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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