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 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!
