public abstract class Decoder extends Object
readLong()
and readString(org.apache.avro.util.Utf8)
).
The other type of methods support the reading of maps and arrays. These
methods are readArrayStart()
, arrayNext()
, and similar methods
for maps). See readArrayStart()
for details on these methods.)
DecoderFactory
contains Decoder construction and configuration
facilities.DecoderFactory
,
Encoder
Constructor and Description |
---|
Decoder() |
Modifier and Type | Method and Description |
---|---|
abstract long |
arrayNext()
Processes the next block of an array and returns the number of items in the
block and let's the caller read those items.
|
abstract long |
mapNext()
Processes the next block of map entries and returns the count of them.
|
abstract long |
readArrayStart()
Reads and returns the size of the first block of an array.
|
abstract boolean |
readBoolean()
Reads a boolean value written by
Encoder.writeBoolean(boolean) . |
abstract ByteBuffer |
readBytes(ByteBuffer old)
Reads a byte-string written by
Encoder.writeBytes(java.nio.ByteBuffer) . |
abstract double |
readDouble()
Reads a double written by
Encoder.writeDouble(double) . |
abstract int |
readEnum()
Reads an enumeration.
|
void |
readFixed(byte[] bytes)
A shorthand for readFixed(bytes, 0, bytes.length).
|
abstract void |
readFixed(byte[] bytes,
int start,
int length)
Reads fixed sized binary object.
|
abstract float |
readFloat()
Reads a float written by
Encoder.writeFloat(float) . |
abstract int |
readIndex()
Reads the tag of a union written by
Encoder.writeIndex(int) . |
abstract int |
readInt()
Reads an integer written by
Encoder.writeInt(int) . |
abstract long |
readLong()
Reads a long written by
Encoder.writeLong(long) . |
abstract long |
readMapStart()
Reads and returns the size of the next block of map-entries.
|
abstract void |
readNull()
"Reads" a null value.
|
abstract String |
readString()
Reads a char-string written by
Encoder.writeString(org.apache.avro.util.Utf8) . |
abstract Utf8 |
readString(Utf8 old)
Reads a char-string written by
Encoder.writeString(org.apache.avro.util.Utf8) . |
abstract long |
skipArray()
Used for quickly skipping through an array.
|
abstract void |
skipBytes()
Discards a byte-string written by
Encoder.writeBytes(java.nio.ByteBuffer) . |
abstract void |
skipFixed(int length)
Discards fixed sized binary object.
|
abstract long |
skipMap()
Support for quickly skipping through a map similar to
skipArray() . |
abstract void |
skipString()
Discards a char-string written by
Encoder.writeString(org.apache.avro.util.Utf8) . |
public abstract void readNull() throws IOException
AvroTypeException
- If this is a stateful reader and null is not the
type of the next value to be readIOException
public abstract boolean readBoolean() throws IOException
Encoder.writeBoolean(boolean)
.AvroTypeException
- If this is a stateful reader and boolean is not the
type of the next value to be readIOException
public abstract int readInt() throws IOException
Encoder.writeInt(int)
.AvroTypeException
- If encoded value is larger than 32-bitsAvroTypeException
- If this is a stateful reader and int is not the
type of the next value to be readIOException
public abstract long readLong() throws IOException
Encoder.writeLong(long)
.AvroTypeException
- If this is a stateful reader and long is not the
type of the next value to be readIOException
public abstract float readFloat() throws IOException
Encoder.writeFloat(float)
.AvroTypeException
- If this is a stateful reader and is not the type of
the next value to be readIOException
public abstract double readDouble() throws IOException
Encoder.writeDouble(double)
.AvroTypeException
- If this is a stateful reader and is not the type of
the next value to be readIOException
public abstract Utf8 readString(Utf8 old) throws IOException
Encoder.writeString(org.apache.avro.util.Utf8)
.AvroTypeException
- If this is a stateful reader and char-string is not
the type of the next value to be readIOException
public abstract String readString() throws IOException
Encoder.writeString(org.apache.avro.util.Utf8)
.AvroTypeException
- If this is a stateful reader and char-string is not
the type of the next value to be readIOException
public abstract void skipString() throws IOException
Encoder.writeString(org.apache.avro.util.Utf8)
.AvroTypeException
- If this is a stateful reader and char-string is not
the type of the next value to be readIOException
public abstract ByteBuffer readBytes(ByteBuffer old) throws IOException
Encoder.writeBytes(java.nio.ByteBuffer)
. if old is
not null and has sufficient capacity to take in the bytes being read, the
bytes are returned in old.AvroTypeException
- If this is a stateful reader and byte-string is not
the type of the next value to be readIOException
public abstract void skipBytes() throws IOException
Encoder.writeBytes(java.nio.ByteBuffer)
.AvroTypeException
- If this is a stateful reader and byte-string is not
the type of the next value to be readIOException
public abstract void readFixed(byte[] bytes, int start, int length) throws IOException
bytes
- The buffer to store the contents being read.start
- The position where the data needs to be written.length
- The size of the binary object.AvroTypeException
- If this is a stateful reader and fixed sized binary
object is not the type of the next value to be read
or the length is incorrect.IOException
public void readFixed(byte[] bytes) throws IOException
AvroTypeException
- If this is a stateful reader and fixed sized binary
object is not the type of the next value to be read
or the length is incorrect.IOException
public abstract void skipFixed(int length) throws IOException
length
- The size of the binary object to be skipped.AvroTypeException
- If this is a stateful reader and fixed sized binary
object is not the type of the next value to be read
or the length is incorrect.IOException
public abstract int readEnum() throws IOException
AvroTypeException
- If this is a stateful reader and enumeration is not
the type of the next value to be read.IOException
public abstract long readArrayStart() throws IOException
arrayNext()
to find out the number of items in the next
block. The typical pattern for consuming an array looks like:
for(long i = in.readArrayStart(); i != 0; i = in.arrayNext()) { for (long j = 0; j < i; j++) { read next element of the array; } }
AvroTypeException
- If this is a stateful reader and array is not the
type of the next value to be readIOException
public abstract long arrayNext() throws IOException
AvroTypeException
- When called outside of an array contextIOException
public abstract long skipArray() throws IOException
readArrayStart()
), but
you can't mix the two on the same array.
This method will skip through as many items as it can, all of them if
possible. It will return zero if there are no more items to skip through, or
an item count if it needs the client's help in skipping. The typical usage
pattern is:
for(long i = in.skipArray(); i != 0; i = i.skipArray()) { for (long j = 0; j < i; j++) { read and discard the next element of the array; } }Note that this method can automatically skip through items if a byte-count is found in the underlying data, or if a schema has been provided to the implementation, but otherwise the client will have to skip through items itself.
AvroTypeException
- If this is a stateful reader and array is not the
type of the next value to be readIOException
public abstract long readMapStart() throws IOException
readArrayStart()
.
As an example, let's say you want to read a map of records, the record
consisting of an Long field and a Boolean field. Your code would look
something like this:
Mapm = new HashMap (); Record reuse = new Record(); for (long i = in.readMapStart(); i != 0; i = in.readMapNext()) { for (long j = 0; j < i; j++) { String key = in.readString(); reuse.intField = in.readInt(); reuse.boolField = in.readBoolean(); m.put(key, reuse); } }
AvroTypeException
- If this is a stateful reader and map is not the
type of the next value to be readIOException
public abstract long mapNext() throws IOException
arrayNext()
. See readMapStart()
for details.AvroTypeException
- When called outside of a map contextIOException
public abstract long skipMap() throws IOException
skipArray()
.
As an example, let's say you want to skip a map of records, the record
consisting of an Long field and a Boolean field. Your code would look
something like this:
for (long i = in.skipMap(); i != 0; i = in.skipMap()) { for (long j = 0; j < i; j++) { in.skipString(); // Discard key in.readInt(); // Discard int-field of value in.readBoolean(); // Discard boolean-field of value } }
AvroTypeException
- If this is a stateful reader and array is not the
type of the next value to be readIOException
public abstract int readIndex() throws IOException
Encoder.writeIndex(int)
.AvroTypeException
- If this is a stateful reader and union is not the
type of the next value to be readIOException
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