需要在属性上添加

@JsonSerialize(using = Base64Serializer.class)
@JsonDeserialize(using = Base64Deserializer.class)
private String documentId;

序列化

public class Base64Serializer extends JsonSerializer<String> {

    @Override
    public void serialize(String s, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException {
        if (!ObjectUtils.isEmpty(s)){
            // 对返回的非空字符串进行base64编码
            s = Base64.getEncoder().encodeToString(s.getBytes(StandardCharsets.UTF_8));
        }
        jsonGenerator.writeObject(s);
    }
}

反序列化

public class Base64Deserializer extends JsonDeserializer<String> {
    private final static Logger logger = LoggerFactory.getLogger(Base64Deserializer.class);

    @Override
    public String deserialize(JsonParser jsonParser, DeserializationContext deserializationContext) throws IOException, JsonProcessingException {
        String text = jsonParser.getText();
        return decodeBase64(text);
    }

    /**
     * 对非空的值，尝试base64解码，失败不改变原值
     * @param text 待解码的字符串
     * @return base64解码后的字符串
     */
    public static String decodeBase64(String text){
        if (!ObjectUtils.isEmpty(text)){
            try {
                // 对非空的值，尝试base64解码，失败不改变原值
                byte[] txtBytes = Base64.getDecoder().decode(text.getBytes(StandardCharsets.UTF_8));
                text = new String(txtBytes, StandardCharsets.UTF_8);
            } catch (Exception e){
                // 解码失败，text原数返回
                logger.error(e.getMessage());
            }
        }
        return text;
    }
}