HttpURLConnection简单用法

转自：http://blog.csdn.net/anyoneking/article/details/5177927

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。

[java] view
plain copy

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

[java] view
plain copy

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"));

}



@Override

protected 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"));

}



@Override

protected 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。