鍵值對轉化成：key1=value1&key2=value2 的形式
174      * 
175      * @param parameterMap
176      *            須要轉化的鍵值對集合
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=我是誰"));
205 
206     }
207 }

HttpConnectionUtil

測試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>