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package uk.org.ury.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.config.ConfigReader;
import uk.org.ury.database.exceptions.ConnectionFailureException;
import uk.org.ury.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();
}
}
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