請(qǐng)不要再使用判斷進(jìn)行參數(shù)校驗(yàn)了

1. 前言

2. 數(shù)據(jù)校驗(yàn)的痛點(diǎn)

3. JSR 303 校驗(yàn)規(guī)范及其實(shí)現(xiàn)

Hibernate Validator 提供的常用約束注解

4. 驗(yàn)證注解的使用

在Spring Boot開發(fā)中使用Hibernate Validator是非常容易的，引入下面的starter就可以了：

<dependency>
????<groupId>org.springframework.bootgroupId>
????<artifactId>spring-boot-starter-validationartifactId>
dependency>

一種可以實(shí)現(xiàn)接口來(lái)定制Validator，一種是使用約束注解。胖哥覺得注解可以滿足絕大部分的需求，所以建議使用注解來(lái)進(jìn)行數(shù)據(jù)校驗(yàn)。而且注解更加靈活，控制的粒度也更加細(xì)。接下來(lái)我們來(lái)學(xué)習(xí)如何使用注解進(jìn)行數(shù)據(jù)校驗(yàn)。

4.1 約束注解的基本使用

我們對(duì)需要校驗(yàn)的方法入?yún)⑦M(jìn)行注解約束標(biāo)記，例子如下：

@Data
public?class?Student?{

????@NotBlank(message?=?"姓名必須填")
????private?String?name;
????@NotNull(message?=?"年齡必須填寫")
????@Range(min?=?1,max?=50,?message?=?"年齡取值范圍1-50")
????private?Integer?age;
????@NotEmpty(message?=?"成績(jī)必填")
????private?List?scores;
}

POST 請(qǐng)求

然后定義一個(gè)POST請(qǐng)求的Spring MVC接口：

@RestController
@RequestMapping("/student")
public?class?StudentController?{


????@PostMapping("/add")
????public?Rest?addStudent(@Valid?@RequestBody?Student?student)?{
????????return?RestBody.okData(student);
????}
}

通過(guò)對(duì)addStudent方法入?yún)⑻砑?/span>@Valid來(lái)啟用參數(shù)校驗(yàn)。當(dāng)使用下面數(shù)據(jù)進(jìn)行請(qǐng)求將會(huì)拋出MethodArgumentNotValidException異常，提示age范圍超出1-50。

POST /student/add HTTP/1.1
Host: localhost:8888
Content-Type: application/json

{
    "name": "felord.cn",
    "age": 77,
    "scores": [
        55
    ]
}

GET 請(qǐng)求

如法炮制，我們定義一個(gè)GET請(qǐng)求的接口：

@GetMapping("/get")
public?Rest?getStudent(@Valid?Student?student)?{
????return?RestBody.okData(student);
}

使用下面的請(qǐng)求可以正確對(duì)學(xué)生分?jǐn)?shù)scores進(jìn)行了校驗(yàn)，但是拋出的并不是MethodArgumentNotValidException異常，而是BindException異常。這和使用@RequestBody注解有關(guān)系，這對(duì)我們后面的統(tǒng)一處理非常十分重要。

GET /student/get?name=felord.cn&age=12 HTTP/1.1
Host: localhost:8888

自定義注解

可能有些同學(xué)注意到上面的年齡我進(jìn)行了這樣的標(biāo)記：

@NotNull(message?=?"年齡必須填寫")
@Range(min?=?1,max?=50,?message?=?"年齡取值范圍1-50")
private?Integer?age;

這是因?yàn)?/span>@Range不會(huì)去校驗(yàn)為空的情況，它只處理非空的時(shí)候是否符合范圍約束。所以要用多個(gè)注解來(lái)約束。如果我們某些場(chǎng)景需要重復(fù)的捆綁多個(gè)注解來(lái)使用時(shí)，可以使用自定義注解將它們封裝起來(lái)組合使用，下面這個(gè)注解就是將@NotNull和@Range進(jìn)行了組合，你可以仿一個(gè)出來(lái)用用看。

import?org.hibernate.validator.constraints.Range;

import?javax.validation.Constraint;
import?javax.validation.Payload;
import?javax.validation.ReportAsSingleViolation;
import?javax.validation.constraints.NotNull;
import?javax.validation.constraintvalidation.SupportedValidationTarget;
import?javax.validation.constraintvalidation.ValidationTarget;
import?java.lang.annotation.*;

/**
?*?@author?a
?*?@since?17:31
?**/
@Constraint(
????????validatedBy?=?{}
)
@SupportedValidationTarget({ValidationTarget.ANNOTATED_ELEMENT})
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.METHOD,?ElementType.FIELD,
????????ElementType.ANNOTATION_TYPE,?ElementType.CONSTRUCTOR,
????????ElementType.PARAMETER,?ElementType.TYPE_USE})
@NotNull
@Range(min?=?1,?max?=?50)
@Documented
@ReportAsSingleViolation
public?@interface?Age?{
????//?message?必須有
????String?message()?default?"年齡必須填寫，且范圍為?1-50?";

????//?可選
????Class[]?groups()?default?{};

????//?可選
????Class[]?payload()?default?{};
}

還有一種情況，我們?cè)诤笈_(tái)定義了枚舉值來(lái)進(jìn)行狀態(tài)的流轉(zhuǎn)，也是需要校驗(yàn)的，比如我們定義了顏色枚舉：

public?enum?Colors?{

????RED,?YELLOW,?BLUE

}

我們希望入?yún)⒉荒艹?/span>Colors的范圍["RED", "YELLOW", "BLUE"]，這就需要實(shí)現(xiàn)ConstraintValidator接口來(lái)定義一個(gè)顏色約束了，其中泛型A為自定義的約束注解，泛型T為入?yún)⒌念愋?，這里使用字符串,然后我們的實(shí)現(xiàn)如下：

/**
?*?@author?felord.cn
?*?@since?17:57
?**/
public?class?ColorConstraintValidator?implements?ConstraintValidator<Color,?String>?{
????private?static?final?Set?COLOR_CONSTRAINTS?=?new?HashSet<>();

????@Override
????public?void?initialize(Color?constraintAnnotation)?{
????????Colors[]?value?=?constraintAnnotation.value();
????????List?list?=?Arrays.stream(value)
????????????????.map(Enum::name)
????????????????.collect(Collectors.toList());
????????COLOR_CONSTRAINTS.addAll(list);

????}

????@Override
????public?boolean?isValid(String?value,?ConstraintValidatorContext?context)?{
????????return?COLOR_CONSTRAINTS.contains(value);
????}
}

/**
?*?@author?felord.cn
?*?@since?17:55
?**/
@Constraint(validatedBy?=?ColorConstraintValidator.class)
@Documented
@Target({ElementType.METHOD,?ElementType.FIELD,
????????ElementType.ANNOTATION_TYPE,?ElementType.CONSTRUCTOR,
????????ElementType.PARAMETER,?ElementType.TYPE_USE})
@Retention(RetentionPolicy.RUNTIME)
public?@interface?Color?{
????//?錯(cuò)誤提示信息
????String?message()?default?"顏色不符合規(guī)格";

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

????Class[]?payload()?default?{};

????//?約束的類型
????Colors[]?value();
}

@Data
public?class?Param?{
????@Color({Colors.BLUE,Colors.YELLOW})
???private?String?color;
}

GET /student/color?color=CAY HTTP/1.1
Host: localhost:8888

@GetMapping("/color")
public?Rest?color(@Valid?@Color({Colors.BLUE,Colors.YELLOW})?String?color)?{
????return?RestBody.okData(color);
}

@GetMapping("/rest/{color}")
public?Rest?rest(@Valid?@Color({Colors.BLUE,?Colors.YELLOW})?@PathVariable?String?color)?{
????return?RestBody.okData(color);
}

/**
?*?集合類型參數(shù)元素.
?*
?*?@param?student?the?student
?*?@return?the?rest
?*/
@PostMapping("/batchadd")
public?Rest?batchAddStudent(@Valid?@RequestBody?List?student)?{
????return?RestBody.okData(student);
}

@Data
public?class?Student?{

????@NotBlank(message?=?"姓名必須填")
????private?String?name;
????@Age
????private?Integer?age;
????@NotEmpty(message?=?"成績(jī)必填")
????private?List?scores;
????@NotNull(message?=?"學(xué)校不能為空")
????private?School?school;
}


@Data
public?class?School?{
????@NotBlank(message?=?"學(xué)校名稱不能為空")
????private?String?name;
????@Min(value?=?0,message?="校齡大于0"?)
????private?Integer?age;
}

@Data
public?class?Student?{

????@NotBlank(message?=?"姓名必須填")
????private?String?name;
????@Age
????private?Integer?age;
????@NotEmpty(message?=?"成績(jī)必填")
????private?List?scores;
????@Valid
????@NotNull(message?=?"學(xué)校不能為空")
????private?School?school;
}