org.eclipse.swt.dnd.FileTransfer.java Source code

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Here is the source code for org.eclipse.swt.dnd.FileTransfer.java

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/*******************************************************************************
 * Copyright (c) 2000, 2008 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.swt.dnd;

import org.eclipse.rap.rwt.SingletonUtil;

/**
 * The class <code>FileTransfer</code> provides a platform specific mechanism
 * for converting a list of files represented as a java <code>String[]</code> to
 * a platform specific representation of the data and vice versa. Each
 * <code>String</code> in the array contains the absolute path for a single file
 * or directory.
 * <p>
 * An example of a java <code>String[]</code> containing a list of files is
 * shown below:
 * </p>
 * <code><pre>
 *     File file1 = new File("C:\temp\file1");
 *     File file2 = new File("C:\temp\file2");
 *     String[] fileData = new String[2];
 *     fileData[0] = file1.getAbsolutePath();
 *     fileData[1] = file2.getAbsolutePath();
 * </code></pre>
 * 
 * @see Transfer
 * @since 1.3
 */
public class FileTransfer extends ByteArrayTransfer {

    private static final String TYPE_NAME = "CF_HDROP "; //$NON-NLS-1$
    private static final int TYPE_ID = registerType(TYPE_NAME);

    private FileTransfer() {
    }

    /**
     * Returns the singleton instance of the FileTransfer class.
     * 
     * @return the singleton instance of the FileTransfer class
     */
    public static FileTransfer getInstance() {
        return SingletonUtil.getSessionInstance(FileTransfer.class);
    }

    /**
     * This implementation of <code>javaToNative</code> converts a list of file
     * names represented by a java <code>String[]</code> to a platform specific
     * representation. Each <code>String</code> in the array contains the absolute
     * path for a single file or directory.
     * 
     * @param object a java <code>String[]</code> containing the file names to be
     *          converted
     * @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
     */
    public void javaToNative(Object object, TransferData transferData) {
        if (!checkFile(object) || !isSupportedType(transferData)) {
            DND.error(DND.ERROR_INVALID_DATA);
        }
        String[] fileNames = (String[]) object;
        transferData.data = fileNames;
        transferData.result = 1;
    }

    /**
     * This implementation of <code>nativeToJava</code> converts a platform
     * specific representation of a list of file names to a java
     * <code>String[]</code>. Each String in the array contains the absolute path
     * for a single file or directory.
     * 
     * @param transferData the platform specific representation of the data to be
     *          converted
     * @return a java <code>String[]</code> containing a list of file names if the
     *         conversion was successful; otherwise null
     * @see Transfer#javaToNative
     */
    public Object nativeToJava(TransferData transferData) {
        if (!isSupportedType(transferData) || transferData.data == null)
            return null;
        if (transferData.result != 1)
            return null;
        String[] fileNames = (String[]) transferData.data;
        String[] result = new String[fileNames.length];
        System.arraycopy(fileNames, 0, result, 0, fileNames.length);
        return result;
    }

    protected int[] getTypeIds() {
        return new int[] { TYPE_ID };
    }

    protected String[] getTypeNames() {
        return new String[] { TYPE_NAME };
    }

    boolean checkFile(Object object) {
        if (object == null || !(object instanceof String[]) || ((String[]) object).length == 0)
            return false;
        String[] strings = (String[]) object;
        for (int i = 0; i < strings.length; i++) {
            if (strings[i] == null || strings[i].length() == 0)
                return false;
        }
        return true;
    }

    protected boolean validate(Object object) {
        return checkFile(object);
    }
}