Package org.apache.commons.fileupload2.core

Class DiskFileItem

  • All Implemented Interfaces:
    FileItem<DiskFileItem>, FileItemHeadersProvider<DiskFileItem>
    public final class DiskFileItem
extends java.lang.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.

    State model: Instances of DiskFileItem are subject to a carefully designed state model. Depending on the so-called threshold, either of the three models are possible:

    1. threshold = -1 Uploaded data is never kept in memory. Instead, a temporary file is being created immediately. isInMemory() will always return false, getPath() will always return the path of an existing file. The temporary file may be empty.
    2. threshold = 0 Uploaded data is never kept in memory. (Same as threshold=-1.) However, the temporary file is only created, if data was uploaded. Or, in other words: The uploaded file will never be empty. isInMemory() will return true, if no data was uploaded, otherwise it will be false. In the former case getPath() will return null, but in the latter case it returns the path of an existing, non-empty file.
    3. threshold > 0 Uploaded data will be kept in memory, if the size is below the threshold. If the size is equal to, or above the threshold, then a temporary file has been created, and all uploaded data has been transferred to that file. isInMemory() returns true, if the size of the uploaded data is below the threshold. If so, getPath() returns null. Otherwise, isInMemory() returns false, and getPath() returns the path of an existing, temporary file. The size of the temporary file is equal to, or above the threshold.

    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 Summary

      Fields 
      Modifier and Type Field Description
      static java.nio.charset.Charset DEFAULT_CHARSET
      Default content charset to be used when no explicit charset parameter is provided by the sender.

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods Deprecated Methods 
      Modifier and Type Method Description
      static DiskFileItem.Builder builder()
      Constructs a new DiskFileItem.Builder.
      static java.lang.String checkFileName​(java.lang.String fileName)
      Tests if the file name is valid.
      DiskFileItem delete()
      Deletes the underlying storage for a file item, including deleting any associated temporary disk file.
      byte[] get()
      Deprecated.
      Since 2.0.0, use getInputStream(), or getReader(), instead.
      java.nio.charset.Charset getCharset()
      Gets the content charset passed by the agent or null if not defined.
      java.nio.charset.Charset getCharsetDefault()
      Gets the default charset for use when no explicit charset parameter is provided by the sender.
      java.lang.String getContentType()
      Gets the content type passed by the agent or null if not defined.
      java.lang.String getFieldName()
      Gets the name of the field in the multipart form corresponding to this file item.
      org.apache.commons.io.FileCleaningTracker getFileCleaningTracker()
      Returns the FileCleaningTracker, which is being used to remove temporary files.
      FileItemHeaders getHeaders()
      Gets the file item headers.
      java.io.InputStream getInputStream()
      Gets an InputStream that can be used to retrieve the contents of the file.
      java.lang.String getName()
      Gets the original file name in the client's file system.
      java.io.OutputStream getOutputStream()
      Gets an OutputStream that can be used for storing the contents of the file.
      java.nio.file.Path getPath()
      Gets the Path for the FileItem's data's temporary location on the disk.
      java.io.Reader getReader()
      Returns the contents of the file as a Reader, using the specified getCharset().
      long getSize()
      Gets the size of the file.
      java.lang.String getString()
      Deprecated.
      Since 2.0.0, use getReader() instead.
      java.lang.String getString​(java.nio.charset.Charset charset)
      Gets the contents of the file as a String, using the specified encoding.
      int getThreshold()
      Returns the file items threshold.
      boolean isFormField()
      Tests whether or not a FileItem instance represents a simple form field.
      boolean isInMemory()
      Provides a hint as to whether or not the file contents will be read from memory.
      DiskFileItem setCharsetDefault​(java.nio.charset.Charset charset)
      Sets the default charset for use when no explicit charset parameter is provided by the sender.
      DiskFileItem setFieldName​(java.lang.String fieldName)
      Sets the field name used to reference this file item.
      void setFileCleaningTracker​(org.apache.commons.io.FileCleaningTracker fileCleaningTracker)
      Sets the FileCleaningTracker, which is being used to remove temporary files.
      DiskFileItem setFormField​(boolean state)
      Specifies whether or not a FileItem instance represents a simple form field.
      DiskFileItem setHeaders​(FileItemHeaders headers)
      Sets the file item headers.
      java.lang.String toString()
      Returns a string representation of this object.
      DiskFileItem write​(java.nio.file.Path file)
      Writes an uploaded item to disk.

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

    • Field Detail

      • DEFAULT_CHARSET

        public static final java.nio.charset.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.

    • Method Detail

      • checkFileName

        public static java.lang.String checkFileName​(java.lang.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:
        java.nio.file.InvalidPathException - The file name is invalid.

      • delete

        public DiskFileItem delete()
                    throws java.io.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 instance.
        Throws:
        java.io.IOException - if an error occurs.

      • get

        public byte[] get()
           throws java.io.IOException
        Deprecated.
        Since 2.0.0, use getInputStream(), or getReader(), instead.
        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:
        java.io.IOException - if an I/O error occurs.
        java.lang.OutOfMemoryError - See Files.readAllBytes(Path): If an array of the required size cannot be allocated, for example the file is larger than 2GB. If so, you should use getInputStream().
        See Also:
        getInputStream()

      • getCharset

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

      • getContentType

        public java.lang.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.

      • getFileCleaningTracker

        public org.apache.commons.io.FileCleaningTracker getFileCleaningTracker()
        Returns the FileCleaningTracker, which is being used to remove temporary files.
        Returns:
        The FileCleaningTracker, which is being used to remove temporary files.

      • getInputStream

        public java.io.InputStream getInputStream()
                                   throws java.io.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:
        java.io.IOException - if an error occurs.

      • getName

        public java.lang.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:
        java.nio.file.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 java.io.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 java.nio.file.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 a 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.

      • getReader

        public java.io.Reader getReader()
                         throws java.io.IOException,
                                java.io.UnsupportedEncodingException
        Returns the contents of the file as a Reader, using the specified getCharset(). If the contents are not yet available, returns null. This is the case, for example, if the underlying output stream has not yet been closed.
        Returns:
        The contents of the file as a Reader
        Throws:
        java.io.UnsupportedEncodingException - The character set, which is specified in the files "content-type" header, is invalid.
        java.io.IOException - An I/O error occurred, while the underlying input stream was created.

      • getString

        public java.lang.String getString()
                           throws java.io.IOException,
                                  java.io.UnsupportedEncodingException,
                                  java.lang.OutOfMemoryError
        Deprecated.
        Since 2.0.0, use getReader() instead.
        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.
        Specified by:
        getString in interface FileItem<DiskFileItem>
        Returns:
        The contents of the file, as a string, if available, or null.
        Throws:
        java.io.IOException - if an I/O error occurs
        java.lang.OutOfMemoryError - See Files.readAllBytes(Path): If a string of the required size cannot be allocated, for example the file is larger than 2GB. If so, you should use getReader().
        java.io.UnsupportedEncodingException - The character set, which is specified in the files "content-type" header, is invalid.

      • getString

        public java.lang.String getString​(java.nio.charset.Charset charset)
                           throws java.io.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:
        java.io.IOException - if an I/O error occurs

      • getThreshold

        public int getThreshold()
        Returns the file items threshold.
        Returns:
        The threshold.

      • 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:
        setFormField(boolean)

      • 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​(java.nio.charset.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 instance.

      • setFileCleaningTracker

        public void setFileCleaningTracker​(org.apache.commons.io.FileCleaningTracker fileCleaningTracker)
        Sets the FileCleaningTracker, which is being used to remove temporary files.
        Parameters:
        fileCleaningTracker - The FileCleaningTracker, which is being used to remove temporary files.

      • 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 instance.
        See Also:
        isFormField()

      • toString

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

      • write

        public DiskFileItem write​(java.nio.file.Path file)
                   throws java.io.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 instance.
        Throws:
        java.io.IOException - if an error occurs.