如何使用PHP和Vue.js开发防御恶意文件下载攻击的应用程序

<template>
  <div>
    <div v-if="warning">{{ warning }}</div>

    <a :href="fileUrl" download v-on:click.prevent="checkFile()">下载文件</a>
  </div>
</template>

<script>
import axios from 'axios';

export default {
  data() {
    return {
      warning: '',
      fileUrl: ''
    }
  },
  methods: {
    checkFile() {
      axios.head('/file/url') // 替换成实际的文件URL
        .then(response => {
          const contentType = response.headers['content-type'];
          if (!contentType.includes('application/pdf')) {
            this.warning = '文件类型错误';
          } else if (response.headers['content-length'] > 10485760) {
            this.warning = '文件过大';
          } else {
            this.warning = '';
          }
        })
        .catch(error => {
          this.warning = '文件不存在';
        });
    }
  }
}
</script>

<?php
if ($_FILES['file']['error'] === UPLOAD_ERR_OK) {
  $fileTempName = $_FILES['file']['tmp_name'];
  $fileSize = $_FILES['file']['size'];
  $fileType = $_FILES['file']['type'];
  $fileName = basename($_FILES['file']['name']);

  // 文件类型验证
  $allowedFileTypes = ['application/pdf', 'image/jpeg', 'image/png'];
  if (!in_array($fileType, $allowedFileTypes)) {
    die('文件类型不允许');
  }

  // 文件大小验证
  if ($fileSize > 10485760) {
    die('文件过大');
  }

  // 存储文件
  $fileUrl = '/path/to/file/' . uniqid() . '_' . $fileName;
  move_uploaded_file($fileTempName, $fileUrl);

  // 返回文件URL
  echo $fileUrl;
}
?>