Java 接收空对象的验证器¿；为什么？

首先感谢所有试图帮助我的人：如果我使用

Set<ConstraintViolation<Object>> constraintViolations = VALIDATOR.validate(anObj);

---

请查收。这个问题与BV无关，而是与jpa合并语义和多对多关系有关。

你能发布TeamDAO.updateEntity的代码吗？当然，我在上一版中添加了。DAO层是一个抽象类，TeamDAO只对其进行了扩展以提供一些方法，正如您在代码中看到的那样，但我现在没有更多的方法。在上一张图片中，您可以看到该方法的异常ThrownThrough谢谢，您是对的，现在它正在工作

public class Team implements Serializable {
//...
@AtLeastOneNotNull
@ManyToMany
@JoinTable(
    name="teams_players"
    , joinColumns={
        @JoinColumn(name="id_team")
        }
    , inverseJoinColumns={
        @JoinColumn(name="id_player")
        }
    )   
private List<Player> players;
//...
}

public class AtLeastOneNotNullValidator implements ConstraintValidator<AtLeastOneNotNull, List<?>> {

@Override
public void initialize(AtLeastOneNotNull constraint) {

}

@Override
public boolean isValid(List<?> aCollection, ConstraintValidatorContext aConstraintValidatorContext) {
    if(aCollection == null || aCollection.isEmpty())
        return false;
    else
        return true;
}
}

@Target({ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Constraint(validatedBy = AtLeastOneNotNullValidator.class)
public @interface AtLeastOneNotNull {

String message() default "{[ERROR] Collection must have at least one element}";

Class<?>[] groups() default {};

Class<? extends Payload>[] payload() default {};

}

public class TeamDAOTest {

private static Validator VALIDATOR;

TeamTestHelper teamTestHelper = null;
TeamDAO teamDaoTest = null;

@Before
public void initTestClass() {
    teamDaoTest = new TeamDAO();
    teamTestHelper = new TeamTestHelper();
    ValidatorFactory factory = Validation.buildDefaultValidatorFactory();
    VALIDATOR = factory.getValidator();
}

@After
public void endTestClass() {

}

@Test
public void savingRightTeam() {
    Team testTeam = teamTestHelper.getTeamOK();

 //     Set<ConstraintViolation<Team>> constraintViolations = VALIDATOR.validate(testTeam);
 //     
 //     assertEquals(0, constraintViolations.size());
 //             
    assertEquals("Inserting right Team", true, teamDaoTest.updateEntity(testTeam));
}

@Test
public void savingWrongTeam() {
    Team testTeam = teamTestHelper.getTeamKO_WithoutPlayers();

//      Set<ConstraintViolation<Team>> constraintViolations = VALIDATOR.validate(testTeam);
//      
//      assertEquals(1, constraintViolations.size());

    assertEquals("Inserting empty Team", false, teamDaoTest.updateEntity(testTeam));
}

public List<Player> getPlayers() {
    if(this.players == null)
        this.players = new ArrayList<Player>();

    return this.players;
}

public boolean addPlayer(Player aPlayer){
    if(!getPlayers().contains(aPlayer)){
        this.players.add(aPlayer);
        return true;
    }
    else return false;

}

public class TeamDAO extends AbstractDAOLayer<Team> {

public boolean updateEntity(T anObject){
    try{
        this.beginTransaction();
        this.entityManager.merge(anObject);
        this.finishtTransaction();
        return true;
    }
    catch(Exception e){
        return false;
    }
}