如何真正解決表單重復提交問題php代碼

<script type="text/javascript">
var checkSubmitFlg = false;
function checkSubmit() {
 if (!checkSubmitFlg) {

/pic/>   checkSubmitFlg = true;
  return true;
 } else {

/pic/>   alert("Submit again!");
  return false;
 }
}
</script>

/pic/p>

<form onsubmit="return checkSubmit();">

<input type="submit" onclick="return checkSubmit();" />

<input type="button" onclick="document.forms[0].action='./test';document.forms[0].submit();return checkSubmit();" />

    <form
    
    method="post">
    <p>
    <label for="test">隨便輸入點什么www.45it.com</label>
    <input type="text" name="data" id="test" />
    </p>
    <p>
    <input type="submit" value="提交" name="submit" />
    </p>
    </ul>
    </form>

/pic/mytest/token/form.php?data=test&submit=%E6%8F%90%E4%BA%A4

<?php
    if ( isset( $_POST['submit'] ) ) {
    /pic/>     $data = isset(
    
    $_POST['data'] ) ? htmlspecialchars( $_POST['data'] ) : '';
    /pic/>     mysql_connect( 'localhost', 'root', 'root' );
    
    /pic/>     mysql_select_db( 'test' );
    /pic/>     mysql_query( 'set names "utf8"' );
    /pic/>     $sql = "insert
    
    into `token` (string) values ('$data')";
    /pic/>     mysql_query( $sql );
    $insert_id = mysql_insert_id();
    if (
    
    $insert_id ) {
    $state = 1;
    } else {
    $state = 0;
    }
    }
    ?>

    <?php if ( isset( $state )

    && $state ) { /pic/p>

    <p>插入成功 <a href="form.php">返回</a></p>

    <?php } else { /pic/p>

    作 ?>

    <form method="post">

    <p>

    <label for="test">隨便輸入點什么</label>

    <input type="text"

    name="data" id="test" />

    </p>

    <p>

    <input type="submit" value="提交" name="submit" />

    </p>

    </ul>

    </form>

    <?php } ?>

<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');

class Welcome extends CI_Controller {

 public function index()
 {
  $this->load->view('welcome_message');
 }

        public function token()
        {
            $this->load->helper( array('form') );
            $this->load->library('form_validation');
            if ( $this->input->post( 'submit' ) && $this->form_validation->valid_token() )
            {
                /pic/>                 /pic/>                 echo 'ok';
            }

            /pic/>             $token = $this->form_validation->create_token();

            /pic/>             echo form_open();
            echo form_input('token', '');
            echo $token;
            echo form_submit('submit', 'submit');
            echo form_close();
        }
}

<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');
/**
 * @abstract 繼承CI的Form_validation類在其基礎上增加令牌
 */
class MY_Form_validation extends CI_Form_validation {

    /**
     * 令牌鍵值
     * @var string
     */
    var $key = 'token';
   
    /**
     * 表單令牌有效時間(秒)
     * @abstract 如果某些表單需要限制輸入時間，則設置該值，為0則不限制
     * @var int 秒
     */
    var $token_validtime = 5;

    /**
     * 調試模式
     * @var bool
     */
    var $debug = false;

    /**
     * CI對象
     * @var <type>
     */
    private $_CI;

    public function __construct()
    {
        parent::__construct();
        $this->_CI =& get_instance();
        /pic/>         $encryption_key = config_item('encryption_key');
        if ( empty( $encryption_key ) ) $this->_CI->config->set_item( 'encryption_key', $this->key );
        /pic/>         if ( !isset( $this->_CI->session ) ) $this->_CI->load->library('session');
    }

    /**
     * 設置令牌有效時間
     * @param int $second 秒數
     */
    public function set_token_validtime( $second )
    {
        $this->token_validtime = intval( $second );
    }

    /**
     * 獲取表單令牌有效時間
     * @return int 秒數
     */
    public function get_token_validtime()
    {
        return $this->token_validtime;
    }

    /**
     * 驗證表單令牌是否合法
     * @return bool
     */
    public function valid_token()
    {
        if ( $this->debug ) return true;
        /pic/>         $source_hash = $this->_CI->session->userdata( $this->key );
        if ( empty( $source_hash ) ) return false;
       
        /pic/>         if ( $this->is_token_exprie() ) return false;

        /pic/>         $post_formhash = $this->_CI->input->post( $this->key );
        if ( empty( $post_formhash ) ) return false;

        if ( md5( $source_hash ) == $post_formhash )
        {
            $this->_CI->session->unset_userdata( $this->key );
            return true;
        }
        return false;
    }

    /**
     * 生成表單令牌（連同input元素）
     * @return string
     */
    public function create_token( $output = false )
    {
        $code = time() . '|' .  $this->get_random( 5 );
        $this->_CI->session->set_userdata( $this->key , $code);
        $result = function_exists('form_hidden') ? form_hidden( $this->key, md5( $code ) ) : '<input type="hidden" name="token" value="'. md5( $code ) .'" />';
        if ( $output )
        {
            echo $result;
        }
        else
        {
            return $result;
        }
    }
   
    /**
     * 獲取隨機數（自己可以擴展）
     * @param int $number 上限
     * @return string
     */
    public function get_random( $number )
    {
        return rand( 0, $number );
    }
   
    /**
     * 判斷表單令牌是否過期
     * @return bool
     */
    public function is_token_exprie()
    {
        if ( empty( $this->token_validtime ) ) return false;
        $token = $this->_CI->session->userdata( $this->key );
        if ( empty( $token ) ) return false;
        $create_time = array_shift( explode('|', $token) );
        return ( time() - $create_time > $this->token_validtime );
    }
}