johnspurlock.com - java projects

ProjectGhostData

A basic framework for object persistence.

Binary packages

com.johnspurlock.ghost.data.jar

Source code packages

com.johnspurlock.ghost.data-src.zip

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Library References

Description:

This is meant to be a simple mechanism for storing regular java objects to (and retrieving them from) a "datastore". Some features:

Very few lines of code to persist regular java domain objects.
Underlying storage details of the datastore are completely hidden (no JDBC needed to persist to a SQL database).
No object-level xml mapping documents (doing my part to cut down on xml overload...)
Object transformations are basic java constructs, no reflection or runtime trickery.
Zero-impact on the existing domain objects, the persistence can be completely separate if necessary.
Rudimentary query language to limit results

To make an existing object persistable, you write two proxy classes: the proxy to put a simple java object into a datastore is the IFieldProvider, and the proxy to pull an object out of a datastore is the IObjectBuilder.

(Domain Object) -> (IFieldProvider) -> (IDatastore)

(Domain Object) <- (IObjectBuilder) <- (IDatastore)

There are five tested sql datastore implementations included, for Postgres, Hsql, Cloudscape, Microsoft Sql Server & Access.

Example:

     Album album = whatever.getAlbum();
     
     
     // define the datastore, in this case it is a sql server database
     IDatastore datastore = GhostDataMinistry.getDatastore("mssql|servername|instancename|databasename|username|password");
     
     
     // store the album
     datastore.add(album.new DefaultFieldProvider());
     
     
     // retrieve a list of albums using a query
     List results = datastore.getObjects(new Album.DefaultObjectBuilder(),"where artist = 'Wilco'");
     
     // retrieve a single album
     Album album123 = (Album)datastore.getObjects(new Album.DefaultObjectBuilder(),"where artist = 'Wilco' and album='A ghost is born'");