Java tutorial
/* * Copyright 2004-2009 the original author or authors. * * 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.compass.gps.device.jdbc.snapshot; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.compass.gps.device.jdbc.JdbcGpsDeviceException; /** * A FS (File System) based snapshot persister. The persister will store and * load the snapshot to the file system, using the given file path (using * {@link #setPath(String)}). The data will be saved using Java * <code>ObjectOutputStream</code>, and loaded using * <code>ObjectInputStream</code>. * <p> * Note that the path set is the path to the actual file that will be created. * * @author kimchy */ public class FSJdbcSnapshotPersister implements JdbcSnapshotPersister { private static final Log log = LogFactory.getLog(FSJdbcSnapshotPersister.class); private String path; public FSJdbcSnapshotPersister() { } public FSJdbcSnapshotPersister(String path) { this.path = path; } public JdbcSnapshot load() throws JdbcGpsDeviceException { File file = new File(path); if (!file.exists()) { if (log.isDebugEnabled()) { log.debug("No snapshot data found at [" + path + "], creating a new one"); } return new JdbcSnapshot(); } try { if (log.isDebugEnabled()) { log.debug("Snapshot data found at [" + path + "], loading [" + file.length() + "bytes]"); } ObjectInputStream objStream = new ObjectInputStream(new FileInputStream(path)); return (JdbcSnapshot) objStream.readObject(); } catch (Exception e) { throw new JdbcGpsDeviceException("Failed to load jdbc snapshot", e); } } public void save(JdbcSnapshot snapshot) throws JdbcGpsDeviceException { try { ObjectOutputStream objStream = new ObjectOutputStream(new FileOutputStream(path)); objStream.writeObject(snapshot); objStream.flush(); objStream.close(); if (log.isDebugEnabled()) { File file = new File(path); log.debug("Saved snapshot data to [" + path + "] size [" + file.length() + "bytes]"); } } catch (IOException e) { throw new JdbcGpsDeviceException("Failed to save jdbc snapshot", e); } } public String getPath() { return path; } public void setPath(String path) { this.path = path; } }