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对于最新的稳定版本，请使用 Spring Framework 6.2.0！ |
使用 Spring 的 Validator 接口进行验证
Spring 具有Validator可用于验证对象的接口。这Validatorinterface 通过使用Errors对象，以便在验证时，
验证者可以向Errors对象。
请考虑以下小型数据对象示例：
-
Java
-
Kotlin
public class Person {
private String name;
private int age;
// the usual getters and setters...
}class Person(val name: String, val age: Int)下一个示例提供了Person类，方法是实现
以下两种方法org.springframework.validation.Validator接口：
-
supports(Class)： 这个可以吗Validator验证提供的Class? -
validate(Object, org.springframework.validation.Errors)：验证给定的对象 并且，如果出现验证错误，则使用给定的Errors对象。
实施Validator相当简单，尤其是当您知道ValidationUtilshelper 类。以下内容
示例 implementsValidator为Person实例：
-
Java
-
Kotlin
public class PersonValidator implements Validator {
/**
* This Validator validates only Person instances
*/
public boolean supports(Class clazz) {
return Person.class.equals(clazz);
}
public void validate(Object obj, Errors e) {
ValidationUtils.rejectIfEmpty(e, "name", "name.empty");
Person p = (Person) obj;
if (p.getAge() < 0) {
e.rejectValue("age", "negativevalue");
} else if (p.getAge() > 110) {
e.rejectValue("age", "too.darn.old");
}
}
}class PersonValidator : Validator {
/**
* This Validator validates only Person instances
*/
override fun supports(clazz: Class<*>): Boolean {
return Person::class.java == clazz
}
override fun validate(obj: Any, e: Errors) {
ValidationUtils.rejectIfEmpty(e, "name", "name.empty")
val p = obj as Person
if (p.age < 0) {
e.rejectValue("age", "negativevalue")
} else if (p.age > 110) {
e.rejectValue("age", "too.darn.old")
}
}
}这static rejectIfEmpty(..)方法上的ValidationUtilsclass 用于
reject 的nameproperty （如果是null或空字符串。看看ValidationUtilsJavadoc
以查看除了前面显示的示例之外，它还提供了哪些功能。
虽然当然可以实现单个Validator类来验证每个
的嵌套对象中，最好将验证
每个嵌套类的对象在其自己的 logicValidator实现。一个简单的
“rich” 对象的示例是Customer它由两个String属性（名字和第二个名称）和复杂Address对象。Address对象
可以独立使用Customer对象，因此AddressValidator已实施。如果您希望您的CustomerValidator以重用包含的 logic
在AddressValidator类，而无需使用复制和粘贴，则可以
dependency-inject 或实例化AddressValidator在您的CustomerValidator,
如下例所示：
-
Java
-
Kotlin
public class CustomerValidator implements Validator {
private final Validator addressValidator;
public CustomerValidator(Validator addressValidator) {
if (addressValidator == null) {
throw new IllegalArgumentException("The supplied [Validator] is " +
"required and must not be null.");
}
if (!addressValidator.supports(Address.class)) {
throw new IllegalArgumentException("The supplied [Validator] must " +
"support the validation of [Address] instances.");
}
this.addressValidator = addressValidator;
}
/**
* This Validator validates Customer instances, and any subclasses of Customer too
*/
public boolean supports(Class clazz) {
return Customer.class.isAssignableFrom(clazz);
}
public void validate(Object target, Errors errors) {
ValidationUtils.rejectIfEmptyOrWhitespace(errors, "firstName", "field.required");
ValidationUtils.rejectIfEmptyOrWhitespace(errors, "surname", "field.required");
Customer customer = (Customer) target;
try {
errors.pushNestedPath("address");
ValidationUtils.invokeValidator(this.addressValidator, customer.getAddress(), errors);
} finally {
errors.popNestedPath();
}
}
}class CustomerValidator(private val addressValidator: Validator) : Validator {
init {
if (addressValidator == null) {
throw IllegalArgumentException("The supplied [Validator] is required and must not be null.")
}
if (!addressValidator.supports(Address::class.java)) {
throw IllegalArgumentException("The supplied [Validator] must support the validation of [Address] instances.")
}
}
/*
* This Validator validates Customer instances, and any subclasses of Customer too
*/
override fun supports(clazz: Class<>): Boolean {
return Customer::class.java.isAssignableFrom(clazz)
}
override fun validate(target: Any, errors: Errors) {
ValidationUtils.rejectIfEmptyOrWhitespace(errors, "firstName", "field.required")
ValidationUtils.rejectIfEmptyOrWhitespace(errors, "surname", "field.required")
val customer = target as Customer
try {
errors.pushNestedPath("address")
ValidationUtils.invokeValidator(this.addressValidator, customer.address, errors)
} finally {
errors.popNestedPath()
}
}
}验证错误将报告给Errors对象传递给验证器。在这种情况下
的 Spring Web MVC 中，您可以使用<spring:bind/>标签来检查错误消息，但
您还可以检查Errors反对自己。有关
它提供的方法可以在 Javadoc 中找到。