Description or Example
# 核心代码
```java
@GetMapping("/countItem")
public String changeCount(@RequestParam Long skuId, @RequestParam Integer num) {
cartService.changeCount(skuId, num);
return "redirect:http://cart.bitmall.com/cart.html";
}
```
```java
@Override
public void changeCount(Long skuId, Integer num) {
BoundHashOperations<String, Object, Object> hashHandle = getHashHandle();
String cartItemJson = (String) hashHandle.get(skuId.toString());
CartItemVO cartItemVO = JSON.parseObject(cartItemJson, CartItemVO.class);
hashHandle.put(skuId.toString(), JSON.toJSONString(cartItemVO.setCount(num)));
}
```