Package org.apache.commons.fileupload2.core

Class DiskFileItem

java.lang.Object
org.apache.commons.fileupload2.core.DiskFileItem
All Implemented Interfaces:
FileItem<DiskFileItem>, FileItemHeadersProvider<DiskFileItem>
public final class DiskFileItem extends Object implements FileItem<DiskFileItem>
The default implementation of the FileItem interface.

After retrieving an instance of this class from a DiskFileItemFactory instance (see org.apache.commons.fileupload2.core.servlet.ServletFileUpload #parseRequest(javax.servlet.http.HttpServletRequest)), you may either request all contents of file at once using get() or request an InputStream with getInputStream() and process the file without attempting to load it into memory, which may come handy with large files.

Temporary files, which are created for file items, should be deleted later on. The best way to do this is using a FileCleaningTracker, which you can set on the DiskFileItemFactory. However, if you do use such a tracker, then you must consider the following: Temporary files are automatically deleted as soon as they are no longer needed. (More precisely, when the corresponding instance of File is garbage collected.) This is done by the so-called reaper thread, which is started and stopped automatically by the FileCleaningTracker when there are files to be tracked. It might make sense to terminate that thread, for example, if your web application ends. See the section on "Resource cleanup" in the users guide of Commons FileUpload.

  • Field Details

    • DEFAULT_CHARSET

      public static final Charset DEFAULT_CHARSET
      Default content charset to be used when no explicit charset parameter is provided by the sender. Media subtypes of the "text" type are defined to have a default charset value of "ISO-8859-1" when received via HTTP.

    • UID

      private static final String UID
      UID used in unique file name generation.

    • COUNTER

      private static final AtomicInteger COUNTER
      Counter used in unique identifier generation.

    • fieldName

      private String fieldName
      The name of the form field as provided by the browser.

    • contentType

      private final String contentType
      The content type passed by the browser, or null if not defined.

    • isFormField

      private boolean isFormField
      Whether or not this item is a simple form field.

    • fileName

      private final String fileName
      The original file name in the user's file system.

    • size

      private long size
      The size of the item, in bytes. This is used to cache the size when a file item is moved from its original location.

    • threshold

      private final int threshold
      The threshold above which uploads will be stored on disk.

    • repository

      private final Path repository
      The directory in which uploaded files will be stored, if stored on disk.

    • cachedContent

      private byte[] cachedContent
      Cached contents of the file.

    • dfos

      private org.apache.commons.io.output.DeferredFileOutputStream dfos
      Output stream for this item.

    • tempFile

      private final Path tempFile
      The temporary file to use.

    • fileItemHeaders

      private FileItemHeaders fileItemHeaders
      The file items headers.

    • charsetDefault

      private Charset charsetDefault
      Default content Charset to be used when no explicit Charset parameter is provided by the sender.

  • Constructor Details

    • DiskFileItem

      private DiskFileItem(String fieldName, String contentType, boolean isFormField, String fileName, int threshold, Path repository, FileItemHeaders fileItemHeaders, Charset defaultCharset)
      Constructs a new DiskFileItem instance.
      Parameters:
      fieldName - The name of the form field.
      contentType - The content type passed by the browser or null if not specified.
      isFormField - Whether or not this item is a plain form field, as opposed to a file upload.
      fileName - The original file name in the user's file system, or null if not specified.
      threshold - The threshold, in bytes, below which items will be retained in memory and above which they will be stored as a file.
      repository - The data repository, which is the directory in which files will be created, should the item size exceed the threshold.
      fileItemHeaders - The file item headers.
      defaultCharset - The default Charset.

  • Method Details

    • builder

      public static DiskFileItem.Builder builder()
      Constructs a new DiskFileItem.Builder.
      Returns:
      a new DiskFileItem.Builder.

    • checkFileName

      public static String checkFileName(String fileName)
      Tests if the file name is valid. For example, if it contains a NUL characters, it's invalid. If the file name is valid, it will be returned without any modifications. Otherwise, throw an InvalidPathException.
      Parameters:
      fileName - The file name to check
      Returns:
      Unmodified file name, if valid.
      Throws:
      InvalidPathException - The file name is invalid.

    • getUniqueId

      private static String getUniqueId()
      Gets an identifier that is unique within the class loader used to load this class, but does not have random-like appearance.
      Returns:
      A String with the non-random looking instance identifier.

    • delete

      public DiskFileItem delete() throws IOException
      Deletes the underlying storage for a file item, including deleting any associated temporary disk file. This method can be used to ensure that this is done at an earlier time, thus preserving system resources.
      Specified by:
      delete in interface FileItem<DiskFileItem>
      Returns:
      this
      Throws:
      IOException - if an error occurs.

    • get

      public byte[] get() throws UncheckedIOException
      Gets the contents of the file as an array of bytes. If the contents of the file were not yet cached in memory, they will be loaded from the disk storage and cached.
      Specified by:
      get in interface FileItem<DiskFileItem>
      Returns:
      The contents of the file as an array of bytes or null if the data cannot be read.
      Throws:
      UncheckedIOException - if an I/O error occurs.
      OutOfMemoryError - See Files.readAllBytes(Path): If an array of the required size cannot be allocated, for example the file is larger that 2GB

    • getCharset

      public Charset getCharset()
      Gets the content charset passed by the agent or null if not defined.
      Returns:
      The content charset passed by the agent or null if not defined.

    • getCharsetDefault

      public Charset getCharsetDefault()
      Gets the default charset for use when no explicit charset parameter is provided by the sender.
      Returns:
      the default charset

    • getContentType

      public String getContentType()
      Gets the content type passed by the agent or null if not defined.
      Specified by:
      getContentType in interface FileItem<DiskFileItem>
      Returns:
      The content type passed by the agent or null if not defined.

    • getFieldName

      public String getFieldName()
      Gets the name of the field in the multipart form corresponding to this file item.
      Specified by:
      getFieldName in interface FileItem<DiskFileItem>
      Returns:
      The name of the form field.
      See Also:

    • getHeaders

      public FileItemHeaders getHeaders()
      Gets the file item headers.
      Specified by:
      getHeaders in interface FileItemHeadersProvider<DiskFileItem>
      Returns:
      The file items headers.

    • getInputStream

      public InputStream getInputStream() throws IOException
      Gets an InputStream that can be used to retrieve the contents of the file.
      Specified by:
      getInputStream in interface FileItem<DiskFileItem>
      Returns:
      An InputStream that can be used to retrieve the contents of the file.
      Throws:
      IOException - if an error occurs.

    • getName

      public String getName()
      Gets the original file name in the client's file system.
      Specified by:
      getName in interface FileItem<DiskFileItem>
      Returns:
      The original file name in the client's file system.
      Throws:
      InvalidPathException - The file name contains a NUL character, which might be an indicator of a security attack. If you intend to use the file name anyways, catch the exception and use InvalidPathException.getInput().

    • getOutputStream

      public OutputStream getOutputStream()
      Gets an OutputStream that can be used for storing the contents of the file.
      Specified by:
      getOutputStream in interface FileItem<DiskFileItem>
      Returns:
      An OutputStream that can be used for storing the contents of the file.

    • getPath

      public Path getPath()
      Gets the Path for the FileItem's data's temporary location on the disk. Note that for FileItems that have their data stored in memory, this method will return null. When handling large files, you can use Files.move(Path,Path,CopyOption...) to move the file to new location without copying the data, if the source and destination locations reside within the same logical volume.
      Returns:
      The data file, or null if the data is stored in memory.

    • getSize

      public long getSize()
      Gets the size of the file.
      Specified by:
      getSize in interface FileItem<DiskFileItem>
      Returns:
      The size of the file, in bytes.

    • getString

      public String getString()
      Gets the contents of the file as a String, using the default character encoding. This method uses get() to retrieve the contents of the file.

      TODO Consider making this method throw UnsupportedEncodingException.

      Specified by:
      getString in interface FileItem<DiskFileItem>
      Returns:
      The contents of the file, as a string.

    • getString

      public String getString(Charset charset) throws IOException
      Gets the contents of the file as a String, using the specified encoding. This method uses get() to retrieve the contents of the file.
      Specified by:
      getString in interface FileItem<DiskFileItem>
      Parameters:
      charset - The charset to use.
      Returns:
      The contents of the file, as a string.
      Throws:
      IOException - if an I/O error occurs

    • getTempFile

      protected Path getTempFile()
      Creates and returns a File representing a uniquely named temporary file in the configured repository path. The lifetime of the file is tied to the lifetime of the FileItem instance; the file will be deleted when the instance is garbage collected.

      Note: Subclasses that override this method must ensure that they return the same File each time.

      Returns:
      The File to be used for temporary storage.

    • isFormField

      public boolean isFormField()
      Tests whether or not a FileItem instance represents a simple form field.
      Specified by:
      isFormField in interface FileItem<DiskFileItem>
      Returns:
      true if the instance represents a simple form field; false if it represents an uploaded file.
      See Also:

    • isInMemory

      public boolean isInMemory()
      Provides a hint as to whether or not the file contents will be read from memory.
      Specified by:
      isInMemory in interface FileItem<DiskFileItem>
      Returns:
      true if the file contents will be read from memory; false otherwise.

    • setCharsetDefault

      public DiskFileItem setCharsetDefault(Charset charset)
      Sets the default charset for use when no explicit charset parameter is provided by the sender.
      Parameters:
      charset - the default charset
      Returns:
      this

    • setFieldName

      public DiskFileItem setFieldName(String fieldName)
      Sets the field name used to reference this file item.
      Specified by:
      setFieldName in interface FileItem<DiskFileItem>
      Parameters:
      fieldName - The name of the form field.
      Returns:
      this
      See Also:

    • setFormField

      public DiskFileItem setFormField(boolean state)
      Specifies whether or not a FileItem instance represents a simple form field.
      Specified by:
      setFormField in interface FileItem<DiskFileItem>
      Parameters:
      state - true if the instance represents a simple form field; false if it represents an uploaded file.
      Returns:
      this
      See Also:

    • setHeaders

      public DiskFileItem setHeaders(FileItemHeaders headers)
      Sets the file item headers.
      Specified by:
      setHeaders in interface FileItemHeadersProvider<DiskFileItem>
      Parameters:
      headers - The file items headers.
      Returns:
      this

    • toString

      public String toString()
      Returns a string representation of this object.
      Overrides:
      toString in class Object
      Returns:
      a string representation of this object.

    • write

      public DiskFileItem write(Path file) throws IOException
      Writes an uploaded item to disk.

      The client code is not concerned with whether or not the item is stored in memory, or on disk in a temporary location. They just want to write the uploaded item to a file.

      This implementation first attempts to rename the uploaded item to the specified destination file, if the item was originally written to disk. Otherwise, the data will be copied to the specified file.

      This method is only guaranteed to work once, the first time it is invoked for a particular item. This is because, in the event that the method renames a temporary file, that file will no longer be available to copy or rename again at a later time.

      Specified by:
      write in interface FileItem<DiskFileItem>
      Parameters:
      file - The File into which the uploaded item should be stored.
      Returns:
      this
      Throws:
      IOException - if an error occurs.