2、检查文件是否允许：
file.canExecute(); – return true, file is executable; false is not.
file.canWrite(); – return true, file is writable; false is not.
file.canRead(); – return true, file is readable; false is not.
3、设置文件权限：
file.setExecutable(boolean); – true, allow execute operations; false to disallow it.
file.setReadable(boolean); – true, allow read operations; false to disallow it.
file.setWritable(boolean); – true, allow write operations; false to disallow it.
Runtime.getRuntime().exec("chmod 777 filename");
原文：https://www.cnblogs.com/java-h/p/10641462.html