上一节内容结束后确实可以写入文件了，但还有两个问题：

1.一个是players.txt中，每次重启服务器，当注册新账号创建角色时，players.txt之前内容都会清空。

2.players.txt之前已经注册3次的账号，新注册的角色信息不会写入players.txt，猜测与userPlayerIds.txt中的残留内容有关。但userPlayerIds.txt中的内容感觉不全！

先解决第一个问题：上边 userPlayerIds.txt的内容是可以成功读出来并且转化的，players.txt中的内容转化失败，所以此时就是空的！

就是json转换结构体上出现了问题，账号那可以的，换到这就出问题了！

对比来看AccountModel和PlayerModel基本上大同小异

Newtonsoft.Json.JsonSerializationException:“Unable to find a constructor to use for type GameServer.model.PlayerModel. A class should either have a default constructor, one constructor with arguments or a constructor marked with the JsonConstructor attribute. Path '431b0501-457f-46ba-91dd-353c8a3c8c0c.id', line 3, position 9.” 

Newtonsoft。Json。JsonSerializationException：“找不到用于类型GameServer.model.PlayerModel的构造函数。类应该有一个默认构造函数、一个带参数的构造函数或一个用JsonConstructor属性标记的构造函数。路径'431b0501-457f-46ba-91dd-353c8a3c8c8c.id'，第3行，位置9。”

就是PlayerModel类没有构造函数！

namespace GameServer.model
{
  internal class PlayerModel
  {
    public string id { get; set; }

    public string name { get; set; }

    public int job { get; set; }

    public int level { get; set; }

    public int exp { get; set; }

    public int atk { get; set; }

    public int def { get; set; }

    public int hp { get; set; }

    public int maxHp { get; set; }

    public Vector3 point { get; set; }

    public Vector4 rotation { get; set; }

    public int map { get; set; }

    public PlayerModel(PlayerModel model)
    {
      this.job = model.job;
      this.level = model.level;
      this.exp = model.exp;
      this.atk = model.atk;
      this.def = model.def;
      this.hp = model.hp;
      this.maxHp = model.maxHp;
    }

    public PlayerModel(
      int job,
      int level,
      int exp,
      int atk,
      int def,
      int map,
      int hp,
      int maxHp)
    {
      this.job = job;
      this.level = level;
      this.exp = exp;
      this.atk = atk;
      this.def = def;
      this.map = map;
      this.hp = hp;
      this.maxHp = maxHp;
    }
  }
}

很明显是有构造函数的，还有2个，没想到再加一个 

public PlayerModel()
 { }

的确是解决了！：