public interface DataSerializable extends Serializable
ObjectOutputStream
, a
DataSerializable
can serialize itself to a DataOutput
. By implementing this
interface, objects can be serialized faster and in a more compact format than standard Java
serialization. The DataSerializer
class contains a number of static methods that may be
helpful to implementations of DataSerializable
.
When possible, GemFire respects the DataSerializable
contract to provide optimal
object serialization. For instance, if a DataSerializable
object is
placed into a distributed cache
region, its toData
method will be used to serialize it when it is sent to another
member of the distributed system.
To avoid the overhead of Java reflection, DataSerializable
classes may register an
Instantiator
to be used during deserialization. Alternatively, classes that implement
DataSerializable
can provide a zero-argument constructor that will be invoked when
they are read with DataSerializer.readObject(java.io.DataInput)
.
Some classes (especially third-party classes that you may not have the source code to) cannot be
modified to implement DataSerializable
. These classes can be data serialized by an
instance of DataSerializer
.
DataSerializable
offers improved performance over standard Java serialization, but
does not offer all of the features of standard Java serialization. In particular, data
serialization does not attempt to maintain referential integrity among the objects it is writing
or reading. As a result, data serialization should not be used with complex object graphs.
Attempting to data serialize graphs that contain object cycles will result in infinite recursion
and a StackOverflowError
. Attempting to deserialize an object graph that contains
multiple reference paths to the same object will result in multiple copies of the objects that
are referred to through multiple paths.
Serializable
,
DataSerializer
,
Instantiator
Modifier and Type | Interface and Description |
---|---|
static interface |
DataSerializable.Replaceable
Replaceable allows an object to write an alternative version of itself to a
DataOutput . |
Modifier and Type | Method and Description |
---|---|
void |
fromData(DataInput in)
Reads the state of this object as primitive data from the given
DataInput . |
void |
toData(DataOutput out)
Writes the state of this object as primitive data to the given
DataOutput . |
void toData(DataOutput out) throws IOException
DataOutput
.
Since 5.7 it is possible for any method call to the specified DataOutput
to throw
GemFireRethrowable
. It should not be caught by user code. If it is it
must be rethrown.
out
- the DataOutput
to write toIOException
- A problem occurs while writing to out
void fromData(DataInput in) throws IOException, ClassNotFoundException
DataInput
.in
- the DataInput
to read fromIOException
- A problem occurs while reading from in
ClassNotFoundException
- A class could not be loaded while reading from in