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#PHP image file upload type limit, extension limit, size limit and automatic detection of directory creation.
The code is divided into two parts:
Part form form: (Recommended learning: PHP video tutorial)
<!doctype html><br/><html><br/><head><br/><title>文件上传案例-file upload example</title><br/><meta http-equiv="content-type" contnet="text/html" charset="utf-8"/><br/></head><br/><body><br/><h1>文件上传支持图片.gif.png.jpg.jpeg限制200kb大小的文件</h1><br/><form method="POST" action="upload_file.php" enctype="multipart/form-data"><br/><lable for="file">File:</lable><br/><input name="file" type="file" id="file"/><br/><br/><input type="submit" value="上传文件"/><br/></form><br/></body><br/></html><br/>
two Part of the PHP background upload verification program:
<meta charset="utf-8"/><br/><?php<br/>$array=array("gif","png","jpg","jpeg");//赋值一个数组<br/>$tmp=explode(".",$_FILES['file']['name']);//用explode()函数把字符串打散成为数组。<br/>$extension=end($tmp);//用end获取数组最后一个元素<br/>if($_FILES['file']['error']>0){//判断提交上的文件是否为空或错误<br/> echo "文件未选择，或非法文件！错误：".$_FILES['file']['error'];<br/>}else{<br/> if((($_FILES['file']['type']=="image/gif")//判断提交上的文件的文件类型是否正确和文件扩展名是否正确，文件大小是否超2048kb。<br/> ||($_FILES['file']['type']=="image/png")<br/> ||($_FILES['file']['type']=="image/jpeg")<br/> ||($_FILES['file']['type']=="image/jpg")<br/> ||($_FILES['file']['type']=="image/pjpeg")<br/> ||($_FILES['file']['type']=="image/x-png"))<br/> &&($_FILES['file']['size']<204800)<br/> &&in_array($extension,$array)){<br/> echo "文件大小和文件扩展名验成功！<br/>";<br/> if(file_exists("upload/")){//用file_exists函数检测是否有upload目录，用if判断。<br/> if(file_exists("upload/".$_FILES['file']['name'])){//用file_exists函数检测是否在upload目录下有['name']文件。用if判断。<br/> echo "已存在该文件名！位置：upload/".$_FILES['file']['name'];<br/> }else{//显示各个信息，然后用move_upload_file函数把临时目录文件移动到upload目录。<br/> echo "上传完成，下面是信息：<br/>";<br/> echo "上传文件名：".$_FILES['file']['name']."<br/>";<br/> echo "上传类型：".$_FILES['file']['type']."<br/>";<br/> echo "上传文件大小：".$_FILES['file']['size']."<br/>";<br/> echo "上传文件临时缓存位置：".$_FILES['file']['tmp_name']."<br/>";<br/> move_uploaded_file($_FILES['file']['tmp_name'],"upload/".$_FILES['file']['name']);//这里我们用到两个参数，一是被移到的文件，二是移动到的目标位置。<br/> echo "储存服务器相对的位置为：/upload/".$_FILES['file']['name'];<br/> }<br/> }else{//没有目录的情况下，使用mkdir函数创建upload目录。<br/> echo "不存在upload目录，已自动创建upload/目录";<br/> mkdir("upload");<br/> }<br/> }else{<br/> echo "扩展名和文件大小不正确，扩展名支持gif，jpg，png，jpeg，文件大小支持200kb";<br/> }<br/> //echo "文件临时储存的位置：".$_FILES['file']['tmp_name'];//把文件获取到临时储存的位置里面，并打印出来;<br/> //move_uploaded_file($_FILES['file']['tmp_name'],"upload/".$_FILES['file']['name']);//把临时储存的文件移到upload目录下。<br/>}<br/>?><br/>The background PHP program passes four if judgments to determine the uploaded file four times:
The first if judgment is the uploaded file Whether it is an empty submission or whether there is an error.
The second if determines whether the uploaded file type is correct, whether the extension matches, and whether the size is reasonable.
The third if determines whether the directory to which the uploaded file belongs exists. If it does not exist, the system will automatically create an upload directory using the mkdir function;
The fourth if determines Whether the uploaded file already exists. If it does, it will prompt and stop uploading. On the contrary, if it does not exist, the upload operation will be performed;
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