public static Field getJoinLeftTable(Class<?> clazz) {
		if(clazz == null) {
			throw new NoJoinTableMemberException("clazz is null");
		}
		List<Field> result = _getAnnotationColumns(clazz, JoinLeftTable.class);
		if(result == null || result.isEmpty()) {
			throw new NoJoinTableMemberException("class " + clazz.getName()
			    + " does not have @JoinLeftTable field");
		}
		return result.get(0);
	}
public static Field getJoinLeftTable ( Class < ? > clazz ) { if ( clazz == null ) { throw new NoJoinTableMemberException ( "clazz is null" ) ; } List < Field > result = _getAnnotationColumns ( clazz , JoinLeftTable . class ) ; if ( result == null || result . isEmpty ( ) ) { throw new NoJoinTableMemberException ( "class " + clazz . getName ( ) + " does not have @JoinLeftTable field" ) ; } return result . get ( 0 ) ; }
获得注解了@JoinLeftTable的字段，如果没有注解，抛出NoJoinTableMemberException
@param clazz
@return