com.healthmarketscience.jackcess.util

Interface OleBlob

All Superinterfaces:

AutoCloseable, Blob, Closeable

public interface OleBlob
extends Blob, Closeable

Extensions of the Blob interface with additional functionality for working with the OLE content from an access database. The ole data type in access has a wide range of functionality (including wrappers with nested wrappers with nested filesystems!), and jackcess only supports a small portion of it. That said, jackcess should support the bulk of the common functionality.

The main Blob methods will interact with the entire OLE field data which, in most cases, contains additional wrapper information. In order to access the ultimate "content" contained within the OLE data, the getContent() method should be used. The type of this content may be a variety of formats, so additional sub-interfaces are available to interact with it. The most specific sub-interface can be determined by the OleBlob.ContentType of the Content.

Once an OleBlob is no longer useful, it should be closed using Blob.free() or Closeable.close() methods (after which, the instance will no longer be functional).

Note, the OleBlob implementation is read-only (through the interface). In order to modify blob contents, create a new OleBlob instance using OleBlob.Builder and write it to the access database.

Example for interpreting an existing OLE field:

   OleBlob oleBlob = null;
   try {
     oleBlob = row.getBlob("MyOleColumn");
     Content content = oleBlob.getContent()
     if(content.getType() == OleBlob.ContentType.SIMPLE_PACKAGE) {
       FileOutputStream out = ...;
       ((SimplePackageContent)content).writeTo(out);
       out.closee();
     }
   } finally {
     if(oleBlob != null) { oleBlob.close(); }
   }

Example for creating new, embedded ole data:

   OleBlob oleBlob = null;
   try {
     oleBlob = new OleBlob.Builder()
       .setSimplePackage(new File("some_data.txt"))
       .toBlob();
     db.addRow(1, oleBlob);
   } finally {
     if(oleBlob != null) { oleBlob.close(); }
   }

Example for creating new, linked ole data:

   OleBlob oleBlob = null;
   try {
     oleBlob = new OleBlob.Builder()
       .setLink(new File("some_data.txt"))
       .toBlob();
     db.addRow(1, oleBlob);
   } finally {
     if(oleBlob != null) { oleBlob.close(); }
   }

Author:

James Ahlborn

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	OleBlob.Builder Builder style class for constructing an OleBlob.
static interface	OleBlob.CompoundContent Sub-interface for Content which has the OleBlob.ContentType.COMPOUND_STORAGE type.
static interface	OleBlob.Content
static class	OleBlob.ContentType Enum describing the types of blob contents which are currently supported/understood
static interface	OleBlob.EmbeddedContent Intermediate sub-interface for Content which has embedded content.
static interface	OleBlob.LinkContent Sub-interface for Content which has the OleBlob.ContentType.LINK type.
static interface	OleBlob.OtherContent Sub-interface for Content which has the OleBlob.ContentType.OTHER type.
static interface	OleBlob.PackageContent Intermediate sub-interface for Content which has a nested package.
static interface	OleBlob.SimplePackageContent Sub-interface for Content which has the OleBlob.ContentType.SIMPLE_PACKAGE type.

Method Summary

Modifier and Type	Method and Description
OleBlob.Content	getContent() Returns the decoded form of the blob contents, if understandable.
void	writeTo(OutputStream out) Writes the entire raw blob data to the given stream (this is the access db internal format, which includes all wrapper information).

Methods inherited from interface java.sql.Blob

free, getBinaryStream, getBinaryStream, getBytes, length, position, position, setBinaryStream, setBytes, setBytes, truncate

Methods inherited from interface java.io.Closeable

close

Method Detail

writeTo

void writeTo(OutputStream out)
      throws IOException

Writes the entire raw blob data to the given stream (this is the access db internal format, which includes all wrapper information).

Parameters:

out - stream to which the blob will be written

Throws:

IOException

getContent

OleBlob.Content getContent()
                    throws IOException

Returns the decoded form of the blob contents, if understandable.

Throws:

IOException