Class QAbstractFileEngineHandler

  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.QAbstractFileEngineHandler
All Implemented Interfaces:

public abstract class QAbstractFileEngineHandler
extends QtJambiObject

The QAbstractFileEngineHandler class provides a way to register custom file engines with your application. QAbstractFileEngineHandler is a factory for creating QAbstractFileEngine objects (file engines), which are used internally by QFile, QFileInfo, and QDir when working with files and directories.

When you open a file, Qt chooses a suitable file engine by passing the file name from QFile or QDir through an internal list of registered file engine handlers. The first handler to recognize the file name is used to create the engine. Qt provides internal file engines for working with regular files and resources, but you can also register your own QAbstractFileEngine subclasses.

To install an application-specific file engine, you subclass QAbstractFileEngineHandler and reimplement create(). When you instantiate the handler (e.g. by creating an instance on the stack or on the heap), it will automatically register with Qt. (The latest registered handler takes precedence over existing handlers.)

For example:

    public static class ZipEngineHandler extends QAbstractFileEngineHandler
        public QAbstractFileEngine create(String fileName)
            // ZipEngineHandler returns a ZipEngine for all .zip files
            if (fileName.toLowerCase().endsWith(".zip")) {
                return new ZipEngine(fileName);
            } else {
                return null;

    // ...

    public static void main(String args[])

        ZipEngineHandler engine = new ZipEngineHandler();

        MainWindow window = new MainWindow(null);;

When the handler is destroyed, it is automatically removed from Qt.

The most common approach to registering a handler is to create an instance as part of the start-up phase of your application. It is also possible to limit the scope of the file engine handler to a particular area of interest (e.g. a special file dialog that needs a custom file engine). By creating the handler inside a local scope, you can precisely control the area in which your engine will be applied without disturbing file operations in other parts of your application.

See also:
QAbstractFileEngine, and QAbstractFileEngine::create().

Nested Class Summary
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
Field Summary
Fields inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
Constructor Summary
          Constructs a file handler and registers it with Qt.
Method Summary
abstract  QAbstractFileEngine create(java.lang.String fileName)
          Creates a file engine for file fileName.
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
Methods inherited from class java.lang.Object
clone, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Methods inherited from interface com.trolltech.qt.QtJambiInterface
disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership

Constructor Detail


public QAbstractFileEngineHandler()
Constructs a file handler and registers it with Qt. Once created this handler's create() function will be called (along with all the other handlers) for any paths used. The most recently created handler that recognizes the given path (i.e. that returns a QAbstractFileEngine) is used for the new path.

See also:

Method Detail


public abstract QAbstractFileEngine create(java.lang.String fileName)
Creates a file engine for file fileName. Returns 0 if this file handler cannot handle fileName.


    public QAbstractFileEngine create(String fileName)
        // ZipEngineHandler returns a ZipEngine for all .zip files
        if (fileName.toLowerCase().endsWith(".zip")) {
            return new ZipEngine(fileName);
        } else {
            return null;

See also: