• 代码结构

├─ann
    └─ DesensitizationAnn
└─processor
    └─impl
        └─ IdCardProcessor
        └─ PhoneProcessor
    └─DesensitizationProcessorFactory
    └─DesensitizationProcessor
└─DesensitizationSerializer

• DesensitizationAnn

/**
 * 基于Jackson的数据脱敏注解
 *
 * @author futaosmile@gmail.com
 * @date 2022/7/18
 * @since 2022/7/18
 */
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
@Documented
@JsonSerialize(using = DesensitizationSerializer.class)
@JacksonAnnotationsInside
public @interface DesensitizationAnn {
    /**
     * 数据脱敏处理器
     *
     * @return 数据脱敏处理器
     */
    Class<? extends DesensitizationProcessor> value();
}

• DesensitizationProcessor

/**
 * 数据脱敏处理器接口
 *
 * @author futaosmile@gmail.com
 * @date 2022/7/18
 * @since 2022/7/18
 */
public interface DesensitizationProcessor {
    /**
     * 数据脱敏实现
     *
     * @param target 需要脱敏的数据
     * @return 脱敏后的数据
     */
    String desensitize(String target);
}

• IdCardProcessor

/**
 * 18位身份证数据脱敏处理器
 *
 * @author futaosmile@gmail.com
 * @date 2022/7/18
 * @since 2022/7/18
 */
public class IdCardProcessor implements DesensitizationProcessor {

    private static final String IC_CARD_REG = "(.{6}).*(.{4})";
    private static final String REPLACE = "$1********$2";

    @Override
    public String desensitize(String target) {
        if (StringUtils.isBlank(target)) {
            return null;
        }
        return target.replaceAll(IC_CARD_REG, REPLACE);
    }
}

• PhoneProcessor

/**
 * 11位手机号脱敏
 *
 * @author futaosmile@gmail.com
 * @date 2022/7/18
 * @since 2022/7/18
 */
public class PhoneProcessor implements DesensitizationProcessor {

    private static final String IC_CARD_REG = "(.{3}).*(.{4})";
    private static final String REPLACE = "$1****$2";

    @Override
    public String desensitize(String target) {
        if (StringUtils.isBlank(target)) {
            return null;
        }
        return target.replaceAll(IC_CARD_REG, REPLACE);
    }
}

• DesensitizationProcessorFactory

/**
 * 序列化器工厂类
 *
 * @author futaosmile@gmail.com
 * @date 2022/7/18
 * @since 2022/7/18
 */
@NoArgsConstructor(access = AccessLevel.PRIVATE)
@Slf4j
public class DesensitizationProcessorFactory {

    private static final Map<String, DesensitizationProcessor> CACHE = new HashMap<>();

    public static DesensitizationProcessor getDesensitizationProcessor(Class<? extends DesensitizationProcessor> aClass) {
        if (aClass == null) {
            return null;
        }
        String aClassName = aClass.getName();
        DesensitizationProcessor desensitizationProcessor = CACHE.get(aClassName);
        if (desensitizationProcessor == null) {
            try {
                DesensitizationProcessor desensitizationProcessorInstance = aClass.newInstance();
                CACHE.put(aClassName, desensitizationProcessorInstance);
                return desensitizationProcessorInstance;
            } catch (InstantiationException | IllegalAccessException e) {
                log.error("实例化脱敏处理器失败", e);
                return null;
            }
        } else {
            return desensitizationProcessor;
        }
    }
}

• DesensitizationSerializer

/**
 * 数据脱敏序列化器
 *
 * @author futaosmile@gmail.com
 * @date 2022/7/18
 * @since 2022/7/18
 */
@Slf4j
public class DesensitizationSerializer extends StdSerializer<String> implements ContextualSerializer {

    private transient DesensitizationProcessor desensitizationProcessor;

    protected DesensitizationSerializer() {
        // 支持的类型
        super(String.class);
    }

    /**
     * 创建上下文信息
     *
     * @param prov     Serializer provider to use for accessing config, other serializers
     * @param property Method or field that represents the property
     *                 (and is used to access value to serialize).
     *                 Should be available; but there may be cases where caller can not provide it and
     *                 null is passed instead (in which case impls usually pass 'this' serializer as is)
     * @return
     */
    @Override
    public JsonSerializer<String> createContextual(SerializerProvider prov, BeanProperty property) {
        DesensitizationAnn desensitizationAnn = property.getAnnotation(DesensitizationAnn.class);
        if (desensitizationAnn != null) {
            Class<? extends DesensitizationProcessor> value = desensitizationAnn.value();
            DesensitizationProcessor curDesensitizationProcessor = DesensitizationProcessorFactory.getDesensitizationProcessor(value);
            log.debug("cur processor is:{}", curDesensitizationProcessor);
            if (curDesensitizationProcessor == null) {
                log.error("无法获取{}对应的processor实例", value);
            } else {
                this.desensitizationProcessor = curDesensitizationProcessor;
            }
        }
        return this;
    }

    @Override
    public void serialize(String value, JsonGenerator gen, SerializerProvider provider) throws IOException {
        log.debug("cur obj is:{}", this);
        if (this.desensitizationProcessor != null) {
            try {
                gen.writeObject(desensitizationProcessor.desensitize(value));
            } catch (Exception e) {
                log.error("自定义脱敏处理器数据脱敏失败", e);
                gen.writeObject(value);
            }
        } else {
            gen.writeObject(value);
        }
    }


}