Tag (Apache HBase 1.2.12 API)

java.lang.Object
- org.apache.hadoop.hbase.Tag

```
@InterfaceAudience.Private
@InterfaceStability.Evolving
public class Tag
extends Object
```
Tags are part of cells and helps to add metadata about the KVs. Metadata could be ACLs per cells, visibility labels, etc.

Field Summary

Fields
Modifier and Type	Field and Description
`private byte[]`	`bytes`
`static int`	`INFRASTRUCTURE_SIZE`
`private int`	`length`
`static int`	`MAX_TAG_LENGTH`
`private int`	`offset`
`static int`	`TAG_LENGTH_SIZE`
`private byte`	`type`
`static int`	`TYPE_LENGTH_SIZE`

Constructor Summary

Constructors
Constructor and Description
`Tag(byte[] bytes, int offset)` Creates a Tag from the specified byte array and offset.
`Tag(byte[] bytes, int offset, int length)` Creates a Tag from the specified byte array, starting at offset, and for length `length`.
`Tag(byte tagType, byte[] tag)`
`Tag(byte tagType, String tag)`

Method Summary

Methods
Modifier and Type	Method and Description
`static List<Tag>`	`asList(byte[] b, int offset, int length)` Creates the list of tags from the byte array b.
`static List<Tag>`	`carryForwardTags(Cell cell)`
`static List<Tag>`	`carryForwardTags(List<Tag> tagsOrNull, Cell cell)`
`static byte[]`	`fromList(List<Tag> tags)` Write a list of tags into a byte array
`byte[]`	`getBuffer()`
`(package private) int`	`getLength()` Returns the total length of the entire tag entity
`private static int`	`getLength(byte[] bytes, int offset)`
`(package private) int`	`getOffset()` Returns the offset of the entire tag entity
`static Tag`	`getTag(byte[] b, int offset, int length, byte type)` Retrieve the first tag from the tags byte array matching the passed in tag type
`int`	`getTagLength()`
`int`	`getTagOffset()`
`byte`	`getType()`
`byte[]`	`getValue()` Returns tag value in a new byte array.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - TYPE_LENGTH_SIZE
```
public static final int TYPE_LENGTH_SIZE
```
    See Also:
    Constant Field Values
  - TAG_LENGTH_SIZE
```
public static final int TAG_LENGTH_SIZE
```
    See Also:
    Constant Field Values
  - INFRASTRUCTURE_SIZE
```
public static final int INFRASTRUCTURE_SIZE
```
    See Also:
    Constant Field Values
  - MAX_TAG_LENGTH
```
public static final int MAX_TAG_LENGTH
```
    See Also:
    Constant Field Values
  - type
```
private final byte type
```
  - bytes
```
private final byte[] bytes
```
  - offset
```
private int offset
```
  - length
```
private int length
```
- Constructor Detail
  - Tag
```
public Tag(byte tagType,
   String tag)
```
  - Tag
```
public Tag(byte tagType,
   byte[] tag)
```
    Parameters:
    tagType -
    tag -
  - Tag
```
public Tag(byte[] bytes,
   int offset)
```
    Creates a Tag from the specified byte array and offset. Presumes bytes content starting at offset is formatted as a Tag blob. The bytes to include the tag type, tag length and actual tag bytes.
    
    Parameters:
    bytes - byte array
    offset - offset to start of Tag
  - Tag
```
public Tag(byte[] bytes,
   int offset,
   int length)
```
    Creates a Tag from the specified byte array, starting at offset, and for length length. Presumes bytes content starting at offset is formatted as a Tag blob.
    
    Parameters:
    bytes - byte array
    offset - offset to start of the Tag
    length - length of the Tag
- Method Detail
  - getLength
```
private static int getLength(byte[] bytes,
            int offset)
```
  - getBuffer
```
public byte[] getBuffer()
```
    Returns:
    The byte array backing this Tag.
  - getType
```
public byte getType()
```
    Returns:
    the tag type
  - getTagLength
```
public int getTagLength()
```
    Returns:
    Length of actual tag bytes within the backed buffer
  - getTagOffset
```
public int getTagOffset()
```
    Returns:
    Offset of actual tag bytes within the backed buffer
  - getValue
```
public byte[] getValue()
```
    Returns tag value in a new byte array. Primarily for use client-side. If server-side, use getBuffer() with appropriate getTagOffset() and getTagLength() instead to save on allocations.
    
    Returns:
    tag value in a new byte array.
  - asList
```
public static List<Tag> asList(byte[] b,
               int offset,
               int length)
```
    Creates the list of tags from the byte array b. Expected that b is in the expected tag format
    
    Parameters:
    b -
    offset -
    length -
    
    Returns:
    List of tags
  - fromList
```
public static byte[] fromList(List<Tag> tags)
```
    Write a list of tags into a byte array
    
    Parameters:
    tags -
    
    Returns:
    the serialized tag data as bytes
  - getTag
```
public static Tag getTag(byte[] b,
         int offset,
         int length,
         byte type)
```
    Retrieve the first tag from the tags byte array matching the passed in tag type
    
    Parameters:
    b -
    offset -
    length -
    type -
    
    Returns:
    null if there is no tag of the passed in tag type
  - getLength
```
int getLength()
```
    Returns the total length of the entire tag entity
  - getOffset
```
int getOffset()
```
    Returns the offset of the entire tag entity
  - carryForwardTags
```
public static List<Tag> carryForwardTags(Cell cell)
```
    Returns:
    A List of any Tags found in cell else null.
  - carryForwardTags
```
public static List<Tag> carryForwardTags(List<Tag> tagsOrNull,
                         Cell cell)
```
    Returns:
    Add to tagsOrNull any Tags cell is carrying or null if it is carrying no Tags AND the passed in tagsOrNull is null (else we return new List with Tags found).

Class Tag

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

TYPE_LENGTH_SIZE

TAG_LENGTH_SIZE

INFRASTRUCTURE_SIZE

MAX_TAG_LENGTH

type

bytes

offset

length

Constructor Detail

Tag

Tag

Tag

Tag

Method Detail

getLength

getBuffer

getType

getTagLength

getTagOffset

getValue

asList

fromList

getTag

getLength

getOffset

carryForwardTags

carryForwardTags