Java에서 유효성 검증 배경 매개변수 검증 사용에 대한 자세한 설명

<dependency>

  <groupId>javax.validation</groupId>

  <artifactId>validation-api</artifactId>

  <version>1.1.0.Final</version>

</dependency>

package com.shishang;

import javax.validation.constraints.*;
import java.io.Serializable;
import java.math.BigDecimal;
import java.util.Date;

public class Student implements Serializable {


  @NotNull(message = "名字不能为空")
  private String name;

  @Size(min = 6,max = 30,message = "地址应该在6-30字符之间")
  private String address;

  @DecimalMax(value = "100.00",message = "体重有些超标哦")
  @DecimalMin(value = "60.00",message = "多吃点饭吧")
  private BigDecimal weight;

  private String friendName;
  @AssertTrue
  private Boolean isHaveFriend(){
    return friendName != null?true:false;
  }

  @Future(message = "生日必须在当前实践之前")
  private Date birthday;

  @Pattern(regexp = "^(.+)@(.+)$",message = "邮箱的格式不合法")
  private String email;


  public String getName() {
    return name;
  }

  public void setName(String name) {
    this.name = name;
  }

  public String getAddress() {
    return address;
  }

  public void setAddress(String address) {
    this.address = address;
  }

  public BigDecimal getWeight() {
    return weight;
  }

  public void setWeight(BigDecimal weight) {
    this.weight = weight;
  }

  public String getFriendName() {
    return friendName;
  }

  public void setFriendName(String friendName) {
    this.friendName = friendName;
  }

  public Date getBirthday() {
    return birthday;
  }

  public void setBirthday(Date birthday) {
    this.birthday = birthday;
  }

  public String getEmail() {
    return email;
  }

  public void setEmail(String email) {
    this.email = email;
  }
}

package com.use;

import javax.validation.ConstraintViolation;
import javax.validation.Validation;
import javax.validation.Validator;
import javax.validation.ValidatorFactory;
import java.io.Serializable;
import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.Set;

public class StudentTest implements Serializable {
  public static void main(String[] args) {
    Student xiaoming = getBean();
    List<String> validate = validate(xiaoming);
    validate.forEach(row -> {
      System.out.println(row.toString());
    });

  }

  private static Student getBean() {
    Student bean = new Student();
    bean.setName(null);
    bean.setAddress("北京");
    bean.setBirthday(new Date());
    bean.setFriendName(null);
    bean.setWeight(new BigDecimal(30));
    bean.setEmail("xiaogangfan163.com");
    return bean;
  }

  private static ValidatorFactory factory = Validation.buildDefaultValidatorFactory();

  public static <T> List<String> validate(T t) {
    Validator validator = factory.getValidator();
    Set<ConstraintViolation<T>> constraintViolations = validator.validate(t);

    List<String> messageList = new ArrayList<>();
    for (ConstraintViolation<T> constraintViolation : constraintViolations) {
      messageList.add(constraintViolation.getMessage());
    }
    return messageList;
  }
}

 package com.defineconstrain;

/**
 * created by xiaogangfan
 * on 16/10/25.
 */
public enum CaseMode {
  UPPER,
  LOWER;
}

package com.defineconstrain;

/**
 * created by xiaogangfan
 * on 16/10/25.
 */
import static java.lang.annotation.ElementType.*;
import static java.lang.annotation.RetentionPolicy.*;

import java.lang.annotation.Documented;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;

import javax.validation.Constraint;
import javax.validation.Payload;

@Target( { METHOD, FIELD, ANNOTATION_TYPE })
@Retention(RUNTIME)
@Constraint(validatedBy = CheckCaseValidator.class)
@Documented
public @interface CheckCase {

  String message() default "{com.mycompany.constraints.checkcase}";

  Class<?>[] groups() default {};

  Class<? extends Payload>[] payload() default {};

  CaseMode value();

}

package com.defineconstrain;

/**
 * created by xiaogangfan
 * on 16/10/25.
 */
import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;

public class CheckCaseValidator implements ConstraintValidator<CheckCase, String> {

  private CaseMode caseMode;

  public void initialize(CheckCase constraintAnnotation) {
    this.caseMode = constraintAnnotation.value();
  }

  public boolean isValid(String object, ConstraintValidatorContext constraintContext) {

    if (object == null)
      return true;

    if (caseMode == CaseMode.UPPER)
      return object.equals(object.toUpperCase());
    else
      return object.equals(object.toLowerCase());
  }

}

@CheckCase(value = CaseMode.LOWER,message = "名字的拼音需要小写")
private String spellName;

bean.setSpellName("XIAOGANGFAN");