spring 如何在春季@Validate 唯一用户名？
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原文地址: http://stackoverflow.com/questions/17092601/
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How to @Validate unique username in spring?
提问by user902691
Let's assume that I have a form where I might submit username(@NaturalId)and passwordfor a new user.
让我们假设我有一个表格，我会提交username(@NaturalId)并password为新用户。
I would like to add the user with a unique username. How can I use @Validannotations to validate this constraint? And if username is not unique how can I display this information in jsp via <form:error/>?
我想为用户添加一个独特的username. 如何使用@Valid注释来验证此约束？如果用户名不是唯一的，我如何通过在 jsp 中显示此信息<form:error/>？
回答by shazinltc
AFAIK there isn't an annotation to do this. You have two options
AFAIK 没有注释可以做到这一点。你有两个选择
One, create a custom validator annotation. Hereis a very good example. Make a call to your DAO class and check the availability in the validator implementation
一，创建自定义验证器注释。这是一个很好的例子。调用您的 DAO 类并检查验证器实现中的可用性
public boolean isValid(String object, ConstraintValidatorContext constraintContext) {
return userDAO.userNameAvailable(object); //some method to check username availability
}
OR
或者
Set unique = true on your property in your entity class.
在实体类中的属性上设置 unique = true 。
@Column(unique = true)
private String userName;
But this will not work with @valid, instead throw an exception on persistence. You have to use an appropriate logic to handle that.
但这不适用于@valid，而是在持久性上抛出异常。您必须使用适当的逻辑来处理它。
The first solution isn't fool proof. Check thisanswer on SO.
第一个解决方案不是万无一失的。在 SO 上查看此答案。
The second will will never fail.
第二个永远不会失败。
UPDATE
更新
As NimChimpsky commented, using both together will be a concrete solution.
正如 NimChimpsky 评论的那样，将两者结合使用将是一个具体的解决方案。
回答by lunr
JSR-303 does not support what you want (something like a @Uniqueconstraint). You have to write you own validator. How can this be done is explained here: https://community.jboss.org/wiki/AccessingtheHibernateSessionwithinaConstraintValidator
JSR-303 不支持您想要的（类似于@Unique约束）。您必须编写自己的验证器。这里解释了如何做到这一点：https: //community.jboss.org/wiki/AccessingtheHibernateSessionwithinaConstraintValidator
But before doing that make sure you read this answer: https://stackoverflow.com/a/3499111/1981720
但在此之前，请确保您阅读此答案：https: //stackoverflow.com/a/3499111/1981720
And this sentence from the previous article:
还有上一篇文章中的这句话：
The reason @Unique is not part of the built-in constraints is the fact that accessing the Session/EntityManager during a valiation is opening yourself up for potenital phantom reads.
@Unique 不是内置约束的一部分的原因是，在验证期间访问 Session/EntityManager 会为潜在的幻读打开自己的大门。
回答by Pasha GR
You can use UserDetailsService prepared spring class and extend it and customize it :
您可以使用 UserDetailsService 准备好的 spring 类并对其进行扩展和自定义：
@Service
public class LoginDetailsServiceImpl implements UserDetailsService, Serializable {
@Autowired
LoginService loginService;
@Override
public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
if (username == "" || username.isEmpty()) {
throw new UsernameNotFoundException(String.format("User %s is invalid!", username));
}
Login login = loginService.find(username);
if (login == null) {
throw new UsernameNotFoundException(String.format("User %s does not exist!", username));
}
if (!loginService.scheduleChecking(login.getScheduled())) {
throw new UsernameNotFoundException(String.format("User %s is not authorized this time!", username));
}
//....
