Java创建不可删除文件

Question

Is there any method to create a file in java that cannot be deleted. I have googled it and found processes involving the cmd. However, I require a pure "java" way that can be done on any platform.

Thanks in advance.

Answer 1

Thank you for your help. I finally got it right. I used the following code to deny access to user

public static void main() throws IOException
{
    Path file = Paths.get("c:/b.txt");
    AclFileAttributeView aclAttr = Files.getFileAttributeView(file, AclFileAttributeView.class);
    //System.out.println();

    UserPrincipalLookupService upls = file.getFileSystem().getUserPrincipalLookupService();
    UserPrincipal user = upls.lookupPrincipalByName(System.getProperty("user.name"));
    AclEntry.Builder builder = AclEntry.newBuilder();       
    builder.setPermissions(EnumSet.of(AclEntryPermission.APPEND_DATA, AclEntryPermission.DELETE, AclEntryPermission.DELETE_CHILD, AclEntryPermission.EXECUTE, AclEntryPermission.READ_ACL, AclEntryPermission.READ_ATTRIBUTES, AclEntryPermission.READ_DATA, AclEntryPermission.READ_NAMED_ATTRS, AclEntryPermission.SYNCHRONIZE, AclEntryPermission.WRITE_ACL, AclEntryPermission.WRITE_ATTRIBUTES, AclEntryPermission.WRITE_DATA, AclEntryPermission.WRITE_NAMED_ATTRS, AclEntryPermission.WRITE_OWNER));
    builder.setPrincipal(user);
    builder.setType(AclEntryType.DENY);
    aclAttr.setAcl(Collections.singletonList(builder.build()));
}

Answer 2

Try the method setPosixFilePermissions() and set the permissions to read only for all the classes of users. Refer this - http://docs.oracle.com/javase/7/docs/api/java/nio/file/Files.html#setPosixFilePermissions%28java.nio.file.Path,%20java.util.Set%29

Answer 3

If you want to create a file that can't be accidentally overwritten, then look at the various answers to this: How do i programmatically change file permissions?

If you want to create a file that the current program cannot delete at all (but a privileged one could), it might be possible by setting permissions appropriately on the parent directory, or possibly using SELinux Mandatory Access Control cleverness.

If you want to create a truly undeleteable file, then you are out of luck. I am not aware of any operating system that supports creation of files that can never be deleted. It would be an "anti-feature".

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I would also agree with @Teifi's comment. Create a file that cannot ever be deleted on the user's machine is not acceptable ... unless done by, or with the authorization of the system's administrators. I would call any software that did that "malicious" too.

Answer 4

You can lock the file using java.nio.* . Here is a tutorial how to use it http://www.javabeat.net/2007/10/locking-files-using-java/ .