public abstract class Encoder extends Object implements Flushable
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.)
EncoderFactory
contains Encoder construction and configuration
facilities.EncoderFactory
,
Decoder
Constructor and Description |
---|
Encoder() |
Modifier and Type | Method and Description |
---|---|
abstract void |
setItemCount(long itemCount)
Call this method before writing a batch of items in an array or a map.
|
abstract void |
startItem()
Start a new item of an array or map.
|
abstract void |
writeArrayEnd()
Call this method to finish writing an array.
|
abstract void |
writeArrayStart()
Call this method to start writing an array.
|
abstract void |
writeBoolean(boolean b)
Write a boolean value.
|
void |
writeBytes(byte[] bytes)
Writes a byte string.
|
abstract void |
writeBytes(byte[] bytes,
int start,
int len)
Write a byte string.
|
abstract void |
writeBytes(ByteBuffer bytes)
Write a byte string.
|
abstract void |
writeDouble(double d)
Write a double.
|
abstract void |
writeEnum(int e)
Writes an enumeration.
|
void |
writeFixed(byte[] bytes)
A shorthand for writeFixed(bytes, 0, bytes.length)
|
abstract void |
writeFixed(byte[] bytes,
int start,
int len)
Writes a fixed size binary object.
|
void |
writeFixed(ByteBuffer bytes)
Writes a fixed from a ByteBuffer.
|
abstract void |
writeFloat(float f)
Write a float.
|
abstract void |
writeIndex(int unionIndex)
Call this method to write the tag of a union.
|
abstract void |
writeInt(int n)
Writes a 32-bit integer.
|
abstract void |
writeLong(long n)
Write a 64-bit integer.
|
abstract void |
writeMapEnd()
Call this method to terminate the inner-most, currently-opened map.
|
abstract void |
writeMapStart()
Call this to start a new map.
|
abstract void |
writeNull()
"Writes" a null value.
|
void |
writeString(CharSequence charSequence)
Write a Unicode character string.
|
void |
writeString(String str)
Write a Unicode character string.
|
abstract void |
writeString(Utf8 utf8)
Write a Unicode character string.
|
public abstract void writeNull() throws IOException
AvroTypeException
- If this is a stateful writer and a null is not
expectedIOException
public abstract void writeBoolean(boolean b) throws IOException
AvroTypeException
- If this is a stateful writer and a boolean is not
expectedIOException
public abstract void writeInt(int n) throws IOException
AvroTypeException
- If this is a stateful writer and an integer is not
expectedIOException
public abstract void writeLong(long n) throws IOException
AvroTypeException
- If this is a stateful writer and a long is not
expectedIOException
public abstract void writeFloat(float f) throws IOException
IOException
AvroTypeException
- If this is a stateful writer and a float is not
expectedpublic abstract void writeDouble(double d) throws IOException
AvroTypeException
- If this is a stateful writer and a double is not
expectedIOException
public abstract void writeString(Utf8 utf8) throws IOException
AvroTypeException
- If this is a stateful writer and a char-string is
not expectedIOException
public void writeString(String str) throws IOException
Utf8
. Some Encoder implementations
may want to do something different as a performance optimization.AvroTypeException
- If this is a stateful writer and a char-string is
not expectedIOException
public void writeString(CharSequence charSequence) throws IOException
Utf8
it writes this directly, otherwise the
CharSequence is converted to a String via toString() and written.AvroTypeException
- If this is a stateful writer and a char-string is
not expectedIOException
public abstract void writeBytes(ByteBuffer bytes) throws IOException
AvroTypeException
- If this is a stateful writer and a byte-string is
not expectedIOException
public abstract void writeBytes(byte[] bytes, int start, int len) throws IOException
AvroTypeException
- If this is a stateful writer and a byte-string is
not expectedIOException
public void writeBytes(byte[] bytes) throws IOException
IOException
AvroTypeException
- If this is a stateful writer and a byte-string is
not expectedpublic abstract void writeFixed(byte[] bytes, int start, int len) throws IOException
bytes
- The contents to writestart
- The position within bytes where the contents start.len
- The number of bytes to write.AvroTypeException
- If this is a stateful writer and a byte-string is
not expectedIOException
public void writeFixed(byte[] bytes) throws IOException
bytes
- IOException
public void writeFixed(ByteBuffer bytes) throws IOException
IOException
public abstract void writeEnum(int e) throws IOException
e
- AvroTypeException
- If this is a stateful writer and an enumeration is
not expected or the e is out of range.IOException
public abstract void writeArrayStart() throws IOException
writeArrayStart()
. Then,
before writing any data for any item call setItemCount(long)
followed by a
sequence of startItem()
and the item itself. The number of
startItem()
should match the number specified in
setItemCount(long)
. When actually writing the data of the item, you can
call any Encoder
method (e.g., writeLong(long)
). When all items of
the array have been written, call 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();
AvroTypeException
- If this is a stateful writer and an array is not
expectedIOException
public abstract void setItemCount(long itemCount) throws IOException
startItem()
followed by any of the other write
methods of Encoder
. The number of calls to startItem()
must
be equal to the count specified in setItemCount(long)
. Once a batch is
completed you can start another batch with setItemCount(long)
.itemCount
- The number of startItem()
calls to follow.IOException
public abstract void startItem() throws IOException
writeArrayStart()
for usage
information.AvroTypeException
- If called outside of an array or map contextIOException
public abstract void writeArrayEnd() throws IOException
writeArrayStart()
for
usage information.AvroTypeException
- If items written does not match count provided to
writeArrayStart()
AvroTypeException
- If not currently inside an arrayIOException
public abstract void writeMapStart() throws IOException
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.Entryentry : map.entrySet()) { out.startItem(); out.writeString(entry.getKey()); out.writeLong(entry.getValue().longField); out.writeBoolean(entry.getValue().boolField); } out.writeMapEnd();
AvroTypeException
- If this is a stateful writer and a map is not
expectedIOException
public abstract void writeMapEnd() throws IOException
writeArrayStart()
for more details.AvroTypeException
- If items written does not match count provided to
writeMapStart()
AvroTypeException
- If not currently inside a mapIOException
public abstract void writeIndex(int unionIndex) throws IOException
out.writeIndex(1); out.writeLong(record.longField); out.writeBoolean(record.boolField);
AvroTypeException
- If this is a stateful writer and a map is not
expectedIOException
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