listservlet.java

详细讲述Servlet

package com.briup.status;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Map;
import java.util.Set;

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

public class ListServlet extends HttpServlet {

	/**
	 * Constructor of the object.
	 */
	public ListServlet() {
		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 {
		process(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 {
		process(request, response);
	}

	public void process(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		response.setContentType("text/html");
		PrintWriter out = response.getWriter();

		HttpSession session = request.getSession(false);

		if (isSession(session)) {
			Map users = (Map) session.getAttribute("users");
			Set<Map.Entry> set = users.entrySet();
			for (Map.Entry<String, String> entry : set) {
				out.println("username=" + entry.getKey());
				out.println("password=" + entry.getValue());
			}
		} else {
			out.println("session is null");
		}

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

	private boolean isSession(HttpSession session) {
		boolean status = false;
		if (session != null) {
			String login = (String) session.getAttribute("login.status");
			if (login != null && login.equals("success"))
				status = true;
		}
		return status;
	}

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

}