java.lang.ClassCastException：类 java.lang.Integer 不能转换为类 java.lang.Long

Question

当我尝试显示购物车时，我不断收到 classcastexception。我正在使用 spring 实现一个书店系统，直到之后一切正常。下面是我的购物车控制器和相关类。我会很感激我能得到的任何帮助。谢谢

package com.bookstore.controller;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;

import com.bookstore.domain.Book;
import com.bookstore.domain.CartItem;
import com.bookstore.domain.CustomerUserDetails;
import com.bookstore.domain.ShoppingCart;
import com.bookstore.domain.User;
import com.bookstore.repository.UserRepo;
import com.bookstore.services.BookService;
import com.bookstore.services.CartItemService;
import com.bookstore.services.ShoppingCartService;
import com.bookstore.services.UserServices;

@Controller
@RequestMapping("/shoppingCart")
public class ShoppingCartController {
    
    @Autowired
    private UserServices userService;
    
    @Autowired
    private UserRepo repo;
    
    @Autowired
    private BookService bookService;
    
    @Autowired
    private CartItemService cartItemService;
    
    @Autowired
    private ShoppingCartService ShoppingCartService;
    
    @RequestMapping("/cart")
    public String shoppingCart(Model model) {
        
        Object principal =   SecurityContextHolder.getContext().getAuthentication().getPrincipal();
        String emailaddress = null;
        if(principal != null )
        {
            emailaddress = ((CustomerUserDetails)principal).getEmailaddress();
        }
        User user = repo.findByEmail(emailaddress);
        ShoppingCart shoppingCart = (ShoppingCart) user.getShoppingCart();
        
        List<CartItem> cartItemList = cartItemService.findByShoppingCart(shoppingCart);
        
        ShoppingCartService.updateShoppingCart(shoppingCart);
        
        model.addAttribute("cartItemList", cartItemList);
        model.addAttribute("shoppingCart", shoppingCart);
        
        return "cartView";
    }
    
    
    
    @RequestMapping(value = "/addItem", method = RequestMethod.POST)
    public String addItem(
            @ModelAttribute("book") Book book,
            @ModelAttribute("qty") String qty,
            Model model
            ) {
        
        Object principal =   SecurityContextHolder.getContext().getAuthentication().getPrincipal();
        String emailaddress = null;
        if(principal != null)
        {
            emailaddress = ((CustomerUserDetails)principal).getEmailaddress();
        }
        User user = repo.findByEmail(emailaddress);
        book = bookService.findById(book.getBookid());
        System.out.println(book.getBookid());
        System.out.println(emailaddress);
        if (Integer.parseInt(qty) > book.getInStockNumber()) {
            model.addAttribute("notEnoughStock", true);
            return "forward:/bookDetail?id="+book.getBookid();
        }
        
        CartItem cartItem = cartItemService.addBookToCartItem(book, user, Integer.parseInt(qty));
        model.addAttribute("addBookSuccess", true);
        
        return "forward:/bookDetail?id="+book.getBookid();
    }

    @RequestMapping("/updateCartItem")
    public String updateShoppingCart(
            @ModelAttribute("id") Long cartItemId,
            @ModelAttribute("qty") int qty
            ) {
        CartItem cartItem = cartItemService.findById(cartItemId);
        cartItem.setQty(qty);
        cartItemService.updateCartItem(cartItem);
        System.out.println("true");
        return "forward:/shoppingCart/cart";
    }
    
    @RequestMapping("/removeItem")
    public String removeItem(@RequestParam("id") Long id) {
        cartItemService.removeCartItem(cartItemService.findById(id));
        
        return "forward:/shoppingCart/cart";
    }
}

这是错误跟踪

Wed Apr 28 05:06:37 EDT 2021
There was an unexpected error (type=Internal Server Error, status=500).
class java.lang.Integer cannot be cast to class java.lang.Long (java.lang.Integer and java.lang.Long are in module java.base of loader 'bootstrap')
java.lang.ClassCastException: class java.lang.Integer cannot be cast to class java.lang.Long (java.lang.Integer and java.lang.Long are in module java.base of loader 'bootstrap')
    at org.hibernate.type.descriptor.java.LongTypeDescriptor.unwrap(LongTypeDescriptor.java:19)
    at org.hibernate.type.descriptor.sql.BigIntTypeDescriptor$1.doBind(BigIntTypeDescriptor.java:46)
    at org.hibernate.type.descriptor.sql.BasicBinder.bind(BasicBinder.java:73)
    at org.hibernate.type.AbstractStandardBasicType.nullSafeSet(AbstractStandardBasicType.java:276)
    at org.hibernate.type.AbstractStandardBasicType.nullSafeSet(AbstractStandardBasicType.java:271)
    at org.hibernate.loader.Loader.bindPositionalParameters(Loader.java:2227)
    at org.hibernate.loader.Loader.bindParameterValues(Loader.java:2196)
    at org.hibernate.loader.Loader.bindPreparedStatement(Loader.java:2131)
    at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:2108)
    at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:2040)
    at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:2018)
    at org.hibernate.loader.Loader.doQuery(Loader.java:948)
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:349)
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:319)
    at org.hibernate.loader.Loader.loadEntity(Loader.java:2421)
    at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:77)
    at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:66)
    at org.hibernate.persister.entity.AbstractEntityPersister.loadByUniqueKey(AbstractEntityPersister.java:2471)
    at org.hibernate.type.EntityType.loadByUniqueKey(EntityType.java:754)
    at org.hibernate.type.EntityType.resolve(EntityType.java:467)
    at org.hibernate.engine.internal.TwoPhaseLoad$EntityResolver.lambda$static$0(TwoPhaseLoad.java:605)
    at org.hibernate.engine.internal.TwoPhaseLoad.initializeEntityEntryLoadedState(TwoPhaseLoad.java:248)
    at org.hibernate.engine.internal.TwoPhaseLoad.initializeEntity(TwoPhaseLoad.java:182)
    at org.hibernate.engine.internal.TwoPhaseLoad.initializeEntity(TwoPhaseLoad.java:151)
    at org.hibernate.loader.plan.exec.process.internal.AbstractRowReader.performTwoPhaseLoad(AbstractRowReader.java:247)
    at org.hibernate.loader.plan.exec.process.internal.AbstractRowReader.finishUp(AbstractRowReader.java:208)
    at org.hibernate.loader.plan.exec.process.internal.ResultSetProcessorImpl.extractResults(ResultSetProcessorImpl.java:96)
    at org.hibernate.loader.plan.exec.internal.AbstractLoadPlanBasedLoader.executeLoad(AbstractLoadPlanBasedLoader.java:105)
    at org.hibernate.loader.entity.plan.AbstractLoadPlanBasedEntityLoader.load(AbstractLoadPlanBasedEntityLoader.java:285)
    at org.hibernate.persister.entity.AbstractEntityPersister.doLoad(AbstractEntityPersister.java:4436)
    at org.hibernate.persister.entity.AbstractEntityPersister.load(AbstractEntityPersister.java:4426)
    at org.hibernate.event.internal.DefaultLoadEventListener.loadFromDatasource(DefaultLoadEventListener.java:569)
    at org.hibernate.event.internal.DefaultLoadEventListener.doLoad(DefaultLoadEventListener.java:537)
    at org.hibernate.event.internal.DefaultLoadEventListener.load(DefaultLoadEventListener.java:208)
    at org.hibernate.event.internal.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:332)
    at org.hibernate.event.internal.DefaultLoadEventListener.doOnLoad(DefaultLoadEventListener.java:108)
    at org.hibernate.event.internal.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:74)
    at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:104)
    at org.hibernate.internal.SessionImpl.fireLoadNoChecks(SessionImpl.java:1186)
    at org.hibernate.internal.SessionImpl.internalLoad(SessionImpl.java:1051)
    at org.hibernate.type.EntityType.resolveIdentifier(EntityType.java:697)
    at org.hibernate.type.EntityType.resolve(EntityType.java:464)
    at org.hibernate.type.ManyToOneType.resolve(ManyToOneType.java:240)
    at org.hibernate.engine.internal.TwoPhaseLoad$EntityResolver.lambda$static$0(TwoPhaseLoad.java:605)
    at org.hibernate.engine.internal.TwoPhaseLoad.initializeEntityEntryLoadedState(TwoPhaseLoad.java:248)
    at org.hibernate.engine.internal.TwoPhaseLoad.initializeEntity(TwoPhaseLoad.java:182)
    at org.hibernate.engine.internal.TwoPhaseLoad.initializeEntity(TwoPhaseLoad.java:151)
    at org.hibernate.loader.Loader.initializeEntitiesAndCollections(Loader.java:1199)
    at org.hibernate.loader.Loader.processResultSet(Loader.java:1001)
    at org.hibernate.loader.Loader.doQuery(Loader.java:959)
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:349)
    at org.hibernate.loader.Loader.doList(Loader.java:2849)
    at org.hibernate.loader.Loader.doList(Loader.java:2831)
    at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2663)
    at org.hibernate.loader.Loader.list(Loader.java:2658)
    at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:506)
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:400)
    at org.hibernate.engine.query.spi.HQLQueryPlan.performList(HQLQueryPlan.java:219)
    at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1414)
    at org.hibernate.query.internal.AbstractProducedQuery.doList(AbstractProducedQuery.java:1625)
    at org.hibernate.query.internal.AbstractProducedQuery.list(AbstractProducedQuery.java:1593)
    at org.hibernate.query.Query.getResultList(Query.java:165)
    at org.hibernate.query.criteria.internal.compile.CriteriaQueryTypeQueryAdapter.getResultList(CriteriaQueryTypeQueryAdapter.java:76)
    at org.springframework.data.jpa.repository.query.JpaQueryExecution$CollectionExecution.doExecute(JpaQueryExecution.java:126)
    at org.springframework.data.jpa.repository.query.JpaQueryExecution.execute(JpaQueryExecution.java:88)
    at org.springframework.data.jpa.repository.query.AbstractJpaQuery.doExecute(AbstractJpaQuery.java:155)
    at org.springframework.data.jpa.repository.query.AbstractJpaQuery.execute(AbstractJpaQuery.java:143)
    at org.springframework.data.repository.core.support.RepositoryMethodInvoker.doInvoke(RepositoryMethodInvoker.java:137)
    at org.springframework.data.repository.core.support.RepositoryMethodInvoker.invoke(RepositoryMethodInvoker.java:121)
    at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.doInvoke(QueryExecutorMethodInterceptor.java:152)
    at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.invoke(QueryExecutorMethodInterceptor.java:131)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:123)
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:388)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:119)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:137)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:145)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:97)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:215)
    at com.sun.proxy.$Proxy112.findByShoppingCart(Unknown Source)
    at com.bookstore.services.impl.CartItemServiceImpl.findByShoppingCart(CartItemServiceImpl.java:30)
    at com.bookstore.controller.ShoppingCartController.shoppingCart(ShoppingCartController.java:56)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:566)
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:197)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:141)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:106)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:894)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1060)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:962)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:626)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
    at org.springframework.web.servlet.resource.ResourceUrlEncodingFilter.doFilter(ResourceUrlEncodingFilter.java:67)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:327)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:115)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:81)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336)
    at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:119)
    at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336)
    at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:126)
    at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:81)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336)
    at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:105)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336)
    at org.springframework.security.web.authentication.rememberme.RememberMeAuthenticationFilter.doFilter(RememberMeAuthenticationFilter.java:101)
    at org.springframework.security.web.authentication.rememberme.RememberMeAuthenticationFilter.doFilter(RememberMeAuthenticationFilter.java:92)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336)
    at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:149)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336)
    at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:63)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336)
    at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:218)
    at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:212)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336)
    at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:103)
    at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:89)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336)
    at org.springframework.security.web.header.HeaderWriterFilter.doHeadersAfter(HeaderWriterFilter.java:90)
    at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:75)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336)
    at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:110)
    at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:80)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336)
    at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:55)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336)
    at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:211)
    at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:183)
    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:358)
    at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:271)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
    at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:143)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:357)
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:374)
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:893)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1707)
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.base/java.lang.Thread.run(Thread.java:834)

这是 cartItemServiceImpl 类

package com.bookstore.services.impl;

import java.math.BigDecimal;
import java.math.RoundingMode;
import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import com.bookstore.domain.Book;
import com.bookstore.domain.BookToCartItem;
import com.bookstore.domain.CartItem;
import com.bookstore.domain.ShoppingCart;
import com.bookstore.domain.User;
import com.bookstore.repository.CartItemRepository;
import com.bookstore.services.CartItemService;
import com.bookstore.repository.BookToCartItemRepository;

@Service
public class CartItemServiceImpl implements CartItemService{
    
    @Autowired
    private CartItemRepository cartItemRepository;
    
    @Autowired
    private BookToCartItemRepository bookToCartItemRepository;
    
    
    public List<CartItem> findByShoppingCart(ShoppingCart shoppingCart) {
        return cartItemRepository.findByShoppingCart(shoppingCart);
    }
    
    public CartItem updateCartItem(CartItem cartItem) {
        BigDecimal bigDecimal = new BigDecimal(cartItem.getBook().getPrice()).multiply(new BigDecimal(cartItem.getQty()));
        
        bigDecimal = bigDecimal.setScale(2, RoundingMode.HALF_UP);
        cartItem.setSubtotal(bigDecimal);
        
        cartItemRepository.save(cartItem);
        
        return cartItem;
    }

    public CartItem addBookToCartItem(Book book, User user, int qty) {
        List<CartItem> cartItemList = findByShoppingCart(user.getShoppingCart());
        
        for (CartItem cartItem : cartItemList) {
            if(book.getBookid() == cartItem.getBook().getBookid()) {
                cartItem.setQty(cartItem.getQty()+qty);
                cartItem.setSubtotal(new BigDecimal(book.getPrice()).multiply(new BigDecimal(qty)));
                cartItemRepository.save(cartItem);
                return cartItem;
            }
        }
        
        CartItem cartItem = new CartItem();
        cartItem.setShoppingCart(user.getShoppingCart());
        cartItem.setBook(book);
        
        cartItem.setQty(qty);
        cartItem.setSubtotal(new BigDecimal(book.getPrice()).multiply(new BigDecimal(qty)));
        cartItem = cartItemRepository.save(cartItem);
        
        BookToCartItem bookToCartItem = new BookToCartItem();
        bookToCartItem.setBook(book);
        bookToCartItem.setCartItem(cartItem);
        bookToCartItemRepository.save(bookToCartItem);
        
        return cartItem;
    }
    
    public CartItem findById(Long id) {
        return cartItemRepository.findById(id).orElse(null);
    }
    
    public void removeCartItem(CartItem cartItem) {
        bookToCartItemRepository.deleteByCartItem(cartItem);
        cartItemRepository.delete(cartItem);
    }
    
    public CartItem save(CartItem cartItem) {
        return cartItemRepository.save(cartItem);
    }

}

这是 cartItemRepository

@Transactional
public interface CartItemRepository extends CrudRepository<CartItem, Long>{
    List<CartItem> findByShoppingCart(ShoppingCart shoppingCart);
}

这里是 caritem 实体，我从来没有将 id 定义为 Integer

package com.bookstore.domain;

import java.math.BigDecimal;
import java.util.List;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;
import javax.persistence.OneToOne;

import com.fasterxml.jackson.annotation.JsonIgnore;

@Entity
public class CartItem {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
    private int qty;
    private BigDecimal subtotal;
    
    @OneToOne
    private Book book;
    
    @OneToMany(mappedBy = "cartItem")
    @JsonIgnore
    private List<BookToCartItem> bookToCartItemList;
    
    @ManyToOne
    @JoinColumn(name="shopping_cart_id")
    private ShoppingCart shoppingCart;
    
    @ManyToOne
    @JoinColumn(name="order_id")
    private Order order;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public int getQty() {
        return qty;
    }

    public void setQty(int qty) {
        this.qty = qty;
    }

    public BigDecimal getSubtotal() {
        return subtotal;
    }

    public void setSubtotal(BigDecimal subtotal) {
        this.subtotal = subtotal;
    }

    public Book getBook() {
        return book;
    }

    public void setBook(Book book) {
        this.book = book;
    }

    public List<BookToCartItem> getBookToCartItemList() {
        return bookToCartItemList;
    }

    public void setBookToCartItemList(List<BookToCartItem> bookToCartItemList) {
        this.bookToCartItemList = bookToCartItemList;
    }

    public ShoppingCart getShoppingCart() {
        return shoppingCart;
    }

    public void setShoppingCart(ShoppingCart shoppingCart) {
        this.shoppingCart = shoppingCart;
    }

    public Order getOrder() {
        return order;
    }

    public void setOrder(Order order) {
        this.order = order;
    }
    
    
}

Answer 1

很可能，您在 CartItem 中将主 ID 定义为 Integer，这与您在存储库接口中定义的通用类型 Long 冲突。请发布 CartItem 类 - 这将有助于确认这一点。

Answer 2

我认为问题在于book，因为它没有定义连接列。在加载CartItem 期间，它会像您定义的那样急切地加载图书（@OneToOne 和@ManyToOne 上的默认获取类型是 EAGER）。我猜 Hibernate 在这种情况下使用主键作为连接列，它的类型为Long。 Book 的主键可能是Integer。调整此映射，它将起作用。