hibernate-validator以aop的形式进行参数检验

    一般用validator时，会在controller上的方法加BindingResult,还要在方法上加注解，又臭又长。

    我这里的思路是把validator和spring mvc分开，在controller方法上加注解，然后用aop切入这个controller方法，获取需要验证的对象，然后进行验证及其他操作。

    这里只验证第一个参数，要验证其他参数的请自行修改代码，用注解传入参数下标。

项目结构：

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.6.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>validate</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>validate</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
<!--        简化java bean-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-aop</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

Person.java 需要验证的参数

package com.example.validate.demo;

import lombok.Data;
import lombok.experimental.Accessors;

import javax.validation.constraints.Max;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;

@Data
@Accessors(chain = true)
public class Person {
    @Max(value = 100, message = "年龄不能大于100岁")
    int age;

    @NotNull
    @Size(min = 1, max = 5, message = "姓名长度错误")
    String name;
}

JsonResult.java  controller返回对象

package com.example.validate.demo;

import lombok.Data;
import lombok.experimental.Accessors;
import org.springframework.http.HttpStatus;

@Data
@Accessors(chain = true)
public class JsonResult<T> {
    private Integer status;
    private String message;
    private T data;
    JsonResult(){
        status= HttpStatus.OK.value();
    }

    public JsonResult(Integer status) {
        this.status = status;
    }

    public JsonResult(Integer status, String message, T data) {
        this.status = status;
        this.message = message;
        this.data = data;
    }
}

AspectDemo.java  aop操作

package com.example.validate.demo;

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.springframework.stereotype.Component;
import org.springframework.util.StringUtils;

import javax.validation.ConstraintViolation;
import javax.validation.Validation;
import javax.validation.Validator;
import javax.validation.groups.Default;
import java.util.Iterator;
import java.util.Set;

@Aspect
@Component
public class AspectDemo<T> {
    private static Validator validator = Validation.buildDefaultValidatorFactory().getValidator();
    //切入含有ValidateFirstParam注解的方法
    @Pointcut("@annotation(ValidateFirstParam)")
    public void cut() {
    }

    @Around("cut()")
    public JsonResult before(ProceedingJoinPoint point) throws Throwable {
        //0为controller里前端接口方法的参数序号，从左到右，从0开始算。
        Object object = point.getArgs()[0];
        String result = check((T) object);
        if (StringUtils.isEmpty(result)) {
            //验证通过，执行controller里de方法
            return (JsonResult) point.proceed();
        } else {
            //验证不通过，返回验证不通过的信息
            return new JsonResult().setMessage(result);
        }
    }

    //hibernate-validator进行验证
    public String check(T t) {
        Set<ConstraintViolation<T>> result = validator.validate(t, Default.class);
        Iterator<ConstraintViolation<T>> iterator = result.iterator();
        StringBuilder builder = new StringBuilder();
        while (iterator.hasNext()) {
            ConstraintViolation<T> next = iterator.next();
            builder.append(next.getMessage());
            builder.append(",");
        }
        String s = builder.toString();
        return StringUtils.isEmpty(s) ? null : s.substring(0, s.length() - 1);
    }
}

DemoController.java  标记该方法需要验证参数

package com.example.validate.demo;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class DemoController {
    @RequestMapping("/test")
    @ValidateFirstParam //标记需要验证参数的方法
    public JsonResult t1(Person person) {
        System.out.println(person.toString());
        return new JsonResult().setData(person.toString());
    }
}

ValidateFirstParam.java  注解

package com.example.validate.demo;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface ValidateFirstParam {
}