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):http://www.shengshiyouxi.com


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 sflj


            for (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!