PHP learning path PHP File Upload considerations and solutions ($ _ files, $ _ server, substr, strrpos, file_exists, move_uploaded_file, is_uploa

Problem:

① How to control the file types uploaded by users
② How to control the size of files uploaded by users
③ How to prevent users from overwriting Images
④ How to prevent conflicting file names uploaded by the same user
Answer:

① You can use the PHP Global Array $ _ FILES ['myfile'] ['type'] to determine the type of the uploaded file.

② You can use the PHP Global Array $ _ FILES ['myfile'] ['SIZE'] to determine the size of the uploaded file.

③ You can dynamically create folders based on the user name you enter.

③ Using time (), Rand (), the generated number to name the file can solve the file name conflict problem.

PHP codes:

 1 <? PHP
 2   Echo "<PRE> ";
 3   Print_r ( $ _ Files );
 4   Echo "<PRE> ";
 5   $ File_size = $ _ Files ['Myfile'] ['SIZE']; //  Get the file size  
 6   Echo "Current file size :". $ File_size . "B =". (INT) $ File_size /(1024). "kb <br> ";
 7   $ File_type = $ _ Files ['Myfile'] ['type'];
 8   //  How to control the file types uploaded by users  
  9   If ( $ File_type = 'Image/JPEG '| $ File_type = 'Image/pjpeg '){ //  Only JPG images can be uploaded.
  10   // How to control the size of uploaded files  
  11       If ( $ File_size > 2*1024*1024 ){
 12           Echo "The file size is limited to 2 MB ...";
 13   // Echo "<meta content = \" 3, http://www.baidu.com \ "http-equiv = \" Refresh \ "/>"; // page Jump  
  14           Exit ();
 15 }
 16       If ( Is_uploaded_file ( $ _ Files ['Myfile'] ['tmp _ name']) { //  Use the if statement to determine whether the object has been uploaded successfully  
  17          $ Move_from = $ _ Files ['Myfile'] ['tmp _ name'];
 18   //  How to Prevent Users From overwriting images ==> you can create folders based on the user name you enter  
  19           $ User_path = $ _ Server ['Document _ root']. "/upload /". $ _ Post ['Name']; //  Move the uploaded file to the desired directory.  
  20          If (! File_exists ( $ User_path )){ //  If this folder does not exist, create it. Next, move the image to this folder.  
  21               Mkdir ( $ User_path );
 22 } 
23  //  How to prevent conflict of file names uploaded by the same user 
 24          $ Suffix = Substr ( $ _ Files ['Myfile'] ['name'], Strrpos ( $ _ Files ['Myfile'] ['name'], '.'); //  Get File suffix  
  25           $ Move_to = $ User_path ."/". Time (). Rand (). $ Suffix ; //  Time (), Rand () can solve the file name conflict problem.  
  26           If ( Move_uploaded_file ( $ Move_from , Iconv ("UTF-8", "GBK ", $ Move_to ))){
 27           Echo "File Uploaded successfully! ";
 28           Echo "Path :".$ Move_to ;
 29   //  Echo "<meta content = \" 3, http://www.baidu.com \ "http-equiv = \" Refresh \ "/> ";  
  30 }
 31 } Else {
 32           Echo "File Upload Failed ...";
 33       // Echo "<meta content = \" 3, http://www.baidu.com \ "http-equiv = \" Refresh \ "/>"; // page Jump  
  34           Die ();
 35 }
 36 }
 37   Else {
 38       Echo "<SCRIPT> alert ('only images can be uploaded, and only images in JPG format are supported '); </SCRIPT> ";
 39   // Echo "<meta content = \" 3, http://www.baidu.com \ "http-equiv = \" Refresh \ "/>"; // page Jump  
  40       Die ();
 41 }
 42 ?>

Form:

 <  Form  Action  = "Upload. php"  Method  = "Post" Enctype  = "Multipart/form-Data"  > 
User name: <  Input  Name  = "Name"  Type  = "Text"  > 
File description: <  Textarea  Name  = "File_info"  > </ Textarea  > 
 <  Input  Type  = "File"  Name  = "Myfile"  /> 
 <  Input  Type  = "Submit"  Value  = "Upload"  /> 
</  Form  > 

Result:

File name before upload: 1.jpg

File name before upload:13222172242955. jpg

RelatedArticle: File Upload Functions

• Address: http://www.cnblogs.com/hongfei/articles/uploadfiles.html
• Reprinted please note