Package org.postgresql.util

Interface ByteStreamWriter

All Known Implementing Classes:

ByteBufferByteStreamWriter

public interface ByteStreamWriter

A class that can be used to set a byte array parameter by writing to an OutputStream.

The intended use case is wanting to write data to a byte array parameter that is stored off heap in a direct memory pool or in some other form that is inconvenient to assemble into a single heap-allocated buffer.

Users should write their own implementation depending on the original data source. The driver provides a built-in implementation supporting the ByteBuffer class, see ByteBufferByteStreamWriter.

Intended usage is to simply pass in an instance using PreparedStatement.setObject(int, Object):

     int bufLength = someBufferObject.length();
     preparedStatement.setObject(1, new MyByteStreamWriter(bufLength, someBufferObject));
 

The length must be known ahead of the stream being written to.

This provides the application more control over memory management than calling PreparedStatement.setBinaryStream(int, InputStream) as with the latter the caller has no control over the buffering strategy.

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static interface	ByteStreamWriter.ByteStreamTarget	Provides a target to write bytes to.

Method Summary

Modifier and Type	Method	Description
int	getLength()	Returns the length of the stream.
static ByteStreamWriter	of(ByteBuffer... buf)
void	writeTo(ByteStreamWriter.ByteStreamTarget target)	Write the data to the provided OutputStream.

Method Details

getLength

int getLength()

Returns the length of the stream.

This must be known ahead of calling writeTo(ByteStreamTarget).

Returns:

the number of bytes in the stream.

writeTo

void writeTo(ByteStreamWriter.ByteStreamTarget target)
      throws IOException

Write the data to the provided OutputStream.

Should not write more than getLength() bytes. If attempted, the provided stream will throw an IOException.

Parameters:

target - the stream to write the data to

Throws:

IOException - if the underlying stream throws or there is some other error.

of

static ByteStreamWriter of(ByteBuffer... buf)