经典的jdbc连接数据库语句
public List<User> query() {

List<User> userList = new ArrayList<User>();
String sql = "select * from User";

Connection con = null;
PreparedStatement pst = null;
ResultSet rs = null;
try {
con = HsqldbUtil.getConnection();
pst = con.prepareStatement(sql);
rs = pst.executeQuery();

User user = null;
while (rs.next()) {

user = new User();
user.setId(rs.getInt("id"));
user.setUserName(rs.getString("user_name"));
user.setBirth(rs.getDate("birth"));
user.setCreateDate(rs.getDate("create_date"));
userList.add(user);
}


} catch (SQLException e) {
e.printStackTrace();
}finally{
if(rs != null){
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
try {
pst.close();
} catch (SQLException e) {
e.printStackTrace();
}
try {
if(!con.isClosed()){
try {
con.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
} catch (SQLException e) {
e.printStackTrace();
}

}
return userList;
}