servlet-使用dopost方式提交数据（代码示例）

代码来自：http://blog.csdn.net/neu_yousei/article/details/22486983

客户端代码

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);

	}

}

服务器端代码

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
	}

}