JdbcTemplate 常用方法
update:
实现增删改
//update方法 (增 删 改)
@Override
public void add(Users user) {
String sql = "insert into users values(null,?,?)";
jdbcTemplate.update(sql, user.getUname(), user.getPassword());
}
queryForObject:
查询的结果是一个对象或单个值
//测试 根据id号查询
public Users selectUsersById(int uid)
{
String sql="select * from users where uid=?";
//查询 单行数据
Users user= jdbcTemplate.queryForObject(sql, new Object[]{uid}, new RowMapper<Users>() {
@Override
public Users mapRow(ResultSet resultSet, int i) throws SQLException {
return rowMapHandler(resultSet);
}
});
return user;
}
//自己组装对象
public Users rowMapHandler(ResultSet resultSet) throws SQLException {
Users user=new Users();
user.setUid(resultSet.getInt("uid"));
user.setUname(resultSet.getString("uname"));
user.setPassword(resultSet.getString("password"));
return user;
}
查询的结果是一个数值 public int selectUsersCount() {
String sql = "select count(*) from users"; int num = jdbcTemplate.queryForObject(sql, Integer.class); return num; }
query
//查询 返回集合
public List<Users> selectUsers() {
String sql = "select * from users";
List<Users> usersList= jdbcTemplate.query(sql, new RowMapper<Users>() {
//遍历结果集 将结果集中的每条数据 组装成Users对象
@Override
public Users mapRow(ResultSet resultSet, int i) throws SQLException {
return rowMapHander(resultSet);
}
});
return usersList;
}
//自己组装对象public Users rowMapHander(ResultSet resultSet) throws SQLException {
Users user=new Users();
user.setUid(resultSet.getInt("uid"));
user.setUname(resultSet.getString("uname"));
user.setPassword(resultSet.getString("password"));
return user;
}