Spring 具有可用于验证对象的界面。该接口通过使用对象来工作,以便在验证时,
验证者可以向对象报告验证失败。Validator
Validator
Errors
Errors
请考虑以下小型数据对象的示例:
-
Java
-
Kotlin
public class Person {
private String name;
private int age;
// the usual getters and setters...
}
class Person(val name: String, val age: Int)
下一个示例通过实现
以下两种接口方法:Person
org.springframework.validation.Validator
-
supports(Class)
:这可以验证提供的实例吗?Validator
Class
-
validate(Object, org.springframework.validation.Errors)
:验证给定对象 并且,如果出现验证错误,则将这些错误注册到给定对象。Errors
实现 a 是相当简单的,特别是当你知道 Spring 框架也提供的帮助程序类时。以下
实例的示例实现:Validator
ValidationUtils
Validator
Person
-
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")
}
}
}
类上的方法用于
如果属性是,则拒绝该属性或空字符串。看一看 ValidationUtils
javadoc
查看除了前面显示的示例之外,它还提供哪些功能。static
rejectIfEmpty(..)
ValidationUtils
name
null
虽然当然可以实现单个类来验证每个
在富对象中的嵌套对象中,最好封装验证
每个嵌套类对象在其自己的实现中的逻辑。一个简单的
“丰富”对象的示例是由两个属性(第一个和第二个名称)和一个复杂对象组成的 A。 对象
可以独立于对象使用,因此已经实现了不同的。如果您希望重用所包含的逻辑
在类中,无需求助于复制和粘贴,您可以
依赖注入或实例化 在你的 ,
如以下示例所示:Validator
Validator
Customer
String
Address
Address
Customer
AddressValidator
CustomerValidator
AddressValidator
AddressValidator
CustomerValidator
-
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()
}
}
}
验证错误将报告给传递给验证程序的对象。在案例中
的Spring Web MVC,您可以使用标签来检查错误消息,但是
您也可以自己检查对象。有关
它提供的方法可以在 Javadoc 中找到。Errors
<spring:bind/>
Errors
验证器也可以在本地调用,以立即验证给定对象,
不涉及绑定过程。从 6.1 开始,这已通过一种新方法进行了简化,该方法现在默认可用,返回
可以检查的简单“错误”表示:通常调用或将错误摘要消息转换为异常的新方法
(例如)。Validator.validateObject(Object)
hasErrors()
failOnError
validator.validateObject(myObject).failOnError(IllegalArgumentException::new)