Java自定义注解对枚举类型参数的校验方法_Java

1.前提准备条件

java注解了解

1.1 pom.xml文件依赖:

<?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 https://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>3.3.8-snapshot</version>
        <relativepath/> <!-- lookup parent from repository -->
    </parent>
    <groupid>com.knife4j</groupid>
    <artifactid>myknife4jdemo</artifactid>
    <version>0.0.1-snapshot</version>
    <name>myknife4jdemo</name>
    <description>demo project for spring boot</description>
    <properties>
        <java.version>17</java.version>
    </properties>
    <dependencymanagement>
        <dependencies>
            <dependency>
                <groupid>com.github.xiaoymin</groupid>
                <artifactid>knife4j-dependencies</artifactid>
                <version>4.5.0</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencymanagement>
    <dependencies>
        <dependency>
            <groupid>org.springframework.boot</groupid>
            <artifactid>spring-boot-starter-web</artifactid>
        </dependency>
        <dependency>
            <groupid>org.projectlombok</groupid>
            <artifactid>lombok</artifactid>
            <version>1.18.24</version>
        </dependency>
        <dependency>
            <groupid>com.github.xiaoymin</groupid>
            <artifactid>knife4j-openapi3-jakarta-spring-boot-starter</artifactid>
        </dependency>
        <dependency>
            <groupid>org.springframework.boot</groupid>
            <artifactid>spring-boot-starter-test</artifactid>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupid>org.hibernate.validator</groupid>
            <artifactid>hibernate-validator</artifactid>
            <version>8.0.0.final</version>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupid>org.springframework.boot</groupid>
                <artifactid>spring-boot-maven-plugin</artifactid>
            </plugin>
        </plugins>
    </build>
    <repositories>
        <repository>
            <id>nexus-maven</id>
            <name>nexus-maven</name>
            <url>https://oss.sonatype.org/content/repositories/snapshots/</url>
        </repository>
    </repositories>
</project>

1.2 枚举类：

@getter
@allargsconstructor
public enum roleenum {
    admin("a", "administrator"),
    user("u", "user"),
    guest("g", "guest");
    private final string code;
    private final string name;
    public static roleenum fromcode(string code) {
        for (roleenum role : roleenum.values()) {
            if (role.getcode().equals(code)) {
                return role;
            }
        }
        throw new illegalargumentexception("unknown code: " + code);
    }
}

1.3 controller接口：

@requestmapping("/user")
@restcontroller
@tag(name = "用户控制类")
public class usercontroller {
    @postmapping("/add")
    @operation(description = "添加数据")
    public userdto validcreate(@requestbody @valid userdto userdto) {
        return userdto;
    }
}

1.4 实体参数：

@noargsconstructor
@allargsconstructor
@data
@schema(description = "用户新增--dto")
public class userdto {
    @schema(description = "用户名")
    @notblank(message = "用户名不能为空")
    private string username;
    @schema(description = "用户编号")
    @notblank(message = "用户编号不能为空")
    private string userno;
    @schema(description = "角色编码")
    private string rolecode;
}

1.5 knife4j的配置

我是结合knife4j来使用的，knife4j的详细了解使用如下链接：

knife4j的配置如下：

@configuration
@enableknife4j
public class knife4jconfig {
    @bean
    public openapi openapi() {
        return new openapi()
                .info(new info()
                        .title("knife4j-openapi3入门测试")
                        .version("1.0")
                        .description("knife4j-openapi3项目的接口文档"));
    }
    @bean
    public groupedopenapi userapi() {
        return groupedopenapi.builder().group("用户信息管理").
                pathstomatch("/user/**").
                build();
    }
}

2.实现要求

希望对参数userdto中的字段rolecode进行自动校验，校验rolecode参数必须且只能是枚举类中的编码的其中一个。通过注解的方式实现，最大程度上提高参数的灵活性。

3.实现步骤

3.1 自定义注解类：

@target({elementtype.field, elementtype.parameter})
@retention(retentionpolicy.runtime)
@constraint(validatedby = enumcodevalidator.class)
public @interface validenumcode {
    string message() default "must be any of enum {enumclass} codes";
    class<?>[] groups() default {};
    class<? extends payload>[] payload() default {};
    class<? extends enum<?>> enumclass();
}

3.2 使用注解：

在字段rolecode上添加自定义注解：

@noargsconstructor
@allargsconstructor
@data
@schema(description = "用户新增--dto")
public class userdto {
    @schema(description = "用户名")
    @notblank(message = "用户名不能为空", groups = {create.class})
    private string username;
    @schema(description = "用户编号")
    @notblank(message = "用户编号不能为空", groups = {update.class})
    private string userno;
    @schema(description = "角色编码")
    @validenumcode(enumclass = roleenum.class,message = "role code must be any of {codes} from {enumclass}")
    private string rolecode;
}

3.3 添加注解校验类：

public class enumcodevalidator implements constraintvalidator<validenumcode, charsequence> {
    private list<string> acceptedcodes;
    private string messagetemplate;
    private string enumclassname;
    @override
    public void initialize(validenumcode constraintannotation) {
        class<? extends enum<?>> enumclass = constraintannotation.enumclass();
        acceptedcodes = stream.of(enumclass.getenumconstants())
                .map(this::getenumcode)
                .collect(collectors.tolist());
        messagetemplate = constraintannotation.message();
        enumclassname = enumclass.getsimplename();
    }
    private string getenumcode(enum<?> enumconstant) {
        try {
            method getcodemethod = enumconstant.getclass().getmethod("getcode");
            return (string) getcodemethod.invoke(enumconstant);
        } catch (exception e) {
            throw new runtimeexception("failed to get enum code", e);
        }
    }
    @override
    public boolean isvalid(charsequence value, constraintvalidatorcontext context) {
        if (value == null) {
            return true;
        }
        if (!acceptedcodes.contains(value.tostring())) {
            string message = messagetemplate.replace("{enumclass}", enumclassname)
                    .replace("{codes}", string.join(", ", acceptedcodes));
            context.disabledefaultconstraintviolation();
            context.buildconstraintviolationwithtemplate(message)
                    .addconstraintviolation();
            return false;
        }
        return true;
    }
}