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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
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 17 18 /** 19 * Java原生的API可用于发送HTTP请求 20 * 即java.net.URL、java.net.URLConnection，JDK自带的类； 21 * 22 * 1.通过统一资源定位器（java.net.URL）获取连接器（java.net.URLConnection） 23 * 2.设置请求的参数 24 * 3.发送请求 25 * 4.以输入流的形式获取返回内容 26 * 5.关闭输入流 27 * 28 * @author H__D 29 * 30 */ 31 public class HttpRequestor { 32 33 //post请求 34 public static final String HTTP_POST = "POST"; 35 36 //get请求 37 public static final String HTTP_GET = "GET"; 38 39 // utf-8字符编码 40 public static final String CHARSET_UTF_8 = "utf-8"; 41 42 // HTTP内容类型。如果未指定ContentType，默认为TEXT/HTML 43 public static final String CONTENT_TYPE_TEXT_HTML = "text/xml"; 44 45 // HTTP内容类型。相当于form表单的形式，提交暑假 46 public static final String CONTENT_TYPE_FORM_URL = "application/x-www-form-urlencoded"; 47 48 //请求超时时间 49 public static final int SEND_REQUEST_TIME_OUT = 5000; 50 51 //将读超时时间 52 public static final int READ_TIME_OUT = 5000; 53 54 55 /** 56 * http请求的主要方法 57 * @param requestType 请求类型 58 * @param urlStr 请求地址 59 * @param body 请求发送内容 60 * @return 返回内容 61 */ 62 public static String requestMethod(String requestType,String urlStr,String body) { 63 64 //是否有http正文提交 65 boolean isDoInput = false; 66 if(body != null && body.length() > 0) isDoInput = true; 67 OutputStream outputStream = null; 68 OutputStreamWriter outputStreamWriter = null; 69 InputStream inputStream = null; 70 InputStreamReader inputStreamReader = null; 71 BufferedReader reader = null; 72 StringBuffer resultBuffer = new StringBuffer(); 73 String tempLine = null; 74 try { 75 // 统一资源 76 URL url = new URL(urlStr); 77 // 连接类的父类，抽象类 78 URLConnection urlConnection = url.openConnection(); 79 // http的连接类 80 HttpURLConnection httpURLConnection = (HttpURLConnection) urlConnection; 81 82 83 // 设置是否向httpUrlConnection输出，因为这个是post请求，参数要放在 84 // http正文内，因此需要设为true, 默认情况下是false; 85 if(isDoInput){ 86 httpURLConnection.setDoOutput(true); 87 httpURLConnection.setRequestProperty("Content-Length", String.valueOf(body.length())); 88 } 89 // 设置是否从httpUrlConnection读入，默认情况下是true; 90 httpURLConnection.setDoInput(true); 91 //设置一个指定的超时值（以毫秒为单位） 92 httpURLConnection.setConnectTimeout(SEND_REQUEST_TIME_OUT); 93 //将读超时设置为指定的超时，以毫秒为单位。 94 httpURLConnection.setReadTimeout(READ_TIME_OUT); 95 // Post 请求不能使用缓存 96 httpURLConnection.setUseCaches(false); 97 //设置字符编码 98 httpURLConnection.setRequestProperty("Accept-Charset", CHARSET_UTF_8); 99 //设置内容类型 100 httpURLConnection.setRequestProperty("Content-Type", CONTENT_TYPE_FORM_URL); 101 // 设定请求的方法，默认是GET 102 httpURLConnection.setRequestMethod(requestType); 103 104 //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）。 105 //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。 106 httpURLConnection.connect(); 107 108 if(isDoInput){ 109 outputStream = httpURLConnection.getOutputStream(); 110 outputStreamWriter = new OutputStreamWriter(outputStream); 111 outputStreamWriter.write(body); 112 outputStreamWriter.flush();// 刷新 113 } 114 if (httpURLConnection.getResponseCode() >= 300) { 115 throw new Exception( 116 "HTTP Request is not success, Response code is " + httpURLConnection.getResponseCode()); 117 } 118 119 if (httpURLConnection.getResponseCode() == HttpURLConnection.HTTP_OK) { 120 inputStream = httpURLConnection.getInputStream(); 121 inputStreamReader = new InputStreamReader(inputStream); 122 reader = new BufferedReader(inputStreamReader); 123 124 while ((tempLine = reader.readLine()) != null) { 125 resultBuffer.append(tempLine); 126 resultBuffer.append("\n"); 127 } 128 } 129 130 } catch (MalformedURLException e) { 131 // TODO Auto-generated catch block 132 e.printStackTrace(); 133 } catch (IOException e) { 134 // TODO Auto-generated catch block 135 e.printStackTrace(); 136 } catch (Exception e) { 137 // TODO Auto-generated catch block 138 e.printStackTrace(); 139 } finally {//关闭流 140 141 try { 142 if (outputStreamWriter != null) { 143 outputStreamWriter.close(); 144 } 145 } catch (Exception e) { 146 // TODO Auto-generated catch block 147 e.printStackTrace(); 148 } 149 try { 150 if (outputStream != null) { 151 outputStream.close(); 152 } 153 } catch (Exception e) { 154 // TODO Auto-generated catch block 155 e.printStackTrace(); 156 } 157 try { 158 if (reader != null) { 159 reader.close(); 160 } 161 } catch (Exception e) { 162 // TODO Auto-generated catch block 163 e.printStackTrace(); 164 } 165 try { 166 if (inputStreamReader != null) { 167 inputStreamReader.close(); 168 } 169 } catch (Exception e) { 170 // TODO Auto-generated catch block 171 e.printStackTrace(); 172 } 173 try { 174 if (inputStream != null) { 175 inputStream.close(); 176 } 177 } catch (Exception e) { 178 // TODO Auto-generated catch block 179 e.printStackTrace(); 180 } 181 } 182 return resultBuffer.toString(); 183 } 184 185 /** 186 * 将map集合的键值对转化成：key1=value1&key2=value2 的形式 187 * @param parameterMap 需要转化的键值对集合 188 * @return 字符串 189 */ 190 public static String convertStringParamter(Map parameterMap ){ 191 StringBuffer parameterBuffer = new StringBuffer(); 192 if (parameterMap != null) { 193 Iterator iterator = parameterMap.keySet().iterator(); 194 String key = null; 195 String value = null; 196 while (iterator.hasNext()) { 197 key = (String)iterator.next(); 198 if (parameterMap.get(key) != null) { 199 value = (String)parameterMap.get(key); 200 } else { 201 value = ""; 202 } 203 parameterBuffer.append(key).append("=").append(value); 204 if (iterator.hasNext()) { 205 parameterBuffer.append("&"); 206 } 207 } 208 } 209 return parameterBuffer.toString(); 210 } 211 212 213 214 215 public static void main(String[] args) throws MalformedURLException { 216 217 System.out.println(requestMethod(HTTP_GET, "http://127.0.0.1:8080/test/TestHttpRequestServlet", "username=123&password=我是谁")); 218 219 } 220 221 }
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 }
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>
【JAVA】通过URLConnection/HttpURLConnection发送HTTP请求的方法
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原文地址：http://www.cnblogs.com/h--d/p/5495524.html
