1.依赖包

Newtonsoft请在PacakgeManager处下载。
参考：打工人小棋

2.原理：

把要存储的对象数据等使用JsonConvert.SerializeObject(object T)进行序列化为字符串，并且通过File.WriteAllText写入json文本文件。
读取的时候就通过反序列化读取存储的数据。
T data = JsonConvert.DeserializeObject(jsonContent);

3.代码

Unity官方推荐把存档文件放置到Application.persistentDataPath目录下。在Windows环境下路径为：

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using Newtonsoft.Json;
using System.IO;
public class LocalConfig
{
    public static void SavaUserData(UserData userData)
    {
        if(!File.Exists(Application.persistentDataPath + "/users"))
        {
            System.IO.Directory.CreateDirectory(Application.persistentDataPath + "/users");
        }
        // 序列化
        string jsonContent = JsonConvert.SerializeObject(userData);
        // 输出一个json文件 {0} 是占位符 类似printf的%d
        File.WriteAllText(Application.persistentDataPath + string.Format("/users/{0}.json", userData.name), jsonContent);
    }
    public static UserData LoadUserData(string userName)
    {
        string path = Application.persistentDataPath + string.Format("/users/{0}.json", userName);
        if(File.Exists(path))
        {
            // 读取路径文本数据
            string jsonContent = File.ReadAllText(path);
            // 反序列化
            UserData userData = JsonConvert.DeserializeObject<UserData>(jsonContent);
            return userData;
        }
        else
        {
            Debug.LogError("DO NOT EXIST");
            return null;
        }
    }
}

public class UserData
{
    public int level;
    public string name;
}

4.可用优化

由于硬盘的读写是比较耗时的操作，我们可以用字典存储<userName,userData>的键值对。
好处：读取相同的数据只有第一次需要使用文件读取，后续只需要使用字典访问。
由于每次退出程序DIctionary都会清空所以第一次访问同一个对象会比后续慢。

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using Newtonsoft.Json;
using System.IO;
public class LocalConfig
{
    public static Dictionary<string, UserData> userDataDic = new Dictionary<string, UserData>();
    public static void SavaUserData(UserData userData)
    {
        if(!File.Exists(Application.persistentDataPath + "/users"))
        {
            System.IO.Directory.CreateDirectory(Application.persistentDataPath + "/users");
        }
        // 序列化
        string jsonContent = JsonConvert.SerializeObject(userData);
        // 输出一个json文件 {0} 是占位符 类似printf的%d
        File.WriteAllText(Application.persistentDataPath + string.Format("/users/{0}.json", userData.name), jsonContent);
        if(userDataDic.ContainsKey(userData.name))
        {
            userDataDic[userData.name] = userData;
        }
        else
        {
            userDataDic.Add(userData.name, userData);
        }

    }
    public static UserData LoadUserData(string userName)
    {

        if(userDataDic.ContainsKey(userName))
        {
            return userDataDic[userName];
        }

        string path = Application.persistentDataPath + string.Format("/users/{0}.json", userName);
        if(File.Exists(path))
        {
            // 读取路径文本数据
            string jsonContent = File.ReadAllText(path);
            // 反序列化
            UserData userData = JsonConvert.DeserializeObject<UserData>(jsonContent);
            return userData;
        }
        else
        {
            Debug.LogError("DO NOT EXIST");
            return null;
        }
    }
}

public class UserData
{
    public int level;
    public string name;
}

5.数据加密

因为一个数字异或同一个数字两次能得到原来的结果，所以可以借此来加密解密。

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using Newtonsoft.Json;
using System.IO;
public class LocalConfig
{
    public static Dictionary<string, UserData> userDataDic = new Dictionary<string, UserData>();

    private static char[] chars = {'4','5','6'};
    private static string Encrypt(string data)
    {
        char[] temp = data.ToCharArray();
        for(int i = 0; i < temp.Length; i++)
        {
            temp[i] = (char) (temp[i] ^ chars[i % 3]);
        }
        return new string(temp);
    }
    public static void SavaUserData(UserData userData)
    {
        if(!File.Exists(Application.persistentDataPath + "/users"))
        {
            System.IO.Directory.CreateDirectory(Application.persistentDataPath + "/users");
        }
        // 序列化
        string jsonContent = JsonConvert.SerializeObject(userData);
        jsonContent = Encrypt(jsonContent);
        // 输出一个json文件 {0} 是占位符 类似printf的%d
        File.WriteAllText(Application.persistentDataPath + string.Format("/users/{0}.json", userData.name), jsonContent);
        if(userDataDic.ContainsKey(userData.name))
        {
            userDataDic[userData.name] = userData;
        }
        else
        {
            userDataDic.Add(userData.name, userData);
        }

    }
    public static UserData LoadUserData(string userName)
    {

        if(userDataDic.ContainsKey(userName))
        {
            return userDataDic[userName];
        }

        string path = Application.persistentDataPath + string.Format("/users/{0}.json", userName);
        if(File.Exists(path))
        {
            // 读取路径文本数据
            string jsonContent = File.ReadAllText(path);
            // 反序列化
            jsonContent = Encrypt(jsonContent);
            UserData userData = JsonConvert.DeserializeObject<UserData>(jsonContent);
            return userData;
        }
        else
        {
            Debug.LogError("DO NOT EXIST");
            return null;
        }
    }
}

public class UserData
{
    public int level;
    public string name;
}