SequenceFile.Reader (Hadoop 1.2.2-SNAPSHOT API)

java.lang.Object
- org.apache.hadoop.io.SequenceFile.Reader

所有已实现的接口:

Closeable, AutoCloseable

封闭类:

SequenceFile
```
public static class SequenceFile.Reader
extends Object
implements Closeable
```
Reads key/value pairs from a sequence-format file.

构造器概要

构造器
构造器和说明

SequenceFile.Reader(FileSystem fs, Path file, Configuration conf)
Open the named file.

构造器
构造器和说明
`SequenceFile.Reader(FileSystem fs, Path file, Configuration conf)` Open the named file.

方法概要

方法
限定符和类型	方法和说明
`void`	`close()` Close the file.
`SequenceFile.ValueBytes`	`createValueBytes()`
`CompressionCodec`	`getCompressionCodec()` Returns the compression codec of data in this file.
`Object`	`getCurrentValue(Object val)` Get the 'value' corresponding to the last read 'key'.
`void`	`getCurrentValue(Writable val)` Get the 'value' corresponding to the last read 'key'.
`Class<?>`	`getKeyClass()` Returns the class of keys in this file.
`String`	`getKeyClassName()` Returns the name of the key class.
`SequenceFile.Metadata`	`getMetadata()` Returns the metadata object of the file
`long`	`getPosition()` Return the current byte position in the input file.
`Class<?>`	`getValueClass()` Returns the class of values in this file.
`String`	`getValueClassName()` Returns the name of the value class.
`boolean`	`isBlockCompressed()` Returns true if records are block-compressed.
`boolean`	`isCompressed()` Returns true if values are compressed.
`int`	`next(DataOutputBuffer buffer)` 已过时。 Call `nextRaw(DataOutputBuffer,SequenceFile.ValueBytes)`.
`Object`	`next(Object key)` Read the next key in the file, skipping its value.
`boolean`	`next(Writable key)` Read the next key in the file into `key`, skipping its value.
`boolean`	`next(Writable key, Writable val)` Read the next key/value pair in the file into `key` and `val`.
`int`	`nextRaw(DataOutputBuffer key, SequenceFile.ValueBytes val)` Read 'raw' records.
`int`	`nextRawKey(DataOutputBuffer key)` Read 'raw' keys.
`int`	`nextRawValue(SequenceFile.ValueBytes val)` Read 'raw' values.
`protected FSDataInputStream`	`openFile(FileSystem fs, Path file, int bufferSize, long length)` Override this method to specialize the type of `FSDataInputStream` returned.
`void`	`seek(long position)` Set the current byte position in the input file.
`void`	`sync(long position)` Seek to the next sync mark past a given position.
`boolean`	`syncSeen()` Returns true iff the previous call to next passed a sync mark.
`String`	`toString()` Returns the name of the file.

从类继承的方法 java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- 构造器详细资料
  - SequenceFile.Reader
```
public SequenceFile.Reader(FileSystem fs,
                   Path file,
                   Configuration conf)
                    throws IOException
```
    Open the named file.
    
    抛出:
    
    IOException
- 方法详细资料
  - openFile
```
protected FSDataInputStream openFile(FileSystem fs,
                         Path file,
                         int bufferSize,
                         long length)
                              throws IOException
```
    Override this method to specialize the type of FSDataInputStream returned.
    
    抛出:
    
    IOException
  - close
```
public void close()
           throws IOException
```
    Close the file.
    
    指定者:
    
    close 在接口中 Closeable
    
    指定者:
    
    close 在接口中 AutoCloseable
    
    抛出:
    
    IOException
  - getKeyClassName
```
public String getKeyClassName()
```
    Returns the name of the key class.
  - getKeyClass
```
public Class<?> getKeyClass()
```
    Returns the class of keys in this file.
  - getValueClassName
```
public String getValueClassName()
```
    Returns the name of the value class.
  - getValueClass
```
public Class<?> getValueClass()
```
    Returns the class of values in this file.
  - isCompressed
```
public boolean isCompressed()
```
    Returns true if values are compressed.
  - isBlockCompressed
```
public boolean isBlockCompressed()
```
    Returns true if records are block-compressed.
  - getCompressionCodec
```
public CompressionCodec getCompressionCodec()
```
    Returns the compression codec of data in this file.
  - getMetadata
```
public SequenceFile.Metadata getMetadata()
```
    Returns the metadata object of the file
  - getCurrentValue
```
public void getCurrentValue(Writable val)
                     throws IOException
```
    Get the 'value' corresponding to the last read 'key'.
    
    参数:
    val - : The 'value' to be read.
    
    抛出:
    
    IOException
  - getCurrentValue
```
public Object getCurrentValue(Object val)
                       throws IOException
```
    Get the 'value' corresponding to the last read 'key'.
    
    参数:
    val - : The 'value' to be read.
    
    抛出:
    
    IOException
  - next
```
public boolean next(Writable key)
             throws IOException
```
    Read the next key in the file into key, skipping its value. True if another entry exists, and false at end of file.
    
    抛出:
    
    IOException
  - next
```
public boolean next(Writable key,
           Writable val)
             throws IOException
```
    Read the next key/value pair in the file into key and val. Returns true if such a pair exists and false when at end of file
    
    抛出:
    
    IOException
  - next
```
public int next(DataOutputBuffer buffer)
         throws IOException
```
    已过时。 Call nextRaw(DataOutputBuffer,SequenceFile.ValueBytes).
    
    抛出:
    
    IOException
  - createValueBytes
```
public SequenceFile.ValueBytes createValueBytes()
```
  - nextRaw
```
public int nextRaw(DataOutputBuffer key,
          SequenceFile.ValueBytes val)
            throws IOException
```
    Read 'raw' records.
    
    参数:
    key - - The buffer into which the key is read
    val - - The 'raw' value
    
    返回:
    Returns the total record length or -1 for end of file
    
    抛出:
    
    IOException
  - nextRawKey
```
public int nextRawKey(DataOutputBuffer key)
               throws IOException
```
    Read 'raw' keys.
    
    参数:
    key - - The buffer into which the key is read
    
    返回:
    Returns the key length or -1 for end of file
    
    抛出:
    
    IOException
  - next
```
public Object next(Object key)
            throws IOException
```
    Read the next key in the file, skipping its value. Return null at end of file.
    
    抛出:
    
    IOException
  - nextRawValue
```
public int nextRawValue(SequenceFile.ValueBytes val)
                 throws IOException
```
    Read 'raw' values.
    
    参数:
    val - - The 'raw' value
    
    返回:
    Returns the value length
    
    抛出:
    
    IOException
  - seek
```
public void seek(long position)
          throws IOException
```
    Set the current byte position in the input file.
    The position passed must be a position returned by SequenceFile.Writer.getLength() when writing this file. To seek to an arbitrary position, use sync(long).
    
    抛出:
    
    IOException
  - sync
```
public void sync(long position)
          throws IOException
```
    Seek to the next sync mark past a given position.
    
    抛出:
    
    IOException
  - syncSeen
```
public boolean syncSeen()
```
    Returns true iff the previous call to next passed a sync mark.
  - getPosition
```
public long getPosition()
                 throws IOException
```
    Return the current byte position in the input file.
    
    抛出:
    
    IOException
  - toString
```
public String toString()
```
    Returns the name of the file.
    
    覆盖:
    
    toString 在类中 Object

类 SequenceFile.Reader

构造器概要

方法概要

从类继承的方法 java.lang.Object

构造器详细资料

SequenceFile.Reader

方法详细资料

openFile

close

getKeyClassName

getKeyClass

getValueClassName

getValueClass

isCompressed

isBlockCompressed

getCompressionCodec

getMetadata

getCurrentValue

getCurrentValue

next

next

next

createValueBytes

nextRaw

nextRawKey

next

nextRawValue

seek

sync

syncSeen

getPosition

toString