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java.lang.Objectcom.trolltech.qt.QSignalEmitter
com.trolltech.qt.QtJambiObject
com.trolltech.qt.core.QObject
com.trolltech.qt.core.QIODevice
com.trolltech.qt.core.QFile
com.trolltech.qt.core.QTemporaryFile
public class QTemporaryFile
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; 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.
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().
Nested Class Summary |
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Nested classes/interfaces inherited from class com.trolltech.qt.core.QFile |
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QFile.FileError, QFile.Permission, QFile.Permissions |
Nested classes/interfaces inherited from class com.trolltech.qt.core.QIODevice |
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QIODevice.OpenMode, QIODevice.OpenModeFlag |
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter |
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QSignalEmitter.AbstractSignal, QSignalEmitter.Signal0, QSignalEmitter.Signal1<A>, QSignalEmitter.Signal2<A,B>, QSignalEmitter.Signal3<A,B,C>, QSignalEmitter.Signal4<A,B,C,D>, QSignalEmitter.Signal5<A,B,C,D,E>, QSignalEmitter.Signal6<A,B,C,D,E,F>, QSignalEmitter.Signal7<A,B,C,D,E,F,G>, QSignalEmitter.Signal8<A,B,C,D,E,F,G,H>, QSignalEmitter.Signal9<A,B,C,D,E,F,G,H,I> |
Field Summary |
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Fields inherited from class com.trolltech.qt.core.QIODevice |
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aboutToClose, bytesWritten, readyRead |
Constructor Summary | |
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QTemporaryFile()
Constructs a QTemporaryFile in QDir::tempPath(), using the file template "qt_temp.XXXXXX". |
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QTemporaryFile(QObject parent)
Constructs a QTemporaryFile (with the given parent) in QDir::tempPath(), using the file template "qt_temp.XXXXXX". |
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QTemporaryFile(java.lang.String templateName)
Constructs a QTemporaryFile with a template filename of templateName. |
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QTemporaryFile(java.lang.String templateName,
QObject parent)
Constructs a QTemporaryFile with a template filename of templateName and the specified parent. |
Method Summary | |
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boolean |
autoRemove()
Returns true if the QTemporaryFile is in auto remove mode. |
static QTemporaryFile |
createLocalFile(QFile file)
Creates and returns a local temporary file whose contents are a copy of the contents of the given file. |
static QTemporaryFile |
createLocalFile(java.lang.String fileName)
Works on the given fileName rather than an existing QFile object. |
QAbstractFileEngine |
fileEngine()
This function is reimplemented for internal reasons. |
java.lang.String |
fileTemplate()
Returns the set file template. |
static QTemporaryFile |
fromNativePointer(QNativePointer nativePointer)
This function returns the QTemporaryFile instance pointed to by nativePointer |
boolean |
open()
A QTemporaryFile will always be opened in QIODevice::ReadWrite mode, this allows easy access to the data in the file. |
boolean |
open(QIODevice.OpenMode flags)
This function is reimplemented for internal reasons. |
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 |
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atEnd, close, copy, copy, decodeName, decodeName, encodeName, error, exists, exists, fileName, flush, handle, isSequential, link, link, open, open, permissions, permissions, pos, readData, readLineData, remove, remove, rename, rename, resize, resize, seek, setFileName, setPermissions, setPermissions, setPermissions, setPermissions, size, symLinkTarget, symLinkTarget, unsetError, writeData |
Methods inherited from class com.trolltech.qt.core.QIODevice |
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bytesAvailable, bytesToWrite, canReadLine, errorString, getByte, isOpen, isReadable, isTextModeEnabled, isWritable, open, openMode, peek, peek, putByte, read, read, readAll, readLine, readLine, readLine, reset, setErrorString, setOpenMode, setOpenMode, setTextModeEnabled, ungetByte, waitForBytesWritten, waitForReadyRead, write, write |
Methods inherited from class com.trolltech.qt.core.QObject |
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blockSignals, childEvent, children, connectSlotsByName, customEvent, disposeLater, dumpObjectInfo, dumpObjectTree, dynamicPropertyNames, event, eventFilter, findChild, findChild, findChild, findChildren, findChildren, findChildren, findChildren, installEventFilter, isWidgetType, killTimer, moveToThread, objectName, parent, property, removeEventFilter, setObjectName, setParent, setProperty, signalsBlocked, startTimer, thread, timerEvent |
Methods inherited from class com.trolltech.qt.QtJambiObject |
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dispose, disposed, finalize, reassignNativeResources, tr, tr, tr |
Methods inherited from class com.trolltech.qt.QSignalEmitter |
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disconnect, disconnect, signalSender |
Methods inherited from class java.lang.Object |
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clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Methods inherited from interface com.trolltech.qt.QtJambiInterface |
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disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership |
Constructor Detail |
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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.
public QTemporaryFile(QObject parent)
Constructs a QTemporaryFile (with the given parent) in QDir::tempPath(), using the file template "qt_temp.XXXXXX".
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 end in 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.
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.
Method Detail |
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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.
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.
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().
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.
public final void setAutoRemove(boolean b)
Sets the QTemporaryFile into auto-remove mode if b is true.
Auto-remove is on by default.
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.
public QAbstractFileEngine fileEngine()
This function is reimplemented for internal reasons.
fileEngine
in class QFile
public boolean open(QIODevice.OpenMode flags)
This function is reimplemented for internal reasons.
open
in class QFile
public static QTemporaryFile createLocalFile(java.lang.String fileName)
Works on the given fileName rather than an existing QFile object.
public static QTemporaryFile createLocalFile(QFile file)
Creates and returns a local temporary file whose contents are a copy of the contents of the given file.
public static QTemporaryFile fromNativePointer(QNativePointer nativePointer)
nativePointer
- the QNativePointer of which object should be returned.
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