GREAT PACKAGE RESHUFFLE: Everything is now organised into frontend, backend and common (to frontend and backend) packages. Things may have been broken. Doc refresh.

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diff --git a/src/uk/org/ury/backend/database/DatabaseDriver.java b/src/uk/org/ury/backend/database/DatabaseDriver.java
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+++ b/src/uk/org/ury/backend/database/DatabaseDriver.java
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+package uk.org.ury.backend.database;
+
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+
+import uk.org.ury.backend.config.ConfigReader;
+import uk.org.ury.backend.database.exceptions.ConnectionFailureException;
+import uk.org.ury.backend.database.exceptions.MissingCredentialsException;
+
+/**
+ * A database connection manager that connects to the URY databases using
+ * suitably privileged accounts, and handles the processing of SQL queries.
+ * 
+ * @author Matt Windsor
+ * @author Nathan Lasseter
+ * 
+ */
+public class DatabaseDriver {
+    /* The JDBC path used to connect to the URY database. */
+    private String DATABASE_PATH = "jdbc:postgresql://";
+
+    /* The database connection. */
+    private Connection conn;
+
+    /**
+     * Construct a new DatabaseDriver with the given user class.
+     * 
+     * @param config
+     *            The config with login details.
+     * 
+     * @param type
+     *            The user class to log in to the database with.
+     * 
+     * @throws IllegalArgumentException
+     *             if the user class is not supported (this should not happen).
+     * 
+     * @throws MissingCredentialsException
+     *             if the user class login credentials could not be loaded.
+     * 
+     * @throws ConnectionFailureException
+     *             if the database backend failed to connect to the database
+     *             server.
+     */
+    public DatabaseDriver(ConfigReader config, UserClass type)
+	    throws MissingCredentialsException, ConnectionFailureException {
+	try {
+	    connect(config, type);
+	} catch (SQLException e) {
+	    throw new ConnectionFailureException(e.getMessage());
+	}
+
+    }
+
+    /**
+     * Connect to the URY database.
+     * 
+     * @param config
+     *            The config to use for the connection.
+     * @param type
+     *            The access level of the connection
+     * 
+     * @throws SQLException
+     *             if the database connection failed.
+     */
+    private void connect(ConfigReader config, UserClass type)
+	    throws SQLException {
+	if (config == null)
+	    throw new IllegalArgumentException("Supplied null config.");
+
+	if (config.getDatabase().getHost() == null)
+	    throw new IllegalArgumentException("config has no associated host.");
+
+	if (config.getDatabase().getDb() == null)
+	    throw new IllegalArgumentException(
+		    "config has no associated database.");
+
+	DATABASE_PATH = DATABASE_PATH + config.getDatabase().getHost() + "/"
+		+ config.getDatabase().getDb();
+
+	if (type == UserClass.READ_ONLY) {
+	    if (config.getRoAuth().getUser() == null)
+		throw new IllegalArgumentException(
+			"config has no associated username.");
+	    if (config.getRoAuth().getPass() == null)
+		throw new IllegalArgumentException(
+			"config has no associated password.");
+	    conn = DriverManager.getConnection(DATABASE_PATH, config
+		    .getRoAuth().getUser(), config.getRoAuth().getPass());
+	} else if (type == UserClass.READ_WRITE) {
+	    if (config.getRwAuth().getUser() == null)
+		throw new IllegalArgumentException(
+			"config has no associated username.");
+	    if (config.getRwAuth().getPass() == null)
+		throw new IllegalArgumentException(
+			"config has no associated password.");
+	    conn = DriverManager.getConnection(DATABASE_PATH, config
+		    .getRwAuth().getUser(), config.getRwAuth().getPass());
+	}
+    }
+
+    /**
+     * Execute an unprepared SQL statement with no arguments.
+     * 
+     * @param sql
+     *            The SQL statement to execute.
+     * @param fetchSize
+     *            The maximum number of query rows to return.
+     * 
+     * @return the JDBC results set.
+     * 
+     * @throws SQLException
+     *             if a SQL error occurs.
+     */
+    public ResultSet executeQuery(String sql, int fetchSize)
+	    throws SQLException {
+	Statement st = conn.createStatement();
+	st.setFetchSize(fetchSize);
+
+	return st.executeQuery(sql);
+    }
+
+    /**
+     * Perform a SQL statement with arguments.
+     * 
+     * This accepts an array of parameter objects, which must each either be
+     * String or Integer objects. The objects will be used sequentially to fill
+     * in '?' placeholders in the query text.
+     * 
+     * @param sql
+     *            The SQL statement to execute.
+     * @param params
+     *            A list of parameter objects.
+     * @param fetchSize
+     *            The maximum number of query rows to return.
+     * 
+     * @return the set of results from the query.
+     * 
+     * @throws IllegalArgumentException
+     *             if any of the parameters is unsupported by the database as a
+     *             statement parameter.
+     * 
+     * @throws SQLException
+     *             if a SQL error occurs.
+     */
+    public ResultSet executeQuery(String sql, Object[] params, int fetchSize)
+	    throws SQLException {
+	PreparedStatement st = conn.prepareStatement(sql);
+
+	st.setFetchSize(fetchSize);
+
+	for (int i = 0; i < params.length; i++)
+	    if (params[i] instanceof String)
+		st.setString(i + 1, (String) params[i]);
+	    else if (params[i] instanceof Integer)
+		st.setInt(i + 1, (Integer) params[i]);
+	    else
+		throw new IllegalArgumentException("Unsupported parameter #"
+			+ (i + 1));
+
+	return st.executeQuery();
+    }
+}