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前言

没看过前面的教程请先阅读前面的教程，本期将会讲到Netcode联机的申请，当一个Client想连接进来，应向Server发送申请联机的信息，然后由服务端向客户端下发数据，所有数据应该在服务端，而不是在客户端。

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适用场景

举几个常见的例子需要用到ConnectionApproval的场景

• 使用密码加入房间
• 玩家选择不同的角色
• 房间人数
• 各种需要服务端下发的信息等等

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1. 准备

需要在第二期上添加多的一个Player预制体

每个Player都需要挂载上NetworkObject这个组件

最重要的一点是在NetworkManager上开启ConnectionApproval

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2.新建GameManager

新建一个GameManager空物体，添加NetworkObject这个组件

在Scripts目录下新建一个GameManager脚本，挂载到GameManager的空物体上

using UnityEngine;
using Unity.Netcode;
using System.Text;

public class GameManager : NetworkBehaviour
{
    public GameObject Man;
    public GameObject Girl;

    public override void OnNetworkSpawn()
    {
        if (IsServer)
        {
            NetworkManager.ConnectionApprovalCallback = ApprovalCheck;
        }
    }

    private void Update()
    {
        if (Input.GetKeyDown(KeyCode.O))
        {
            NetworkManager.Singleton.NetworkConfig.PlayerPrefab = Man;
            NetworkManager.Singleton.StartHost();
        }

        if (Input.GetKeyDown(KeyCode.P))
        {
            NetworkManager.Singleton.NetworkConfig.ConnectionData = Encoding.UTF8.GetBytes("Girl");
            NetworkManager.Singleton.StartClient();
        }
    }

    private void ApprovalCheck(NetworkManager.ConnectionApprovalRequest request, NetworkManager.ConnectionApprovalResponse response)
    {
        // The client identifier to be authenticated
        var clientId = request.ClientNetworkId;

        // Additional connection data defined by user code
        var connectionData = request.Payload;

        var _character = Encoding.UTF8.GetString(connectionData);

        if (_character == "Girl")
        {
            response.PlayerPrefabHash = Girl.GetComponent<NetworkObject>().PrefabIdHash;
        }
        else
        {
            response.PlayerPrefabHash = Man.GetComponent<NetworkObject>().PrefabIdHash;
        }

        // Your approval logic determines the following values
        response.Approved = true;
        response.CreatePlayerObject = true;

        // Position to spawn the player object (if null it uses default of Vector3.zero)
        response.Position = Vector3.zero;

        // Rotation to spawn the player object (if null it uses the default of Quaternion.identity)
        response.Rotation = Quaternion.identity;

        // If response.Approved is false, you can provide a message that explains the reason why via ConnectionApprovalResponse.Reason
        // On the client-side, NetworkManager.DisconnectReason will be populated with this message via DisconnectReasonMessage
        response.Reason = "Some reason for not approving the client";

        // If additional approval steps are needed, set this to true until the additional steps are complete
        // once it transitions from true to false the connection approval response will be processed.
        response.Pending = false;
    }
}

在Inspector窗口绑定一下两个角色到脚本中

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3.编译运行

分别按下O键与P键，可以看到有两个不同的Player Prefab实例化了。

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4.脚本详解

• GameManager继承的是NetworkBehaviour而非MonoBehaviour

重写OnNetworkSpawn()方法，让NetworkManager放入回调方法ApprovalCheck让服务端处理

public override void OnNetworkSpawn()
    {
        if (IsServer)
        {
            NetworkManager.ConnectionApprovalCallback = ApprovalCheck;
        }
    }

ApprovalCheck这个回调方法传入两个类型的参数，分别是NetworkManager.ConnectionApprovalRequest和NetworkManager.ConnectionApprovalResponse

• NetworkManager.ConnectionApprovalRequest 是客户端的请求，一共两个字段
  – ClientNetworkId 是客户端的唯一标识ID
  – Payload是客户端发送的信息，封装成byte类型，这也是我们主要使用的

private void ApprovalCheck(NetworkManager.ConnectionApprovalRequest request, NetworkManager.ConnectionApprovalResponse response)
    {
        // The client identifier to be authenticated
        var clientId = request.ClientNetworkId;

        // Additional connection data defined by user code
        var connectionData = request.Payload;

        var _character = Encoding.UTF8.GetString(connectionData);

        if (_character == "Girl")
        {
            response.PlayerPrefabHash = Girl.GetComponent<NetworkObject>().PrefabIdHash;
        }
        else
        {
            response.PlayerPrefabHash = Man.GetComponent<NetworkObject>().PrefabIdHash;
        }

        // Your approval logic determines the following values
        response.Approved = true;
        response.CreatePlayerObject = true;

        // Position to spawn the player object (if null it uses default of Vector3.zero)
        response.Position = Vector3.zero;

        // Rotation to spawn the player object (if null it uses the default of Quaternion.identity)
        response.Rotation = Quaternion.identity;

        // If response.Approved is false, you can provide a message that explains the reason why via ConnectionApprovalResponse.Reason
        // On the client-side, NetworkManager.DisconnectReason will be populated with this message via DisconnectReasonMessage
        response.Reason = "Some reason for not approving the client";

        // If additional approval steps are needed, set this to true until the additional steps are complete
        // once it transitions from true to false the connection approval response will be processed.
        response.Pending = false;
    }

• NetworkManager.ConnectionApprovalResponse是服务端给客户端的响应，一共有八个字段
  – Approved：是否同意客户端加入
  – Reason： 如果Approved为false，填写拒绝理由
  – CreatePlayerObject 是否生成玩家实体
  – PlayerPrefabHash 如果null则生成在NetworkManager默认的Player Prefab，这个值要填入NetworkObject的PrefabIdHash
  – Position生成玩家实体的position
  – Rotation生成玩家实体的rotation
  – Pending 挂起approval延迟授权，直到其他客户端完成approval， 官方解释：Provides the ability to mark the approval as pending to delay the authorization until other user-specific code finishes the approval process.

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后话

官方相关的阅读文档：

• https://docs-multiplayer.unity3d.com/netcode/current/basics/connection-approval/
• https://docs-multiplayer.unity3d.com/netcode/current/basics/object-spawning/
• GitHub