org.apache.tomcat.util.http.fileupload (Apache Tomcat 9.0.71 API Documentation)

# Package org.apache.tomcat.util.http.fileupload

NOTE: This code has been copied from commons-fileupload trunk 1.3 and commons-io 1.4 and package renamed to avoid clashes with any web apps that may wish to use these libraries.

A component for handling HTML file uploads as specified by RFC 1867. This component provides support for uploads within both servlets (JSR 53) and portlets (JSR 168).

While this package provides the generic functionality for file uploads, these classes are not typically used directly. Instead, normal usage involves one of the provided extensions of `FileUpload` such as `ServletFileUpload` together with a factory for `FileItem` instances, such as `DiskFileItemFactory`.

The following is a brief example of typical usage in a servlet, storing the uploaded files on disk.

    public void doPost(HttpServletRequest req, HttpServletResponse res) {
       DiskFileItemFactory factory = new DiskFileItemFactory();
       // maximum size that will be stored in memory
       factory.setSizeThreshold(4096);
       // the location for saving data that is larger than getSizeThreshold()
       factory.setRepository(new File("/tmp"));

       ServletFileUpload upload = new ServletFileUpload(factory);
       // maximum size before a FileUploadException will be thrown
       upload.setSizeMax(1000000);

       List fileItems = upload.parseRequest(req);
       // assume we know there are two files. The first file is a small
       // text file, the second is unknown and is written to a file on
       // the server
       Iterator i = fileItems.iterator();
       String comment = ((FileItem)i.next()).getString();
       FileItem fi = (FileItem)i.next();
       // file name on the client
       String fileName = fi.getName();
       // save comment and file name to database
       ...
       // write the file
       fi.write(new File("/www/uploads/", fileName));
     }

In the example above, the first file is loaded into memory as a `String`. Before calling the `getString` method, the data may have been in memory or on disk depending on its size. The second file we assume it will be large and therefore never explicitly load it into memory, though if it is less than 4096 bytes it will be in memory before it is written to its final location. When writing to the final location, if the data is larger than the threshold, an attempt is made to rename the temporary file to the given location. If it cannot be renamed, it is streamed to the new location.

Please see the FileUpload User Guide for further details and examples of how to use this package.

- Interface Summary
  Interface | Description
  --- | ---
  FileItem | This class represents a file or form item that was received within a `multipart/form-data` POST request.
  FileItemFactory | A factory interface for creating `FileItem` instances.
  FileItemHeaders | This class provides support for accessing the headers for a file or form item that was received within a `multipart/form-data` POST request.
  FileItemHeadersSupport | Interface that will indicate that `FileItem` or `FileItemStream` implementations will accept the headers read for the item.
  FileItemIterator | An iterator, as returned by `FileUploadBase.getItemIterator(RequestContext)`.
  FileItemStream | This interface provides access to a file or form item that was received within a `multipart/form-data` POST request.
  ProgressListener | The `ProgressListener` may be used to display a progress bar or do stuff like that.
  RequestContext | Abstracts access to the request information needed for file uploads.
  UploadContext | Enhanced access to the request information needed for file uploads, which fixes the Content Length data access in `RequestContext`.

- Class Summary
  Class | Description
  --- | ---
  ByteArrayOutputStream | This class implements an output stream in which the data is written into a byte array.
  DeferredFileOutputStream | An output stream which will retain data in memory until a specified threshold is reached, and only then commit it to disk.
  FileUpload | High level API for processing file uploads.
  FileUploadBase | High level API for processing file uploads.
  FileUtils | General file manipulation utilities.
  IOUtils | General IO stream manipulation utilities.
  MultipartStream | Low level API for processing file uploads.
  MultipartStream.ProgressNotifier | Internal class, which is used to invoke the `ProgressListener`.
  ParameterParser | A simple parser intended to parse sequences of name/value pairs.
  ThresholdingOutputStream | An output stream which triggers an event when a specified number of bytes of data have been written to it.

- Exception Summary
  Exception | Description
  --- | ---
  FileItemStream.ItemSkippedException | This exception is thrown, if an attempt is made to read data from the `InputStream`, which has been returned by `FileItemStream.openStream()`, after `Iterator.hasNext()` has been invoked on the iterator, which created the `FileItemStream`.
  FileUploadException | Exception for errors encountered while processing the request.
  InvalidFileNameException | This exception is thrown in case of an invalid file name.
  MultipartStream.IllegalBoundaryException | Thrown upon attempt of setting an invalid boundary token.
  MultipartStream.MalformedStreamException | Thrown to indicate that the input stream fails to follow the required syntax.