防止反复提交 js

document.getElementById('submitBtn').addEventListener('click', function() {
    var btn = this;
    btn.disabled = true; // 禁用按钮
    document.getElementById('myForm').submit(); // 提交表单
});

<?php
session_start();
$_SESSION['token'] = bin2hex(random_bytes(16)); // 生成Token
?>
<form action="submit.php" method="post">
    <input type="hidden" name="token" value="<?php echo $_SESSION['token']; ?>">
    <!-- 其他表单字段 -->
    <button type="submit" id="submitBtn">提交</button>
</form>

<?php
session_start();
if ($_POST['token'] !== $_SESSION['token']) {
    die('Invalid Token');
}
// 处理表单数据
unset($_SESSION['token']); // 使Token失效
?>

public class FormController {
    private Set<String> submittedTokens = new HashSet<>();

    public ResponseEntity<?> submitForm(@RequestParam String token, @RequestBody FormData formData) {
        if (submittedTokens.contains(token)) {
            return ResponseEntity.status(HttpStatus.BAD_REQUEST).body("Duplicate submission");
        }
        submittedTokens.add(token);
        // 处理表单数据
        return ResponseEntity.ok("Form submitted successfully");
    }
}