userstore.java

OpenJMS是一个开源的Java Message Service API 1.0.2 规范的实现,它包含有以下特性： *. 它既支持点到点（point-to-point）（PTP）模型和发布/订

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 *    please contact [e-mail].
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 * 4. Products derived from this Software may not be called "Exolab"
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 */
package org.exolab.jms.tools.migration.proxy;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import javax.jms.JMSException;

import org.exolab.jms.authentication.User;
import org.exolab.jms.persistence.PersistenceException;
import org.exolab.jms.persistence.SQLHelper;
import org.exolab.jms.tools.migration.IteratorAdapter;
import org.exolab.jms.tools.migration.Store;
import org.exolab.jms.tools.migration.StoreIterator;


/**
 * Provides persistency for {@link User} instances.
 *
 * @author <a href="mailto:[e-mail]">Tim Anderson</a>
 * @version $Revision: 1.1 $ $Date: 2005/10/20 14:07:03 $
 */
public class UserStore implements Store, DBConstants {

    /**
     * The database connection.
     */
    private final Connection _connection;


    /**
     * Construct a new <code>UserStore</code>.
     *
     * @param connection the database connection
     */
    public UserStore(Connection connection) {
        _connection = connection;
    }

    /**
     * Export the users.
     *
     * @return an iterator over the collection
     * @throws JMSException         for any JMS error
     * @throws PersistenceException for any persistence error
     */
    public StoreIterator exportCollection() throws JMSException,
            PersistenceException {
        List users = getUsers();
        return new IteratorAdapter(users.iterator());
    }

    /**
     * Import users into the store.
     *
     * @param iterator an iterator over the collection
     * @throws JMSException         for any JMS error
     * @throws PersistenceException for any persistence error
     */
    public void importCollection(StoreIterator iterator) throws JMSException,
            PersistenceException {
        while (iterator.hasNext()) {
            User user = (User) iterator.next();
            add(user);
        }
    }

    /**
     * Returns the number of elements in the collection.
     *
     * @return the number of elements in the collection
     * @throws PersistenceException for any persistence error
     */
    public int size() throws PersistenceException {
        return getUsers().size();
    }

    /**
     * Add a new user.
     *
     * @param user the user to add
     * @throws PersistenceException for any persistence error
     */
    private void add(User user) throws PersistenceException {
        PreparedStatement insert = null;
        try {
            insert = _connection.prepareStatement(
                    "insert into " + USER_TABLE + " values (?, ?)");

            insert.setString(1, user.getUsername());
            insert.setString(2, user.getPassword());
            insert.executeUpdate();
        } catch (SQLException exception) {
            throw new PersistenceException("Failed to add consumer",
                                           exception);
        } finally {
            SQLHelper.close(insert);
        }
    }

    /**
     * Returns the users.
     *
     * @return a list of {@link User} instances
     * @throws PersistenceException for any persistence error
     */
    private List getUsers() throws PersistenceException {
        ArrayList result = new ArrayList();

        PreparedStatement select = null;
        ResultSet set = null;
        try {
            select = _connection.prepareStatement(
                    "select * from " + USER_TABLE);

            set = select.executeQuery();
            while (set.next()) {
                String user = set.getString("username");
                String password = set.getString("password");
                result.add(new User(user, password));
            }
        } catch (SQLException exception) {
            throw new PersistenceException("Failed to retrieve users",
                                           exception);
        } finally {
            SQLHelper.close(set);
            SQLHelper.close(select);
        }
        return result;
    }

}