com.safi.workshop.sqlexplorer.preview.LargeTextPreviewer.java Source code

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Here is the source code for com.safi.workshop.sqlexplorer.preview.LargeTextPreviewer.java

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/*
 * Copyright (C) 2007 SQL Explorer Development Team
 * http://sourceforge.net/projects/eclipsesql
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
package com.safi.workshop.sqlexplorer.preview;

import java.io.Reader;

import org.eclipse.jface.dialogs.MessageDialog;
import org.eclipse.swt.SWT;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Text;

import com.safi.workshop.sqlexplorer.Messages;
import com.safi.workshop.sqlexplorer.dataset.LargeTextDataType;
import com.safi.workshop.sqlexplorer.plugin.SQLExplorerPlugin;

/**
 * Implements a previewer for large text (CLOB). The reason that this is not just
 * implemented as a String is because that would require every CLOB to be loaded into the
 * JVM when the query is retrieved, whereas this allows us to only load one at a time.
 * 
 * @author John Spackman
 * 
 */
public class LargeTextPreviewer implements Previewer {

    // Largest amount of text that we're prepared to read
    private static final int MAX_TEXT_SIZE = 64 * 1024;

    /*
     * (non-JavaDoc)
     * 
     * @see
     * com.safi.workshop.sqlexplorer.preview.Previewer#createControls(org.eclipse.swt.widgets
     * .Composite, java.lang.Object)
     */
    public void createControls(final Composite parent, Object obj) {
        if (obj == null)
            return;
        String content = null;

        if (obj instanceof LargeTextDataType) {
            LargeTextDataType data = (LargeTextDataType) obj;
            try {
                Reader reader = data.getTextData();
                char[] buffer = new char[4096];
                StringBuffer result = new StringBuffer();
                int pos;
                int length = 0;
                while ((pos = reader.read(buffer)) > -1) {
                    result.append(buffer);
                    length += pos;
                    if (length > MAX_TEXT_SIZE) {
                        parent.getDisplay().asyncExec(new Runnable() {
                            public void run() {
                                MessageDialog.openWarning(parent.getShell(),
                                        Messages.getString("LargeTextPreviewer.TooMuchData.Title"),
                                        Messages.getString("LargeTextPreviewer.TooMuchData.Message"));
                            }
                        });
                        break;
                    }
                }
                content = result.toString();
            } catch (Exception e) {
                SQLExplorerPlugin.error("Cannot read CLOB", e);
                return;
            }
        } else
            content = obj.toString();

        if (content == null)
            return;

        Text text = new Text(parent, SWT.NONE);
        text.setEditable(false);
        text.setText(content);
    }

    public void dispose() {
    }
}