当涉及校验用户输入时，如果由开发人员编码校验数据，那么验证数据的代码和业务逻辑代码会耦合在一起。Spring Framework 4.0支持Bean Validation 1.0(JSR-303)和Bean Validation 1.1(JSR-349)，也将其改写成了Spring的Validator接口。使用Spring Validation可以方便的进行数据校验。

1.引入依赖

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

2.实体类中添加校验注解

package io.github.lmy.springbootinaction.request;

import io.github.lmy.springbootinaction.entity.User;
import lombok.Data;
import org.hibernate.validator.constraints.Range;
import org.springframework.beans.BeanUtils;

import javax.validation.constraints.Email;
import javax.validation.constraints.NotBlank;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Pattern;

@Data
public class UserRequest {

    @NotBlank(message = "用户名不能为空")
    private String name;

    @Range(min = 0, max = 150, message = "年龄格式不正确")
    @NotNull
    private Integer age;

    @Email(message = "邮箱格式不正确")
    @NotBlank(message = "邮箱不能为空")
    private String email;

    @Pattern(regexp = "^1(3|4|5|7|8)\\d{9}$", message = "手机号码格式不正确")
    @NotBlank(message = "手机号不能为空")
    private String phone;

    @NotBlank(message = "密码不能为空")
    private String password;
    
}

3.在Controller层校验数据

对需要校验的参数添加注解@Valid或@Validated，如果需要获取校验的信息，可以在被校验参数后面添加一个BindingResult参数，Spring会将校验的信息填充到该校验参数后面的BindingResult中。

package io.github.lmy.springbootinaction.controller;

import io.github.lmy.springbootinaction.request.LoginRequest;
import io.github.lmy.springbootinaction.request.UserRequest;
import io.github.lmy.springbootinaction.service.UserService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.validation.BindingResult;
import org.springframework.validation.FieldError;
import org.springframework.validation.annotation.Validated;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import javax.validation.Valid;

@Controller
@RequestMapping("/user")
@Slf4j
public class UserController {

    @Autowired
    private UserService userService;

    @PostMapping("/register")
    @ResponseBody
    public boolean register(@Valid @RequestBody UserRequest userRequest, BindingResult result) {
        if (result.hasErrors()) {
            for (FieldError fieldError : result.getFieldErrors()) {
                log.info("field: {}, message: {}", fieldError.getField(), fieldError.getDefaultMessage());
            }
            return false;
        }
        boolean success = userService.register(userRequest);
        return success;
    }

    @PostMapping("/login")
    public String login(@Validated @RequestBody LoginRequest loginRequest) {
        userService.login(loginRequest);
        return "index";
    }

}

4.校验失败统一处理

如果校验参数后没有BindingResult参数，且校验参数校验失败，则会抛出MethodArgumentNotValidException 异常。可以使用 @ExceptionHandler 注解统一处理参数校验失败。

package io.github.lmy.springbootinaction.global;

import org.springframework.http.HttpStatus;
import org.springframework.validation.FieldError;
import org.springframework.web.bind.MethodArgumentNotValidException;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseStatus;
import org.springframework.web.bind.annotation.RestControllerAdvice;

import java.util.Map;
import java.util.stream.Collectors;

@RestControllerAdvice
public class GlobalExceptionHandler {

    @ResponseStatus(HttpStatus.BAD_REQUEST)
    @ExceptionHandler(MethodArgumentNotValidException.class)
    public Map<String, String> handleValidationExceptions(MethodArgumentNotValidException ex) {
        Map<String, String> result = ex.getBindingResult()
                .getFieldErrors()
                .stream()
                .collect(Collectors.toMap(FieldError::getField, FieldError::getDefaultMessage));
        return result;
    }

}

参考链接:

• 使用 spring validation 完成数据后端校验
• SpringBoot 参数校验
• Validation in Spring Boot