Question

我有一个hibernate实体类

public class MyComplexClass implements  Serializable {

    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    Long id;

    String name;
    int number;
    @ElementCollection
    Map<String,String> myMap;

    @ManyToOne
    Simple simple;

    public MyComplexClass(String name, int number, Map<String,String> myMap) {
        this.name = name;
        this.port = number;
        this.myMap = myMap;
    }

    public MyComplexClass() {
        // TODO Auto-generated constructor stub
    }

    public void setName(String name) {
        this.name = name;

    }

    public String getName() {
        return name;
    }

    public void setNumber(int number) {
        this.port = number;
    }

    public int getPort() {
        return port;
    }

    public void setMyMap(Map<String,String> myMap) {
        this.myMap = myMap;
    }

    public Map<String,String> getMyMap() {
        return this.myMap;
    }


    public Simple getSimple() {
        return this.simple;
    }

在类中，我有一个表单的映射

    @Entity
    @Table(name = "Simple")


    public class Simple  implements Comparable<Simple>, Serializable {
    @JsonProperty
    @OneToMany(mappedBy="simple",fetch = FetchType.EAGER,cascade = CascadeType.ALL)
    List<MyComplexClass> myComplexClass;

    public void setMyComplexClass(List<MyComplexClass> myComplexClass) {
        this.myComplexClass = myComplexClass;
    }

    public List<MyComplexClass> getMyComplexClass() {
        return this.myComplexClass;
    }

系统中的某处我将值设置为

Map<String, String> myMap = new HashMap<String,String>();
myMap.put("value","value");
MyComplexClass myComplexClass = new MyComplexclass("a", 123, myMap)
List<MyComplexClass> myComplexClassList = new ArrayList<MyComplexClass>();
myComplexClassList.add(myComplexClassList)
simple.setMyComplexClass(myComplexClassList);
// save to the database
dao.save(simple);

但是当我得到值为

时

Simple simple = dao.getSimple(simple.id);
`simple.getMyComplexClass.get(0).getMyMap.get("value")`

。它返回一个空指针。当我调试时，我看到simple.getMyComplexClass()本身为null

为什么不返回设置的值？它与数据库或内存缓存有关吗？

在数据库中，我确实在MyComplex类表的外键列中看到一个null，这是原因吗？

Hibernate实体类getters在设置值后返回null

0 个答案: