JSR303

http://blog.csdn.net/caihaijiang/article/details/7463514

JSR 303 – Bean Validation 是一个数据验证的规范。

在任何时候,当你要处理一个应用程序的业务逻辑时,必须要考虑数据校验,确保输入进来的数据从语义上来讲是正确的。在通常的情况下,应用程序是分层的,不同的层由不同的开发人员来完成。很多时候同样的数据验证逻辑会出现在不同的层,这样就会导致代码冗余、不利于维护等问题。使用Bean Validation,将验证逻辑与相应的域模型进行绑定,能够很好的避免发生这样的问题。

Bean Validation 为 JavaBean 验证定义了相应的元数据模型和 API。缺省的元数据是 Java Annotations。在应用程序中,通过使用 Bean Validation 或是你自己定义的 constraint,例如@NotNull,@Max,@Size, 就可以确保数据模型 (JavaBean) 的正确性。Bean Validation 是一个运行时的数据验证框架,在验证之后验证的错误信息会被马上返回。

Hibernate Validator 是 Bean Validation 的参考实现 . Hibernate Validator 提供了 JSR 303 规范中所有内置 constraint 的实现,除此之外还有一些附加的 constraint。借助Hibernate Validator,可以很好的进行参数验证。

例子如下 (摘自参考文档2的内容) :

maven依赖:

  
<dependency>
  
<groupId>com.alibaba.external</groupId>
  
<artifactId>sourceforge.hibernate.validator</artifactId>
  
<version>4.0.2.GA</version>
  
</dependency>
  
<dependency>
  
<groupId>com.alibaba.external</groupId>
  
<artifactId>java.validation.api</artifactId>
  
<version>1.0.0.GA</version>
  
</dependency>
  
<dependency>
  
<groupId>com.alibaba.external</groupId>
  
<artifactId>org.slf4j.slf4j-api</artifactId>
  
<version>1.5.6</version>
  
</dependency>
  
<dependency>
  
<groupId>com.alibaba.external</groupId>
  
<artifactId>org.slf4j.slf4j-log4j12</artifactId>
  
<version>1.5.6</version>
  
</dependency>
  
<dependency>
  
<groupId>com.alibaba.external</groupId>
  
<artifactId>jakarta.log4j</artifactId>
  
<version>1.2.16</version>
  
</dependency>
  
<dependency>
  
<groupId>com.alibaba.external</groupId>
  
<artifactId>sourceforge.spring</artifactId>
  
<version>2.5.6</version>
  
</dependency>
  
2. 要校验的Java Bean


```java 
  
package com.mycompany;
  
import javax.validation.constraints.Min;
  
import javax.validation.constraints.NotNull;
  
import javax.validation.constraints.Size;
  
public class Car {
  
@NotNull
  
private String manufacturer;
  
@NotNull
  
@Size(min = 2, max = 14)
  
private String licensePlate;
  
@Min(2)
  
private int seatCount;
  
public Car(String manufacturer, String licencePlate, int seatCount) {
  
this.manufacturer = manufacturer;
  
this.licensePlate = licencePlate;
  
this.seatCount = seatCount;
  
}
  
//getters and setters ...
  
}
  
3. 进行的校验


```java 
  
import javax.validation.Validation;
  
import javax.validation.Validator;
  
import javax.validation.ValidatorFactory;
  
import org.junit.BeforeClass;
  
import org.junit.Test;
  
public class CarTest {
  
private static Validator validator;
  
@BeforeClass
  
public static void setUp() {
  
ValidatorFactory factory = Validation.buildDefaultValidatorFactory();
  
validator = factory.getValidator();
  
}
  
@Test
  
public void manufacturerIsNull() {
  
Car car = new Car(null, "DD-AB-123", 4);
  
Set<ConstraintViolation<Car>> constraintViolations =
  
validator.validate(car);
  
assertEquals(1, constraintViolations.size());
  
assertEquals("may not be null",
  
constraintViolations.iterator().next().getMessage());
  
}
  
@Test
  
public void licensePlateTooShort() {
  
Car car = new Car("Morris", "D", 4);
  
Set<ConstraintViolation<Car>> constraintViolations =
  
validator.validate(car);
  
assertEquals(1, constraintViolations.size());
  
assertEquals("size must be between 2 and
  
14", constraintViolations.iterator().next().getMessage());
  
}
  
}
  
更详细的使用,请看参考文档2.


参考文档: 

1. JSR 303: http://jcp.org/en/jsr/summary?id=303

2. HIBERNATE Validator: http://docs.jboss.org/hibernate/validator/4.2/reference/en-US/pdf/hibernate_validator_reference.pdf

3. 中文版的: http://docs.jboss.org/hibernate/validator/4.2/reference/zh-CN/html/validator-usingvalidator.html

JSR303#

JSR303