courseservlet.java

dns系统

package com.livechance;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;
import java.util.Vector;
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 CourseServlet extends HttpServlet {

	private static final long serialVersionUID = -77956983322135908L;

	@Override
	protected void service(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		response.setContentType("text/html;charset=GB2312");
		PrintWriter pw = response.getWriter();
		
		HttpSession session = request.getSession();
		String sessionName = (String)session.getAttribute("name");
		String sessionPassword = (String)session.getAttribute("password");
		if(sessionName==null || sessionPassword==null) {
			response.sendRedirect("/login.html");
			return;
		}
		String courseSelect = request.getParameter("course");
		if(courseSelect!=null) {
			Vector vector = (Vector)session.getAttribute("courses");
			if(vector==null) {
				vector = new Vector();
				vector.add(courseSelect);
				session.setAttribute("courses", vector);
			} else {
				if(vector.contains(courseSelect)) {
					pw.println("Already choose!");
				} else {
					vector.add(courseSelect);
				}
			}
		}
		
		String[] courses = {"C#","C++","Java","ASP","JSP","A","B","C"};
		pw.println("Hello:"+sessionName+",please help yourself...<br>");
		
		for(int i=0;i<courses.length;i++) {
			pw.println(courses[i]+"&nbsp;&nbsp;&nbsp;<a href='CourseServlet?course="+courses[i]+"'>choose</a><br>");
		}
		pw.println("<hr>");
		Vector vector = (Vector)session.getAttribute("courses");
		pw.println(sessionName+" already selected...");
		if(vector!=null) {
			for (Enumeration em = vector.elements();em.hasMoreElements();) {
				pw.println((String)em.nextElement()+"<br>");
			}
		}
		
		
	}

}