Unity调用系统窗口选择文件或文件路径

1.OpenFileName数据接收类，如下：

using UnityEngine;
using System.Collections;
using System;
using System.Runtime.InteropServices;
 
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
public class OpenFileName
{
    public int structSize = 0;
    public IntPtr dlgOwner = IntPtr.Zero;
    public IntPtr instance = IntPtr.Zero;
    public String filter = null;
    public String customFilter = null;
    public int maxCustFilter = 0;
    public int filterIndex = 0;
    public String file = null;
    public int maxFile = 0;
    public String fileTitle = null;
    public int maxFileTitle = 0;
    public String initialDir = null;
    public String title = null;
    public int flags = 0;
    public short fileOffset = 0;
    public short fileExtension = 0;
    public String defExt = null;
    public IntPtr custData = IntPtr.Zero;
    public IntPtr hook = IntPtr.Zero;
    public String templateName = null;
    public IntPtr reservedPtr = IntPtr.Zero;
    public int reservedInt = 0;
    public int flagsEx = 0;
}

2.系统函数调用类， 如下：
public class LocalDialog
{
    //链接指定系统函数       打开文件对话框
    [DllImport("Comdlg32.dll", SetLastError = true, ThrowOnUnmappableChar = true, CharSet = CharSet.Auto)]
    public static extern bool GetOpenFileName([In, Out] OpenFileName ofn);
    public static bool GetOFN([In, Out] OpenFileName ofn)
    {
        return GetOpenFileName(ofn);
    }
 
    //链接指定系统函数        另存为对话框
    [DllImport("Comdlg32.dll", SetLastError = true, ThrowOnUnmappableChar = true, CharSet = CharSet.Auto)]
    public static extern bool GetSaveFileName([In, Out] OpenFileName ofn);
    public static bool GetSFN([In,Out] OpenFileName ofn)
    {
        return GetSaveFileName(ofn); 
    }
}

3.测试入口类，如下：

using UnityEngine;
using System.Collections;
using System.Runtime.InteropServices;
 
public class DialogTest : MonoBehaviour {
 
    void OnGUI()
    {
        if (GUI.Button(new Rect(10,10,100,50),"Open"))
        {
            OpenFileName openFileName = new OpenFileName();
            openFileName.structSize = Marshal.SizeOf(openFileName);
            openFileName.filter = "Excel文件(*.xlsx)\0*.xlsx";
            openFileName.file = new string(new char[256]);
            openFileName.maxFile = openFileName.file.Length;
            openFileName.fileTitle = new string(new char[64]);
            openFileName.maxFileTitle = openFileName.fileTitle.Length;
            openFileName.initialDir = Application.streamingAssetsPath.Replace('/','\\');//默认路径
            openFileName.title = "窗口标题";
            openFileName.flags = 0x00080000 | 0x00001000 | 0x00000800 | 0x00000008;
 
            if (LocalDialog.GetSaveFileName(openFileName))
            {
                Debug.Log(openFileName.file);
                Debug.Log(openFileName.fileTitle);
            }
        }
    }
}