PHP implements upload restrictions on file upload and download

Client restrictions

The code is as follows:

       
  
  请选择您要上传的文件： 
  
  

The input attributes are used here to limit the size and type of uploaded files. But I personally feel that

1.html code is "visible"

2. It often doesn't work (I haven't found the reason, but because of the first one I also want to give up on it, just know it.

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##Server Side Limitations

Main Limitations Size and Type , and then there is the method.

$maxsize) { exit("上传文件过大！"); } if (!in_array($ext, $allowExt)) { exit("非法文件类型"); } if (!is_uploaded_file($tmp_name)) { exit("上传方式有误，请使用post方式"); } //判断是否为真实图片（防止伪装成图片的病毒一类的 if (!getimagesize($tmp_name)) {//getimagesize真实返回数组，否则返回false exit("不是真正的图片类型"); } //move_uploaded_file($tmp_name, "uploads/".$filename); if (@move_uploaded_file($tmp_name, $destination)) {//@错误抑制符，不让用户看到警告 echo "文件".$filename."上传成功!"; }else{ echo "文件".$filename."上传失败!"; } }else{ switch ($error){ case 1: echo "超过了上传文件的最大值，请上传2M以下文件"; break; case 2: echo "上传文件过多，请一次上传20个及以下文件！"; break; case 3: echo "文件并未完全上传，请再次尝试！"; break; case 4: echo "未选择上传文件！"; break; case 7: echo "没有临时文件夹"; break; } }

Here, the specific implementation is commented, and you can actually try it yourself, which is very interesting

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