checkservlet.java

servlet的几个简单的例子

    /*
     * CheckServlet.java
     *
     * Created on 2008年4月25日, 下午12:34
     */

import java.io.*;
import java.net.*;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

import javax.servlet.*;
import javax.servlet.http.*;

/**
 *
 * @author wlz
 * @version
 */
public class CheckServlet extends HttpServlet {
    
    /** Processes requests for both HTTP <code>GET</code> and <code>POST</code> methods.
     * @param request servlet request
     * @param response servlet response
     */
    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
        HttpSession hsession = request.getSession();
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        String userid =  request.getParameter("userid");
        int result = 0;
        Connection conn = null;
        Statement stat;
        String hostName = "localhost"; // 主机名或者IP地址
        String portNumber = "1433"; // 端口号，默认为1521
        String databaseSID = "student"; // SID名称
        String userName = "sa"; // 用户名
        String password = "sa"; // 用户密码
        String url = "jdbc:microsoft:sqlserver://" + hostName + ":" + portNumber +
                ";databaseName=" + databaseSID; // 连接字符串
        try {
            Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver"); // 装载驱动程序
            conn = DriverManager.getConnection(url, userName, password); // 建立连接
        } catch (Exception e) {
            e.printStackTrace();
        }
        try {
            stat = conn.createStatement();
            String actionStat = "select userid,username from users where userid='"+userid+"'";
            ResultSet rs = stat.executeQuery(actionStat);
            result = rs.next() ? 1 : 0;
            if (result == 1) {
                // response.sendRedirect("index.htm");
                if(hsession!=null){
                    hsession.setAttribute("userid",userid); 
                }
                out.println("<script language='javascript'>alert('登陆成功')</script>");
                  
            }else{
                try{
                     hsession.removeAttribute("userid");
                }catch(Exception e){
                    e.printStackTrace();
                }
                out.println("<script language='javascript'>alert('没有该用户存在')</script>");
                 
            }
        } catch (Exception e) {
            System.out.println("驱动错误!" + e.getMessage());
        }
        out.close();
    }
    
    // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
    /** Handles the HTTP <code>GET</code> method.
     * @param request servlet request
     * @param response servlet response
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
        processRequest(request, response);
    }
    
    /** Handles the HTTP <code>POST</code> method.
     * @param request servlet request
     * @param response servlet response
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
        processRequest(request, response);
    }
    
    /** Returns a short description of the servlet.
     */
    public String getServletInfo() {
        return "Short description";
    }
    // </editor-fold>
}