Java Code Examples for java.nio.file.attribute.UserDefinedFileAttributeView#read()

private long getInode(File file) throws IOException {

        UserDefinedFileAttributeView view = null;
        // windows system and file customer Attribute
        if (OS_WINDOWS.equals(os)) {
            view = Files.getFileAttributeView(file.toPath(), UserDefinedFileAttributeView.class);// 把文件的内容属性值放置在view里面？
            try {
                ByteBuffer buffer = ByteBuffer.allocate(view.size(INODE));// view.size得到inode属性值大小
                view.read(INODE, buffer);// 把属性值放置在buffer中
                buffer.flip();
                return Long.parseLong(Charset.defaultCharset().decode(buffer).toString());// 返回编码后的inode的属性值

            }
            catch (NoSuchFileException e) {
                long winode = random.nextLong();
                view.write(INODE, Charset.defaultCharset().encode(String.valueOf(winode)));
                return winode;
            }
        }
        long inode = (long) Files.getAttribute(file.toPath(), "unix:ino");// 返回unix的inode的属性值
        return inode;
    }
 

Optional<Long> readFileAttributeAsLong(
  Path file,
  String attribute,
  UserDefinedFileAttributeView view,
  List<String> knownAttributes
) {
  if (knownAttributes.contains(attribute)) {
    try {
      LOG.trace("Attempting to read attribute {}, from file {}", attribute, file);
      ByteBuffer buf = ByteBuffer.allocate(view.size(attribute));
      view.read(attribute, buf);
      buf.flip();
      String value = Charset.defaultCharset().decode(buf).toString();
      if (Strings.isNullOrEmpty(value)) {
        LOG.debug("No attrbiute {} found for file {}", attribute, file);
        return Optional.empty();
      }
      return Optional.of(Long.parseLong(value));
    } catch (Exception e) {
      LOG.error("Error getting extra file metadata for {}", file, e);
      return Optional.empty();
    }
  } else {
    return Optional.empty();
  }
}
 

public String getMetadata(Path file, String key) {
    
    if (supportsUserDefinedAttributes(file)) {
        UserDefinedFileAttributeView view = Files.getFileAttributeView(file, UserDefinedFileAttributeView.class);
        try {
            ByteBuffer bb = ByteBuffer.allocate(view.size(key));
            view.read(key, bb);
            bb.flip();
            return Charset.defaultCharset().decode(bb).toString();
        } catch (IOException e) {
            return null;
        }
    }
    return null;
}
 

private static String getAttrValue(UserDefinedFileAttributeView view, String name) throws IOException {
    int attrSize = view.size(name);
    ByteBuffer buffer = ByteBuffer.allocateDirect(attrSize);
    view.read(name, buffer);
    buffer.flip();
    return Charset.defaultCharset().decode(buffer).toString();
}
 

/**
 * Test for bug 240953 - Netbeans Deletes User Defined Attributes.
 *
 * @throws java.io.IOException
 */
public void testWritingKeepsFileAttributes() throws IOException {

    final String attName = "User_Attribute";
    final String attValue = "User_Attribute_Value";

    if (Utilities.isWindows()) {
        clearWorkDir();
        File f = new File(getWorkDir(), "fileWithAtts.txt");
        f.createNewFile();
        UserDefinedFileAttributeView attsView = Files.getFileAttributeView(
                f.toPath(), UserDefinedFileAttributeView.class);
        ByteBuffer buffer = Charset.defaultCharset().encode(attValue);
        attsView.write(attName, buffer);

        buffer.rewind();
        attsView.read(attName, buffer);
        buffer.flip();
        String val = Charset.defaultCharset().decode(buffer).toString();
        assertEquals(attValue, val);

        FileObject fob = FileUtil.toFileObject(f);
        OutputStream os = fob.getOutputStream();
        try {
            os.write(55);
        } finally {
            os.close();
        }

        buffer.rewind();
        attsView.read(attName, buffer);
        buffer.flip();
        String val2 = Charset.defaultCharset().decode(buffer).toString();
        assertEquals(attValue, val2);
    }
}
 

public static boolean getExecutable ( final Path path ) throws IOException
{
    final UserDefinedFileAttributeView ua = Files.getFileAttributeView ( path, UserDefinedFileAttributeView.class );

    if ( !ua.list ().contains ( ATTR_EXECUTE ) )
    {
        // check first, otherwise the size() call with give an exception
        return false;
    }

    final ByteBuffer buf = ByteBuffer.allocate ( ua.size ( ATTR_EXECUTE ) );
    ua.read ( ATTR_EXECUTE, buf );
    buf.flip ();
    return Boolean.parseBoolean ( CHARSET.decode ( buf ).toString () );
}
 

@Test
public void getCustomerAttr() throws IOException {

    Path target = Paths.get("/Users/fathead/temp/file4");
    UserDefinedFileAttributeView view2 = Files.getFileAttributeView(target, UserDefinedFileAttributeView.class);
    ByteBuffer buf = ByteBuffer.allocate(view2.size(name));
    view2.read(name, buf);
    buf.flip();
    String value = Charset.defaultCharset().decode(buf).toString();
    System.out.println("value=" + value);
}
 

/**
 * @param view the attribute view of the extendet attribute for a specific
 * file
 * @param name the name of the attribute for which the value should be
 * returned
 * @return the value of an user extended attribute from the given attribute
 * view
 */
private static String getAttrValue(UserDefinedFileAttributeView view, String name) throws IOException {
    int attrSize = view.size(name);
    ByteBuffer buffer = ByteBuffer.allocateDirect(attrSize);
    view.read(name, buffer);
    buffer.flip();
    return Charset.defaultCharset().decode(buffer).toString();
}