org.apache.avro.io

Class BinaryEncoder

java.lang.Object

org.apache.avro.io.Encoder

org.apache.avro.io.BinaryEncoder

All Implemented Interfaces:

Flushable

Direct Known Subclasses:

BufferedBinaryEncoder, DirectBinaryEncoder

public abstract class BinaryEncoder
extends Encoder

An abstract Encoder for Avro's binary encoding.

To construct and configure instances, use EncoderFactory

See Also:

EncoderFactory, BufferedBinaryEncoder, DirectBinaryEncoder, BlockingBinaryEncoder, Encoder, Decoder

Constructor Summary

Constructors

Constructor and Description
BinaryEncoder()

Method Summary

Modifier and Type	Method and Description
abstract int	bytesBuffered() Returns the number of bytes currently buffered by this encoder.
void	setItemCount(long itemCount) Call this method before writing a batch of items in an array or a map.
void	startItem() Start a new item of an array or map.
void	writeArrayEnd() Call this method to finish writing an array.
void	writeArrayStart() Call this method to start writing an array.
void	writeBytes(byte[] bytes, int start, int len) Write a byte string.
void	writeBytes(ByteBuffer bytes) Write a byte string.
void	writeEnum(int e) Writes an enumeration.
void	writeIndex(int unionIndex) Call this method to write the tag of a union.
void	writeMapEnd() Call this method to terminate the inner-most, currently-opened map.
void	writeMapStart() Call this to start a new map.
void	writeNull() "Writes" a null value.
void	writeString(String string) Write a Unicode character string.
void	writeString(Utf8 utf8) Write a Unicode character string.
protected abstract void	writeZero() Write a zero byte to the underlying output.

Methods inherited from class org.apache.avro.io.Encoder

writeBoolean, writeBytes, writeDouble, writeFixed, writeFixed, writeFixed, writeFloat, writeInt, writeLong, writeString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.io.Flushable

flush

Constructor Detail

BinaryEncoder

public BinaryEncoder()

Method Detail

writeNull

public void writeNull()
               throws IOException

Description copied from class: Encoder

"Writes" a null value. (Doesn't actually write anything, but advances the state of the parser if this class is stateful.)

Specified by:

writeNull in class Encoder

Throws:

IOException

writeString

public void writeString(Utf8 utf8)
                 throws IOException

Description copied from class: Encoder

Write a Unicode character string.

Specified by:

writeString in class Encoder

Throws:

IOException

writeString

public void writeString(String string)
                 throws IOException

Description copied from class: Encoder

Write a Unicode character string. The default implementation converts the String to a Utf8. Some Encoder implementations may want to do something different as a performance optimization.

Overrides:

writeString in class Encoder

Throws:

IOException

writeBytes

public void writeBytes(ByteBuffer bytes)
                throws IOException

Description copied from class: Encoder

Write a byte string.

Specified by:

writeBytes in class Encoder

Throws:

IOException

writeBytes

public void writeBytes(byte[] bytes,
                       int start,
                       int len)
                throws IOException

Description copied from class: Encoder

Write a byte string.

Specified by:

writeBytes in class Encoder

Throws:

IOException

writeEnum

public void writeEnum(int e)
               throws IOException

Description copied from class: Encoder

Writes an enumeration.

Specified by:

writeEnum in class Encoder

Throws:

IOException

writeArrayStart

public void writeArrayStart()
                     throws IOException

Description copied from class: Encoder

Call this method to start writing an array. When starting to serialize an array, call Encoder.writeArrayStart(). Then, before writing any data for any item call Encoder.setItemCount(long) followed by a sequence of Encoder.startItem() and the item itself. The number of Encoder.startItem() should match the number specified in Encoder.setItemCount(long). When actually writing the data of the item, you can call any Encoder method (e.g., Encoder.writeLong(long)). When all items of the array have been written, call Encoder.writeArrayEnd(). As an example, let's say you want to write an array of records, the record consisting of an Long field and a Boolean field. Your code would look something like this:

 out.writeArrayStart();
 out.setItemCount(list.size());
 for (Record r : list) {
   out.startItem();
   out.writeLong(r.longField);
   out.writeBoolean(r.boolField);
 }
 out.writeArrayEnd();
 

Specified by:

writeArrayStart in class Encoder

Throws:

IOException

setItemCount

public void setItemCount(long itemCount)
                  throws IOException

Description copied from class: Encoder

Call this method before writing a batch of items in an array or a map. Then for each item, call Encoder.startItem() followed by any of the other write methods of Encoder. The number of calls to Encoder.startItem() must be equal to the count specified in Encoder.setItemCount(long). Once a batch is completed you can start another batch with Encoder.setItemCount(long).

Specified by:

setItemCount in class Encoder

Parameters:

itemCount - The number of Encoder.startItem() calls to follow.

Throws:

IOException

startItem

public void startItem()
               throws IOException

Description copied from class: Encoder

Start a new item of an array or map. See Encoder.writeArrayStart() for usage information.

Specified by:

startItem in class Encoder

Throws:

IOException

writeArrayEnd

public void writeArrayEnd()
                   throws IOException

Description copied from class: Encoder

Call this method to finish writing an array. See Encoder.writeArrayStart() for usage information.

Specified by:

writeArrayEnd in class Encoder

Throws:

IOException

writeMapStart

public void writeMapStart()
                   throws IOException

Description copied from class: Encoder

Call this to start a new map. See Encoder.writeArrayStart() for details on usage. As an example of usage, let's say you want to write a map of records, the record consisting of an Long field and a Boolean field. Your code would look something like this:

 out.writeMapStart();
 out.setItemCount(list.size());
 for (Map.Entry entry : map.entrySet()) {
   out.startItem();
   out.writeString(entry.getKey());
   out.writeLong(entry.getValue().longField);
   out.writeBoolean(entry.getValue().boolField);
 }
 out.writeMapEnd();
 

Specified by:

writeMapStart in class Encoder

Throws:

IOException

writeMapEnd

public void writeMapEnd()
                 throws IOException

Description copied from class: Encoder

Call this method to terminate the inner-most, currently-opened map. See Encoder.writeArrayStart() for more details.

Specified by:

writeMapEnd in class Encoder

Throws:

IOException

writeIndex

public void writeIndex(int unionIndex)
                throws IOException

Description copied from class: Encoder

Call this method to write the tag of a union. As an example of usage, let's say you want to write a union, whose second branch is a record consisting of an Long field and a Boolean field. Your code would look something like this:

 out.writeIndex(1);
 out.writeLong(record.longField);
 out.writeBoolean(record.boolField);
 

Specified by:

writeIndex in class Encoder

Throws:

IOException

writeZero

protected abstract void writeZero()
                           throws IOException

Write a zero byte to the underlying output.

Throws:

IOException

bytesBuffered

public abstract int bytesBuffered()

Returns the number of bytes currently buffered by this encoder. If this Encoder does not buffer, this will always return zero.

Call Flushable.flush() to empty the buffer to the underlying output.