Detailed explanation of the usage of PHP file upload code_PHP tutorial

This article is an article suitable for PHP beginners to tell you how to edit the PHP file upload code. Before editing, we need to understand a few points and understand the FILES global variable. There are friends who need to learn PHP file upload. You can refer to this article.

php file upload code writing process

1. First determine whether to upload the file
2. If there is any error, please check again to see if there is an error in the upload
3. If an error occurs, an error message will be prompted
4. If there are no errors, then determine the file type
5. If the type meets the conditions, then determine whether the file exists in the specified directory
6. If not, move the file to the specified directory

Some things you must know when uploading files in php

$_FILES['myfile']['name'] refers to the name of the uploaded file
$_FILES['myfile']['type'] refers to the type of file being uploaded
$_FILES['myfile']['size'] refers to the size of the uploaded file, in bytes (B)
$_FILES['myfile']['tmp_name'] refers to the name of the temporary copy file of the uploaded file stored in the server. After the file is moved to the specified directory, the temporary file will be automatically destroyed.
$_FILES['myfile']["error"] refers to the status code of errors that may occur during file upload. The meaning of each status will be explained later.

Let’s take a look at the HTML part first.

The code is as follows

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? 上传：

?

Upload:

Description:

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if($_FILES['myfile']['name'] != '') { 　　if($_FILES['myfile']['error'] > 0) { 　　　　echo "错误状态：" . $_FILES['myfile']['error']; 　　} else { 　　　　move_uploaded_file($_FILES['myfile']['tmp_name'] , "uploads/" . $FILES['myfile']['name']); 　　　　echo "<script>alert(上传成功！);</script>"; 　　} } else{ 　　echo "<script>alert(请上传文件！);</script>"; } ?>

The action="upload.php" in the form tag means that when you click submit in this form, the upload command will be sent to the page called upload.php for processing. method="post" refers to sending in post mode. The enctype="multipart/form-data" attribute specifies which content type to use when submitting this form. When the form requires binary data, such as file content, please use "multipart/form-data", this attribute is necessary if you want to upload files. Type="file" in input specifies that the input should be processed as a file, and there will be a browse button behind the input. Let’s look at a PHP processing page upload.php

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if($_FILES['myfile']['name'] != '') { ​if($_FILES['myfile']['error'] > 0) { echo "Error status:" . $_FILES['myfile']['error']; } else { 　　move_uploaded_file($_FILES['myfile']['tmp_name'] , "uploads/" . $FILES['myfile']['name']); echo "<script>alert(Upload successful!);</script>"; } } else{ echo "<script>alert(Please upload files!);</script>"; } ?>

The above is super simple, let’s upgrade it now

1. upload.php

                                                                                                                                               

The code is as follows

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 代码如下

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请填写用户名
请简单介绍文件
请上传你的文件

   

 

                                                                                                                                                                                                                         When uploading files, please note: 1. Enctyp is required, 2. method = " post " -- >

                                                                                        & Lt; TR & gt; & lt; td & gt; please fill in the username & lt;/td & lt; & lt; & lt; input type = "text" name = "username" & lt;/td & gt; & lt;/tr & gt;

Please briefly introduce the file

< ;/textarea>

Please upload your file

2. uploadProcess.php

//Receive $username=$_POST['username'];

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//接收     $username=$_POST['username'];     $fileintro=$_POST['fileintro'];         //echo $username.$fileintro;     //获取文件信息 /*    echo " ";<br>     print_r($_FILES);<br>     echo " "; */        //获取文件的大小     $file_size=$_FILES['myfile']['size'];     if($file_size>2*1024*1024){         echo "";         exit();     }     //获取文件类型     $file_type=$_FILES['myfile']['type'];     if($file_type!="image/jpeg" && $file_type!="image/pjpeg"){         echo "文件类型只能是 jpg 格式";         exit();     }         //判断上传是否OK     if(is_uploaded_file($_FILES['myfile']['tmp_name'])){         //得到上传的文件 转存到你希望的目录         $upload_file=$_FILES['myfile']['tmp_name'];                 //防止图片覆盖问题，为每个用户建立一个文件夹            $user_path=$_SERVER['DOCUMENT_ROOT']."/file/up/".$username;         if(!file_exists($user_path)){             mkdir ($user_path);         }         //$move_to_file=$user_path."/".$_FILES['myfile']['name'];         //防止用户上传用户名相同的问题         $file_true_name=$_FILES['myfile']['name'];         $move_to_file=$user_path."/".time().rand(1,1000).substr($file_true_name,strripos($file_true_name,"."));         //echo $upload_file.$move_to_file;         //中文要转码         if(move_uploaded_file($upload_file,iconv("utf-8","gb2312","$move_to_file"))){             echo $_FILES['myfile']['name']."上传成功";         }else{             echo "上传失败";         }     }else{         echo "上传失败";     } ?>

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$fileintro=$_POST['fileintro'];   //echo $username.$fileintro; //Get file information /* echo "

";
Print_r($_FILES);
echo "

"; */  //Get the file size $file_size=$_FILES['myfile']['size']; If($file_size>2*1024*1024){             echo ""; exit(); } //Get file type $file_type=$_FILES['myfile']['type']; If($file_type!="image/jpeg" && $file_type!="image/pjpeg"){ echo "The file type can only be jpg format"; exit(); }   //Determine whether the upload is OK If(is_uploaded_file($_FILES['myfile']['tmp_name'])){ //Get the uploaded file and transfer it to the directory you want           $upload_file=$_FILES['myfile']['tmp_name'];                               //To prevent image overwriting problems, create a folder for each user          $user_path=$_SERVER['DOCUMENT_ROOT']."/file/up/".$username; If(!file_exists($user_path)){                mkdir ($user_path); } //$move_to_file=$user_path."/".$_FILES['myfile']['name']; //Prevent users from uploading the same username           $file_true_name=$_FILES['myfile']['name'];           $move_to_file=$user_path."/".time().rand(1,1000).substr($file_true_name,strripos($file_true_name,".")); //echo $upload_file.$move_to_file; //Chinese needs to be transcoded If(move_uploaded_file($upload_file,iconv("utf-8","gb2312","$move_to_file"))){ echo $_FILES['myfile']['name']."Upload successful";          }else{                    echo "Upload failed"; } }else{             echo "Upload failed"; } ?> Note: Let me give you an example, and everyone knows, for example, a picture file pic.jpg, we use strrchr to process it, strrchr(pic.jpg,'.'), it will return .jpg, do you understand? This function returns the character following the last occurrence of the specified character in the string. With substr(), we can get jpg, so that we can get the file extension to determine whether the uploaded file conforms to the specified format. This program puts the specified format in an array, which can be added as needed during actual use. Next, look at the file name that generates random numbers. We see the mt_srand() function. The manual calls it "sowing a better random number generator seed". In fact, it is a function that initializes a random number. The parameter is (double )microtime() * 1000000, if this is not a parameter here, a random number will be automatically set. Of course, this does not meet our needs. In this way, the random number will have a certain length, ensuring that the uploaded file does not have the same name

http://www.bkjia.com/PHPjc/628774.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/628774.htmlTechArticleThis article is an article suitable for PHP beginners to tell you how to edit the PHP file upload code before editing. We need to understand a few points, and if we have an understanding of the FILES global variable, we need to learn...