The implementation principle of PHP upload and download
First, the user submits the file to the PHP server, and PHP will automatically temporarily store the file; Then the business code saves the file to the server and returns the file access address; finally, the front end accesses and downloads the file based on the access address.
File upload example
HTML：
<html>
<head>
<title>简单文件上传</title>
</head>
<body>
<form action="./upload_file.php" method="POST" enctype="multipart/form-data">
<label for="file">文件:</label>
<input type="file" name="myfile" id="file">
<button type="submit">上传文件</button>
</form>
</body>
</html>PHP：
<?php
header("content-type:text/html;charset=utf-8");
//获取文件配置信息
$myfile = $_FILES["myfile"]["name"];
//临时目录
$tmp = $_FILES['myfile']['tmp_name'];
//文件大小
$size = $_FILES['myfile']['size'];
//文件类型
$type = $_FILES['myfile']['type'];
//文件上传
$error = $_FILES['myfile']['error'];
if($_FILES["myfile"]["error"] > 0){
echo "错误信息".$_FILES["myfile"]["error"];
} else {
echo $myfile.'<br>';
echo $tmp.'<br>';
echo $size/1024 .'KB<br>';
echo $type.'<br>';
echo $error.'<br>';
}
if(file_exists("./".$_FILES["myfile"]["name"])){
echo $_FILES["myfile"]["name"] . " 文件存在";
} else {
move_uploaded_file($_FILES['myfile']['tmp_name'],"./". $_FILES["myfile"]["name"]);
echo "文件位置："."./". $_FILES["myfile"]["name"];
}Recommended tutorial:《PHP Tutorial》
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