gov.nasa.ensemble.common.ui.preferences.FileFieldEditor.java Source code

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Here is the source code for gov.nasa.ensemble.common.ui.preferences.FileFieldEditor.java

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/*******************************************************************************
 * Copyright 2014 United States Government as represented by the
 * Administrator of the National Aeronautics and Space Administration.
 * All Rights Reserved.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 ******************************************************************************/
package gov.nasa.ensemble.common.ui.preferences;

import java.io.File;

import org.eclipse.jface.resource.JFaceResources;
import org.eclipse.swt.SWT;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.FileDialog;

/**
* A variant of org.eclipse.jface.preference.DirectoryFieldEditor that has been modified
* to extend ExtendedStringButtonFieldEditor in order to expose the label and the change button.
* Also supports specifying a file chooser style -- SWT.OPEN or SWT.SAVE
* 
* A field editor for a file path type preference. A standard file 
* dialog appears when the user presses the change button.
*/
public class FileFieldEditor extends ExtendedStringButtonFieldEditor {

    /**
     * List of legal file extension suffixes, or <code>null</code>
     * for system defaults.
     */
    private String[] extensions = null;

    /**
     * Indicates whether the path must be absolute;
     * <code>false</code> by default.
     */
    private boolean enforceAbsolute = false;

    private int style = SWT.OPEN;

    /**
     * Creates a file field editor.
     * 
     * @param name the name of the preference this field editor works on
     * @param labelText the label text of the field editor
     * @param parent the parent of the field editor's control
     */
    public FileFieldEditor(String name, String labelText, Composite parent) {
        this(name, labelText, false, parent);
    }

    /**
     * Creates a file field editor.
     * 
     * @param name the name of the preference this field editor works on
     * @param labelText the label text of the field editor
     * @param enforceAbsolute <code>true</code> if the file path
     *  must be absolute, and <code>false</code> otherwise
     * @param parent the parent of the field editor's control
     */
    public FileFieldEditor(String name, String labelText, boolean enforceAbsolute, Composite parent) {
        init(name, labelText, parent);
        this.enforceAbsolute = enforceAbsolute;
        setErrorMessage(JFaceResources.getString("FileFieldEditor.errorMessage"));//$NON-NLS-1$
        setChangeButtonText(JFaceResources.getString("openBrowse"));//$NON-NLS-1$
        setValidateStrategy(VALIDATE_ON_FOCUS_LOST);
        createControl(parent);
    }

    /* (non-Javadoc)
     * Method declared on StringButtonFieldEditor.
     * Opens the file chooser dialog and returns the selected file.
     */
    @Override
    protected String changePressed() {
        File f = new File(getTextControl().getText());
        File d = getFile(f);
        if (d == null) {
            return null;
        }
        return d.getAbsolutePath();
    }

    /* (non-Javadoc)
     * Method declared on StringFieldEditor.
     * Checks whether the text input field specifies an existing file.
     */
    @Override
    protected boolean checkState() {

        String msg = null;

        String path = getTextControl().getText();
        if (path != null) {
            path = path.trim();
        } else {
            path = "";//$NON-NLS-1$
        }
        if (path.length() == 0) {
            if (!isEmptyStringAllowed()) {
                msg = getErrorMessage();
            }
        } else {
            File file = new File(path);
            if (file.isFile()) {
                if (enforceAbsolute && !file.isAbsolute()) {
                    msg = JFaceResources.getString("FileFieldEditor.errorMessage2");//$NON-NLS-1$
                }
            } else if (style == SWT.OPEN) {
                msg = getErrorMessage();
            } else if (file.exists() && !file.canWrite()) {
                msg = "Do not have the necessary permissions to write to this file, may be in use";
            }
        }

        if (msg != null) { // error
            showErrorMessage(msg);
            return false;
        }

        // OK!
        clearErrorMessage();
        return true;
    }

    /**
     * Helper to open the file chooser dialog.
     * @param startingDirectory the directory to open the dialog on.
     * @return File The File the user selected or <code>null</code> if they
     * do not.
     */
    protected File getFile(File startingDirectory) {
        FileDialog dialog = new FileDialog(getShell(), style);
        if (startingDirectory != null) {
            dialog.setFilterPath(startingDirectory.getParent());
            dialog.setFileName(startingDirectory.getName());
        }
        if (extensions != null) {
            dialog.setFilterExtensions(extensions);
        }
        String file = dialog.open();
        if (file != null) {
            file = file.trim();
            if (file.length() > 0) {
                return new File(file);
            }
        }
        return null;
    }

    /**
     * Sets this file field editor's file extension filter.
     *
     * @param extensions a list of file extension, or <code>null</code> 
     * to set the filter to the system's default value
     */
    public void setFileExtensions(String[] extensions) {
        this.extensions = extensions;
    }

    /**
     * Set the file chooser type
     */
    public void setFileChooserStyle(int style) {
        this.style = style;
    }

}