Frequently Asked Questions about PHP File Upload (Basic)

Since the previous article "The problem of garbled file names when uploading Chinese files in PHP" encountered the problem of file upload, let's summarize several problems that are often encountered when uploading files in PHP, so that you don't have to look for them when you use them in the future.

1. First make the simplest upload file

<span> 1</span> <span><span>html</span><span>></span>
<span> 2</span> <span><span>head</span><span>></span>
<span> 3</span> <span><span>meta </span><span>http-equiv</span><span>="Content-Type"</span><span> content</span><span>="text/html; charset=utf-8"</span><span>></span>
<span> 4</span> <span></span><span>head</span><span>></span>
<span> 5</span> <span><span>body</span><span>></span>
<span> 6</span> 
<span> 7</span> <span><span>form </span><span>action</span><span>="upload_file.php"</span><span> method</span><span>="post"</span>
<span> 8</span> <span>enctype</span><span>="multipart/form-data"</span><span>></span>
<span> 9</span> <span><span>label </span><span>for</span><span>="file"</span><span>></span>Filename:<span></span><span>label</span><span>></span>
<span>10</span> <span><span>input </span><span>type</span><span>="file"</span><span> name</span><span>="file"</span><span> id</span><span>="file"</span> <span>/></span> 
<span>11</span> <span><span>br </span><span>/></span>
<span>12</span> <span><span>input </span><span>type</span><span>="submit"</span><span> name</span><span>="submit"</span><span> value</span><span>="Submit"</span> <span>/></span>
<span>13</span> <span></span><span>form</span><span>></span>
<span>14</span> 
<span>15</span> <span></span><span>body</span><span>></span>
<span>16</span> <span></span><span>html</span><span>></span></span></span></span></span></span></span></span></span></span>

<span> 1</span> <span>php
</span><span> 2</span> <span>if</span> ((<span>$_FILES</span>["file"]["size"] )
<span> 3</span> <span>  {
</span><span> 4</span>   <span>if</span> (<span>$_FILES</span>["file"]["error"] > 0<span>)
</span><span> 5</span> <span>    {
</span><span> 6</span>     <span>echo</span> "Return Code: " . <span>$_FILES</span>["file"]["error"] . "<br>"<span>;
</span><span> 7</span> <span>    } 
</span><span> 8</span>   <span>else</span>
<span> 9</span> <span>    {
</span><span>10</span>     <span>echo</span> "Upload: " . <span>$_FILES</span>["file"]["name"] . "<br>"<span>;
</span><span>11</span>     <span>echo</span> "Type: " . <span>$_FILES</span>["file"]["type"] . "<br>"<span>;
</span><span>12</span>     <span>echo</span> "Size: " . (<span>$_FILES</span>["file"]["size"] / 1024) . " Kb<br>"<span>;
</span><span>13</span>     <span>echo</span> "Temp file: " . <span>$_FILES</span>["file"]["tmp_name"] . "<br>"<span>;
</span><span>14</span> 
<span>15</span>     <span>if</span> (<span>file_exists</span>("upload/" . <span>$_FILES</span>["file"]["name"<span>]))
</span><span>16</span> <span>      {
</span><span>17</span>       <span>echo</span> <span>$_FILES</span>["file"]["name"] . " already exists. "<span>;
</span><span>18</span> <span>      }
</span><span>19</span>     <span>else</span>
<span>20</span> <span>      {
</span><span>21</span>       <span>move_uploaded_file</span>(<span>$_FILES</span>["file"]["tmp_name"],
<span>22</span>       "upload/" . <span>$_FILES</span>["file"]["name"<span>]);
</span><span>23</span>       <span>echo</span> "Stored in: " . "upload/" . <span>$_FILES</span>["file"]["name"<span>];
</span><span>24</span> <span>      }
</span><span>25</span> <span>    }
</span><span>26</span> <span>  }
</span><span>27</span> <span>else</span>
<span>28</span> <span>  {
</span><span>29</span>   <span>echo</span> "Invalid file"<span>;
</span><span>30</span> <span>  }
</span><span>31</span> ?>

2. Then understand the value of the super global variable $_FILES

$_FILES['userfile']['name']

$_FILES['userfile']['type']

$_FILES['userfile']['size']

$_FILES['userfile']['tmp_name']

$_FILES['userfile']['error']

Among them, all values ​​of $_FILES['userfile']['error']:

UPLOAD_ERR_OK The value is 0, no error occurs, and the file is uploaded successfully.

UPLOAD_ERR_INI_SIZE Its value is 1, and the uploaded file exceeds the value limited by the upload_max_filesize option in php.ini.

UPLOAD_ERR_FORM_SIZE Its value is 2, and the size of the uploaded file exceeds the value specified by the MAX_FILE_SIZE option in the HTML form.

UPLOAD_ERR_PARTIAL Its value is 3, the file is only partially uploaded.

UPLOAD_ERR_NO_FILE Its value is 4, no file is uploaded.

UPLOAD_ERR_NO_TMP_DIR its value is 6, the temporary folder cannot be found. Introduced in PHP 4.3.10 and PHP 5.0.3.

UPLOAD_ERR_CANT_WRITE Its value is 7, file writing failed. Introduced in PHP 5.1.0.

3. Many situations: it is necessary to strictly judge the type of uploaded files

We know that it is unwise to use $_FILES['userfile']['type'] to determine the type of uploaded file, because the judgment is based on the suffix name of the file. Anyone can change the suffix of an mp3 file. It can be uploaded as a jpg and disguised as a picture. Therefore, PHP officially recommends using the PHP extension php_fileinfo to determine the mime of the file. There are many ways to enable the extension on Baidu. Win and Linux are slightly different.

4. Scenario 1: Automatically rename the uploaded file after the same name

<span> 1</span> <span>if</span> (<span>file_exists</span>("./upload/" . <span>$_FILES</span>["file"]["name"<span>]))  
</span><span> 2</span> <span>{    
</span><span> 3</span>    <span>do</span><span>{  
</span><span> 4</span>        <span>$suffix</span> =""<span>;  
</span><span> 5</span>        <span>$suffix_length</span> = 4<span>;  
</span><span> 6</span>        <span>$str</span> = "0123456789abcdefghijklmnopqrstuvwxyz"<span>;  
</span><span> 7</span>        <span>$len</span> = <span>strlen</span>(<span>$str</span>)-1<span>; 
</span><span> 8</span>        <span>//</span><span>文件名后追加4个随机字符  </span>
<span> 9</span>        <span>for</span>(<span>$i</span>=0 ; <span>$i</span>$suffix_length; <span>$i</span>++<span>){  
</span><span>10</span>           <span>$suffix</span> .= <span>$str</span>[<span>rand</span>(0,<span>$len</span><span>)];  
</span><span>11</span> <span>       }  
</span><span>12</span>        <span>$upload_filename</span> = <span>$_FILES</span>['file']['name'<span>];                                            
</span><span>13</span>        <span>$filename</span> = <span>substr</span>(<span>$upload_filename</span>,0,<span>strrpos</span>(<span>$upload_filename</span>,".")).<span>$suffix</span>.".".<span>substr</span>(<span>$upload_filename</span>,<span>strrpos</span>(<span>$_FILES</span>["file"]["name"],".")+1<span>); 
</span><span>14</span>    }<span>while</span>(<span>file_exists</span>("./upload/".<span>$filename</span><span>));  
</span><span>15</span>        <span>move_uploaded_file</span>(<span>$_FILES</span>["file"]["tmp_name"],"./upload/" . <span>$filename</span><span>);  
</span><span>16</span> }<span>else</span><span>{  
</span><span>17</span>        <span>move_uploaded_file</span>(<span>$_FILES</span>["file"]["tmp_name"], "upload/" . <span>$_FILES</span>["file"]["name"<span>]);   
</span><span>18</span> }  

5. Scenario 2: Upload files into directories based on date

<span>1</span> <span>$structure</span> = './'.<span>date</span>("Y").'/'.<span>date</span>("m").'/'.<span>date</span>("d").'/'<span>;
</span><span>2</span> 
<span>3</span> 
<span>4</span> <span>if</span> (!<span>mkdir</span>(<span>$structure</span>, 0777, <span>true</span><span>)) {
</span><span>5</span>     <span>die</span>('Failed to create folders...'<span>);
</span><span>6</span> <span>}
</span><span>7</span> 
<span>8</span> <span>move_uploaded_file</span>(<span>$_FILES</span>["file"]["tmp_name"],<span>$structure</span> . <span>$_FILES</span>["file"]["name"]);

6. Scenario 3: Multiple file upload

<span>1</span> <span><span>form </span><span>action</span><span>=""</span><span> method</span><span>="post"</span><span> enctype</span><span>="multipart/form-data"</span><span>></span>
<span>2</span> <span><span>p</span><span>></span><span>Pictures:
</span><span>3</span> <span><span>input </span><span>type</span><span>="file"</span><span> name</span><span>="pictures[]"</span> <span>/></span>
<span>4</span> <span><span>input </span><span>type</span><span>="file"</span><span> name</span><span>="pictures[]"</span> <span>/></span>
<span>5</span> <span><span>input </span><span>type</span><span>="file"</span><span> name</span><span>="pictures[]"</span> <span>/></span>
<span>6</span> <span><span>input </span><span>type</span><span>="submit"</span><span> value</span><span>="Send"</span> <span>/></span>
<span>7</span> <span></span><span>p</span><span>></span>
<span>8</span> <span></span><span>form</span><span>></span></span></span></span></span></span></span>

<span>1</span> <span>php
</span><span>2</span> <span>foreach</span> (<span>$_FILES</span>["pictures"]["error"] <span>as</span> <span>$key</span> => <span>$error</span><span>) {
</span><span>3</span>     <span>if</span> (<span>$error</span> ==<span> UPLOAD_ERR_OK) {
</span><span>4</span>         <span>$tmp_name</span> = <span>$_FILES</span>["pictures"]["tmp_name"][<span>$key</span><span>];
</span><span>5</span>         <span>$name</span> = <span>$_FILES</span>["pictures"]["name"][<span>$key</span><span>];
</span><span>6</span>         <span>move_uploaded_file</span>(<span>$tmp_name</span>, "data/<span>$name</span>"<span>);
</span><span>7</span> <span>    }
</span><span>8</span> <span>}
</span><span>9</span> ?>

In some cases, this variable structure for multiple files is not easy to use:

array(1) {

["upload"]=>array(2) {

...

                                                                                                                                                                                                                                          ​ & [1] = & gt; string (9) "file1.txt"

                                                                                ...

                                                                                                                                                                                                                              ​

                                                                                                                                                                                                                                   ​ 

                                                                               

}

}

In many cases what we need is a structure similar to this

array(1) {

["upload"]=>array(2) {

[0]=>array(2) {

"[" Name "] = & gt; string (9)" file0.txt "

                                                                                                                                                                                                                                         ​ },

[1]=>array(2) {

"[" Name "] = & gt; string (9)" file1.txt "

"[" Type "] = & gt; string (10)" text/html "

      }

}

}

Use the following function to easily convert the structure

<span>1</span> <span>function</span> diverse_array(<span>$vector</span><span>) { 
</span><span>2</span>     <span>$result</span> = <span>array</span><span>(); 
</span><span>3</span>     <span>foreach</span>(<span>$vector</span> <span>as</span> <span>$key1</span> => <span>$value1</span><span>) 
</span><span>4</span>         <span>foreach</span>(<span>$value1</span> <span>as</span> <span>$key2</span> => <span>$value2</span><span>) 
</span><span>5</span>             <span>$result</span>[<span>$key2</span>][<span>$key1</span>] = <span>$value2</span><span>; 
</span><span>6</span>     <span>return</span> <span>$result</span><span>; 
</span><span>7</span> <span>} 
</span><span>8</span> <span>$upload</span> = diverse_array(<span>$_FILES</span>["upload"]);

7.

Sometimes: you need to configure the server to modify the maximum upload file size

First, on the form

<span><span>input </span><span>type</span><span>="hidden"</span><span> name</span><span>="MAX_FILE_SIZE"</span><span> value</span><span>="字节"</span> <span>/></span></span>

Can limit upload file size (can be bypassed).

Then you also need to adjust the configuration on the server

php.ini:

max_execution_time = 30 每个脚本运行的最长时间，单位秒
max_input_time = 60，每个脚本可以消耗的时间，单位也是秒
memory_limit = 128M，这个是脚本运行最大消耗的内存
post_max_size = 8M，表单提交最大数据为 8M，此项不是限制上传单个文件的大小,而是针对整个表单的提交数据进行限制的。
upload_max_filesize = 2M ，上载文件的最大许可大小 

nginx:

<span>1</span> <span>location / {
</span><span>2</span>     root   html<span>;
</span><span>3</span>     index  index.html index.htm<span>;
</span><span>4     </span>client_max_body_size    1000m<span>;
</span><span>5</span>  }

以上就介绍了php上传文件常见问题(基础)，包括了方面的内容，希望对PHP教程有兴趣的朋友有所帮助。