QueryWrapper

QueryWrapper<OrderEntity> queryWrapper = new QueryWrapper<OrderEntity>().select("id","order_msg").eq("order_msg","571");
orderMapper.selectOne(queryWrapper); // SELECT id,order_msg FROM my_mysql.order WHERE (order_msg = '571')

LambdaQueryWrapper

LambdaQueryWrapper<OrderEntity> lambdaQueryWrapper = new LambdaQueryWrapper<OrderEntity>().select(OrderEntity::getId, OrderEntity::getOrderMsg).eq(OrderEntity::getOrderMsg,"572");
orderMapper.selectOne(lambdaQueryWrapper); // SELECT id,order_msg FROM my_mysql.order WHERE (order_msg = '572')

QueryChainWrapper

QueryChainWrapper<OrderEntity> queryChainWrapper = new QueryChainWrapper<>(orderMapper).select("id", "order_msg").eq("order_msg","573");
queryChainWrapper.one(); // SELECT id,order_msg FROM my_mysql.order WHERE (order_msg = '573')

LambdaQueryChainWrapper

LambdaQueryChainWrapper<OrderEntity> lambdaQueryChainWrapper = new LambdaQueryChainWrapper<>(orderMapper).select(OrderEntity::getId, OrderEntity::getOrderMsg).eq(OrderEntity::getOrderMsg,"574");
lambdaQueryChainWrapper.one(); // SELECT id,order_msg FROM my_mysql.order WHERE (order_msg = '574')

總結(jié)

QueryWrapper 和 lambdaQueryWrapper 需要將 封裝的wrapper 提供給 orderMapper，調(diào)用orderMapper的方法，才可以使用。
QueryChainWrapper 和 LambdaQueryChainWrapper 可以直接鏈?zhǔn)秸{(diào)用數(shù)據(jù)執(zhí)行操作的方法
帶 lambda 的 wrapper 可以使用lambda表達(dá)式，選擇列，設(shè)置列值，反之不帶lambda的就需要手動(dòng)指定列名