Java 键值对数据本地保存与读取

代码：

package com.sux.demo.utils;

import com.alibaba.fastjson.JSONObject;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.charset.Charset;
import java.util.HashMap;
import java.util.Map;

/**
 * 存储工具类
 */
public class StoreUtil {

    private static final String fileDir = "/home/server/import/wifi/log/";

    private static final String fileName = "store-kafka-delay-check.log";

    private static Object lock = new Object();

    public static void write(String key, Object value) throws IOException {
        Map<String, Object> map = read();
        if (map.containsKey(key)) {
            map.remove(key);
        }
        map.put(key, value);
        String strJson = JSONObject.toJSONString(map);

        synchronized (lock) {
            mkdirs();
            FileOutputStream fos = new FileOutputStream(fileDir + fileName);
            byte[] bytes = strJson.getBytes(Charset.forName("utf-8"));
            fos.write(bytes);
            fos.close();
        }
    }

    public static Object read(String key) throws IOException {
        Map<String, Object> map = read();
        if (map.containsKey(key)) {
            return map.get(key);
        }
        return null;
    }

    private static Map<String, Object> read() throws IOException {
        synchronized (lock) {
            mkdirs();
            File file = new File(fileDir + fileName);
            if (file.exists() && file.isFile()) {
                FileInputStream fis = new FileInputStream(fileDir + fileName);
                byte[] bytes = new byte[fis.available()];
                fis.read(bytes, 0, bytes.length);
                fis.close();
                String strJson = new String(bytes, Charset.forName("utf-8"));
                return JSONObject.parseObject(strJson);
            } else {
                return new HashMap<>();
            }
        }
    }

    private static void mkdirs() {
        File file = new File(fileDir);
        if (!file.exists() && !file.isDirectory()) {
            file.mkdirs();
        }
    }

}

自己写的一个服务程序需要这个功能，为什么我会需要一个这么low的工具类呢？