定义一个校验工具_import javax.validation.constraintviolation;-优快云博客

本文详细介绍如何使用Java Bean Validation API进行参数校验，包括引入依赖、自定义校验工具及异常处理。涵盖常用校验注解如@NotBlank、@NotNull等，并提供代码示例。

作用：说白点了就是我们平时所说的参数检查

1. 通过校验注解修饰java bean

2. 通过自定义校验工具对其校验，校验失败抛出异常，返回前端

1. 引入依赖

<dependency>
  <groupId>javax.validation</groupId>
  <artifactId>validation-api</artifactId>
  <version>1.1.0.Final</version>
</dependency>
<dependency>
  <groupId>org.hibernate</groupId>
  <artifactId>hibernate-validator</artifactId>
  <version>5.2.4.Final</version>
</dependency>

2. 自定义一个校验工具

mport com.google.common.base.Preconditions;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import com.mmall.exception.ParamException;
import org.apache.commons.collections.MapUtils;

import javax.validation.ConstraintViolation;
import javax.validation.Validation;
import javax.validation.Validator;
import javax.validation.ValidatorFactory;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Set;

public class BeanValidator {

    private static ValidatorFactory validatorFactory = Validation.buildDefaultValidatorFactory();

    public static <T> Map<String, String> validate(T t, Class... groups) {
        Validator validator = validatorFactory.getValidator();
        Set validateResult = validator.validate(t, groups);
        if (validateResult.isEmpty()) {
            return Collections.emptyMap();
        } else {
            LinkedHashMap errors = Maps.newLinkedHashMap();
            Iterator iterator = validateResult.iterator();
            while (iterator.hasNext()) {
                ConstraintViolation violation = (ConstraintViolation)iterator.next();
                errors.put(violation.getPropertyPath().toString(), violation.getMessage());
            }
            return errors;
        }
    }

    public static Map<String, String> validateList(Collection<?> collection) {
        Preconditions.checkNotNull(collection);
        Iterator iterator = collection.iterator();
        Map errors;

        do {
            if (!iterator.hasNext()) {
                return Collections.emptyMap();
            }
            Object object = iterator.next();
            errors = validate(object, new Class[0]);
        } while (errors.isEmpty());

        return errors;
    }

    public static Map<String, String> validateObject(Object first, Object... objects) {
        if (objects != null && objects.length > 0) {
            return validateList(Lists.asList(first, objects));
        } else {
            return validate(first, new Class[0]);
        }
    }

    public static void check(Object param) throws ParamException {
        Map<String, String> map = BeanValidator.validateObject(param);
        if (MapUtils.isNotEmpty(map)) {
            throw new ParamException(map.toString());
        }
    }
}

ps:使用时直接调check（需要校验的bean）

3. 自定义一个异常，用于校验失败后抛出

public class ParamException extends RuntimeException {
    public ParamException() {
        super();
    }

    public ParamException(String message) {
        super(message);
    }

    public ParamException(String message, Throwable cause) {
        super(message, cause);
    }

    public ParamException(Throwable cause) {
        super(cause);
    }

    
    protected ParamException(String message, Throwable cause, boolean enableSuppression, boolean writableStackTrace) {
        super(message, cause, enableSuppression, writableStackTrace);
    }
}

ps：常用的校验注解

1.@NotBlank---修饰字符串

2.@NotNull--修饰对象

3.@NotEmpty---修饰集合

4.@Max(10)--修饰数字 Max(value=10,message="xx不能大于10"

5.@Min(5)--修饰数字