Unity如何获取程序外双击文件路径？单例音乐播放器MP3路径获取

1. 如何在Unity中获取程序外部鼠标双击文件的路径？ #

获取路径分两种场景处理：

场景A：双击文件启动Unity程序 #

系统会将目标文件路径作为命令行参数传递给程序，直接通过Environment.GetCommandLineArgs()获取：

void Start()
{
    string[] cmdArgs = Environment.GetCommandLineArgs();
    if (cmdArgs.Length > 1)
    {
        string targetPath = cmdArgs[1];
        Debug.Log("双击启动的文件路径：" + targetPath);
        // 后续文件逻辑处理
    }
}

注：cmdArgs[0]是程序自身的路径，cmdArgs[1]及以后是传递的外部参数。

场景B：程序已运行时双击外部文件 #

这种情况需要监听系统平台的文件激活消息，Unity无原生API，需做平台适配：

Windows平台

通过Windows API监听WM_DROPFILES消息，实现代码如下：

using System;
using System.Runtime.InteropServices;
using UnityEngine;

public class ExternalFileHandler : MonoBehaviour
{
    [DllImport("user32.dll", CharSet = CharSet.Auto)]
    private static extern IntPtr SetWindowLongPtr(IntPtr hWnd, int nIndex, IntPtr dwNewLong);

    [DllImport("user32.dll", CharSet = CharSet.Auto)]
    private static extern IntPtr GetWindowLongPtr(IntPtr hWnd, int nIndex);

    [DllImport("user32.dll")]
    private static extern bool DragAcceptFiles(IntPtr hWnd, bool fAccept);

    private delegate IntPtr WndProcDelegate(IntPtr hWnd, uint msg, IntPtr wParam, IntPtr lParam);
    private WndProcDelegate _oldWndProc;
    private const int GWL_WNDPROC = -4;
    private const uint WM_DROPFILES = 0x0233;

    void Start()
    {
        IntPtr windowPtr = UnityEngine.Windows.Window.GetWindowPtr();
        _oldWndProc = (WndProcDelegate)Marshal.GetDelegateForFunctionPointer(GetWindowLongPtr(windowPtr, GWL_WNDPROC), typeof(WndProcDelegate));
        SetWindowLongPtr(windowPtr, GWL_WNDPROC, Marshal.GetFunctionPointerForDelegate(new WndProcDelegate(WndProc)));
        DragAcceptFiles(windowPtr, true);
    }

    private IntPtr WndProc(IntPtr hWnd, uint msg, IntPtr wParam, IntPtr lParam)
    {
        if (msg == WM_DROPFILES)
        {
            char[] pathBuffer = new char[260];
            DragQueryFile(wParam, 0, pathBuffer, pathBuffer.Length);
            string filePath = new string(pathBuffer).TrimEnd('\0');
            Debug.Log("接收外部文件路径：" + filePath);
            
            DragFinish(wParam);
        }
        return _oldWndProc(hWnd, msg, wParam, lParam);
    }

    [DllImport("shell32.dll")]
    private static extern uint DragQueryFile(IntPtr hDrop, uint iFile, char[] lpszFile, uint cch);

    [DllImport("shell32.dll")]
    private static extern void DragFinish(IntPtr hDrop);
}

macOS平台

通过Objective-C扩展Unity的AppController，监听application:openFile:事件：

1. 编写Objective-C插件代码（编译为.bundle）：

#import <Cocoa/Cocoa.h>
#import "UnityAppController.h"

@interface CustomAppController : UnityAppController
@end

@implementation CustomAppController
- (BOOL)application:(NSApplication *)app openFile:(NSString *)filePath
{
    UnitySendMessage("FileReceiver", "OnGetExternalFile", [filePath UTF8String]);
    return YES;
}
@end

IMPL_APP_CONTROLLER_SUBCLASS(CustomAppController)

2. Unity侧C#接收代码：

public class FileReceiver : MonoBehaviour
{
    public void OnGetExternalFile(string filePath)
    {
        Debug.Log("接收外部文件路径：" + filePath);
        // 后续处理逻辑
    }
}

2. 运行中的单例MP3播放器获取双击文件路径 #

基于上述场景B的实现，结合单例播放器逻辑，只需将接收的路径传递给单例实例即可：

步骤1：单例音乐播放器实现 #

public class MusicPlayer : MonoBehaviour
{
    public static MusicPlayer Instance { get; private set; }

    void Awake()
    {
        if (Instance == null)
        {
            Instance = this;
            DontDestroyOnLoad(gameObject);
        }
        else
        {
            Destroy(gameObject);
        }
    }

    public void LoadAndPlay(string mp3Path)
    {
        // 实现MP3加载、播放逻辑
        Debug.Log("开始播放：" + mp3Path);
    }
}

步骤2：传递路径给单例播放器 #

• Windows平台：在WndProc方法中添加调用

private IntPtr WndProc(IntPtr hWnd, uint msg, IntPtr wParam, IntPtr lParam)
{
    if (msg == WM_DROPFILES)
    {
        // ... 省略路径获取代码
        MusicPlayer.Instance?.LoadAndPlay(filePath);
        DragFinish(wParam);
    }
    return _oldWndProc(hWnd, msg, wParam, lParam);
}

• macOS平台：在接收方法中添加调用

public void OnGetExternalFile(string filePath)
{
    MusicPlayer.Instance?.LoadAndPlay(filePath);
}

额外注意 #

需确保程序已完成MP3文件关联注册：

• Windows：通过注册表或安装包配置文件类型关联
• macOS：在Info.plist中添加CFBundleDocumentTypes，指定UTI为public.mp3

内容的提问来源于stack exchange，提问作者power display