HttpURLConnection简单用法

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。

package com.sw.study.urlConnection;import java.io.BufferedReader;import java.io.InputStreamReader;import java.io.OutputStream;import java.net.HttpURLConnection;import java.net.URL;import java.net.URLConnection;import java.util.HashMap;import java.util.Map;public class URLConnectionUtil {private static final String SERVLET_POST = "POST" ;private static final String SERVLET_GET = "GET" ;private static final String SERVLET_DELETE = "DELETE" ;private static final String SERVLET_PUT = "PUT" ;private static String prepareParam(Map<String,Object> paramMap){StringBuffer sb = new StringBuffer();if(paramMap.isEmpty()){return "" ;}else{for(String key: paramMap.keySet()){String value = (String)paramMap.get(key);if(sb.length()<1){sb.append(key).append("=").append(value);}else{sb.append("&").append(key).append("=").append(value);}}return sb.toString();}}public static void doPost(String urlStr,Map<String,Object> paramMap ) throws Exception{URL url = new URL(urlStr);HttpURLConnection conn = (HttpURLConnection)url.openConnection();conn.setRequestMethod(SERVLET_POST);String paramStr = prepareParam(paramMap);conn.setDoInput(true);conn.setDoOutput(true);OutputStream os = conn.getOutputStream(); os.write(paramStr.toString().getBytes("utf-8")); os.close(); BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));String line ;String result ="";while( (line =br.readLine()) != null ){result += "/n"+line;}System.out.println(result);br.close();}public static void doGet(String urlStr,Map<String,Object> paramMap ) throws Exception{String paramStr = prepareParam(paramMap);if(paramStr == null || paramStr.trim().length()<1){}else{urlStr +="?"+paramStr;}System.out.println(urlStr);URL url = new URL(urlStr);HttpURLConnection conn = (HttpURLConnection)url.openConnection();conn.setRequestMethod(SERVLET_PUT);conn.setRequestProperty("Content-Type","text/html; charset=UTF-8");conn.connect();BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));String line ;String result ="";while( (line =br.readLine()) != null ){result += "/n"+line;}System.out.println(result);br.close();}public static void doPut(String urlStr,Map<String,Object> paramMap) throws Exception{URL url = new URL(urlStr);HttpURLConnection conn = (HttpURLConnection)url.openConnection();conn.setRequestMethod(SERVLET_PUT);String paramStr = prepareParam(paramMap);conn.setDoInput(true);conn.setDoOutput(true);OutputStream os = conn.getOutputStream(); os.write(paramStr.toString().getBytes("utf-8")); os.close(); BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));String line ;String result ="";while( (line =br.readLine()) != null ){result += "/n"+line;}System.out.println(result);br.close();}public static void doDelete(String urlStr,Map<String,Object> paramMap) throws Exception{String paramStr = prepareParam(paramMap);if(paramStr == null || paramStr.trim().length()<1){}else{urlStr +="?"+paramStr;}System.out.println(urlStr);URL url = new URL(urlStr);HttpURLConnection conn = (HttpURLConnection)url.openConnection();conn.setDoOutput(true);conn.setRequestMethod(SERVLET_DELETE);//屏蔽掉的代码是错误的，java.net.ProtocolException: HTTP method DELETE doesn't support output/*OutputStream os = conn.getOutputStream(); os.write(paramStr.toString().getBytes("utf-8")); os.close(); */ if(conn.getResponseCode() ==200){System.out.println("成功");}else{System.out.println(conn.getResponseCode());}}public static void main(String[] args) throws Exception{String urlStr = "http://localhost:8080/SwTest/ReceiveDataServlet";Map<String,Object> map = new HashMap<String,Object>();map.put("username","张三");map.put("password","88888");//URLConnectionUtil.doGet(urlStr, map);//URLConnectionUtil.doPost(urlStr, map);//URLConnectionUtil.doPut(urlStr, map);URLConnectionUtil.doDelete(urlStr, map);}}

 

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

package com.sw.servlet;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.io.OutputStream;import javax.servlet.ServletException;import javax.servlet.ServletInputStream;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * Servlet implementation class ReceiveDataServlet */public class ReceiveDataServlet extends HttpServlet {private static final long serialVersionUID = 1L; /** * @see HttpServlet#HttpServlet() */ public ReceiveDataServlet() { super(); // TODO Auto-generated constructor stub }/** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {System.out.println("----------get--------------");String username = new String(request.getParameter("username").getBytes("iso-8859-1"),"utf-8");String password = new String(request.getParameter("password").getBytes("iso-8859-1"),"utf-8");System.out.println(username);System.out.println(password);OutputStream os = response.getOutputStream();os.write("get".getBytes("utf-8"));}/** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {System.out.println("----------post--------------");BufferedReader br = new BufferedReader(new InputStreamReader((ServletInputStream)request.getInputStream())); String line = null; StringBuilder sb = new StringBuilder(); while((line = br.readLine())!=null){ sb.append(line); }System.out.println(sb.toString());br.close();/*String username = new String(request.getParameter("username").getBytes("iso-8859-1"),"utf-8");String password = new String(request.getParameter("password").getBytes("iso-8859-1"),"utf-8");System.out.println(username);System.out.println(password);*/OutputStream os = response.getOutputStream();os.write("post".getBytes("utf-8"));}@Overrideprotected void doDelete(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {System.out.println("----------delete--------------");String username = new String(request.getParameter("username").getBytes("iso-8859-1"),"utf-8");String password = new String(request.getParameter("password").getBytes("iso-8859-1"),"utf-8");System.out.println(username);System.out.println(password);OutputStream os = response.getOutputStream();os.write("delete".getBytes("utf-8"));}@Overrideprotected void doPut(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {System.out.println("----------put--------------");/*BufferedReader br = new BufferedReader(new InputStreamReader((ServletInputStream)request.getInputStream())); String line = null; StringBuilder sb = new StringBuilder(); while((line = br.readLine())!=null){ sb.append(line); }System.out.println(sb.toString());br.close();*/String username = new String(request.getParameter("username").getBytes("iso-8859-1"),"utf-8");String password = new String(request.getParameter("password").getBytes("iso-8859-1"),"utf-8");System.out.println(username);System.out.println(password);OutputStream os = response.getOutputStream();os.write("put".getBytes("utf-8"));}}

 

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。

新年快乐。