JSP 【基础】连接数据库的登录及验证

最基础的

index页面

<center>
  <h1>登录操作</h1>
  <hr>
  /*将表单提交到login_check页面*/
  <form action="login_check.jsp" method="post">
    <table border="1">
      <tr>
        <td colspan="2" align="center">用户登录</td>   
      </tr>
      <tr>
        <td>登录ID：</td>
        <td><input type="text" name="id" ></td>
      </tr>
      <tr>
        <td>登录密码：</td>
        <td><input type="password" name="password" ></td>
      </tr>
      <tr>
        <td colspan="2">
            <input type="submit" value="登录">  
          <input type="reset" value="重置">             
          <input type="checkbox" name="remember" checked>记住我   
        </td>   
      </tr>
    </table>
  </form>
   <h5>如果尚未注册，请先点击<a href="register.jsp">这里</a>进行注册！</h5>
</center>

login_check页面

思路：

• 获取到index填写的内容信息，将id和pwd传到check(uid,pwd)方法进行查找
• check方法：先连接数据库
• 再 通过ResultSet ，获取到数据
• 返回uname，若uname不为空则说明找到了。

<%!
String check(String uid, String upassword){
  Connection conn = null;
  PreparedStatement pstmt = null;
  ResultSet rs = null;
  String uname = "";
  try{
    //1.加载数据库
    Class.forName("com.mysql.jdbc.Driver");

    //2.连接数据库
    String url = "jdbc:mysql://localhost:3306/db_news2019";
    String user = "root";
    String password = "admin";
    conn = DriverManager.getConnection(url,user,password);
    
    //3.获取数据库元素
    String sql = "select * from t_user where  uid=? and upassword=?";
    PreparedStatement pstm = conn.prepareStatement(sql);
    pstm.setString(1, uid);
    pstm.setString(2, upassword);
    
    rs = pstm.executeQuery();
    
    if(rs.next()){
      uname = rs.getString("uname");
    }
  }catch (ClassNotFoundException e) {
     System.out.print(e.getMessage());
   }catch (SQLException e) {
     System.out.print(e.getMessage());
   }finally{
    if(rs != null){ 
      try{
          rs.close(); 
      }catch(SQLException e){
        System.out.print(e.getMessage());
      }
    }
    if(pstmt != null){ 
      try{
        pstmt.close(); 
      }catch(SQLException e){
        System.out.print(e.getMessage());
      } 
    }
    if(conn != null){ 
      try{
        conn.close(); 
      }catch(SQLException e){
        System.out.print(e.getMessage());
      } 
    }
    return uname;
  }
}
%>

<%
  request.setCharacterEncoding("utf-8");
  String id = request.getParameter("id");
  String pwd = request.getParameter("password");
  String name = null;
  //名字不为空则说明匹配成功了。
  if(!((name=check(id, pwd)).equals(""))){
    session.setAttribute("username", name);
    response.sendRedirect("login_success.jsp");
  }else{
    response.sendRedirect("login_fail.jsp");
  }

%>

然后再写login_success和login_fail页面就可以了。