com.joanju
Class DataXferStream

java.lang.Object
  com.joanju.DataXferStream

public class DataXferStream
extends java.lang.Object

Serialize objects to a blob optimized for random access. Objects of this class must only be used within a single thread.

Several hours of searching the internet turned up many different tools for serialization, but none of them (that I could find) were designed with direct, fast random access as the primary consideration.

This and Xferable are designed such that it is self-describing, and if the output class 'schemas' are used correctly, there should never be a reason for the addition of new data fields added to the output to break any code using 'old' versions of the schema. Each byte offset is written with a field-reference-name, and the schema is written to every blob.

Constructor Summary

DataXferStream()

Method Summary

void	addSchemaFor(Xferable x) May be used for building an xfer blob just for schema purposes.
void	buildIndexes() Must be called after all objects have been stored.
java.io.ByteArrayOutputStream	getBytes() Once buildIndex() has been called, then use this to get the blob.
int	getIndexOffset()
int	getOffsetOf(java.lang.Object o) Get the offset of an object that's already been stored.
int	getSchemaMapOffset()
void	schemaBool(java.lang.String fieldName)
void	schemaInt(java.lang.String fieldName)
void	schemaRef(java.lang.String fieldName)
int	size() Get the size in bytes.
int	store(java.lang.Object o) Store an object and any object hierarchy that comes with it.
void	writeBool(boolean b) Called by Xferable.writeXferBytes() for boolean fields.
void	writeInt(int i) Called by Xferable.writeXferBytes() for int fields.
void	writeRef(java.lang.Object o) Called by Xferable.writeXferBytes().

Methods inherited from class java.lang.Object

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

Constructor Detail

DataXferStream

public DataXferStream()

Method Detail

addSchemaFor

public void addSchemaFor(Xferable x)

May be used for building an xfer blob just for schema purposes.

buildIndexes

public void buildIndexes()
                  throws java.io.IOException

Must be called after all objects have been stored.

Throws:

java.io.IOException

getBytes

public java.io.ByteArrayOutputStream getBytes()

Once buildIndex() has been called, then use this to get the blob.

getIndexOffset

public int getIndexOffset()

getSchemaMapOffset

public int getSchemaMapOffset()

getOffsetOf

public int getOffsetOf(java.lang.Object o)
                throws java.io.IOException

Get the offset of an object that's already been stored. Returns -1 if the object is not stored.

Throws:

java.io.IOException

schemaBool

public void schemaBool(java.lang.String fieldName)
                throws java.io.IOException

Throws:

java.io.IOException

schemaInt

public void schemaInt(java.lang.String fieldName)
               throws java.io.IOException

Throws:

java.io.IOException

schemaRef

public void schemaRef(java.lang.String fieldName)
               throws java.io.IOException

Throws:

java.io.IOException

size

public int size()

Get the size in bytes.

store

public int store(java.lang.Object o)
          throws java.io.IOException

Store an object and any object hierarchy that comes with it. The process that creates a DataXferStream would typically call this next, and this might be called multiple times, depending on how many object hierarchies are to be stored. After all object hierarchies have been stored, then buildIndex() should be called before getting the byte array. This is NOT TO BE CALLED FROM Xferable.writeXferBytes().

Returns:

The offset of the stored object record.

Throws:

java.io.IOException

writeBool

public void writeBool(boolean b)
               throws java.io.IOException

Called by Xferable.writeXferBytes() for boolean fields. Writes an single byte encoding for true or false.

Throws:

java.io.IOException

writeInt

public void writeInt(int i)
              throws java.io.IOException

Called by Xferable.writeXferBytes() for int fields. Writes a 4 byte int.

Throws:

java.io.IOException

writeRef

public void writeRef(java.lang.Object o)
              throws java.io.IOException

Called by Xferable.writeXferBytes(). Used for Strings, Collections, and any other Object references. Writes -1 for null, otherwise the index to the object's record (4 byte int).

Throws:

java.io.IOException