B/S登陆例子（JSP+JavaBean+MYSQL）

web.xml

  jspLogin

 index.jsp

 

 <%
 if(session.getAttribute("passed")==null){
  response.sendRedirect("login.jsp");
  return;
 }
%>
passed!

 login.jsp

 <%@ page contentType="text/html; charset=utf-8" %>





<%
String flag=request.getParameter("flag");
if(flag!=null&&flag.equals("0")){
  out.println("Pls input valid username and password!

");
}
%>

 

loginSuccess.jsp

<%@ page import="test.LoginCheck"%>
<%
String username=request.getParameter("username");
String password=request.getParameter("password");
boolean flag=false;

LoginCheck lc=new LoginCheck();
if(lc.check(username,password)){
    flag = true ;
 out.print("passed!");
}else{
  out.print("failed!");
}
if(flag){
  session.setAttribute("passed","true");
  response.sendRedirect("index.jsp");
}else{
  response.sendRedirect("login.jsp?flag=0");
}
%>

 

LoginCheck.java

package  test;
import  java.sql. * ;

public   class  LoginCheck  ... {
  public static boolean check(String username,String password) ...{
    boolean flag = false;
    try ...{
      String sql = "select * from user where username='" + username +
          "' and password='" + password + "'";
//
      Class.forName("com.mysql.jdbc.Driver");
      Connection conn = DriverManager.getConnection(
          "jdbc:mysql://localhost:3306/test?user=cwb&password=cwb123&useUnicode=true");
      Statement pstmt = conn.prepareStatement(sql);
      ResultSet rs = pstmt.executeQuery(sql);
      if (rs.next()) ...{
        flag = true;
      }
//
      rs.close();
      pstmt.close();
      conn.close();
    }catch(Exception ex)...{
      ex.printStackTrace();
    }
    return flag;
  }
}