IllegalArgumentException: 未知实体: java.lang.Integer]

Question

我在学习 spring 时做了这个例子，一切正常，现在我正在编写自己的项目，我不明白为什么当我尝试从EntityManager 类从 MySQL 数据库中删除对象产品类（我不会在此处粘贴所有方法，例如 getter 和 setter 等）import javax.persistence.*;@Entitypublic class Product {    @Id    @GeneratedValue(strategy = GenerationType.AUTO)    private Integer id;    private String name;    @OneToOne    private ProductType type;    private float price;    private String description;    //more code...}ProductRepository（我只显示删除方法）import javax.persistence.EntityManager;import javax.persistence.PersistenceContext;import javax.transaction.Transactional;public class DBProductRepository implements ProductRepository{    @PersistenceContext    private EntityManager entityManager;    @Override    @Transactional    public void deleteProduct(Integer id) {        entityManager.remove(id);    }    //more code...}ProductService（我只显示删除方法）@Servicepublic class ProductService {    public void deleteProduct(Integer id) {        productRepository.deleteProduct(id);    }    //more code...}产品控制器@Controllerpublic class ProductController {    @RequestMapping("/products")    public String getProducts(Model model){        List<Product> products = productService.getAllProducts();        model.addAttribute("products",products);        return "products";    }    @RequestMapping(value="/product/delete/{id}")    public String deleteProduct(@PathVariable("id") Integer id){        productService.deleteProduct(id);        return "redirect:/products";    }    //more code...}

Answer 1

EntityManager#remove将实体实例作为参数。你正在路过Integer。

改成：

@Override

@Transactional

public void deleteProduct(Product product) {

    entityManager.remove(product);

}