Network.TestConnection

Description

测试此机器的网络连接。

根据机器具有公共 IP 地址还是仅有私有地址，可执行两种测试。

公共 IP 地址测试主要用于作为服务器运行的情形，因为具有公共地址的客户端无需测试。为了 成功进行公共 IP 测试，必须启动一个服务器实例。测试服务器会尝试连接到本地服务器的 IP 和端口， 以显示该服务器可接受连接。否则，服务器端口很有可能被防火墙阻止。 服务器实例需处于运行状态，以便测试服务器能够建立连接。

另一个测试是检查 NAT 穿透能力。该测试对服务器和客户端均有效， 而且无需事先设置就可以进行测试。NAT 测试会有 4 种结果（请参阅 ConnectionTesterStatus）：__Full Cone_、Address Restricted Cone、Port restricted 及 Symmetric。

前两种提供完全 NAT 穿透支持，可连接到任何类型。端口限制类型无法连接到对称类型，也不能接收来自对称类型的连接。 对称类型是最糟糕的情况，无法连接到其他对称类型或端口限制类型。后两种被标记为 提供有限的 NAT 穿透支持。

此函数是异步函数，可能不会立即返回有效的结果， 因为测试需要一定时间才能完成（1-2 秒）。测试完成后，测试结果仅在下一次再次调用该函数时返回， 不会重复进行一次完整的网络测试。这使得能够安全地频繁轮询该函数。如果希望进行另一个测试， 如网络连接是否发生变化，传入的 forceTest 参数应为 true。

此函数返回一个 ConnectionTesterStatus 枚举。

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour
{
    string testStatus = "Testing network connection capabilities.";
    string testMessage = "Test in progress";
    string shouldEnableNatMessage  = "";
    bool doneTesting = false;
    bool probingPublicIP = false;
    int serverPort = 9999;
    bool useNat = false;
    float timer = 0.0f;

    ConnectionTesterStatus connectionTestResult = ConnectionTesterStatus.Undetermined;

    void OnGUI()
    {
        GUILayout.Label("Current Status: " + testStatus);
        GUILayout.Label("Test result : " + testMessage);
        GUILayout.Label(shouldEnableNatMessage);

        if (!doneTesting)
            TestConnection();
    }

    void TestConnection()
    {
        // Start/Poll the connection test, report the results in a label and
        // react to the results accordingly
        connectionTestResult = Network.TestConnection();
        switch (connectionTestResult)
        {
            case ConnectionTesterStatus.Error:
                testMessage = "Problem determining NAT capabilities";
                doneTesting = true;
                break;

            case ConnectionTesterStatus.Undetermined:
                testMessage = "Undetermined NAT capabilities";
                doneTesting = false;
                break;

            case ConnectionTesterStatus.PublicIPIsConnectable:
                testMessage = "Directly connectable public IP address.";
                useNat = false;
                doneTesting = true;
                break;

            // This case is a bit special as we now need to check if we can
            // circumvent the blocking by using NAT punchthrough
            case ConnectionTesterStatus.PublicIPPortBlocked:
                testMessage = "Non-connectable public IP address (port " +
                    serverPort + " blocked), running a server is impossible.";
                useNat = false;
                // If no NAT punchthrough test has been performed on this public
                // IP, force a test
                if (!probingPublicIP)
                {
                    connectionTestResult = Network.TestConnectionNAT();
                    probingPublicIP = true;
                    testStatus = "Testing if blocked public IP can be circumvented";
                    timer = Time.time + 10;
                }
                // NAT punchthrough test was performed but we still get blocked
                else if (Time.time > timer)
                {
                    probingPublicIP = false;        // reset
                    useNat = true;
                    doneTesting = true;
                }
                break;

            case ConnectionTesterStatus.PublicIPNoServerStarted:
                testMessage = "Public IP address but server not initialized, " +
                    "it must be started to check server accessibility. Restart " +
                    "connection test when ready.";
                break;

            case ConnectionTesterStatus.LimitedNATPunchthroughPortRestricted:
                testMessage = "Limited NAT punchthrough capabilities. Cannot " +
                    "connect to all types of NAT servers. Running a server " +
                    "is ill advised as not everyone can connect.";
                useNat = true;
                doneTesting = true;
                break;

            case ConnectionTesterStatus.LimitedNATPunchthroughSymmetric:
                testMessage = "Limited NAT punchthrough capabilities. Cannot " +
                    "connect to all types of NAT servers. Running a server " +
                    "is ill advised as not everyone can connect.";
                useNat = true;
                doneTesting = true;
                break;

            case ConnectionTesterStatus.NATpunchthroughAddressRestrictedCone:
            case ConnectionTesterStatus.NATpunchthroughFullCone:
                testMessage = "NAT punchthrough capable. Can connect to all " +
                    "servers and receive connections from all clients. Enabling " +
                    "NAT punchthrough functionality.";
                useNat = true;
                doneTesting = true;
                break;

            default:
                testMessage = "Error in test routine, got " + connectionTestResult;
                break;
        }

        if (doneTesting)
        {
            if (useNat)
                shouldEnableNatMessage = "When starting a server the NAT " +
                    "punchthrough feature should be enabled (useNat parameter)";
            else
                shouldEnableNatMessage = "NAT punchthrough not needed";
            testStatus = "Done testing";
        }
    }
}