Java tutorial
/******************************************************************************* * Copyright (c) 2000, 2017 IBM Corporation and others. * * This program and the accompanying materials * are made available under the terms of the Eclipse Public License 2.0 * which accompanies this distribution, and is available at * https://www.eclipse.org/legal/epl-2.0/ * * SPDX-License-Identifier: EPL-2.0 * * Contributors: * IBM Corporation - initial API and implementation *******************************************************************************/ package org.eclipse.swt.snippets; /* * Drag and Drop example snippet: define data transfer types that subclass each * other * * For a list of all SWT example snippets see * http://www.eclipse.org/swt/snippets/ * * @since 3.1 */ import java.io.*; import org.eclipse.swt.*; import org.eclipse.swt.dnd.*; import org.eclipse.swt.layout.*; import org.eclipse.swt.widgets.*; public class Snippet171 { /* * The data being transferred is an <bold>array of type MyType</bold> where * MyType is define as: */ static class MyType { String fileName; long fileLength; long lastModified; } static class MyTransfer extends ByteArrayTransfer { private static final String MYTYPENAME = "MytypeTransfer"; private static final int MYTYPEID = registerType(MYTYPENAME); private static MyTransfer _instance = new MyTransfer(); public static Transfer getInstance() { return _instance; } byte[] javaToByteArray(Object object) { MyType data = (MyType) object; try (ByteArrayOutputStream out = new ByteArrayOutputStream(); DataOutputStream writeOut = new DataOutputStream(out)) { byte[] buffer = data.fileName.getBytes(); writeOut.writeInt(buffer.length); writeOut.write(buffer); writeOut.writeLong(data.fileLength); writeOut.writeLong(data.lastModified); buffer = out.toByteArray(); writeOut.close(); return buffer; } catch (IOException e) { } return null; } Object byteArrayToJava(byte[] bytes) { MyType data = new MyType(); try (ByteArrayInputStream in = new ByteArrayInputStream(bytes); DataInputStream readIn = new DataInputStream(in)) { int size = readIn.readInt(); byte[] buffer = new byte[size]; readIn.read(buffer); data.fileName = new String(buffer); data.fileLength = readIn.readLong(); data.lastModified = readIn.readLong(); readIn.close(); } catch (IOException ex) { return null; } return data; } @Override public void javaToNative(Object object, TransferData transferData) { if (!checkMyType(object) || !isSupportedType(transferData)) { DND.error(DND.ERROR_INVALID_DATA); } byte[] buffer = javaToByteArray(object); super.javaToNative(buffer, transferData); } @Override public Object nativeToJava(TransferData transferData) { if (isSupportedType(transferData)) { byte[] buffer = (byte[]) super.nativeToJava(transferData); if (buffer == null) return null; return byteArrayToJava(buffer); } return null; } @Override protected String[] getTypeNames() { return new String[] { MYTYPENAME }; } @Override protected int[] getTypeIds() { return new int[] { MYTYPEID }; } boolean checkMyType(Object object) { return object != null && object instanceof MyType; } @Override protected boolean validate(Object object) { return checkMyType(object); } } /* * The data being transferred is an <bold>array of type MyType2</bold> * where MyType2 is define as: */ static class MyType2 extends MyType { String version; } static class MyTransfer2 extends MyTransfer { private static final String MYTYPE2NAME = "Mytype2Transfer"; private static final int MYTYPE2ID = registerType(MYTYPE2NAME); private static MyTransfer _instance = new MyTransfer2(); public static Transfer getInstance() { return _instance; } @Override protected String[] getTypeNames() { return new String[] { MYTYPE2NAME }; } @Override protected int[] getTypeIds() { return new int[] { MYTYPE2ID }; } @Override byte[] javaToByteArray(Object object) { MyType2 data = (MyType2) object; try (ByteArrayOutputStream out = new ByteArrayOutputStream(); DataOutputStream writeOut = new DataOutputStream(out)) { byte[] buffer = data.fileName.getBytes(); writeOut.writeInt(buffer.length); writeOut.write(buffer); writeOut.writeLong(data.fileLength); writeOut.writeLong(data.lastModified); buffer = data.version.getBytes(); writeOut.writeInt(buffer.length); writeOut.write(buffer); buffer = out.toByteArray(); writeOut.close(); return buffer; } catch (IOException e) { } return null; } @Override Object byteArrayToJava(byte[] bytes) { MyType2 data = new MyType2(); try (ByteArrayInputStream in = new ByteArrayInputStream(bytes); DataInputStream readIn = new DataInputStream(in)) { int size = readIn.readInt(); byte[] buffer = new byte[size]; readIn.read(buffer); data.fileName = new String(buffer); data.fileLength = readIn.readLong(); data.lastModified = readIn.readLong(); size = readIn.readInt(); buffer = new byte[size]; readIn.read(buffer); data.version = new String(buffer); readIn.close(); } catch (IOException ex) { return null; } return data; } @Override public void javaToNative(Object object, TransferData transferData) { if (!checkMyType2(object)) { DND.error(DND.ERROR_INVALID_DATA); } super.javaToNative(object, transferData); } boolean checkMyType2(Object object) { if (!checkMyType(object)) return false; return object != null && object instanceof MyType2; } @Override protected boolean validate(Object object) { return checkMyType2(object); } } public static void main(String[] args) { Display display = new Display(); Shell shell = new Shell(display); shell.setText("Snippet 171"); shell.setLayout(new FillLayout()); final Label label1 = new Label(shell, SWT.BORDER | SWT.WRAP); label1.setText("Drag Source for MyData and MyData2"); final Label label2 = new Label(shell, SWT.BORDER | SWT.WRAP); label2.setText("Drop Target for MyData"); final Label label3 = new Label(shell, SWT.BORDER | SWT.WRAP); label3.setText("Drop Target for MyData2"); DragSource source = new DragSource(label1, DND.DROP_COPY); source.setTransfer(MyTransfer.getInstance(), MyTransfer2.getInstance()); source.addDragListener(new DragSourceAdapter() { @Override public void dragSetData(DragSourceEvent event) { MyType2 myType = new MyType2(); myType.fileName = "abc.txt"; myType.fileLength = 1000; myType.lastModified = 12312313; myType.version = "version 2"; event.data = myType; } }); DropTarget targetMyType = new DropTarget(label2, DND.DROP_COPY | DND.DROP_DEFAULT); targetMyType.setTransfer(MyTransfer.getInstance()); targetMyType.addDropListener(new DropTargetAdapter() { @Override public void dragEnter(DropTargetEvent event) { if (event.detail == DND.DROP_DEFAULT) event.detail = DND.DROP_COPY; } @Override public void dragOperationChanged(DropTargetEvent event) { if (event.detail == DND.DROP_DEFAULT) event.detail = DND.DROP_COPY; } @Override public void drop(DropTargetEvent event) { if (event.data != null) { MyType myType = (MyType) event.data; if (myType != null) { String string = "MyType: " + myType.fileName; label2.setText(string); } } } }); DropTarget targetMyType2 = new DropTarget(label3, DND.DROP_COPY | DND.DROP_DEFAULT); targetMyType2.setTransfer(MyTransfer2.getInstance()); targetMyType2.addDropListener(new DropTargetAdapter() { @Override public void dragEnter(DropTargetEvent event) { if (event.detail == DND.DROP_DEFAULT) event.detail = DND.DROP_COPY; } @Override public void dragOperationChanged(DropTargetEvent event) { if (event.detail == DND.DROP_DEFAULT) event.detail = DND.DROP_COPY; } @Override public void drop(DropTargetEvent event) { if (event.data != null) { MyType2 myType = (MyType2) event.data; if (myType != null) { String string = "MyType2: " + myType.fileName + ":" + myType.version; label3.setText(string); } } } }); shell.setSize(300, 200); shell.open(); while (!shell.isDisposed()) { if (!display.readAndDispatch()) display.sleep(); } display.dispose(); } }