120 lines
3 KiB
Java
120 lines
3 KiB
Java
/*
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* Copyright (c) 2015 ezivkoc
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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package zutil;
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import java.io.File;
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import java.io.RandomAccessFile;
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import java.nio.channels.FileChannel;
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import java.nio.channels.FileLock;
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import java.nio.channels.OverlappingFileLockException;
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/**
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* This class checks if the application is already running
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* by Locking a file
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*
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* @author Ziver Koc
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*/
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public class OneInstanceFile implements OneInstance{
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private File file;
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private FileChannel channel;
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private FileLock lock;
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/**
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* Creates a OneApp class
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*
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* @param filename The name of the file to be locked
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*/
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public OneInstanceFile(String filename){
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this.file = new File(System.getProperty("user.home"), filename);
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}
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/**
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* Checks if the file have already bean locked
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*
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* @return True if the file is locked else false
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*/
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public boolean check() {
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boolean tmp = lockApp();
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if( tmp ) closeLock();
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return !tmp;
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}
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/**
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* Locks the file
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*
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* @return False if there are a error else true
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*/
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public boolean lockApp() {
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try {
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channel = new RandomAccessFile(file, "rw").getChannel();
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try {
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lock = channel.tryLock();
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}
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catch (OverlappingFileLockException e) {
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// already locked by this application
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return false;
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}
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if (lock == null || lock.isShared()) {
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// already locked by another application
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return false;
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}
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Runtime.getRuntime().addShutdownHook(new Thread() {
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// destroy the lock when the JVM is closing
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public void run() {
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closeLock();
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deleteFile();
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}
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});
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return true;
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}
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catch (Exception e) {
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closeLock();
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return false;
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}
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}
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private void closeLock() {
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try {
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lock.release();
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channel.close();
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}
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catch (Exception e) {
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e.printStackTrace();
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}
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}
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private void deleteFile() {
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try {
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file.delete();
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}
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catch (Exception e) {
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e.printStackTrace();
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}
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}
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}
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