在将map传递给Jackon的valueToTree方法时将java.sql.Timestamp转换为StringNode

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.SerializerProvider;
import com.fasterxml.jackson.databind.node.TextNode;

import java.io.IOException;
import java.sql.Timestamp;

public class TimestampSerializer extends JsonSerializer<Timestamp> {

    @Override
    public void serialize(Timestamp timestamp, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException {
        String timestampString = timestamp.toString();
        TextNode node = new TextNode(timestampString);
        jsonGenerator.writeTree(node);
    }
}

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.annotation.JsonSerialize;

import java.sql.Timestamp;
import java.util.HashMap;
import java.util.Map;

public class Main {

    public static void main(String[] args) throws Exception {
        ObjectMapper objectMapper = new ObjectMapper();

        Map<String, Object> map = new HashMap<>();
        Timestamp timestamp = new Timestamp(System.currentTimeMillis());
        map.put("timestamp", timestamp);

        String json = objectMapper.writeValueAsString(map);
        System.out.println(json);
    }

    public static class MyData {
        @JsonSerialize(using = TimestampSerializer.class)
        private Timestamp timestamp;

        public Timestamp getTimestamp() {
            return timestamp;
        }

        public void setTimestamp(Timestamp timestamp) {
            this.timestamp = timestamp;
        }
    }
}

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.node.ObjectNode;

import java.sql.Timestamp;
import java.util.HashMap;
import java.util.Map;

public class Main {

    public static void main(String[] args) throws Exception {
        ObjectMapper objectMapper = new ObjectMapper();

        Map<String, Object> map = new HashMap<>();
        Timestamp timestamp = new Timestamp(System.currentTimeMillis());
        map.put("timestamp", timestamp);

        JsonNode jsonNode = objectMapper.valueToTree(map);
        System.out.println(jsonNode);
    }
}