支付项目：9、购物车模块

统一表单验证

1、为购物车模块编写符合前端API的类
CartVo.java:

package com.xiaoxin.mall.service.vo;import java.math.BigDecimal;
import java.util.List;public class CartVo {private List<CartProductVo> cartProductVoList;private Boolean selectedAll;private BigDecimal cartTotalPrice;private Integer cartTotalQuantity;}

CartProductVo.java：

package com.xiaoxin.mall.service.vo;import lombok.Data;import java.math.BigDecimal;@Data
public class CartProductVo {private Integer productId;//购买的数量private Integer quantity;private String productName;private String productSubtitle;private String productMainImage;private BigDecimal productPrice;private Integer productStatus;//等于单价乘以购买总数private BigDecimal productTotalPrice;//商品库存private Integer productStock;//是否选中private Boolean productSelected;
}

2、添加商品时需要提供 productId 和 selected 属性，所以为此写一个CartAddForm类：

package com.xiaoxin.mall.form;import lombok.Data;
import lombok.NonNull;import javax.validation.constraints.NotNull;/*** 添加商品时的表单*/
@Data
public class CartAddForm {@NotNullprivate Integer productId;private Boolean selected = true;
}

如果是String类型，可以使用not blank，如果是集合，可以使用not empty，这里是Integer对象，所以使用not null。

3、这次在写controller的时候，我们不写BindingResult

package com.xiaoxin.mall.controller;import com.xiaoxin.mall.form.CartAddForm;
import com.xiaoxin.mall.service.vo.CartVo;
import com.xiaoxin.mall.service.vo.ResponseVo;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;import javax.validation.Valid;@RestController
public class CartController {@PostMapping("/carts")public ResponseVo<CartVo> add(@Valid @RequestBody CartAddForm cartAddForm) {return null;}
}

这时使用postman进行测试时，发现跳转到了/error页面，并且后台抛出MethodArgumentNotValidException异常。

所以这时我们可以捕获这个异常，并进行相应处理。

在RuntimeExceptionHandler.java中编写捕获MethodArgumentNotValidException异常的方法：

@ExceptionHandler(MethodArgumentNotValidException.class)
@ResponseBody
public ResponseVo notValidExceptionhandle(MethodArgumentNotValidException e) {BindingResult bindingResult = e.getBindingResult();FieldError fieldError = bindingResult.getFieldError();return ResponseVo.error(ResponseEnum.PARAM_ERROR,fieldError.getField() + " " + fieldError.getDefaultMessage());
}

测试发现成功，那UserController中的BindingResult也可以去掉啦！

添加商品到购物车 & 展示购物车的商品

用redis将购物车的信息存到数据库中，我们保存productId, quantity, selected这些信息，所以专门为此写个类。
Cart.java：

package com.xiaoxin.mall.pojo;import lombok.Data;@Data
public class Cart {private Integer productId;private Integer quantity;private boolean productSelected;public Cart() {}public Cart(Integer productId, Integer quantity, boolean productSelected) {this.productId = productId;this.quantity = quantity;this.productSelected = productSelected;}
}

ICartServiceImpl.java：

package com.xiaoxin.mall.service.impl;import com.google.gson.Gson;
import com.xiaoxin.mall.dao.ProductMapper;
import com.xiaoxin.mall.enums.ProductStatusEnum;
import com.xiaoxin.mall.enums.ResponseEnum;
import com.xiaoxin.mall.form.CartAddForm;
import com.xiaoxin.mall.pojo.Cart;
import com.xiaoxin.mall.pojo.Product;
import com.xiaoxin.mall.service.ICartService;
import com.xiaoxin.mall.service.vo.CartProductVo;
import com.xiaoxin.mall.service.vo.CartVo;
import com.xiaoxin.mall.service.vo.ResponseVo;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.HashOperations;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Service;
import org.springframework.util.StringUtils;import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.Map;
import java.util.List;@Service
public class ICartServiceImpl implements ICartService {private static final String CART_REDIS_KEY_TEMPLATE = "cart_%d";@Autowiredprivate ProductMapper productMapper;@Autowiredprivate StringRedisTemplate redisTemplate;private Gson gson = new Gson();@Overridepublic ResponseVo<CartVo> add(Integer uid, CartAddForm form) {Integer quantity = 1;Product product = productMapper.selectByPrimaryKey(form.getProductId());//商品是否存在if(product == null) {return ResponseVo.error(ResponseEnum.PRODUCT_NOT_EXIST);}//商品是否正常在售if(product.getStatus().equals(ProductStatusEnum.OFF_SALE.getCode()) ||product.getStatus().equals(ProductStatusEnum.DELETE.getCode())) {return ResponseVo.error(ResponseEnum.PRODUCT_OFF_SALE_OR_DELETE);}//商品库存是否充足if(product.getStock() <= 0) {return ResponseVo.error(ResponseEnum.PRODUCT_STOCK_ERROR);}//写入到redis//key: cart_1HashOperations<String, String, String> opsForHash = redisTemplate.opsForHash();String redisKey = String.format(CART_REDIS_KEY_TEMPLATE, uid);String value = opsForHash.get(redisKey, String.valueOf(product.getId()));Cart cart = null;if(StringUtils.isEmpty(value)) {//没有该商品，新增cart = new Cart(product.getId(), quantity, form.getSelected());} else {cart = gson.fromJson(value, Cart.class);cart.setQuantity(cart.getQuantity() + quantity);}opsForHash.put(redisKey, String.valueOf(product.getId()), gson.toJson(cart));return list(uid);}@Overridepublic ResponseVo<CartVo> list(Integer uid) {HashOperations<String, String, String> opsForHash = redisTemplate.opsForHash();String redisKey = String.format(CART_REDIS_KEY_TEMPLATE, uid);Map<String, String> entries = opsForHash.entries(redisKey);boolean selectedAll = true;Integer cartTotalQuantity = 0;BigDecimal cartTotalPrice = BigDecimal.ZERO;CartVo cartVo = new CartVo();List<CartProductVo> productVoList = new ArrayList<>();for(Map.Entry<String, String> entry : entries.entrySet()) {Integer productId = Integer.valueOf(entry.getKey());Cart cart = gson.fromJson(entry.getValue(), Cart.class);//TODO 不要在for循环里写sql，否则多次查询数据库，时间太多Product product  = productMapper.selectByPrimaryKey(cart.getProductId());if(product != null) {CartProductVo cartProductVo = new CartProductVo(productId,cart.getQuantity(),product.getName(),product.getSubtitle(),product.getMainImage(),product.getPrice(),product.getStatus(),product.getPrice().multiply(BigDecimal.valueOf(cart.getQuantity())),product.getStock(),cart.isProductSelected());productVoList.add(cartProductVo);if(!cart.isProductSelected()) selectedAll = false;//计算总价，只计算选中的if(cart.isProductSelected())cartTotalPrice = cartTotalPrice.add(product.getPrice().multiply(BigDecimal.valueOf(cart.getQuantity())));}cartTotalQuantity += cart.getQuantity();}cartVo.setCartProductVoList(productVoList);cartVo.setCartTotalQuantity(cartTotalQuantity);cartVo.setSelectedAll(selectedAll);cartVo.setCartTotalPrice(cartTotalPrice);return ResponseVo.success(cartVo);}
}

更新、删除购物车的商品

更新时，我们需要提供quantity和selected属性，为此专门写个updateFrom
CartUpdateForm.java：

package com.xiaoxin.mall.form;import lombok.Data;@Data
public class CartUpdateForm {private Integer quantity;private Boolean selected;
}

在ICartServiceImpl.java中添加方法：

@Override
public ResponseVo<CartVo> update(Integer uid, Integer productId, CartUpdateForm form) {HashOperations<String, String, String> opsForHash = redisTemplate.opsForHash();String redisKey = String.format(CART_REDIS_KEY_TEMPLATE, uid);String value = opsForHash.get(redisKey, String.valueOf(productId));Cart cart = null;if(StringUtils.isEmpty(value)) {//购物车中无此商品，报错return ResponseVo.error(ResponseEnum.PRODUCT_NOT_IN_CART);}//已经有了，修改内容cart = gson.fromJson(value, Cart.class);if(form.getQuantity() != null&& form.getQuantity() >= 0) {cart.setQuantity(form.getQuantity());}if(form.getSelected() != null) {cart.setProductSelected(form.getSelected());}opsForHash.put(redisKey, String.valueOf(productId), gson.toJson(cart));return list(uid);
}@Override
public ResponseVo<CartVo> delete(Integer uid, Integer productId) {HashOperations<String, String, String> opsForHash = redisTemplate.opsForHash();String redisKey = String.format(CART_REDIS_KEY_TEMPLATE, uid);String value = opsForHash.get(redisKey, String.valueOf(productId));Cart cart = null;if(StringUtils.isEmpty(value)) {//购物车中无此商品，报错return ResponseVo.error(ResponseEnum.PRODUCT_NOT_IN_CART);}//已经有了，删除opsForHash.delete(redisKey, String.valueOf(productId));return list(uid);
}

全选、全不选和获取商品总数

在ICartServiceImpl.java中添加方法：

@Override
public ResponseVo<CartVo> selectAll(Integer uid) {HashOperations<String, String, String> opsForHash = redisTemplate.opsForHash();String redisKey = String.format(CART_REDIS_KEY_TEMPLATE, uid);for(Cart cart : listForCart(uid)) {if(!cart.isProductSelected()) cart.setProductSelected(true);opsForHash.put(redisKey, String.valueOf(cart.getProductId()), gson.toJson(cart));}return list(uid);
}@Override
public ResponseVo<CartVo> unSelectAll(Integer uid) {HashOperations<String, String, String> opsForHash = redisTemplate.opsForHash();String redisKey = String.format(CART_REDIS_KEY_TEMPLATE, uid);for(Cart cart : listForCart(uid)) {if(cart.isProductSelected()) cart.setProductSelected(false);opsForHash.put(redisKey, String.valueOf(cart.getProductId()), gson.toJson(cart));}return list(uid);
}@Override
public ResponseVo<Integer> sum(Integer uid) {Integer quantity = 0;for(Cart cart : listForCart(uid)) {quantity += cart.getQuantity();}return ResponseVo.success(quantity);
}private List<Cart> listForCart(Integer uid) {HashOperations<String, String, String> opsForHash = redisTemplate.opsForHash();String redisKey = String.format(CART_REDIS_KEY_TEMPLATE, uid);Map<String, String> entries = opsForHash.entries(redisKey);List<Cart> cartList = new ArrayList<>();for(Map.Entry<String, String> entry : entries.entrySet()) {cartList.add(gson.fromJson(entry.getValue(), Cart.class));}return cartList;
}

编写controller

package com.xiaoxin.mall.controller;import com.xiaoxin.mall.consts.MallConst;
import com.xiaoxin.mall.form.CartAddForm;
import com.xiaoxin.mall.form.CartUpdateForm;
import com.xiaoxin.mall.pojo.User;
import com.xiaoxin.mall.service.ICartService;
import com.xiaoxin.mall.service.vo.CartVo;
import com.xiaoxin.mall.service.vo.ResponseVo;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;import javax.servlet.http.HttpSession;
import javax.validation.Valid;@RestController
public class CartController {@Autowiredprivate ICartService cartService;@GetMapping("/carts")public ResponseVo<CartVo> list(HttpSession session) {User user = (User) session.getAttribute(MallConst.CURRENT_USER);return cartService.list(user.getId());}@PostMapping("/carts")public ResponseVo<CartVo> add(@Valid @RequestBody CartAddForm cartAddForm,HttpSession session) {User user = (User) session.getAttribute(MallConst.CURRENT_USER);return cartService.add(user.getId(), cartAddForm);}@PutMapping("/carts/{productId}")public ResponseVo<CartVo> update(@Valid @RequestBody CartUpdateForm cartUpdateForm,@PathVariable Integer productId,HttpSession session) {User user = (User) session.getAttribute(MallConst.CURRENT_USER);return  cartService.update(user.getId(), productId, cartUpdateForm);}@DeleteMapping("/carts/{productId}")public ResponseVo<CartVo> delete(HttpSession session,@PathVariable Integer productId) {User user = (User) session.getAttribute(MallConst.CURRENT_USER);return cartService.delete(user.getId(), productId);}@PutMapping("/carts/selectAll")public ResponseVo<CartVo> selectAll(HttpSession session) {User user = (User) session.getAttribute(MallConst.CURRENT_USER);return cartService.selectAll(user.getId());}@PutMapping("/carts/unSelectAll")public ResponseVo<CartVo> unSelectAll(HttpSession session) {User user = (User) session.getAttribute(MallConst.CURRENT_USER);return cartService.unSelectAll(user.getId());}@GetMapping("/carts/products/sum")public ResponseVo<Integer> sum(HttpSession session) {User user = (User) session.getAttribute(MallConst.CURRENT_USER);return cartService.sum(user.getId());}
}