How does SpringBoot use validation for parameter verification?

1. Add dependencies

Add hibernate-validator directly

<dependency>
            <groupId>org.hibernate.validator</groupId>
            <artifactId>hibernate-validator</artifactId>
            <version>6.0.2.Final</version>
        </dependency>

Add spring-boot-starter-validation

<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-validation</artifactId>
            <version>1.4.0.RELEASE</version>
        </dependency>

Add spring-boot-starter-web

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

2. Configuration file

If you want to set the fail_fast attribute, true means there is If a parameter fails, it will be returned. By default, all parameters are tested, so there must be a configuration file

import org.hibernate.validator.HibernateValidator;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.validation.beanvalidation.MethodValidationPostProcessor;
import org.springframework.validation.beanvalidation.SpringValidatorAdapter;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
import javax.validation.Validation;
import javax.validation.Validator;
import javax.validation.ValidatorFactory;
/**
 * hibernate参数验证配置
 */
@Configuration
public class ValidatorConfig extends WebMvcConfigurerAdapter {


    @Bean
    public Validator validator() {
        ValidatorFactory validatorFactory = Validation.byProvider(HibernateValidator.class)
                .configure()
                // 将fail_fast设置为true即可，如果想验证全部，则设置为false或者取消配置即可
                .failFast(true)
//                .addProperty("hibernate.validator.fail_fast", "true")
                .buildValidatorFactory();

        return validatorFactory.getValidator();
    }

    /**
     * requestParam方式的校验
     * @return
     */
    @Bean
    public MethodValidationPostProcessor methodValidationPostProcessor() {

        MethodValidationPostProcessor methodValidationPostProcessor = new MethodValidationPostProcessor();
        methodValidationPostProcessor.setValidator(validator());
        return methodValidationPostProcessor;
    }
    @Override
    public org.springframework.validation.Validator getValidator() {
        return new SpringValidatorAdapter(validator());
    }
}

The methodValidationPostProcessor works on requestParam

Inheritance WebMvcConfigurerAdapter And rewrite the getValidator() method to let spring's request verification Validator use our validator above to make the set failFast take effect, For details, please refer to org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport#mvcValidatorMethod

3. Unified exception handling

/**
     * hibernate-valid实体类形式接受参数验证失败
     * @param ex
     * @return
     */
    @ExceptionHandler(BindException.class)
    @ResponseBody
    public WebResult validationErrorHandler(BindException ex) {
        List<String> collect = ex.getBindingResult().getAllErrors()
                .stream()
                .map(ObjectError::getDefaultMessage)
                .collect(Collectors.toList());
        return new WebResult(Errors.INCORRECT_PARAM_FORMAT.getError(), StringUtils.join(collect, ";"));
    }

    /**
     * hibernate-valid实体类形式接受参数验证失败
     * @param ex
     * @return
     */
    @ExceptionHandler(MethodArgumentNotValidException.class)
    @ResponseBody
    public WebResult validationErrorHandler(MethodArgumentNotValidException ex) {
        List<String> collect = ex.getBindingResult().getAllErrors()
                .stream()
                .map(ObjectError::getDefaultMessage)
                .collect(Collectors.toList());
        return new WebResult(Errors.INCORRECT_PARAM_FORMAT.getError(), StringUtils.join(collect, ";"));

    }
    /**
     * RequestParam方式参数校验
     * @param ex
     * @return
     */
    @ExceptionHandler(ConstraintViolationException.class)
    @ResponseBody
    public WebResult validationErrorHandler(ConstraintViolationException ex) {
        List<String> errorInformation = ex.getConstraintViolations()
                .stream()
                .map(ConstraintViolation::getMessage)
                .collect(Collectors.toList());
        return new WebResult(Errors.INCORRECT_PARAM_FORMAT.getError(),StringUtils.join(errorInformation, ";"));
    }

4.Use

If @RequestParam is used to directly write parameter verification, add the Validated annotation to the class or corresponding method. If the entity class accepts it, add the Validated annotation to the parameter. Just add

@Valid

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