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How to write php file upload code

angryTomOriginal: 2019-10-26 16:29:323115browse

How to write the php file upload code

When we first learned php, we couldn’t understand the php file upload code , as well as the upload logic, the following code is written from a beginner's perspective, I hope it will be helpful to everyone!

Required knowledge:

Super global array: the value of $_FILES

$_FILES['myfile']['name'] Is: The file name of the client file system

$_FILES['myfile']['type'] The value is: The file type passed by the client

$_FILES['myfile'] The value of ['size'] is: the byte size of the file

The value of $_FILES['myflie']['tmp_name '] is: the temporary full path stored on the server after the file is uploaded

The value of

$_FILES['myfile']['error'] is: the error code of file upload

The value stored in $_FILES['myfile']['error']

A value of 0: indicates that no error occurred.

A value of 1: indicates that the size of the uploaded file exceeds the agreed value. The maximum file size is specified in the PHP configuration file. The instruction is: upload_max_filesize

The value is 2: Indicates that the uploaded file size exceeds the maximum value specified by the MAX_FILE_SIZE element of the HTML form hidden field attribute

A value of 3: Indicates that the file was only partially uploaded

A value of 4: Indicates that no files were uploaded

A value of 6: Indicates that the temporary folder cannot be found

The value is 7: Indicates that the file writing failed.

The error value corresponds to the constant

UPLOAD_ERR_OK: The corresponding value is 0

UPLOAD_ERR_INI_SIZE: The corresponding value is 1

UPLOAD_ERR_FORM_SIZE: Corresponding value 2

UPLOAD_ERR_PARTIAL: Corresponding value 3

UPLOAD_ERR_NO_FILE: Corresponding value 4

UPLOAD_ERR_NO_TMP_DIR: Corresponding value 6

UPLOAD_ERR_CANT_WRITE: Corresponding Value 7

upload.html The code is as follows

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>图片上传</title>
</head>
<body>
    <form action="upload.php" method="post" enctype="multipart/form-data">
        <input type="file"  name="pic"/>
        <!--通过表单限制上传文件的大小 一定要在上传按钮前 大小以字节为主-->
        <input type="hidden" name="MAX_FILE_SIZE"  value="8388608"/>
        <input type="submit" name="sub" value="上传" />
    </form>
</body>
</html>

upload.php The code is as follows

<?php
//var_dump($_FILES);
//exit;
//判断是否是文件上传
$file = $_FILES;
//第一个pic 是input 中的name值
if(is_uploaded_file($file[&#39;pic&#39;][&#39;tmp_name&#39;]))
{
    //声明允许上传的文件类型
    $allowType = [&#39;image/png&#39;,&#39;image/jpeg&#39;,&#39;image/gif&#39;,&#39;image/jpg&#39;];
    //正在上传的文件的类型
    $type = $file[&#39;pic&#39;][&#39;type&#39;];
//    echo $type;
    //判断类型是否是允许的类型
    if(!in_array($type,$allowType))//检查数组中是否存在某个值，返回布尔型
    {
       exit(&#39;上传类型有误&#39;);
    }
    //判断文件上传的大小
    if($file[&#39;pic&#39;][&#39;size&#39;] > 1024 * 1024 * 8) //以字节为主 1024*1024是1M
    {
        exit(&#39;上传的文件太大&#39;);
    }
    //设置新文件名
    $filename = date(&#39;YmdHis&#39;,strtotime(&#39;now&#39;)).rand(1000,9999);
    //获取上传文件的后缀名
    $name = $file[&#39;pic&#39;][&#39;name&#39;];
    //得到文件名字符串
    $filestr      = explode(&#39;.&#39;,$name);
    $ext = array_pop($filestr);
    //拼接新文件名
    $newfilename = $filename.&#39;.&#39;.$ext;
    //拼接上传文件的路径
    $path = &#39;./uploads/&#39;;
    //绝对路径
    $abspath = $path.$newfilename;
    if(move_uploaded_file($file[&#39;pic&#39;][&#39;tmp_name&#39;],$abspath))
    {
        echo &#39;上传成功&#39;;
    }else{
        echo &#39;上传失败&#39;;
    }
}

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