java – 旧数据在OneToMany Mapping中被删除

Product.java:-

@Entity
    @Table(name ="PRODUCT")
    public class Product {
        @Id
        @GeneratedValue(strategy = GenerationType.AUTO)
        private int id;
        private String name;
    Product(String name){
            this.name=name;
        }
    }

ProductLine.java

public class ProductLine {
        @Id
        @GeneratedValue(strategy = GenerationType.AUTO)
        private int id;
        @OneToMany(cascade = CascadeType.ALL)
        @JoinTable(name = "PRODUCTLINE_PRODUCT",joinColumns = @JoinColumn(name = "PRODUCTLINE_ID"),inverseJoinColumns = @JoinColumn(name = "PRODUCT_ID"))
        private List<Product> products=new ArrayList<>();

     public ProductLine(String name){
        this.name=name;
        }
    }

ProductLineRepository.java

public interface ProductLineRepository extends JpaRepository<ProductLine,Integer> {
            ProductLine findOneById(String id);
        ProductLine findOneByName(String name);
        }

控制器： –

在控制器中,我正在以json形式解析用户与产品关联的产品列表,并将其持久保存到DB中.

public void addData(){
        List<Product> products=new ArrayList<>();
        Product product1=new Product("Iphone");
        Product product2=new Product("Mac");
        products.add(product1);
        products.add(product2);
        ProductLine productLine=productLineRepository.findOneByName("Apple");
        productLine.setProducts(products);
        productLineRepository.save(productLine);
    }

现在,如果产品线“Apple”已经存在,那么它将删除名为“Apple”的Product Line表中的条目,然后再次插入数据“IPhone”和“Mac”.但我不希望删除旧数据.我该怎么办？