作者：京东物流 张晓旭
1.背景
在项目中有些敏感信息不能直接展示，比如客户手机号、身份证、车牌号等信息，展示时均需要进行数据脱敏，防止泄露客户隐私。脱敏即是对数据的部分信息用脱敏符号（*）处理。
2.目标
3.主要实现
3.1 基于 Jackson 的自定义脱敏序列化实现
StdSerializer：所有标准序列化程序所使用的基类，这个是编写自定义序列化程序所推荐使用的基类。
**ContextualSerializer：**是 Jackson 提供的另一个序列化相关的接口，它的作用是通过字段已知的上下文信息定制 JsonSerializer。
package com.jd.ccmp.ctm.constraints.serializer;
import com.fasterxml.jackson.core.JsonGenerator;import com.fasterxml.jackson.databind.BeanProperty;import com.fasterxml.jackson.databind.JsonSerializer;import com.fasterxml.jackson.databind.SerializerProvider;import com.fasterxml.jackson.databind.ser.ContextualSerializer;import com.fasterxml.jackson.databind.ser.std.StdSerializer;import com.jd.ccmp.ctm.constraints.Symbol;import com.jd.ccmp.ctm.constraints.annotation.Desensitize;import com.jd.ccmp.ctm.constraints.desensitization.Desensitization;import com.jd.ccmp.ctm.constraints.desensitization.DesensitizationFactory;import com.jd.ccmp.ctm.constraints.desensitization.DefaultDesensitization;
import java.io.IOException;
/** * 脱敏序列化器 * * @author zhangxiaoxu15 * @date 2022/2/8 11:10 */public class ObjectDesensitizeSerializer extends StdSerializer<Object> implements ContextualSerializer { private static final long serialVersionUID = -7868746622368564541L; private transient Desensitization<Object> desensitization; protected ObjectDesensitizeSerializer() { super(Object.class); } public Desensitization<Object> getDesensitization() { return desensitization; } public void setDesensitization(Desensitization<Object> desensitization) { this.desensitization = desensitization; } @Override public JsonSerializer<Object> createContextual(SerializerProvider prov, BeanProperty property) {//获取属性注解 Desensitize annotation = property.getAnnotation(Desensitize.class); return createContextual(annotation.desensitization()); } @SuppressWarnings("unchecked") public JsonSerializer<Object> createContextual(Class<? extends Desensitization<?>> clazz) { ObjectDesensitizeSerializer serializer = new ObjectDesensitizeSerializer(); if (clazz != DefaultDesensitization.class) { serializer.setDesensitization((Desensitization<Object>) DesensitizationFactory.getDesensitization(clazz)); } return serializer; } @Override public void serialize(Object value, JsonGenerator gen, SerializerProvider provider) throws IOException { Desensitization<Object> objectDesensitization = getDesensitization(); if (objectDesensitization != null) { try { gen.writeObject(objectDesensitization.desensitize(value)); } catch (Exception e) { gen.writeObject(value); } } else if (value instanceof String) { gen.writeString(Symbol.getSymbol(((String) value).length(), Symbol.STAR)); } else { gen.writeObject(value); }
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注：createContextual 可以获得字段的类型以及注解。当字段拥有自定义注解时，取出注解中的值创建定制的序列化方式，这样在 serialize 方法中便可以得到这个值了。createContextual 方法只会在第一次序列化字段时调用（因为字段的上下文信息在运行期不会改变），所以无需关心性能问题。
3.2 定义脱敏接口、以及工厂实现
3.2.1 脱敏器接口定义
package com.jd.ccmp.ctm.constraints.desensitization;
/** * 脱敏器 * * @author zhangxiaoxu15 * @date 2022/2/8 10:56 */public interface Desensitization<T> { /** * 脱敏实现 * * @param target 脱敏对象 * @return 脱敏返回结果 */ T desensitize(T target);}
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3.2.2 脱敏器工厂实现
package com.jd.ccmp.ctm.constraints.desensitization;
import java.util.HashMap;import java.util.Map;
/** * 工厂方法 * * @author zhangxiaoxu15 * @date 2022/2/8 10:58 */public class DesensitizationFactory { private DesensitizationFactory() { } private static final Map<Class<?>, Desensitization<?>> map = new HashMap<>();
@SuppressWarnings("all") public static Desensitization<?> getDesensitization(Class<?> clazz) { if (clazz.isInterface()) { throw new UnsupportedOperationException("desensitization is interface, what is expected is an implementation class !"); } return map.computeIfAbsent(clazz, key -> { try { return (Desensitization<?>) clazz.newInstance(); } catch (InstantiationException | IllegalAccessException e) { throw new UnsupportedOperationException(e.getMessage(), e); } });
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3.3 常用的脱敏器实现
3.3.1 默认脱敏实现
可基于默认实现，扩展实现个性化场景
package com.jd.ccmp.ctm.constraints.desensitization;
/** * 默认脱敏实现 * * @author zhangxiaoxu15 * @date 2022/2/8 11:01 */public interface DefaultDesensitization extends Desensitization<String> {}
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3.3.2 手机号脱敏器
实现对手机号中间 4 位号码脱敏
package com.jd.ccmp.ctm.constraints.desensitization;import com.jd.ccmp.ctm.constraints.Symbol;import java.util.regex.Matcher;import java.util.regex.Pattern;
/** * 手机号脱敏器，保留前3位和后4位 * * @author zhangxiaoxu15 * @date 2022/2/8 11:02 */public class MobileNoDesensitization implements DefaultDesensitization { /** * 手机号正则 */ private static final Pattern DEFAULT_PATTERN = Pattern.compile("(13[0-9]|14[579]|15[0-3,5-9]|16[6]|17[0135678]|18[0-9]|19[89])\\d{8}");
@Override public String desensitize(String target) { Matcher matcher = DEFAULT_PATTERN.matcher(target); while (matcher.find()) { String group = matcher.group(); target = target.replace(group, group.substring(0, 3) + Symbol.getSymbol(4, Symbol.STAR) + group.substring(7, 11)); } return target;
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3.4 注解定义
通过 @JacksonAnnotationsInside 实现自定义注解，提高易用性
package com.jd.ccmp.ctm.constraints.annotation;import com.fasterxml.jackson.annotation.JacksonAnnotationsInside;import com.fasterxml.jackson.databind.annotation.JsonSerialize;import com.jd.ccmp.ctm.constraints.desensitization.Desensitization;import com.jd.ccmp.ctm.constraints.serializer.ObjectDesensitizeSerializer;import java.lang.annotation.*;
/** * 脱敏注解 * * @author zhangxiaoxu15 * @date 2022/2/8 11:09 */@Target({ElementType.FIELD, ElementType.ANNOTATION_TYPE})@Retention(RetentionPolicy.RUNTIME)@JacksonAnnotationsInside@JsonSerialize(using = ObjectDesensitizeSerializer.class)@Documentedpublic @interface Desensitize { /** * 对象脱敏器实现 */ @SuppressWarnings("all") Class<? extends Desensitization<?>> desensitization();
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3.4.1 默认脱敏注解
package com.jd.ccmp.ctm.constraints.annotation;import com.fasterxml.jackson.annotation.JacksonAnnotationsInside;import com.jd.ccmp.ctm.constraints.desensitization.DefaultDesensitization;import java.lang.annotation.*;
/** * 默认脱敏注解 * * @author zhangxiaoxu15 * @date 2022/2/8 11:14 */@Target({ElementType.FIELD})@Retention(RetentionPolicy.RUNTIME)@JacksonAnnotationsInside@Desensitize(desensitization = DefaultDesensitization.class)@Documentedpublic @interface DefaultDesensitize {
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3.4.2 手机号脱敏注解
package com.jd.ccmp.ctm.constraints.annotation;import com.fasterxml.jackson.annotation.JacksonAnnotationsInside;import com.jd.ccmp.ctm.constraints.desensitization.MobileNoDesensitization;import java.lang.annotation.*;
/** * 手机号脱敏 * * @author zhangxiaoxu15 * @date 2022/2/8 11:18 */@Target({ElementType.FIELD})@Retention(RetentionPolicy.RUNTIME)@JacksonAnnotationsInside@Desensitize(desensitization = MobileNoDesensitization.class)@Documentedpublic @interface MobileNoDesensitize {}
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3.5 定义脱敏符号
支持指定脱敏符号，例如* 或是 ^_^
package com.jd.ccmp.ctm.constraints;import java.util.stream.Collectors;import java.util.stream.IntStream;
/** * 脱敏符号 * * @author zhangxiaoxu15 * @date 2022/2/8 10:53 */public class Symbol { /** * '*'脱敏符 */ public static final String STAR = "*"; private Symbol() {} /** * 获取符号 * * @param number 符号个数 * @param symbol 符号 */ public static String getSymbol(int number, String symbol) { return IntStream.range(0, number).mapToObj(i -> symbol).collect(Collectors.joining()); }
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4.使用样例 &执行流程剖析
程序类图
**执行流程剖析** 1.调用JsonUtil.toJsonString()开始执行序列化 2.识别属性mobile上的注解@MobileNoDesensitize(上文3.4.2) 3.调用ObjectDesensitizeSerializer#createContextual(上文3.1 & 3.2)，返回JsonSerializer 4.调用手机号脱敏实现MobileNoDesensitization#desensitize(上文3.3.2) 5.输出脱敏后的序列化结果，{"mobile":"133****5678"}
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不难发现核心执行流程是第 3 步，但是 @MobileNoDesensitize 与 ObjectDesensitizeSerializer 又是如何联系起来的呢？
**Jackson元注解**1.提到元注解这个词，大家会想到@Target、@Retention、@Documented、@Inherited2.Jackson也以同样的思路设计了@JacksonAnnotationsInside
/** * Meta-annotation (annotations used on other annotations) * used for indicating that instead of using target annotation * (annotation annotated with this annotation), * Jackson should use meta-annotations it has. * This can be useful in creating "combo-annotations" by having * a container annotation, which needs to be annotated with this * annotation as well as all annotations it 'contains'. * * @since 2.0 */@Target({ElementType.ANNOTATION_TYPE})@Retention(RetentionPolicy.RUNTIME)@JacksonAnnotationpublic @interface JacksonAnnotationsInside{}
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正是通过”combo-annotations”(组合注解、捆绑注解)的机制，实现了指示 Jackson 应该使用其拥有的元注释，而不是使用目标注释，从而实现了自定义脱敏实现设计目标。
5.总结
以上就是利用 Jackson 序列化实现数据脱敏的全过程，如有此类需求的同学可以借鉴上面的实现方法。
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