login.java

：一个用JavaScript开发的用户管理系统。

package test;
import java.io.*;
import java.sql.*;
import java.util.*;
import java.io.IOException;
import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Login  extends HttpServlet{
  PrintWriter out;
  String username,psw;

public void doPost(HttpServletRequest request,
                HttpServletResponse response)
  throws IOException
{
 response.setContentType("text/html;charset=GBK");
 out=response.getWriter();
 HttpSession session=request.getSession(true);

 username=request.getParameter("username");
 psw=request.getParameter("password");
 String password=(new MD5()).convert16(psw);
 DBConn conn=new DBConn();
 try{
   String sql="SELECT * FROM user WHERE username='"+username+"' AND password='"+password+"'";
   ResultSet rs=conn.query(sql);
   if(rs.next()){
    session.setAttribute("user",username);
    Vector vc=new Vector();
    if(session.getServletContext().getAttribute("online")!=null){
      vc=(Vector)session.getServletContext().getAttribute("online");
    }
    vc.add(username);
    session.getServletContext().setAttribute("online",vc);
    out.print("成功登陆！");
   }
   else{
    out.print("登陆不成功！");
   }
   rs.close();
   conn.DBclose();
 }
 catch(Exception e){
    out.print("登陆出现异常，不成功！");
  }
}
 public void doGet(HttpServletRequest request,
                   HttpServletResponse response)
      throws IOException
  {
      doPost(request, response);
  }

}