DBUnit 2.4.9+ 支持数据库唯一键扩展

由于DBUnit在做refresh或者delete操作时是根据数据库的connection获取到meta信息，然后通过meta信息来确定主键列，最后根据这些列构造where条件，进行更新或者删除处理，但是如果表没有定义主键，只定义了唯一键，DBUnit无法处理，而目前我所遇到的就有这种情况，所以我对DBUnit进行了扩展，支持oracle和mysql的唯一键处理，但是要注意唯一键的键值如果有null值，则无法处理，这是一个局限，后续我会做修复。

1、继承DefaultMetadataHandler覆盖getPrimaryKeys方法，如果有主键，则直接用主键，没有就用唯一键，

直接上代码：

/**
 * <p>由于DBUNIT对于没有主键的表不支持，更新，单条删除等，这里做一下扩展</p>
 * <p>支持oracle/mysql的唯一键更新</p>
 * <p>不过注意一点局限，如果唯一键中有某个字段为null,那么可能找不到这条记录</p>
 *
 * @author qingxu
 * @version $$Id: UniquekeyMetadataHandler.java, v 0.1 12-10-17 下午12:46 qingxu Exp $$
 */
public class UniquekeyMetadataHandler extends DefaultMetadataHandler {
    /**
     * Logger for this class
     */
    private static final Logger logger = LoggerFactory.getLogger(UniquekeyMetadataHandler.class);

    private IDatabaseConnection databaseConnection;

    public UniquekeyMetadataHandler(IDatabaseConnection databaseConnection) {
        this.databaseConnection = databaseConnection;
    }

    @Override
    public ResultSet getPrimaryKeys(DatabaseMetaData metaData, String schemaName, String tableName)
                                                                                                   throws SQLException {
        ResultSet rs = super.getPrimaryKeys(metaData, schemaName, tableName);
        if (rs.next()) {
            //            rs.previous();由于不是可移动游标，无法前移，这里只有再查一次了
            rs.close();//must colsed
            rs = super.getPrimaryKeys(metaData, schemaName, tableName);
            return rs;

        }
        rs.close();//must colsed

        if (logger.isTraceEnabled())
            logger
                .trace(
                    "UniquekeyMetadataHandler#getPrimaryKeys(metaData={}, schemaName={}, tableName={}) - start",
                    new Object[] { metaData, schemaName, tableName });

        String productName = metaData.getDatabaseProductName();
        String sql;
        if (StringUtils.equalsIgnoreCase("oracle", productName)) {
            sql = "select col.owner,col.constraint_name,col.table_name,col.column_name,col.position\n"
                  + "  from user_constraints con, user_cons_columns col\n"
                  + " where con.constraint_name = col.constraint_name\n"
                  + "   and con.constraint_type = 'U'\n" + "   and col.table_name = ?";
        } else if (StringUtils.equalsIgnoreCase("mysql", productName)) {
            sql = "select distinct a.table_schema,a.constraint_name,a.table_name,a.column_name,a.ordinal_position\n"
                  + "  from information_schema.key_column_usage  a,\n"
                  + "       information_schema.table_constraints b\n"
                  + " where a.constraint_name = b.constraint_name\n"
                  + "   and b.constraint_type = 'UNIQUE'\n" + "   and a.table_name = ?";

        } else {
            throw new RuntimeException("暂时不支持 数据库[" + productName + "]的唯一键获取~");
        }

        Connection connection = this.databaseConnection.getConnection();
        PreparedStatement preparedStatement = connection.prepareStatement(sql);
        preparedStatement.setString(1, tableName);
        rs = preparedStatement.executeQuery();

        return rs;

    }
}

2、在构建Tester时更换配置处理器

 databaseTester = new DataSourceDatabaseTester(dataSource);
databaseTester.setOperationListener(getOperationListener());
 //替换meta处理器，如果数据库没有主键，则用唯一键代替主键
 protected IOperationListener getOperationListener() {
        logger.debug("getOperationListener() - start");
        if (this.operationListener == null) {
            this.operationListener = new DefaultOperationListener() {
                public void connectionRetrieved(IDatabaseConnection connection) {
                    super.connectionRetrieved(connection);
                    // When a new connection has been created then invoke the setUp method
                    // so that user defined DatabaseConfig parameters can be set.
                    setUpDatabaseConfig(connection, connection.getConfig());
                }
            };
        }
        return this.operationListener;
    }

    /**
     * Designed to be overridden by subclasses in order to set additional configuration
     * parameters for the {@link IDatabaseConnection}.
     *
     * @param connection
     * @param config     The settings of the current {@link IDatabaseConnection} to be configured
     */
    protected void setUpDatabaseConfig(IDatabaseConnection connection, DatabaseConfig config) {
        // Designed to be overridden.
        config.setProperty(DatabaseConfig.PROPERTY_METADATA_HANDLER, new UniquekeyMetadataHandler(
            connection));
        config.setProperty(DatabaseConfig.PROPERTY_DATATYPE_FACTORY, new OracleDataTypeFactory());
        config.setProperty(DatabaseConfig.FEATURE_BATCHED_STATEMENTS, Boolean.TRUE);
    }

OK，其他处理方式照旧，DBUNIT开始支持唯一键处理。