import java.nio.ByteBuffer;
import java.nio.charset.Charset;
import java.nio.file.*;
import java.nio.file.attribute.*;
import java.io.IOException;
/**
* Example code to list/set/get/delete the user-defined attributes of a file.
*/
public class Xdd {
static void usage() {
System.out.println("Usage: java Xdd <file>");
System.out.println(" java Xdd -set <name>=<value> <file>");
System.out.println(" java Xdd -get <name> <file>");
System.out.println(" java Xdd -del <name> <file>");
System.exit(-1);
}
public static void main(String[] args) throws IOException {
// one or three parameters
if (args.length != 1 && args.length != 3)
usage();
Path file = (args.length == 1) ?
Paths.get(args[0]) : Paths.get(args[2]);
// check that user defined attributes are supported by the file store
FileStore store = Files.getFileStore(file);
if (!store.supportsFileAttributeView(UserDefinedFileAttributeView.class)) {
System.err.format("UserDefinedFileAttributeView not supported on %s\n", store);
System.exit(-1);
}
UserDefinedFileAttributeView view = Files.
getFileAttributeView(file, UserDefinedFileAttributeView.class);
// list user defined attributes
if (args.length == 1) {
System.out.println(" Size Name");
System.out.println("-------- --------------------------------------");
for (String name: view.list()) {
System.out.format("%8d %s\n", view.size(name), name);
}
return;
}
// Add/replace a file's user defined attribute
if (args[0].equals("-set")) {
// name=value
String[] s = args[1].split("=");
if (s.length != 2)
usage();
String name = s[0];
String value = s[1];
view.write(name, Charset.defaultCharset().encode(value));
return;
}
// Print out the value of a file's user defined attribute
if (args[0].equals("-get")) {
String name = args[1];
int size = view.size(name);
ByteBuffer buf = ByteBuffer.allocateDirect(size);
view.read(name, buf);
buf.flip();
System.out.println(Charset.defaultCharset().decode(buf).toString());
return;
}
// Delete a file's user defined attribute
if (args[0].equals("-del")) {
view.delete(args[1]);
return;
}
// option not recognized
usage();
}
}