Java tutorial
/******************************************************************************* * Copyright (c) 2000, 20007 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.dnd; import org.eclipse.swt.internal.ole.win32.*; import org.eclipse.swt.internal.win32.*; /** * The class <code>URLTransfer</code> provides a platform specific mechanism * for converting text in URL format represented as a java <code>String</code> * to a platform specific representation of the data and vice versa. The string * must contain a fully specified url. * * <p>An example of a java <code>String</code> containing a URL is shown below:</p> * * <pre><code> * String url = "http://www.eclipse.org"; * </code></pre> * * @see Transfer * @since 3.4 */ public class URLTransfer extends ByteArrayTransfer { static URLTransfer _instance = new URLTransfer(); static final String CFSTR_INETURLW = "UniformResourceLocatorW"; //$NON-NLS-1$ static final int CFSTR_INETURLIDW = registerType(CFSTR_INETURLW); static final String CFSTR_INETURL = "UniformResourceLocator"; //$NON-NLS-1$ static final int CFSTR_INETURLID = registerType(CFSTR_INETURL); private URLTransfer() { } /** * Returns the singleton instance of the URLTransfer class. * * @return the singleton instance of the URLTransfer class */ public static URLTransfer getInstance() { return _instance; } /** * This implementation of <code>javaToNative</code> converts a URL * represented by a java <code>String</code> to a platform specific representation. * * @param object a java <code>String</code> containing a URL * @param transferData an empty <code>TransferData</code> object that will * be filled in on return with the platform specific format of the data * * @see Transfer#nativeToJava */ @Override public void javaToNative(Object object, TransferData transferData) { if (!checkURL(object) || !isSupportedType(transferData)) { DND.error(DND.ERROR_INVALID_DATA); } transferData.result = COM.E_FAIL; // URL is stored as a null terminated byte array String url = ((String) object); if (transferData.type == CFSTR_INETURLIDW) { int charCount = url.length(); char[] chars = new char[charCount + 1]; url.getChars(0, charCount, chars, 0); int byteCount = chars.length * 2; long newPtr = OS.GlobalAlloc(COM.GMEM_FIXED | COM.GMEM_ZEROINIT, byteCount); OS.MoveMemory(newPtr, chars, byteCount); transferData.stgmedium = new STGMEDIUM(); transferData.stgmedium.tymed = COM.TYMED_HGLOBAL; transferData.stgmedium.unionField = newPtr; transferData.stgmedium.pUnkForRelease = 0; transferData.result = COM.S_OK; } else if (transferData.type == CFSTR_INETURLID) { int count = url.length(); char[] chars = new char[count + 1]; url.getChars(0, count, chars, 0); int codePage = OS.GetACP(); int cchMultiByte = OS.WideCharToMultiByte(codePage, 0, chars, -1, null, 0, null, null); if (cchMultiByte == 0) { transferData.stgmedium = new STGMEDIUM(); transferData.result = COM.DV_E_STGMEDIUM; return; } long lpMultiByteStr = OS.GlobalAlloc(OS.GMEM_FIXED | OS.GMEM_ZEROINIT, cchMultiByte); OS.WideCharToMultiByte(codePage, 0, chars, -1, lpMultiByteStr, cchMultiByte, null, null); transferData.stgmedium = new STGMEDIUM(); transferData.stgmedium.tymed = COM.TYMED_HGLOBAL; transferData.stgmedium.unionField = lpMultiByteStr; transferData.stgmedium.pUnkForRelease = 0; transferData.result = COM.S_OK; } } /** * This implementation of <code>nativeToJava</code> converts a platform * specific representation of a URL to a java <code>String</code>. * * @param transferData the platform specific representation of the data to be converted * @return a java <code>String</code> containing a URL if the conversion was successful; * otherwise null * * @see Transfer#javaToNative */ @Override public Object nativeToJava(TransferData transferData) { if (!isSupportedType(transferData) || transferData.pIDataObject == 0) return null; IDataObject data = new IDataObject(transferData.pIDataObject); data.AddRef(); STGMEDIUM stgmedium = new STGMEDIUM(); FORMATETC formatetc = transferData.formatetc; stgmedium.tymed = COM.TYMED_HGLOBAL; transferData.result = getData(data, formatetc, stgmedium); data.Release(); if (transferData.result != COM.S_OK) return null; long hMem = stgmedium.unionField; try { if (transferData.type == CFSTR_INETURLIDW) { /* Ensure byteCount is a multiple of 2 bytes */ int size = OS.GlobalSize(hMem) / 2 * 2; if (size == 0) return null; char[] chars = new char[size / 2]; long ptr = OS.GlobalLock(hMem); if (ptr == 0) return null; try { OS.MoveMemory(chars, ptr, size); int length = chars.length; for (int i = 0; i < chars.length; i++) { if (chars[i] == '\0') { length = i; break; } } return new String(chars, 0, length); } finally { OS.GlobalUnlock(hMem); } } else if (transferData.type == CFSTR_INETURLID) { long lpMultiByteStr = OS.GlobalLock(hMem); if (lpMultiByteStr == 0) return null; try { int codePage = OS.GetACP(); int cchWideChar = OS.MultiByteToWideChar(codePage, OS.MB_PRECOMPOSED, lpMultiByteStr, -1, null, 0); if (cchWideChar == 0) return null; char[] lpWideCharStr = new char[cchWideChar - 1]; OS.MultiByteToWideChar(codePage, OS.MB_PRECOMPOSED, lpMultiByteStr, -1, lpWideCharStr, lpWideCharStr.length); return new String(lpWideCharStr); } finally { OS.GlobalUnlock(hMem); } } } finally { OS.GlobalFree(hMem); } return null; } @Override protected int[] getTypeIds() { return new int[] { CFSTR_INETURLIDW, CFSTR_INETURLID }; } @Override protected String[] getTypeNames() { return new String[] { CFSTR_INETURLW, CFSTR_INETURL }; } boolean checkURL(Object object) { return object != null && (object instanceof String) && ((String) object).length() > 0; } @Override protected boolean validate(Object object) { return checkURL(object); } }