import org.springframework.jdbc.IncorrectResultSetColumnCountException; //导入依赖的package包/类
/**
 * Extract a value for the single column in the current row.
 * <p>Validates that there is only one column selected,
 * then delegates to {@code getColumnValue()} and also
 * {@code convertValueToRequiredType}, if necessary.
 * @see java.sql.ResultSetMetaData#getColumnCount()
 * @see #getColumnValue(java.sql.ResultSet, int, Class)
 * @see #convertValueToRequiredType(Object, Class)
 */
@Override
@SuppressWarnings("unchecked")
public T mapRow(ResultSet rs, int rowNum) throws SQLException {
	// Validate column count.
	ResultSetMetaData rsmd = rs.getMetaData();
	int nrOfColumns = rsmd.getColumnCount();
	if (nrOfColumns != 1) {
		throw new IncorrectResultSetColumnCountException(1, nrOfColumns);
	}

	// Extract column value from JDBC ResultSet.
	Object result = getColumnValue(rs, 1, this.requiredType);
	if (result != null && this.requiredType != null && !this.requiredType.isInstance(result)) {
		// Extracted value does not match already: try to convert it.
		try {
			return (T) convertValueToRequiredType(result, this.requiredType);
		}
		catch (IllegalArgumentException ex) {
			throw new TypeMismatchDataAccessException(
					"Type mismatch affecting row number " + rowNum + " and column type '" +
					rsmd.getColumnTypeName(1) + "': " + ex.getMessage());
		}
	}
	return (T) result;
}
 

import org.springframework.jdbc.IncorrectResultSetColumnCountException; //导入依赖的package包/类
/**
 * Extract a value for the single column in the current row.
 * <p>Validates that there is only one column selected,
 * then delegates to {@code getColumnValue()} and also
 * {@code convertValueToRequiredType}, if necessary.
 * @see java.sql.ResultSetMetaData#getColumnCount()
 * @see #getColumnValue(java.sql.ResultSet, int, Class)
 * @see #convertValueToRequiredType(Object, Class)
 */
@SuppressWarnings("unchecked")
public T mapRow(ResultSet rs, int rowNum) throws SQLException {
	// Validate column count.
	ResultSetMetaData rsmd = rs.getMetaData();
	int nrOfColumns = rsmd.getColumnCount();
	if (nrOfColumns != 1) {
		throw new IncorrectResultSetColumnCountException(1, nrOfColumns);
	}

	// Extract column value from JDBC ResultSet.
	Object result = getColumnValue(rs, 1, this.requiredType);
	if (result != null && this.requiredType != null && !this.requiredType.isInstance(result)) {
		// Extracted value does not match already: try to convert it.
		try {
			return (T) convertValueToRequiredType(result, this.requiredType);
		}
		catch (IllegalArgumentException ex) {
			throw new TypeMismatchDataAccessException(
					"Type mismatch affecting row number " + rowNum + " and column type '" +
					rsmd.getColumnTypeName(1) + "': " + ex.getMessage());
		}
	}
	return (T) result;
}
 

import org.springframework.jdbc.IncorrectResultSetColumnCountException; //导入依赖的package包/类
@Override
public Object mapRow(ResultSet rs, int rowNum) throws SQLException {
	ResultSetMetaData metaData = rs.getMetaData();
	int columns = metaData.getColumnCount();
	if (columns != 1) {
		throw new IncorrectResultSetColumnCountException(1, columns);
	}
	return JdbcUtils.getResultSetValue(rs, 1);
}
 

import org.springframework.jdbc.IncorrectResultSetColumnCountException; //导入依赖的package包/类
protected <E> E getSingleResult(List<E> list) throws DataAccessException {
	E singleResult = null;
	if (!(list == null || list.isEmpty())) {

		if (list.size() != 1) {
			throw new IncorrectResultSetColumnCountException(1, list.size());
		}
		singleResult = list.get(0);

	}
	return singleResult;
}