JdbcTemplate 常用方法

待我称王封你为后i 2024-04-03 08:02 57阅读 0赞

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;
    }