HttpURLConnection请求数据流的写入(write)和读取(read)

URLConnection类给应用程序和web资源之间架设起了通信的桥梁，这些web资源通常是通过url来标记的,本文将讲述如何使用HttpURLConnection来访问web页面(发送数据流)和读取数据流。

在Servlet中对于需要用post方式(get会暴露参数)写入参数的时候就用到了HttpURLConnection.

请求的Servlet，也可以写入main方法中进行测试

package com;import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.HttpURLConnection;
import java.net.URL;import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;@SuppressWarnings("serial")
public class IOServlet extends HttpServlet
{/*** 对于主动请求其它接口的参数流写入(POST方式)*/public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException{System.out.println("begin send");String inputParam = "<?xml version=\"1.0\" encoding=\"UTF-8\"?><page><username>爱心天使</usernaem><age>26</age></page>";URL url = null;HttpURLConnection httpConn = null;OutputStream output = null;OutputStreamWriter outr = null;url = new URL("http://127.0.0.1:8888/iotest/ReadServlet");httpConn = (HttpURLConnection) url.openConnection();HttpURLConnection.setFollowRedirects(true);httpConn.setDoOutput(true);httpConn.setRequestMethod("POST");httpConn.setRequestProperty("Content-Type", "text/xml");httpConn.connect();output = httpConn.getOutputStream();outr = new OutputStreamWriter(output);// 写入请求参数outr.write(inputParam.toString().toCharArray(), 0, inputParam.toString().length());outr.flush();outr.close();System.out.println("send ok");int code = httpConn.getResponseCode();System.out.println("code " + code);System.out.println(httpConn.getResponseMessage());//读取响应内容String sCurrentLine = ""; String sTotalString = ""; if (code == 200){java.io.InputStream is = httpConn.getInputStream();BufferedReader reader = new BufferedReader(new InputStreamReader(is));while ((sCurrentLine = reader.readLine()) != null)if (sCurrentLine.length() > 0)sTotalString = sTotalString + sCurrentLine.trim();} else{sTotalString = "远程服务器连接失败,错误代码:" + code;}System.out.println("response:" + sTotalString);}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException{this.doGet(request, response);}}

ReadServlet(相当于被请求的服务器):

package com;import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;@SuppressWarnings("serial")
public class ReadServlet extends HttpServlet
{public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException{System.out.println("begin read");ServletInputStream inStream = request.getInputStream(); // 取HTTP请求流int size = request.getContentLength(); // 取HTTP请求流长度byte[] buffer = new byte[size]; // 用于缓存每次读取的数据 byte[] in_b = new byte[size]; // 用于存放结果的数组int count = 0;int rbyte = 0;// 循环读取 while (count < size){ rbyte = inStream.read(buffer); // 每次实际读取长度存于rbyte中 sfljfor (int i = 0; i < rbyte; i++){in_b[count + i] = buffer[i];}count += rbyte;}System.out.println("result:" + new String(in_b,0,in_b.length));response.setContentType("text/html");//注意响应中文数据时要设置response.setCharacterEncoding("GBK");PrintWriter out = response.getWriter();//回与响应数据out.write("您已经请求成功，这是响应数据!");}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException{this.doGet(request, response);}}

打开页面:http://localhost:8888/iotest/IOServlet

你会在后台看到如下输出说明你已经成功了:

begin send
send ok
begin read
result:<?xml version="1.0" encoding="UTF-8"?><page><username>爱心天使</usernaem><age>26</age></page>
code 200
OK
response:您已经请求成功，这是响应数据!

源码下载:here

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HttpURLConnection请求数据流的写入(write)和读取(read)

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