有时候我们在开发的过程中，sql语句是由用户自己填写的，这样的话我们就不能预知这条sql语句返回的是什么对象，于是daoImpl中我们在返回数据的时候所需要的rowMapper就不能用某一个对象来概括，下面就是我在开发过程中用到的一个通用的rowMapper：
bean代码（set和get方法就不写了）：
public class CommonData {
??? ??? private String label;
??? ??? private String name;
??? ??? private String value;
??? ??? private int type;
??? ??? private String typeName;
??? ??? private long dateTime;
}
rowMapper代码：
?private class CommonDataRowMapper implements RowMapper {
??? ??? ??????? public Object mapRow(ResultSet rs, int rownum) throws SQLException {
??? ??? ??????? ??? List list = new LinkedList();
??? ??? ??????? ??? ResultSetMetaData meta = rs.getMetaData();
??? ??? ??????? ??? int count =meta.getColumnCount();
??? ??? ??????? ??? for ( int i=1;i<=count; i++)
??? ??? ??????? ??? {
??? ??? ??????? ??? ??? CommonData data = new CommonData();
??? ??? ??????? ??? ??? data.setLabel(meta.getColumnLabel(i));
??? ??? ??????? ??? ??? data.setName(meta.getColumnName(i));
??? ??? ??????? ??? ??? data.setValue(rs.getString(i));
??? ??? ??????? ??? ??? data.setType(meta.getColumnType(i));
??? ??? ??????? ??? ??? data.setTypeName(meta.getColumnTypeName(i));
??? ??? ??????? ??? ???
??? ??? ??????? ??? ??? if (data.getType() == Types.DATE
??? ??? ??????? ??? ??? ??? ??? || data.getType() == Types.TIME
??? ??? ??????? ??? ??? ??? ??? || data.getType() == Types.TIMESTAMP)
??? ??? ??????? ??? ??? {
??? ??? ??????? ??? ??? ??? if (data.getDateTime() <=0)
??? ??? ??????? ??? ??? ??? {
??? ??? ??????? ??? ??? ??? ??? data.setDateTime(rs.getTimestamp(i).getTime());
??? ??? ??????? ??? ??? ??? }
??? ??? ??????? ??? ??? ??? ???
??? ??? ??????? ??? ??? ???
??? ??? ??????? ??? ??? }
??? ??? ??????? ??? ???
??? ??? ??????? ??? ??? list.add(data);
??? ??? ??????? ??? }
??? ??? ??????? ??? ??? ??? ?????
??? ??? ??????????? return list;
??? ??? ?????
??? ??? ??????? }
??? ??? ?}
这里的思想就是，把我们通常的一个对象转换成了一个list，list里面的数据就是这个对象的属性以及属性对应的值，即多个CommonData 对象。举个例子说就是，比如我有一个对象person，有age和name两个属性，那么list里面就有两条数据，两个CommonData对象，这两个对象的name分别是age和name，value则是这两个属性的具体值。