随着ORM框架的应用,使得开发更加面向对象,不用再专门设计数据库,由编写实体,实体映射代替。
所以,实体的编写是非常基础而重要的工作,开发工作能及早做就不要往后拖。比如,验证数据的合法性,我们习惯在action或者controller中做,其实这些工作可以提前在实体做的。
JSR303Bean Validator是数据验证的规范,而hibernate validator 是其中的一个实现。
比如在User实体中,可以使用Hibernate Validator 来对该实体模型进行验证
需要引入包validation-api-1.0.0.GA.jar、hibernate-validator-4.0.0.GA.jar
importjavax.persistence.Column;
importjavax.persistence.Entity;
importjavax.persistence.GeneratedValue;
importjavax.persistence.Id;
importjavax.persistence.Table;
importorg.hibernate.annotations.GenericGenerator;
importorg.hibernate.validator.constraints.Length;
importorg.hibernate.validator.constraints.NotBlank;
@Entity
@Table(name="t_user")
public class User {
@Id
@GeneratedValue(generator ="system-uuid")
@GenericGenerator(name ="system-uuid", strategy = "uuid")
@Column(length=32)
privateString id;
@NotBlank
@Length(min=1,max=32)
@Column(nullable=false,length=32, unique=true, updatable=false)
privateString userName;
@Column(length=32)
privateString age;
publicString getId() {
returnid;
}
publicvoid setId(String id) {
this.id= id;
}
publicString getUserName() {
returnuserName;
}
publicvoid setUserName(String userName) {
this.userName= userName;
}
publicString getAge() {
returnage;
}
publicvoid setAge(String age) {
this.age= age;
}
}
测试类,通过hibernate validator验证输入数据的合法性
importjavax.validation.ConstraintViolation;
importjavax.validation.Validation;
importjavax.validation.Validator;
importjavax.validation.ValidatorFactory;
public static void main(String[] args) {
ValidatorFactoryfactory = Validation.buildDefaultValidatorFactory();
Validator validator = factory.getValidator();
User user = new User();
user.setUserName("");
user.setAge("23");
Set<ConstraintViolation<User>>constraintViolations =validator.validate(user);
for(ConstraintViolation<User> constraintViolation : constraintViolations) {
System.out.print(constraintViolation.getPropertyPath() + ": ");
System.err.println(constraintViolation.getMessage());
}
}
打印异常信息
userName: 长度需要在1和32之间
userName: 不能为空
把hibernate简单用起来是很简单的,但是如果要进行调优,还是很复杂的。后文中会介绍在实体模型中加入hibernate缓存。