1.您可以使用JdbcTemplate的execute()方法執行SQL DDL语句,例如:
jdbcTemplate.execute("CREATE TABLE USER (user_id integer, name varchar(100))");
使用JdbcTemplate进行查询时,可以使用queryForXXX()等方法,例如使用queryForInt()方法传回user表格中的数据数目: jdbcTemplate.quertForInt("select count(*) from user"); 也可以使用queryForObject()传回一个查询后的对象,例如传回一个String对象:
String name=(String)jdbcTemplate.queryForObject(
"selcet name from user where id=?",
new Object[]{id},
java.lang.String.class);
)
单独查询某个数据并赋值给特定对象时:
public BaseObj getBaseObj(final int ID) {
String sql = "select * from " + DB_TABLE_NAME + " where NewsId=" + ID;
BaseObj obj =(BaseObj) getJdbcTemplate().query(sql,new ResultSetExtractor(){
public Object extractData(ResultSet rs) throws SQLException,DataAccessException {
if (rs.next()) {
NewsObj news = new NewsObj();
news.setID(rs.getInt("NewsID"));
news.setTitle(rs.getString("NewsTitle"));
news.setBigClass(rs.getInt("BigClassId"));
news.setNewsContent(rs.getString("NewsContent"));
news.setNewsKey(rs.getString("NewsKey"));
news.setNewsAuthor(rs.getString("NewsAuthor"));
news.setImg(rs.getBoolean("isImg"));
news.setNewsFrom(rs.getString("NewsFrom"));
return news;
}
return null;
}
});
return obj;
}
上面两个例子都是传回单独一笔数据,如果要传回多笔数据,则可以使用queryForList()方法,例如:
List rows=jdbcTemplate().queryForList("select * from user where id="+id.intValue()); 传回的list中包括的是map对象,每个map对象代表查询结果中的一笔数据,每笔数据包括多个字段,要取得字段中的值,就要使用字段名作为key,例如:
Iterator it=rows.iterator();
while(it.hasNext()){
Map result=(Map)it.next();
System.out.println(userMap.get("id"));
System.out.println(userMap.get("name"));
System.out.println(userMap.get("age"));
}
在查询的同时,你可以在返回结果之前先进行一些处理,这就要实现RowCallbackHandler接口
public User find(Integer id){
final User user=new User();
jdbcTemplate.query("select * from user where id=?",new Object[]{id},
new RowCallBackHandler(){
public void proccessRow(ResultSet rs){
user.setId(new Integer(rs.getInt("id")));
uset.setName(rs.getString("name"));
}
});
return user;
}
如果一次要返回多个查询结果对象,则可以实现RowMapper接口
public class UserRowMapper implements RowMapper{
public Object MapRow(ResultSet rsmint rowNum) throws SQLException{
User user=new User();
user.setId(new Integer(rs.getInt("id")));
user.setName(rs.getString("name"));
return user;
}
}
使用RowMapper查询单笔数据
public User find(Integer id){
User user=(User)jdbcTemplate.queryForObject("select * from user where id=?",new Object[]{id},
new UserRowMapper());
return user;
}
使用RowMapper查询多笔数据
class UserRowMapper implements RowMapper {
public Object mapRow(ResultSet rs,int index) throws SQLException
{
User u = new User();
u.setId(rs.getString(”ID”));
u.setName(rs.getString(”Name”));
u.setPassword(rs.getString(”Password”));
return u;
}
}
public List select(String where)
{
List list;
String sql = “select * from admin “+where;
list = jdbcTemplate.query(sql,new RowMapperResultReader(new UserRowMapper()));
return list;
}
传回的users对象中,包括了从数据库查询出来的结果,并已经封装成uer对象
还可以参阅下面链接:
jdbctemplate 语句