org.omnaest.utils.table.impl.persistence.SimpleFileBasedTablePersistence.java Source code

Introduction

Here is the source code for org.omnaest.utils.table.impl.persistence.SimpleFileBasedTablePersistence.java

Source

/*******************************************************************************
 * Copyright 2012 Danny Kunz
 * 
 * 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 org.omnaest.utils.table.impl.persistence;

import java.io.File;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

import org.apache.commons.io.FileUtils;
import org.apache.commons.lang3.SerializationUtils;
import org.omnaest.utils.events.exception.ExceptionHandlerSerializable;
import org.omnaest.utils.structure.collection.list.ListUtils;
import org.omnaest.utils.structure.element.converter.ElementConverter;
import org.omnaest.utils.table.Table;
import org.omnaest.utils.table.TablePersistence;
import org.omnaest.utils.tuple.KeyValue;

/**
 * Simple {@link TablePersistence} which writes the complete data to a {@link File} every time something changes.<br>
 * <br>
 * This implementation caches the data in memory to speed up the write through, but this is still very unperformant for larger
 * {@link Table}s<br>
 * <br>
 * It takes about <b>5-10 seconds</b> for about <b>1000 rows</b>.
 * 
 * @author Omnaest
 * @param <E>
 */
public class SimpleFileBasedTablePersistence<E> implements TablePersistence<E> {
    /* ************************************************** Constants *************************************************** */
    private static final long serialVersionUID = 4587018898135825772L;
    /* ************************************** Variables / State (internal/hiding) ************************************* */
    private List<E[]> elementsList = new ArrayList<E[]>();

    /* ***************************** Beans / Services / References / Delegates (external) ***************************** */
    private final ExceptionHandlerSerializable exceptionHandler;
    private final File file;

    /* *************************************************** Methods **************************************************** */

    /**
     * @see SimpleFileBasedTablePersistence
     * @param file
     *          {@link File}
     * @param exceptionHandler
     *          {@link ExceptionHandlerSerializable}
     */
    public SimpleFileBasedTablePersistence(File file, ExceptionHandlerSerializable exceptionHandler) {
        super();
        this.file = file;
        this.exceptionHandler = exceptionHandler;

        if (file != null && file.exists()) {
            try {
                final byte[] byteArray = FileUtils.readFileToByteArray(file);
                @SuppressWarnings("unchecked")
                final List<E[]> deserializedList = (List<E[]>) SerializationUtils.deserialize(byteArray);
                if (deserializedList != null) {
                    this.elementsList.addAll(deserializedList);
                }
            } catch (Exception e) {
                if (this.exceptionHandler != null) {
                    this.exceptionHandler.handleException(e);
                }
            }
        }
    }

    @Override
    public void add(int id, E[] elements) {
        this.elementsList.add(id, elements);
        this.writeToFile();
    }

    @Override
    public Iterable<KeyValue<Integer, E[]>> allElements() {
        return ListUtils.convert(this.elementsList, new ElementConverter<E[], KeyValue<Integer, E[]>>() {
            private int index = 0;

            @Override
            public KeyValue<Integer, E[]> convert(E[] elements) {
                final Integer key = this.index++;
                final E[] value = elements;
                return new KeyValue<Integer, E[]>(key, value);
            }
        });
    }

    @Override
    public void remove(int id) {
        this.elementsList.remove(id);
        this.writeToFile();
    }

    @Override
    public void removeAll() {
        this.elementsList.clear();
        this.writeToFile();
    }

    @Override
    public void update(int id, E[] elements) {
        this.elementsList.set(id, elements);
        this.writeToFile();
    }

    private void writeToFile() {
        if (this.file != null) {
            try {
                byte[] data = SerializationUtils.serialize((Serializable) this.elementsList);
                FileUtils.writeByteArrayToFile(this.file, data);
            } catch (Exception e) {
                if (this.exceptionHandler != null) {
                    this.exceptionHandler.handleException(e);
                }
            }
        }
    }

    @Override
    public void setTableName(String tableName) {
    }

    @Override
    public void setColumnTitles(String[] columnTitles) {
    }

}