Http使用post方式提交数据(使用java标准接口)

本文内容:使用java标准接口,实现http用post方式提交数据。

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程序组成部分:

1.客户端用eclipse HttpUtils.java 标准java接口,实现http用post方式提交数据。 (用post方式提交 username 和 password)

2.服务器端用myeclipse+tomcat 对客户端请求进行相应。(若用户名密码正确,则返回字符串"login is success !" ,不正确则返回字符串“login is fail !”)

重点注意点:

1. public static String sendPostMessage(Map<String,String> params , String encode)

    目的: 在客户端向服务器端发送 数据 params , 最终获取从服务器返回的输入流,最终将该输入流转换成字符串。注意使用标准java接口如何实现http的post请求,成功与服务器连接,并且获得从服务器端响应返回的数据。

2. public String String changInputStream(InputStream inputStream , String encode)

    目的: 将一个输入流按照指定编码方式转变成一个字符串。(本例中是指,将从服务器端返回的输入流InputStream转变成一个字符串String,编码方式是encode方式)

3. Map<String ,String> 的实例化方法及迭代方法

  Map  的实例化方法:

  Map<String, String> params = new HashMap<String, String>();
  params.put("username", "admin");
  params.put("password", "123");

 

   Map 的迭代方法:

 StringBuffer stringBuffer = new StringBuffer();

 
   for (Map.Entry<String, String> entry : params.entrySet()) {
    try {
     stringBuffer
       .append(entry.getKey())
       .append("=")
       .append(URLEncoder.encode(entry.getValue(), encode))
       .append("&");

    } catch (UnsupportedEncodingException e) {
     // TODO Auto-generated catch block
     e.printStackTrace();
   
   }
   // 删掉最后一个 & 字符
   stringBuffer.deleteCharAt(stringBuffer.length() - 1);

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程序思路:

1. 客户端建立http链接httpURLConnection,使用OutputStream向服务器传入数据

2. 获得从服务器端返回的输入流InputStream

3. 将InputStream转换成字符串String

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程序运行效果:

1.客户端运行效果


2. 服务器端运行结果

关键代码:

1. 客户端 HttpUtils.java

package com.http.post;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLEncoder;
import java.util.HashMap;
import java.util.Map;

public class HttpUtils {

	// 表示服务器端的url
	private static String PATH = "http://192.168.0.100:8080/myhttp/servlet/LoginAction";
	private static URL url;

	public HttpUtils() {
		// TODO Auto-generated constructor stub
	}

	static {
		try {
			url = new URL(PATH);
		} catch (MalformedURLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	/*
	 * params 填写的URL的参数 encode 字节编码
	 */
	public static String sendPostMessage(Map<String, String> params,
			String encode) {

		StringBuffer stringBuffer = new StringBuffer();

		if (params != null && !params.isEmpty()) {
			for (Map.Entry<String, String> entry : params.entrySet()) {
				try {
					stringBuffer
							.append(entry.getKey())
							.append("=")
							.append(URLEncoder.encode(entry.getValue(), encode))
							.append("&");

				} catch (UnsupportedEncodingException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
			// 删掉最后一个 & 字符
			stringBuffer.deleteCharAt(stringBuffer.length() - 1);
			System.out.println("-->>" + stringBuffer.toString());

			try {
				HttpURLConnection httpURLConnection = (HttpURLConnection) url
						.openConnection();
				httpURLConnection.setConnectTimeout(3000);
				httpURLConnection.setDoInput(true);// 从服务器获取数据
				httpURLConnection.setDoOutput(true);// 向服务器写入数据

				// 获得上传信息的字节大小及长度
				byte[] mydata = stringBuffer.toString().getBytes();
				// 设置请求体的类型
				httpURLConnection.setRequestProperty("Content-Type",
						"application/x-www-form-urlencoded");
				httpURLConnection.setRequestProperty("Content-Lenth",
						String.valueOf(mydata.length));

				// 获得输出流,向服务器输出数据
				OutputStream outputStream = (OutputStream) httpURLConnection
						.getOutputStream();
				outputStream.write(mydata);

				// 获得服务器响应的结果和状态码
				int responseCode = httpURLConnection.getResponseCode();
				if (responseCode == 200) {

					// 获得输入流,从服务器端获得数据
					InputStream inputStream = (InputStream) httpURLConnection
							.getInputStream();
					return (changeInputStream(inputStream, encode));

				}

			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}

		return "";
	}

	/*
	 * // 把从输入流InputStream按指定编码格式encode变成字符串String
	 */
	public static String changeInputStream(InputStream inputStream,
			String encode) {

		// ByteArrayOutputStream 一般叫做内存流
		ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
		byte[] data = new byte[1024];
		int len = 0;
		String result = "";
		if (inputStream != null) {

			try {
				while ((len = inputStream.read(data)) != -1) {
					byteArrayOutputStream.write(data, 0, len);

				}
				result = new String(byteArrayOutputStream.toByteArray(), encode);

			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}

		}

		return result;
	}

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Map<String, String> params = new HashMap<String, String>();
		params.put("username", "admin");
		params.put("password", "123");
		String result = sendPostMessage(params, "utf-8");
		System.out.println("-result->>" + result);

	}

}


服务器端servlet: LoginAction.java

package com.login.manager;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class LoginAction extends HttpServlet {

	/**
	 * Constructor of the object.
	 */
	public LoginAction() {
		super();
	}

	/**
	 * Destruction of the servlet. <br>
	 */
	public void destroy() {
		super.destroy(); // Just puts "destroy" string in log
		// Put your code here
	}

	/**
	 * The doGet method of the servlet. <br>
	 * 
	 * This method is called when a form has its tag value method equals to get.
	 * 
	 * @param request
	 *            the request send by the client to the server
	 * @param response
	 *            the response send by the server to the client
	 * @throws ServletException
	 *             if an error occurred
	 * @throws IOException
	 *             if an error occurred
	 */
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		this.doPost(request, response);
	}

	/**
	 * The doPost method of the servlet. <br>
	 * 
	 * This method is called when a form has its tag value method equals to
	 * post.
	 * 
	 * @param request
	 *            the request send by the client to the server
	 * @param response
	 *            the response send by the server to the client
	 * @throws ServletException
	 *             if an error occurred
	 * @throws IOException
	 *             if an error occurred
	 */
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		response.setContentType("text/html;charset=utf-8");
		request.setCharacterEncoding("utf-8");
		response.setCharacterEncoding("utf-8");
		//客户端 HttpUtils并没有写request方法是post ,但服务器端可自动识别
		String method = request.getMethod();
		System.out.println("request method :"+method);
		
		
		PrintWriter out = response.getWriter();
		String username = request.getParameter("username");
		System.out.println("-username->>"+username);
		
		String password = request.getParameter("password");
		System.out.println("-password->>"+password);

		if (username.equals("admin") && password.equals("123")) {
			// 表示服务器段返回的结果
			out.print("login is success !");

		} else {
			out.print("login is fail !");
		}

		out.flush();
		out.close();
	}

	/**
	 * Initialization of the servlet. <br>
	 * 
	 * @throws ServletException
	 *             if an error occurs
	 */
	public void init() throws ServletException {
		// Put your code here
	}

}








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