详述Spring对数据校验支持的核心API：SmartValidator

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> 要致富，先修路。要使用，先...基础是需要垒砌的，做技术切勿空中楼阁

相关阅读

【小家Java】深入了解数据校验：Java Bean Validation 2.0（JSR303、JSR349、JSR380）Hibernate-Validation 6.x使用案例 【小家Java】深入了解数据校验（Bean Validation）：基础类打点（ValidationProvider、ConstraintDescriptor、ConstraintValidator）

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前言

浩浩荡荡的把一般程序员都不太关注的

Bean Validation

Spring

要想深入了解

Spring

Bean Validation

org.springframework.validation.beanvalidation

@Valid

Spring

spring-context

我把这个包内的类图截图如下，供以参考：

Spring

JSR

Spring3.0

Bean Validation

1. 3.0提供了Bean级别的校验
2. 3.1提供了更加强大的

   方法级别

   的校验

BeanValidationPostProcessor

它就是个普通的

BeanPostProcessor

若校验不通过，在违反约束的情况下就会抛出异常，阻止容器的正常启动~

public class BeanValidationPostProcessor implements BeanPostProcessor, InitializingBean {
// 这就是我们熟悉的校验器
// 请注意这里是javax.validation.Validator，而不是org.springframework.validation.Validator
@Nullable
private Validator validator;
// true：表示在Bean初始化之后完成校验
// false：表示在Bean初始化之前就校验
private boolean afterInitialization = false;
... // 省略get/set

// 由此可见使用的是默认的校验器（当然还是Hibernate的）
@Override
public void afterPropertiesSet() {
if (this.validator == null) {
this.validator = Validation.buildDefaultValidatorFactory().getValidator();
}
}

// 这个实现太简单了~~~
@Override
public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
if (!this.afterInitialization) {
doValidate(bean);
}
return bean;
}
@Override
public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
if (this.afterInitialization) {
doValidate(bean);
}
return bean;
}

protected void doValidate(Object bean) {
Assert.state(this.validator != null, "No Validator set");
Object objectToValidate = AopProxyUtils.getSingletonTarget(bean);
if (objectToValidate == null) {
objectToValidate = bean;
}
Set<constraintviolation<object>&gt; result = this.validator.validate(objectToValidate);

// 拼接错误消息最终抛出
if (!result.isEmpty()) {
StringBuilder sb = new StringBuilder("Bean state is invalid: ");
for (Iterator<constraintviolation<object>&gt; it = result.iterator(); it.hasNext();) {
ConstraintViolation<object> violation = it.next();
sb.append(violation.getPropertyPath()).append(" - ").append(violation.getMessage());
if (it.hasNext()) {
sb.append("; ");
}
}
throw new BeanInitializationException(sb.toString());
}
}
}

这个

BeanValidationPostProcessor

前/后

Spring Bean

BeanValidationPostProcessor

==org.springframework.validation.Validator==

应用程序特定对象的验证器，这是Spring自己的抽象，注意区别于

javax.validation.Validator

这个接口完全脱离了任何基础设施或上下文

// 注意：它可不是Spring3后才推出的  最初就有
public interface Validator {
// 此clazz是否可以被validate
boolean supports(Class<!--?--> clazz);
// 执行校验，错误消息放在Errors 装着
// 可以参考ValidationUtils这个工具类，它能帮助你很多
void validate(Object target, Errors errors);
}

它的继承树如下：

SmartValidator

这个子接口它扩展增加了校验分组：hints。

// @since 3.1  这个出现得比较晚
public interface SmartValidator extends Validator {

// 注意：这里的Hints最终都会被转化到JSR的分组里去~~
// 所以这个可变参数，传接口Class对象即可~
void validate(Object target, Errors errors, Object... validationHints);

// @since 5.1  简单的说，这个方法子类请复写 否则不能使用
default void validateValue(Class<!--?--> targetType, String fieldName, @Nullable Object value, Errors errors, Object... validationHints) {
throw new IllegalArgumentException("Cannot validate individual value for " + targetType);
}
}

SpringValidatorAdapter

：校验适配器（重要）

这个实现类Class是非常重要的，它是

javax.validation.Validator

Validator

Bean Validation 2.0

// @since 3.0
public class SpringValidatorAdapter implements SmartValidator, javax.validation.Validator {

// 通用的三个约束注解都需要有的属性
private static final Set<string> internalAnnotationAttributes = new HashSet&lt;&gt;(4);
static {
internalAnnotationAttributes.add("message");
internalAnnotationAttributes.add("groups");
internalAnnotationAttributes.add("payload");
}

// 最终都是委托给它来完成校验的~~~
@Nullable
private javax.validation.Validator targetValidator;
public SpringValidatorAdapter(javax.validation.Validator targetValidator) {
Assert.notNull(targetValidator, "Target Validator must not be null");
this.targetValidator = targetValidator;
}

// 简单的说：默认支持校验所有的Bean类型~~~
@Override
public boolean supports(Class<!--?--> clazz) {
return (this.targetValidator != null);
}
// processConstraintViolations做的事一句话解释：
// 把ConstraintViolations错误消息，全都适配放在Errors（BindingResult）里面存储着
@Override
public void validate(Object target, Errors errors) {
if (this.targetValidator != null) {
processConstraintViolations(this.targetValidator.validate(target), errors);
}
}

@Override
public void validate(Object target, Errors errors, Object... validationHints) {
if (this.targetValidator != null) {
processConstraintViolations(this.targetValidator.validate(target,  asValidationGroups(validationHints)), errors);
}
}

@SuppressWarnings("unchecked")
@Override
public void validateValue(Class<!--?--> targetType, String fieldName, @Nullable Object value, Errors errors, Object... validationHints) {
if (this.targetValidator != null) {
processConstraintViolations(this.targetValidator.validateValue(
(Class) targetType, fieldName, value, asValidationGroups(validationHints)), errors);
}
}

// 把validationHints都转换为group （支识别Class类型哦）
private Class<!--?-->[] asValidationGroups(Object... validationHints) {
Set<class<?>&gt; groups = new LinkedHashSet&lt;&gt;(4);
for (Object hint : validationHints) {
if (hint instanceof Class) {
groups.add((Class<!--?-->) hint);
}
}
return ClassUtils.toClassArray(groups);
}

// 关于Implementation of JSR-303 Validator interface  省略...
}

这个适配器它把所有的Spring接口的校验方法，最终都委托给了

org.springframework.validation.Validator

CustomValidatorBean

可配置（Custom）的Bean类，也同样的实现了

双接口

ValidatorFactory

MessageInterpolator

public class CustomValidatorBean extends SpringValidatorAdapter implements Validator, InitializingBean {

// javax.validation.ValidatorFactory
@Nullable
private ValidatorFactoryvalidatorFactory;
@Nullable
private MessageInterpolatormessageInterpolator;
@Nullable
private TraversableResolver traversableResolver;
... // 省略所有set方法（木有get方法）

// 默认设置~~~~初始化
@Override
public void afterPropertiesSet() {
if (this.validatorFactory == null) {
this.validatorFactory = Validation.buildDefaultValidatorFactory();
}

// 这一句就是new ValidatorContextImpl( this )
ValidatorContext validatorContext = this.validatorFactory.usingContext();

// 插值器
MessageInterpolatortargetInterpolator = this.messageInterpolator;
if (targetInterpolator == null) {
targetInterpolator = this.validatorFactory.getMessageInterpolator();
}
validatorContext.messageInterpolator(new LocaleContextMessageInterpolator(targetInterpolator));
if (this.traversableResolver != null) {
validatorContext.traversableResolver(this.traversableResolver);
}

// 把已经配置好的这个Validator设置进去~
setTargetValidator(validatorContext.getValidator());
}
}

命名中就能可以看出，它是一个Bean，所以可以配合Spring容器一起使用。

Spring

==LocalValidatorFactoryBean==

它和

CustomValidatorBean

SpringValidatorAdapter

Spring

MethodValidationPostProcessor

它是

Spring

javax.validation

// @since 3.0  这个类非常的丰富  实现了接口javax.validation.ValidatorFactory
// 实现了ApplicationContextAware拿到Spring上下文...
// 但其实，它的实际工作都是委托式，自己只提供了各式各样的配置~~~（主要是配置JSR）
public class LocalValidatorFactoryBean extends SpringValidatorAdapter implements ValidatorFactory, ApplicationContextAware, InitializingBean, DisposableBean {
... // 省略所有的配置属性
... // 省略所有的get/set
... // 省略afterPropertiesSet()进行的默认配置初始化  最终调用setTargetValidator(this.validatorFactory.getValidator());

// 备注：还记得上文吗？上文的validator校验器是从上下文拿的，这里是从工厂拿的
// 省略所有对ValidatorFactory接口的方法实现~
}

这个类是非常重要的，虽然它也不被Spring直接使用，但是它是基石。

> 备注：虽然命名后缀是

FactoryBean

org.springframework.beans.factory.FactoryBean

ValidatorFactory

@since 4.0.1

org.springframework.validation.Validator

// @since 4.0.1
public class OptionalValidatorFactoryBean extends LocalValidatorFactoryBean {

@Override
public void afterPropertiesSet() {
try {
super.afterPropertiesSet();
} catch (ValidationException ex) {
LogFactory.getLog(getClass()).debug("Failed to set up a Bean Validation provider", ex);
}
}

}

综上，若你想使用

org.springframework.validation.SmartValidator

ConstraintValidatorFactory

Spring

public class SpringConstraintValidatorFactoryimplements ConstraintValidatorFactory{

private final AutowireCapableBeanFactory beanFactory;
public SpringConstraintValidatorFactory(AutowireCapableBeanFactory beanFactory) {
Assert.notNull(beanFactory, "BeanFactory must not be null");
this.beanFactory = beanFactory;
}

// 注意：此处是直接调用了create方法，放进容器
@Override
public <t extends constraintvalidator<?, ?>&gt; T getInstance(Class<t> key) {
return this.beanFactory.createBean(key);
}
// Bean Validation 1.1 releaseInstance method
public void releaseInstance(ConstraintValidator<!--?, ?--> instance) {
this.beanFactory.destroyBean(instance);
}

}

MessageSourceResourceBundleLocator

这个类也非常有意思，它扩展了

Hibernate

ResourceBundleLocator

org.springframework.context.MessageSource

ResourceBundleLocator

Hibernate

Hibernate

Bean Validation

public class MessageSourceResourceBundleLocator implements ResourceBundleLocator {

private final MessageSource messageSource;
public MessageSourceResourceBundleLocator(MessageSource messageSource) {
Assert.notNull(messageSource, "MessageSource must not be null");
this.messageSource = messageSource;
}

@Override
public ResourceBundle getResourceBundle(Locale locale) {
return new MessageSourceResourceBundle(this.messageSource, locale);
}

}

关于

MessageSourceResourceBundle

MessageSource

java.util.ResourceBundl

//@since 27.02.2003 java.util.ResourceBundle  它是JDK提供来读取国际化的属性配置文件的  是个抽象类
public class MessageSourceResourceBundle extends ResourceBundle {
private final MessageSource messageSource;
private final Locale locale;

public MessageSourceResourceBundle(MessageSource source, Locale locale) {
Assert.notNull(source, "MessageSource must not be null");
this.messageSource = source;
this.locale = locale;
}
public MessageSourceResourceBundle(MessageSource source, Locale locale, ResourceBundle parent) {
this(source, locale);
setParent(parent);
}

@Override
@Nullable
protected Object handleGetObject(String key) {
try {
return this.messageSource.getMessage(key, null, this.locale);
} catch (NoSuchMessageException ex) {
return null;
}
}

// @since 1.6
@Override
public boolean containsKey(String key) {
try {
this.messageSource.getMessage(key, null, this.locale);
return true;
}
catch (NoSuchMessageException ex) {
return false;
}
}
@Override
public Enumeration<string> getKeys() {
throw new UnsupportedOperationException("MessageSourceResourceBundle does not support enumerating its keys");
}
@Override
public Locale getLocale() {
return this.locale;
}
}

Spring

Hibernate

MessageSourceResourceBundleLocator

LocaleContextMessageInterpolator

它是个

javax.validation.MessageInterpolator

LocaleContext

// @since 3.0
// org.springframework.context.i18n.LocaleContextHolder#getLocale()
public class LocaleContextMessageInterpolatorimplements MessageInterpolator{

private final MessageInterpolatortargetInterpolator;
public LocaleContextMessageInterpolator(MessageInterpolatortargetInterpolator) {
Assert.notNull(targetInterpolator, "Target MessageInterpolatormust not be null");
this.targetInterpolator = targetInterpolator;
}

@Override
public String interpolate(String message, Context context) {
return this.targetInterpolator.interpolate(message, context, LocaleContextHolder.getLocale());
}
@Override
public String interpolate(String message, Context context, Locale locale) {
return this.targetInterpolator.interpolate(message, context, locale);
}

}

Demo Show

想来想去，还是给个Demo非常简单的操作一把吧，此处我以

CustomValidatorBean

@Getter
@Setter
@ToString
public class Person {

// 错误消息message是可以自定义的
@NotNull(message = "{message} -> 名字不能为null", groups = Simple.class)
public String name;
@Max(value = 10, groups = Simple.class)
@Positive(groups = Default.class) // 内置的分组：default
public Integer age;

@NotNull(groups = Complex.class)
@NotEmpty(groups = Complex.class)
private List<@Email String> emails;
@Future(groups = Complex.class)
private Date start;

// 定义两个组 Simple组和Complex组
public interface Simple {
}

public interface Complex {

}
}

想容器放入一个校验器：

@Configuration
public class RootConfig {

@Bean
public CustomValidatorBean customValidatorBean() {
return new CustomValidatorBean();
}

}

使用此校验器校验Person对象（本文为了简单就直接new了哈，当然你也可以是容器内的Bean对象）

@Slf4j
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = {RootConfig.class})
public class TestSpringBean {

@Autowired
private SmartValidator smartValidator;

@Test
public void test1() {
Person person = new Person();
person.setAge(-1);
person.setStart(new Date());

Errors errors = new DirectFieldBindingResult(person, "person");
ValidationUtils.invokeValidator(smartValidator, person, errors, Person.Complex.class);
System.out.println(errors);

}

}

打印输出：

org.springframework.validation.DirectFieldBindingResult: 3 errors
Field error in object 'person' on field 'emails': rejected value [null]; codes [NotEmpty.person.emails,NotEmpty.emails,NotEmpty.java.util.List,NotEmpty]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [person.emails,emails]; arguments []; default message [emails]]; default message [不能为空]
Field error in object 'person' on field 'start': rejected value [Fri Jul 26 11:12:21 CST 2019]; codes [Future.person.start,Future.start,Future.java.util.Date,Future]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [person.start,start]; arguments []; default message [start]]; default message [需要是一个将来的时间]
Field error in object 'person' on field 'emails': rejected value [null]; codes [NotNull.person.emails,NotNull.emails,NotNull.java.util.List,NotNull]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [person.emails,emails]; arguments []; default message [emails]]; default message [不能为null]

符合预期。 > 说明：因为前面说了

Bean Validation

javax.validation.Validator

总结

从这篇文章开始，关于

Bean Validation

==下一篇，也就是整个

Bean Validation

@Valid,@Validated

知识交流

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转载于:https://my.oschina.net/fangshixiang/blog/3079440

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