JdbcTemplate 常用方法

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;
}