How does SpringBoot perform parameter verification?

Introduction

In daily interface development, in order to prevent illegal parameters from affecting the business, it is often necessary to verify the parameters of the interface. For example, when logging in, it is necessary to verify whether the user name and password are empty. When adding a user, verify whether the format of the user's email address and mobile phone number is correct. It would be too cumbersome to rely on code to verify interface parameters one by one, and the readability of the code would be extremely poor.

ValidatorThe framework is designed to solve the problem of developers writing less code during development and improving development efficiency; Validator is specially used to verify interface parameters, such as common required verification, email Format verification, the username must be between 6 and 12, etc.

Next let’s take a look at how to integrate the parameter verification framework in SpringbBoot.

1.Integrated parameter verification in SpringBoot

1.1Introducing dependencies

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

1.2Define parameter entity classes

package com.didiplus.modules.sys.domain;

import io.swagger.annotations.ApiModel;
import io.swagger.annotations.ApiModelProperty;
import lombok.Data;

import javax.validation.constraints.Email;
import javax.validation.constraints.NotBlank;
import javax.validation.constraints.NotEmpty;

/**
 * Author: didiplus
 * Email: 972479352@qq.com
 * CreateTime: 2022/4/25
 * Desc: 字典类型领域模型
 */

@Data
@ApiModel(value = "字典类型")
public class SysDictType {

    @ApiModelProperty("ID")
    private String id;

    @NotBlank(message = "字典名称必填项")
    @ApiModelProperty(value = "字典名称",example = "用户ID")
    private String typeName;

    @NotBlank(message = "字典编码不能为空")
    @ApiModelProperty(value = "字典编码")
    private String typeCode;

    @Email(message = "请填写正确的邮箱地址")
    @ApiModelProperty(value = "字典编码")
    private String email;

    @ApiModelProperty(value = "字典描述")
    private String description;

    @NotBlank(message = "字典状态不能为空")
    @ApiModelProperty(value = "字典状态")
    private String enable;
}

Common constraint annotations are as follows:

Annotation	Function
@AssertFalse	can be null, if not null Must be false
@AssertTrue	can be null, if not null it must be true
@DecimalMax	The setting cannot exceed the maximum value
@DecimalMin	The setting cannot exceed the minimum value
@Digits	The setting must be a number and the number of integer digits and decimal digits must be within the specified range
@Future	The date must be within the current date The future
@Past	date must be in the past
@Max	max of the current date This maximum value must not be exceeded
@Min	The maximum must not be less than this minimum value
@NotNull	Cannot be null, can be empty
@Null	Must be null
@Pattern	Must satisfy the specified regular expression
@Size	The size() value of collections, arrays, maps, etc. must be within the specified range
@Email	Must be in email format
@Length	The length must be within the specified range
@NotBlank	The string cannot be null, and the string after trim() cannot be equal to ""
@NotEmpty	Cannot be null, size() of collections, arrays, maps, etc. cannot be 0; string trim() can be equal to ""
@Range	The value must be Within the specified range
@URL	must be a URL

1.3定义校验类进行测试

package com.didiplus.modules.sys.controller;

import com.didiplus.modules.sys.domain.SysDictType;
import io.swagger.annotations.Api;
import io.swagger.annotations.ApiOperation;
import io.swagger.v3.oas.annotations.parameters.RequestBody;
import org.springframework.validation.annotation.Validated;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * Author: didiplus
 * Email: 972479352@qq.com
 * CreateTime: 2022/4/25
 * Desc: 数据字典控制器
 */
@RestController
@Api(tags = "数据字典")
@RequestMapping("/api/sys/dictType")
public class SysDictTypeController {

    @ApiOperation("字典添加")
    @PostMapping("/add")
    public SysDictType add(@Validated @RequestBody SysDictType sysDictType) {
        return  sysDictType;
    }

    @ApiOperation("字典修改")
    @PutMapping("/edit")
    public SysDictType edit(@Validated @RequestBody SysDictType sysDictType) {
        return  sysDictType;
    }


}

这里我们先定义两个方法add,edit，都是使用了 @RequestBody注解，用于接受前端发送的json数据。

1.4打开接口文档模拟提交数据

通过接口文档看到前三个字段都是必填项。

由于email的格式不对就被拦截了，提示是因为邮箱地址不对。

2.参数异常加入全局异常处理器

虽然我们之前定义了全局异常拦截器，也看到了拦截器确实生效了，但是Validator校验框架返回的错误提示太臃肿了，不便于阅读，为了方便前端提示，我们需要将其简化一下。

直接修改之前定义的 RestExceptionHandler，单独拦截参数校验的三个异常：

javax.validation.ConstraintViolationException

org.springframework.validation.BindException

org.springframework.web.bind.MethodArgumentNotValidException

代码如下：

package com.didiplus.common.web.response.Handler;

import com.didiplus.common.web.response.Result;

import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.validation.BindException;
import org.springframework.validation.ObjectError;
import org.springframework.web.bind.MethodArgumentNotValidException;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RestControllerAdvice;

import javax.validation.ConstraintViolation;
import javax.validation.ConstraintViolationException;
import javax.validation.ValidationException;

import java.util.stream.Collectors;

/**
 * Author: didiplus
 * Email: 972479352@qq.com
 * CreateTime: 2022/4/24
 * Desc:  默认全局异常处理。
 */
@RestControllerAdvice
public class RestExceptionHandler {
    /**
     * 默认全局异常处理。
     * @param e the e
     * @return ResultData
     */
    @ExceptionHandler(value = {BindException.class, ValidationException.class, MethodArgumentNotValidException.class})
    public ResponseEntity<Result<String>> handleValidatedException(Exception e) {
            Result<String>  result = null;
            if (e instanceof  MethodArgumentNotValidException) {
                MethodArgumentNotValidException ex =(MethodArgumentNotValidException)  e;
                result = Result.failure(HttpStatus.BAD_REQUEST.value(),
                                ex.getBindingResult().getAllErrors().stream()
                                        .map(ObjectError::getDefaultMessage)
                                        .collect(Collectors.joining(";"))
                                );
            } else  if (e instanceof ConstraintViolationException){
                ConstraintViolationException ex = (ConstraintViolationException) e;
                result = Result.failure(HttpStatus.BAD_REQUEST.value(),
                                        ex.getConstraintViolations().stream()
                                                .map(ConstraintViolation::getMessage)
                                                .collect(Collectors.joining(";"))
                                        );
            }else  if (e instanceof BindException) {
                BindException  ex = (BindException ) e;
                result = Result.failure(HttpStatus.BAD_REQUEST.value(),
                                        ex.getAllErrors().stream()
                                                .map(ObjectError::getDefaultMessage)
                                                .collect(Collectors.joining(";"))
                                        );
            }
            return new ResponseEntity<>(result,HttpStatus.BAD_REQUEST);
    }
}

美化之后错误信息提示更加友好

3.自定义参数校验

虽然Spring Validation 提供的注解基本上够用，但是面对复杂的定义，我们还是需要自己定义相关注解来实现自动校验。
比如上面实体类中添加的sex性别属性，只允许前端传递传 M，F 这2个枚举值，如何实现呢？

3.1创建自定义注解

package com.didiplus.common.annotation;

import javax.validation.Constraint;
import javax.validation.Payload;
import java.lang.annotation.Documented;
import java.lang.annotation.Repeatable;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;

import static java.lang.annotation.ElementType.*;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

/**
 * Author: didiplus
 * Email: 972479352@qq.com
 * CreateTime: 2022/4/26
 * Desc:
 */
@Target({METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE})
@Retention(RUNTIME)
@Repeatable(EnumString.List.class)
@Documented
@Constraint(validatedBy = EnumStringValidator.class)//标明由哪个类执行校验逻辑
public @interface EnumString {

    String message() default "value not in enum values.";

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

    Class<? extends Payload>[] palyload() default {};
    /**
     * @return date must in this value array
     */
    String[] value();

    /**
     * Defines several {@link EnumString} annotations on the same element.
     *
     * @see EnumString
     */
    @Target({METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE})
    @Retention(RUNTIME)
    @Documented
    @interface List {

        EnumString[] value();
    }


}

3.2自定义校验逻辑

package com.didiplus.common.annotation;

import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;
import java.util.Arrays;
import java.util.List;


/**
 * Author: didiplus
 * Email: 972479352@qq.com
 * CreateTime: 2022/4/26
 * Desc:
 */
public class EnumStringValidator implements ConstraintValidator<EnumString,String> {
    private List<String> enumStringList;

    @Override
    public void initialize(EnumString constraintAnnotation) {
        enumStringList = Arrays.asList(constraintAnnotation.value());

    }

    @Override
    public boolean isValid(String value, ConstraintValidatorContext constraintValidatorContext) {
        if(value == null) {
            return true;
        }
        return enumStringList.contains(value);
    }
}

3.3在字段上增加注解

    @ApiModelProperty(value = "性别")
    @EnumString(value = {"F","M"}, message="性别只允许为F或M")
    private String sex;

3.4体验效果

4.分组校验

一个对象在新增的时候某些字段是必填，在更新是有非必填。如上面的 SysDictType中id 属性在新增操作时都是必填。 面对这种场景你会怎么处理呢？

其实 Validator校验框架已经考虑到了这种场景并且提供了解决方案，就是分组校验。 要使用分组校验，只需要三个步骤：

4.1定义分组接口

package com.didiplus.common.base;

import javax.validation.groups.Default;

/**
 * Author: didiplus
 * Email: 972479352@qq.com
 * CreateTime: 2022/4/26
 * Desc:
 */
public interface ValidGroup extends Default {

    interface Crud extends ValidGroup{
        interface Create extends Crud{

        }

        interface Update extends Crud{

        }

        interface Query extends Crud{

        }

        interface Delete extends Crud{

        }
    }
}

4.2在模型中给参数分配分组

    @Null(groups = ValidGroup.Crud.Create.class)
    @NotNull(groups = ValidGroup.Crud.Update.class,message = "字典ID不能为空")
    @ApiModelProperty("ID")
    private String id;

4.3体现效果

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