com.trolltech.qt.core
Class QTemporaryFile

java.lang.Object
  extended by com.trolltech.qt.internal.QSignalEmitterInternal
      extended by com.trolltech.qt.QSignalEmitter
          extended by com.trolltech.qt.QtJambiObject
              extended by com.trolltech.qt.core.QObject
                  extended by com.trolltech.qt.core.QIODevice
                      extended by com.trolltech.qt.core.QFile
                          extended by com.trolltech.qt.core.QTemporaryFile
All Implemented Interfaces:
QtJambiInterface

public class QTemporaryFile
extends QFile

The QTemporaryFile class is an I/O device that operates on temporary files. QTemporaryFile is used to create unique temporary files safely. The file itself is created by calling open(). The name of the temporary file is guaranteed to be unique (i.e., you are guaranteed to not overwrite an existing file), and the file will subsequently be removed upon destruction of the QTemporaryFile object. This is an important technique that avoids data corruption for applications that store data in temporary files. The file name is either auto-generated, or created based on a template, which is passed to QTemporaryFile's constructor.

Example:

        {
            QTemporaryFile file = new QTemporaryFile();
            if (file.open()) {
                // file.fileName() returns the unique file name
            }

            // the QTemporaryFile destructor removes the temporary file
        }
Reopening a QTemporaryFile after calling close() is safe. For as long as the QTemporaryFile object itself is not destroyed, the unique temporary file will exist and be kept open internally by QTemporaryFile.

The file name of the temporary file can be found by calling fileName(). Note that this is only defined while the file is open; the function returns an empty string before the file is opened and after it is closed.

A temporary file will have some static part of the name and some part that is calculated to be unique. The default filename qt_temp will be placed into the temporary path as returned by QDir::tempPath(). If you specify your own filename, a relative file path will not be placed in the temporary directory by default, but be relative to the current working directory.

Specified filenames can contain the following template XXXXXX (six upper case "X" characters), which will be replaced by the auto-generated portion of the filename. Note that the template is case sensitive. If the template is not present in the filename, QTemporaryFile appends the generated part to the filename given.

See also:
QDir::tempPath(), and QFile.


Nested Class Summary
 
Nested classes/interfaces inherited from class com.trolltech.qt.core.QFile
QFile.FileError, QFile.MemoryMapFlags, QFile.Permission, QFile.Permissions
 
Nested classes/interfaces inherited from class com.trolltech.qt.core.QIODevice
QIODevice.OpenMode, QIODevice.OpenModeFlag
 
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter
QSignalEmitter.AbstractSignal, QSignalEmitter.PrivateSignal0, QSignalEmitter.PrivateSignal1, QSignalEmitter.PrivateSignal2, QSignalEmitter.PrivateSignal3, QSignalEmitter.PrivateSignal4, QSignalEmitter.PrivateSignal5, QSignalEmitter.PrivateSignal6, QSignalEmitter.PrivateSignal7, QSignalEmitter.PrivateSignal8, QSignalEmitter.PrivateSignal9, QSignalEmitter.Signal0, QSignalEmitter.Signal1, QSignalEmitter.Signal2, QSignalEmitter.Signal3, QSignalEmitter.Signal4, QSignalEmitter.Signal5, QSignalEmitter.Signal6, QSignalEmitter.Signal7, QSignalEmitter.Signal8, QSignalEmitter.Signal9
 
Nested classes/interfaces inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
com.trolltech.qt.internal.QSignalEmitterInternal.AbstractSignalInternal
 
Field Summary
 
Fields inherited from class com.trolltech.qt.core.QIODevice
aboutToClose, bytesWritten, readChannelFinished, readyRead
 
Fields inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
currentSender
 
Constructor Summary
QTemporaryFile()
          Constructs a QTemporaryFile in QDir::tempPath(), using the file template "qt_temp.XXXXXX".
QTemporaryFile(QObject parent)
          Constructs a QTemporaryFile (with the given parent) in QDir::tempPath(), using the file template "qt_temp.XXXXXX".
QTemporaryFile(java.lang.String templateName)
          Constructs a QTemporaryFile with a template filename of templateName.
QTemporaryFile(java.lang.String templateName, QObject parent)
          Constructs a QTemporaryFile with a template filename of templateName and the specified parent.
 
Method Summary
 boolean autoRemove()
          Returns true if the QTemporaryFile is in auto remove mode.
static QTemporaryFile createLocalFile(QFile file)
          If file is not on a local disk, a temporary file is created on a local disk, file is copied into the temporary local file, and a pointer to the temporary local file is returned.
static QTemporaryFile createLocalFile(java.lang.String fileName)
          This is an overloaded member function, provided for convenience.
 java.lang.String fileTemplate()
          Returns the set file template.
 boolean open()
          A QTemporaryFile will always be opened in QIODevice::ReadWrite mode, this allows easy access to the data in the file.
 void setAutoRemove(boolean b)
          Sets the QTemporaryFile into auto-remove mode if b is true.
 void setFileTemplate(java.lang.String name)
          Sets the static portion of the file name to name.
 java.lang.String uniqueFilename()
          Returns the complete unique filename backing the QTemporaryFile object.
 
Methods inherited from class com.trolltech.qt.core.QFile
copy, copy, decodeName, decodeName, encodeName, error, exists, exists, fileName, flush, handle, link, link, open, open, open, permissions, permissions, remove, remove, rename, rename, resize, resize, setFileName, setPermissions, setPermissions, setPermissions, setPermissions, symLinkTarget, symLinkTarget, unsetError
 
Methods inherited from class com.trolltech.qt.core.QIODevice
atEnd, bytesAvailable, bytesToWrite, canReadLine, close, errorString, getByte, isOpen, isReadable, isSequential, isTextModeEnabled, isWritable, open, openMode, peek, peek, pos, putByte, read, read, readAll, readData, readLine, readLine, readLine, readLineData, reset, seek, setErrorString, setOpenMode, setOpenMode, setTextModeEnabled, size, ungetByte, waitForBytesWritten, waitForReadyRead, write, write, writeData
 
Methods inherited from class com.trolltech.qt.core.QObject
childEvent, children, connectSlotsByName, customEvent, disposeLater, dumpObjectInfo, dumpObjectTree, dynamicPropertyNames, event, eventFilter, findChild, findChild, findChild, findChildren, findChildren, findChildren, findChildren, indexOfProperty, installEventFilter, isWidgetType, killTimer, moveToThread, objectName, parent, properties, property, removeEventFilter, setObjectName, setParent, setProperty, startTimer, timerEvent, toString, userProperty
 
Methods inherited from class com.trolltech.qt.QtJambiObject
dispose, disposed, equals, finalize, reassignNativeResources, tr, tr, tr
 
Methods inherited from class com.trolltech.qt.QSignalEmitter
blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread
 
Methods inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
__qt_signalInitialization
 
Methods inherited from class java.lang.Object
clone, getClass, hashCode, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface com.trolltech.qt.QtJambiInterface
disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership
 

Constructor Detail

QTemporaryFile

public QTemporaryFile()
Constructs a QTemporaryFile in QDir::tempPath(), using the file template "qt_temp.XXXXXX". The file is stored in the system's temporary directory.

See also:
setFileTemplate(), and QDir::tempPath().


QTemporaryFile

public QTemporaryFile(QObject parent)
Constructs a QTemporaryFile (with the given parent) in QDir::tempPath(), using the file template "qt_temp.XXXXXX".

See also:
setFileTemplate().


QTemporaryFile

public QTemporaryFile(java.lang.String templateName)
Constructs a QTemporaryFile with a template filename of templateName. Upon opening the temporary file this will be used to create a unique filename.

If the templateName does not contain XXXXXX it will automatically be appended and used as the dynamic portion of the filename.

If templateName is a relative path, the path will be relative to the current working directory. You can use QDir::tempPath() to construct templateName if you want use the system's temporary directory.

See also:
open(), and fileTemplate().


QTemporaryFile

public QTemporaryFile(java.lang.String templateName,
                      QObject parent)
Constructs a QTemporaryFile with a template filename of templateName and the specified parent. Upon opening the temporary file this will be used to create a unique filename.

If the templateName does not contain XXXXXX it will automatically be appended and used as the dynamic portion of the filename.

If templateName is a relative path, the path will be relative to the current working directory. You can use QDir::tempPath() to construct templateName if you want use the system's temporary directory.

See also:
open(), and fileTemplate().

Method Detail

autoRemove

public final boolean autoRemove()
Returns true if the QTemporaryFile is in auto remove mode. Auto-remove mode will automatically delete the filename from disk upon destruction. This makes it very easy to create your QTemporaryFile object on the stack, fill it with data, read from it, and finally on function return it will automatically clean up after itself.

Auto-remove is on by default.

See also:
setAutoRemove(), and remove().


uniqueFilename

public final java.lang.String uniqueFilename()
Returns the complete unique filename backing the QTemporaryFile object. This string is null before the QTemporaryFile is opened, afterwards it will contain the fileTemplate() plus additional characters to make it unique.

See also:
fileTemplate().


fileTemplate

public final java.lang.String fileTemplate()
Returns the set file template. The default file template will be called qt_temp and be placed in QDir::tempPath().

See also:
setFileTemplate().


open

public final boolean open()
A QTemporaryFile will always be opened in QIODevice::ReadWrite mode, this allows easy access to the data in the file. This function will return true upon success and will set the fileName() to the unique filename used.

See also:
fileName().


setAutoRemove

public final void setAutoRemove(boolean b)
Sets the QTemporaryFile into auto-remove mode if b is true.

Auto-remove is on by default.

See also:
autoRemove(), and remove().


setFileTemplate

public final void setFileTemplate(java.lang.String name)
Sets the static portion of the file name to name. If the file template ends in XXXXXX that will automatically be replaced with the unique part of the filename, otherwise a filename will be determined automatically based on the static portion specified.

If name contains a relative file path, the path will be relative to the current working directory. You can use QDir::tempPath() to construct name if you want use the system's temporary directory.

See also:
fileTemplate().


createLocalFile

public static QTemporaryFile createLocalFile(QFile file)
If file is not on a local disk, a temporary file is created on a local disk, file is copied into the temporary local file, and a pointer to the temporary local file is returned. If file is already on a local disk, a copy is not created and 0 is returned.


createLocalFile

public static QTemporaryFile createLocalFile(java.lang.String fileName)
This is an overloaded member function, provided for convenience.

Works on the given fileName rather than an existing QFile object.