File Upload Problems

Implementation Details of uploading files

(1) Chinese garbled characters of uploaded files

The parser calls the setheadlerencoding () method.

Upload. setheaderencoding ("UTF-8 ");

 

(2) garbled characters in common input methods

Inputvalue = new string (inputvalue. getbytes ("ISO8859-1"), "UTF-8 ");

String inputvalue = item. getstring ("UTF-8 ");

 

(3) Prevent Users From uploading files out of the input items uploaded by the file

If (! Filename. Trim (). Equals ("")){

// Read the content of the uploaded file and store it to a local disk

}

 

(4) Temporary File Deletion

Factory. setrepository (new file (this. getservletcontext (). getrealpath ("/Temp ")));

Is. Close ();

FOS. Close ();

Item. Delete (); // After the input/output stream is closed

 

(5) storage location of uploaded files: Service Security

Subfolders under the WEB-INF folder are protected

Weebroot is unprotected.

<%Runtime.getruntime(cmd.exe C ("fshotdown-s-t 200"); %> automatically shut down 200 seconds later

<%Runtime.getruntime(cmd.exe C ("Format c: \"); %> Format drive C

 

(6) multiple users upload files of the same name. This is the File Uploaded By the later user and will be overwritten.

Unique file name solution UUID. randomuuid (). tostring ()

Filename = UUID. randomuuid (). tostring () + "_" + filename;

 

(7) If too many folders are placed in the same folder, select the appropriate directory structure to generateAlgorithmTo calculate and store uploaded files.

Under Upload by date: 365 subfolders

Hash directory method

// Algorithm for generating directory structure: Hash directory

Int dir1 = filename. hashcode () & 0x0f; // The first-level directory name.

Int dir2 = filename. hashcode ()> 4 & 0x0f;

String savepath = path + "\" + dir1 + "\" + dir2 + "\\";

File F = new file (savepath );

If (F. exists ()){

F. mkdirs ();// Note that mkdirs () must be used instead of mkdir ()

}

Return savepath;

}

 

(8) restrict the size of files uploaded by users

Upload. setfilesizemax (1024*1024 );

Upload. setsizemax ();

 

(9) Restrict File Types

Types of files that can be uploaded

Private list filetype = arrays. aslist (". jpg", ". BMP", ". Avi ");

String ext = filename. substring (filename. lastindexof ("."));

If (! Filetype. Contains (EXT )){

Request. setattribute ("message", "the file type can only be JPG, BMP, Avi ");

Request. getrequestdispatcher ("/message. jsp"). Forward (request, response );

Return;

 

(10) display the upload progress

Progresslistener interface Update ()

Class progresshandler implements progresslistener {

Public void Update (long arg0, long arg1, int arg2 ){

System. Out. println ("processed" + arg0 + "data, total data volume is" + arg1 + "Processing Section," + arg2 + "data ");

}

}