Created base class for JORA-based database repository implementations that

takes care of establishing a JORA session based on JDBC configuration
properties and provides a few other useful patterns.


git-svn-id: https://samskivert.googlecode.com/svn/trunk@38 6335cc39-0255-0410-8fd6-9bcaacd3b74c

projects/samskivert/src/java/com/samskivert/jdbc/Makefile

@@ -1,9 +1,11 @@
 #
-# $Id: Makefile,v 1.1 2000/12/06 00:27:30 mdb Exp $
+# $Id: Makefile,v 1.2 2001/02/13 00:25:14 mdb Exp $
 
 ROOT = ../../..
 
 SRCS = \
 	JDBCUtil.java \
+	MySQLRepository.java \
+	Repository.java \
 
 include $(ROOT)/build/Makefile.java

projects/samskivert/src/java/com/samskivert/jdbc/MySQLRepository.java

@@ -0,0 +1,41 @@
+//
+// $Id: MySQLRepository.java,v 1.1 2001/02/13 00:25:14 mdb Exp $
+
+package com.samskivert.jdbc;
+
+import java.sql.*;
+import java.util.Properties;
+
+/**
+ * The MySQL repository class provides functionality useful to repository
+ * implementations that make use of MySQL as their underlying database.
+ */
+public abstract class MySQLRepository extends Repository
+{
+    /**
+     * Constructs a MySQL repository implementation with the supplied
+     * configuration properties.
+     */
+    public MySQLRepository (Properties props)
+	throws SQLException
+    {
+	super(props);
+    }
+
+    /**
+     * @return the most recent ID generated by an insert into an
+     * AUTO_INCREMENT table.
+     */
+    protected int lastInsertedId ()
+	throws SQLException
+    {
+	// we have to do this by hand. alas all is not roses.
+	Statement stmt = _session.connection.createStatement();
+	ResultSet rs = stmt.executeQuery("select LAST_INSERT_ID()");
+	if (rs.next()) {
+	    return rs.getInt(1);
+	} else {
+	    return -1;
+	}
+    }
+}

projects/samskivert/src/java/com/samskivert/jdbc/Repository.java

@@ -0,0 +1,93 @@
+//
+// $Id: Repository.java,v 1.1 2001/02/13 00:25:14 mdb Exp $
+
+package com.samskivert.jdbc;
+
+import java.sql.*;
+import java.util.List;
+import java.util.Properties;
+
+import com.samskivert.util.*;
+import jora.*;
+
+/**
+ * The repository class provides basic functionality upon which to build
+ * an interface to a repository of information stored in a database (a
+ * table or set of tables).
+ *
+ * <p> These services are based on the JORA Java/RDBMS interoperability
+ * package.
+ */
+public abstract class Repository
+{
+    /**
+     * Creates the repository and opens music database. A properties
+     * object should be supplied with the following fields:
+     *
+     * <pre>
+     * driver=[jdbc driver class]
+     * url=[jdbc driver url]
+     * username=[jdbc username]
+     * password=[jdbc password]
+     * </pre>
+     *
+     * @param props a properties object containing the configuration
+     * parameters for the repository.
+     */
+    public Repository (Properties props)
+	throws SQLException
+    {
+	// create our JORA session
+	String dclass =
+	    requireProp(props, "driver", "No driver class specified.");
+	_session = new Session(dclass);
+
+	// connect the session to the database
+	String url =
+	    requireProp(props, "url", "No driver url specified.");
+	String username =
+	    requireProp(props, "username", "No driver username specified.");
+	String password =
+	    requireProp(props, "password", "No driver password specified.");
+	_session.open(url, username, password);
+
+	// set auto-commit to false
+	_session.connection.setAutoCommit(false);
+
+	// create our table objects
+	createTables();
+    }
+
+    /**
+     * After the database session is begun, this function will be called
+     * to give the repository implementation the opportunity to create its
+     * table objects. As this is done during the initialization of the
+     * repository, the implementation has a chance to fail the entire
+     * repository creation process if the necessary tables do not exist.
+     */
+    protected abstract void createTables () throws SQLException;
+
+    protected static String requireProp (Properties props,
+					 String name, String errmsg)
+	throws SQLException
+    {
+	String value = props.getProperty(name);
+	if (StringUtil.blank(value)) {
+	    throw new SQLException(errmsg);
+	}
+	return value;
+    }
+
+    /**
+     * A repository should be shutdown before the calling code disposes of
+     * it. This allows the repository to cleanly terminate the underlying
+     * database services.
+     */
+    public void shutdown ()
+	throws SQLException
+    {
+	_session.close();
+    }
+
+    protected Session _session;
+}