1.首先创建注解类

import com.fasterxml.jackson.annotation.JacksonAnnotationsInside;
import com.fasterxml.jackson.databind.annotation.JsonSerialize;
import com.jian.common.desen.BaseRule;
import com.jian.common.desen.DefaultRule;
import com.jian.common.desen.MyJsonSerializer;

import java.lang.annotation.*;

/**
 * @author Administrator
 */
@JacksonAnnotationsInside
@JsonSerialize(using = MyJsonSerializer.class)
@Target({ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
public @interface CustomSerializer {

    /**
     * 脱敏规则处理类
     * @return
     */
    Class<? extends BaseRule> value() default DefaultRule.class;

    /**
     * 正则，pattern和format必需同时有值。如果都有值时，优先使用正则进行规则替换
     * @return
     */
    String pattern() default "";

    String format() default "";

}

2.创建注解检查 转换类

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.BeanProperty;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.SerializerProvider;
import com.fasterxml.jackson.databind.ser.ContextualSerializer;
import com.jian.common.annotation.CustomSerializer;
import lombok.extern.slf4j.Slf4j;

import java.io.IOException;

@Slf4j
public class MyJsonSerializer extends JsonSerializer<String> implements ContextualSerializer {

    /**
     * 脱敏规则
     */
    private BaseRule rule;

    @Override
    public void serialize(String value, JsonGenerator gen, SerializerProvider serializers) throws IOException {
        gen.writeString(rule.apply(value));
    }

    @Override
    public JsonSerializer<?> createContextual(SerializerProvider prov, BeanProperty property) throws JsonMappingException {
        //获取对象属性上的自定义注解
        CustomSerializer customSerializer = property.getAnnotation(CustomSerializer.class);
        if (null != customSerializer) {
            try {
                //根据注解的配置信息，创建对应脱敏规则处理类
                this.rule = customSerializer.value().newInstance();
                //如果正则信息不为空，则使用注解上的正则初始化到对应的脱敏规则处理类中
                if (isNotBlank(customSerializer.pattern()) && isNotBlank(customSerializer.format())) {
                    this.rule.setRule(new RuleItem()
                            .setRegex(customSerializer.pattern())
                            .setFormat(customSerializer.format()));
                }
                return this;
            } catch (Exception e) {
                log.error("json转换处理异常", e);
            }
        }
        return prov.findValueSerializer(property.getType(), property);
    }

    private boolean isNotBlank(String str) {
        return null != str && str.trim().length() > 0;
    }
}

3.创建数据脱敏基类

package com.jian.common.desen;

import lombok.Data;

import java.util.function.Function;
//脱敏处理基类
@Data
public abstract class BaseRule implements Function<String, String> {
    /**
     * 脱敏规则对象
     */
    private RuleItem rule;

    @Override
    public String apply(String str) {
        if (null == str) {
            return null;
        }
        //初始化脱敏规则
        initRule();
        if (null == rule || null == rule.getRegex() || null == rule.getFormat()) {
            return str;
        }
        //正则替换
        return str.replaceAll(rule.getRegex(), rule.getFormat());
    }
    abstract void initRule();
}

4.注解参数以及默认处理类

import lombok.Data;
import lombok.experimental.Accessors;

@Data
@Accessors(chain = true)
public class RuleItem {

    /**
     * 正则
     */
    private String regex;

    /**
     * 格式化显示
     */
    private String format;
}

public class DefaultRule extends BaseRule {
    @Override
    void initRule() {

    }
}

5.实现基类，自定义处理脱敏规则

例如手机号脱敏

//手机号脱敏处理类
public class PhoneRule extends BaseRule {

    /**
     * 仅显示前3位和后4位
     */
    @Override
    void initRule() {
        setRule(new RuleItem()
                .setRegex("(\\d{3})\\d*(\\d{4})")
                .setFormat("$1****$2"));
    }

}

身份证号码脱敏

//身份证号脱敏处理类
public class IdCardRule extends BaseRule {

    /**
     * 仅显示前6位和后4位
     */
    @Override
    void initRule() {
        setRule(new RuleItem()
                .setRegex("(\\d{6})\\d*(\\w{4})")
                .setFormat("$1********$2"));
    }

}

用户名脱敏

//姓名脱敏处理类
public class UserNameRule extends BaseRule {

    /**
     * 仅显示最后一个汉字
     */
    @Override
    void initRule() {
        setRule(new RuleItem()
                .setRegex("\\S*(\\S)")
                .setFormat("**$1"));
    }
}

6.实体类属性上面加上注解

 @CustomSerializer(value = PhoneRule.class)
 private String phonenumber;

这样子返回的数据，就会脱敏返回啦