HFileScanner (Apache HBase 1.4.11 API)

All Known Implementing Classes:

AbstractHFileReader.Scanner, HFileReaderV2.AbstractScannerV2, HFileReaderV2.EncodedScannerV2, HFileReaderV2.ScannerV2, HFileReaderV3.EncodedScannerV3, HFileReaderV3.ScannerV3
```
@InterfaceAudience.Private
public interface HFileScanner
```
A scanner allows you to position yourself within a HFile and scan through it. It allows you to reposition yourself as well.
A scanner doesn't always have a key/value that it is pointing to when it is first created and before seekTo()/seekTo(byte[]) are called. In this case, getKey()/getValue() returns null. At most other times, a key and value will be available. The general pattern is that you position the Scanner using the seekTo variants and then getKey and getValue.

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`close()` Close the stream socket to handle RS CLOSE_WAIT.
`ByteBuffer`	`getKey()` Gets a buffer view to the current key.
`String`	`getKeyString()` Convenience method to get a copy of the key as a string - interpreting the bytes as UTF8.
`Cell`	`getKeyValue()`
`Cell`	`getNextIndexedKey()`
`HFile.Reader`	`getReader()`
`ByteBuffer`	`getValue()` Gets a buffer view to the current value.
`String`	`getValueString()` Convenience method to get a copy of the value as a string - interpreting the bytes as UTF8.
`boolean`	`isSeeked()`
`boolean`	`next()` Scans to the next entry in the file.
`int`	`reseekTo(byte[] key)` Deprecated.
`int`	`reseekTo(byte[] key, int offset, int length)` Deprecated.
`int`	`reseekTo(Cell c)`
`boolean`	`seekBefore(byte[] key)` Deprecated.
`boolean`	`seekBefore(byte[] key, int offset, int length)` Deprecated.
`boolean`	`seekBefore(Cell kv)`
`boolean`	`seekTo()` Positions this scanner at the start of the file.
`int`	`seekTo(byte[] key)` Deprecated.
`int`	`seekTo(byte[] key, int offset, int length)` Deprecated.
`int`	`seekTo(Cell c)`

- Method Detail
  - seekTo
```
@Deprecated
int seekTo(byte[] key)
           throws IOException
```
    Deprecated.
    
    SeekTo or just before the passed key. Examine the return code to figure whether we found the key or not. Consider the key stream of all the keys in the file, k[0] .. k[n], where there are n keys in the file.
    
    Parameters:
    key - Key to find.
    
    Returns:
    -1, if key < k[0], no position; 0, such that k[i] = key and scanner is left in position i; and 1, such that k[i] < key, and scanner is left in position i. The scanner will position itself between k[i] and k[i+1] where k[i] < key <= k[i+1]. If there is no key k[i+1] greater than or equal to the input key, then the scanner will position itself at the end of the file and next() will return false when it is called.
    
    Throws:
    
    IOException
  - seekTo
```
@Deprecated
int seekTo(byte[] key,
                    int offset,
                    int length)
           throws IOException
```
    Deprecated.
    
    Throws:
    
    IOException
  - seekTo
```
int seekTo(Cell c)
           throws IOException
```
    Throws:
    
    IOException
  - reseekTo
```
@Deprecated
int reseekTo(byte[] key)
             throws IOException
```
    Deprecated.
    
    Reseek to or just before the passed key. Similar to seekTo except that this can be called even if the scanner is not at the beginning of a file. This can be used to seek only to keys which come after the current position of the scanner. Consider the key stream of all the keys in the file, k[0] .. k[n], where there are n keys in the file after current position of HFileScanner. The scanner will position itself between k[i] and k[i+1] where k[i] < key <= k[i+1]. If there is no key k[i+1] greater than or equal to the input key, then the scanner will position itself at the end of the file and next() will return false when it is called.
    
    Parameters:
    key - Key to find (should be non-null)
    
    Returns:
    -1, if key < k[0], no position; 0, such that k[i] = key and scanner is left in position i; and 1, such that k[i] < key, and scanner is left in position i.
    
    Throws:
    
    IOException
  - reseekTo
```
@Deprecated
int reseekTo(byte[] key,
                      int offset,
                      int length)
             throws IOException
```
    Deprecated.
    
    Throws:
    
    IOException
  - reseekTo
```
int reseekTo(Cell c)
             throws IOException
```
    Throws:
    
    IOException
  - seekBefore
```
@Deprecated
boolean seekBefore(byte[] key)
                   throws IOException
```
    Deprecated.
    
    Consider the key stream of all the keys in the file, k[0] .. k[n], where there are n keys in the file.
    
    Parameters:
    key - Key to find
    
    Returns:
    false if key <= k[0] or true with scanner in position 'i' such that: k[i] < key. Furthermore: there may be a k[i+1], such that k[i] < key <= k[i+1] but there may also NOT be a k[i+1], and next() will return false (EOF).
    
    Throws:
    
    IOException
  - seekBefore
```
@Deprecated
boolean seekBefore(byte[] key,
                            int offset,
                            int length)
                   throws IOException
```
    Deprecated.
    
    Throws:
    
    IOException
  - seekBefore
```
boolean seekBefore(Cell kv)
                   throws IOException
```
    Throws:
    
    IOException
  - seekTo
```
boolean seekTo()
               throws IOException
```
    Positions this scanner at the start of the file.
    
    Returns:
    False if empty file; i.e. a call to next would return false and the current key and value are undefined.
    
    Throws:
    
    IOException
  - next
```
boolean next()
             throws IOException
```
    Scans to the next entry in the file.
    
    Returns:
    Returns false if you are at the end otherwise true if more in file.
    
    Throws:
    
    IOException
  - getKey
```
ByteBuffer getKey()
```
    Gets a buffer view to the current key. You must call seekTo(byte[]) before this method.
    
    Returns:
    byte buffer for the key. The limit is set to the key size, and the position is 0, the start of the buffer view.
  - getValue
```
ByteBuffer getValue()
```
    Gets a buffer view to the current value. You must call seekTo(byte[]) before this method.
    
    Returns:
    byte buffer for the value. The limit is set to the value size, and the position is 0, the start of the buffer view.
  - getKeyValue
```
Cell getKeyValue()
```
    Returns:
    Instance of KeyValue.
  - getKeyString
```
String getKeyString()
```
    Convenience method to get a copy of the key as a string - interpreting the bytes as UTF8. You must call seekTo(byte[]) before this method.
    
    Returns:
    key as a string
  - getValueString
```
String getValueString()
```
    Convenience method to get a copy of the value as a string - interpreting the bytes as UTF8. You must call seekTo(byte[]) before this method.
    
    Returns:
    value as a string
  - getReader
```
HFile.Reader getReader()
```
    Returns:
    Reader that underlies this Scanner instance.
  - isSeeked
```
boolean isSeeked()
```
    Returns:
    True is scanner has had one of the seek calls invoked; i.e. seekBefore(byte[]) or seekTo() or seekTo(byte[]). Otherwise returns false.
  - getNextIndexedKey
```
Cell getNextIndexedKey()
```
    Returns:
    the next key in the index (the key to seek to the next block)
  - close
```
void close()
```
    Close the stream socket to handle RS CLOSE_WAIT. HBASE-9393

Interface HFileScanner

Method Summary

Method Detail

seekTo

seekTo

seekTo

reseekTo

reseekTo

reseekTo

seekBefore

seekBefore

seekBefore

seekTo

next

getKey

getValue

getKeyValue

getKeyString

getValueString

getReader

isSeeked

getNextIndexedKey

close