方法一：主键类用@Embeddable，pojo类仍然用@Entity但是引用主键类的对象用@Id 

主键pojo类： 

@Embeddablepublic class composeIdPK implements Serializable { private String name; private int id;  @Column(length=20,name="pkName") public String getName() {  return name; }    @Column(length=10,name="uuid") public int getId() {  return id; }

 

pojo类： 

@Entitypublic class composeId { private composeIdPK pk; private int uid; private String title; private String address;  @Id public composeIdPK getPk() {  return pk; }

 

方法二：@EmbeddedlD(*)         主键pojo类无需加@EmbeddedlD注解，只需在pojo类新属性“composeIdPK”的get方法前写@EmbeddedlD即可 

方法三：@Id  @IdClass(*)  主键pojo类无需加注解，原pojo类的id，name属性保留不变，也无需新增“ComposeIDPK”属性。 只在id，name的get方法前都加@Id，并在原pojo类前加 @IdClass(*)

如下： 

@Entity@IdClass(com.study.model.composeID.composeIdPK.class)public class composeId { //private composeIdPK pk;    private int id;    private String name;    @Id    @Column(length=10,name="uuid") public int getId() {  return id; } public void setId(int id) {  this.id = id; } @Id  @Column(length=20,name="pkName") public String getName() {  return name; } public void setName(String name) {  this.name = name; } private String title; private String address;

 

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