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:

BlockingBinaryEncoder

public class BinaryEncoder
extends Encoder

Low-level support for serializing Avro values. This class has two types of methods. One type of methods support the writing of leaf values (for example, writeLong(long) and writeString(org.apache.avro.util.Utf8)). These methods have analogs in Decoder. The other type of methods support the writing of maps and arrays. These methods are writeArrayStart(), startItem(), and writeArrayEnd() (and similar methods for maps). Some implementations of Encoder handle the buffering required to break large maps and arrays into blocks, which is necessary for applications that want to do streaming. (See writeArrayStart() for details on these methods.)

See Also:

Decoder

Field Summary

protected OutputStream

out

Constructor Summary

BinaryEncoder(OutputStream out)
Create a writer that sends its output to the underlying stream out.

Method Summary

protected static int	encodeDouble(double d, byte[] b, int pos)
protected static void	encodeDouble(double d, OutputStream o)
protected static int	encodeFloat(float f, byte[] b, int pos)
protected static void	encodeFloat(float f, OutputStream o)
protected static int	encodeLong(long n, byte[] b, int pos)
protected static void	encodeLong(long n, OutputStream o)
void	flush()
void	init(OutputStream out) Redirect output (and reset the parser state if we're checking).
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	writeBoolean(boolean b) Write a boolean value.
void	writeBytes(byte[] bytes, int start, int len) Write a byte string.
void	writeBytes(ByteBuffer bytes) Write a byte string.
void	writeDouble(double d) Write a double.
void	writeEnum(int e) Writes an enumeration.
void	writeFixed(byte[] bytes, int start, int len) Writes a fixed size binary object.
void	writeFloat(float f) Write a float.
void	writeIndex(int unionIndex) Call this method to write the tag of a union.
void	writeInt(int n) Writes a 32-bit integer.
void	writeLong(long n) Write a 64-bit integer.
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.

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

writeBytes, writeFixed, writeString

Methods inherited from class java.lang.Object

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

Field Detail

out

protected OutputStream out

Constructor Detail

BinaryEncoder

public BinaryEncoder(OutputStream out)

Create a writer that sends its output to the underlying stream out.

Method Detail

init

public void init(OutputStream out)
          throws IOException

Description copied from class: Encoder

Redirect output (and reset the parser state if we're checking).

Specified by:

init in class Encoder

Throws:

IOException

flush

public void flush()
           throws IOException

Throws:

IOException

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

writeBoolean

public void writeBoolean(boolean b)
                  throws IOException

Description copied from class: Encoder

Write a boolean value.

Specified by:

writeBoolean in class Encoder

Throws:

IOException

writeInt

public void writeInt(int n)
              throws IOException

Description copied from class: Encoder

Writes a 32-bit integer.

Specified by:

writeInt in class Encoder

Throws:

IOException

writeLong

public void writeLong(long n)
               throws IOException

Description copied from class: Encoder

Write a 64-bit integer.

Specified by:

writeLong in class Encoder

Throws:

IOException

writeFloat

public void writeFloat(float f)
                throws IOException

Description copied from class: Encoder

Write a float.

Specified by:

writeFloat in class Encoder

Throws:

IOException

writeDouble

public void writeDouble(double d)
                 throws IOException

Description copied from class: Encoder

Write a double.

Specified by:

writeDouble 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

writeFixed

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

Description copied from class: Encoder

Writes a fixed size binary object.

Specified by:

writeFixed in class Encoder

Parameters:

bytes - The contents to write

start - The position within bytes where the contents start.

len - The number of bytes to write.

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

encodeLong

protected static void encodeLong(long n,
                                 OutputStream o)
                          throws IOException

Throws:

IOException

encodeLong

protected static int encodeLong(long n,
                                byte[] b,
                                int pos)

encodeFloat

protected static void encodeFloat(float f,
                                  OutputStream o)
                           throws IOException

Throws:

IOException

encodeFloat

protected static int encodeFloat(float f,
                                 byte[] b,
                                 int pos)

encodeDouble

protected static void encodeDouble(double d,
                                   OutputStream o)
                            throws IOException

Throws:

IOException

encodeDouble

protected static int encodeDouble(double d,
                                  byte[] b,
                                  int pos)