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一、前言
在实际开发项目中，我们常常需要对接口入参进行校验，如果直接在业务代码中进行校验，则会显得代码非常冗余，也不够优雅，那么我们可以使用aop的方式校验，这样则会显得更优雅。

二、如何实现？
1.添加maven依赖

<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-validation</artifactId>
</dependency>

2.定义一个工具类ValidationUtil

import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;import javax.servlet.http.HttpServletRequest;
import javax.validation.ConstraintViolation;
import javax.validation.Validation;
import javax.validation.Validator;
import javax.validation.ValidatorFactory;
import java.util.ArrayList;
import java.util.List;
import java.util.Set;public class ValidationUtil {private static ValidationUtil util;private Validator validator;public ValidationUtil() {// TODO Auto-generated constructor stubValidatorFactory factory = Validation.buildDefaultValidatorFactory();this.validator = factory.getValidator();}
/*** @return the validator*/public Validator getValidator() {return validator;}public static ValidationUtil getValidationUtil() {if (util == null) {util = new ValidationUtil();}return util;}public static List<CheckErrorResultDto> validate(Object o) {Set<ConstraintViolation<Object>> set = ValidationUtil.getValidationUtil().getValidator().validate(o);List<CheckErrorResultDto> errorList = null;HttpServletRequest request = ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getRequest();for (ConstraintViolation<Object> cv : set) {if (errorList == null) {errorList = new ArrayList<CheckErrorResultDto>();}String message = MessageResolver.getMessage(request,cv.getMessage());errorList.add(new CheckErrorResultDto(cv.getPropertyPath().toString(), message));}return errorList;}public static List<CheckErrorResultDto> validate(Object o,Class<?> ...c) {Set<ConstraintViolation<Object>> set = ValidationUtil.getValidationUtil().getValidator().validate(o,c);List<CheckErrorResultDto> errorList = null;HttpServletRequest request = ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getRequest();for (ConstraintViolation<Object> cv : set) {if (errorList == null) {errorList = new ArrayList<CheckErrorResultDto>();}String message = MessageResolver.getMessage(request,cv.getMessage());errorList.add(new CheckErrorResultDto(cv.getPropertyPath().toString(), message));}return errorList;}

3.校验错误信息实体类。

import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
public class CheckErrorResultDto {private String fieldName;private String msg;
}

4.编写校验AOP

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.reflect.MethodSignature;
import org.springframework.context.annotation.EnableAspectJAutoProxy;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;
@Order(1)
@Aspect
@Component
@EnableAspectJAutoProxy(exposeProxy=true)
public class ValidAop {/*** 校验传入实体** @param pjp* @throws Throwable*/@Around("@annotation(com.dp.aop.annotation.Valid)")public Object aroundExec(ProceedingJoinPoint pjp) throws Throwable {MethodSignature ms = (MethodSignature) pjp.getSignature();Method method = ms.getMethod();Valid annotation = method.getAnnotation(Valid.class);if (annotation != null) {List<CheckErrorResultDto> errorList=new ArrayList<CheckErrorResultDto>();Object[] args=pjp.getArgs();Class<?>[] checkToken = annotation.value();Class<?>[] group = annotation.group();for (Class c : checkToken) {for (Object obj : args) {if (c == obj.getClass()) {List<CheckErrorResultDto> result=null;if(group.length<1){result= ValidationUtil.validate(obj);}else{result= ValidationUtil.validate(obj,group);}if(result!=null)errorList.addAll(result);}}}if(errorList.size()>0){ResponseData vo=new ResponseData();vo.setCode(ApiCodeEnum.ILLEGAL_PARAMETER.getCode());vo.setMsg(ApiCodeEnum.ILLEGAL_PARAMETER.getMsg());vo.setData(errorList);return vo;}}return pjp.proceed();}
}

5.定义一个校验注解Valid

import java.lang.annotation.*;@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface Valid {Class<?>[] value() default {};Class<?>[] group() default {};
}

6.最后在Controller定义的接口上加上注解指定要校验的对象即可。

大家可以尝试下。