启动单一主线程利用文件锁方式启动单一主线程

public static boolean instanceControl() {
boolean flag = false;
try {
RandomAccessFile raf = new RandomAccessFile(new File(
"jzcdService.lck"),"rw");
FileChannel fc = raf.getChannel();
FileLock lock = fc.tryLock();
if (lock == null) {
flag = true;
}
} catch (Exception ex) {
ex.printstacktrace();
}
return flag;
}

if (instanceControl()) { System.out.println("集中出单影像提取服务已经在运行中，本服务不能启动，自动退出。"); System.exit(0); }