unity 打开系统文件夹并选取图片保存

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;
}

public class WindowDll
{
    [DllImport("Comdlg32.dll", SetLastError = true, ThrowOnUnmappableChar = true, CharSet = CharSet.Auto)]
    public static extern bool GetOpenFileName([In, Out] OpenFileName ofn);
    public static bool GetOpenFileName1([In, Out] OpenFileName ofn)
    {
        return GetOpenFileName(ofn);
    }
}

using UnityEngine;
using System.Collections;
using System.Runtime.InteropServices;
using System.Reflection;
using UnityEngine.UI;
using System.IO;

public class ReadImage : MonoBehaviour
{

    private static ReadImage _instance;
    public static ReadImage Instance
    {
        get { return _instance; }
    }

    [HideInInspector]
    public Sprite sprite;
    void Awake()
    {
        _instance = this;
    }

    void Update()
    {
        if (Input.GetMouseButtonDown(1))
        {
            OnRead();
        }
    }


    public void OnRead()
    {
        OpenFileName ofn = new OpenFileName();
        ofn.structSize = Marshal.SizeOf(ofn);
        ofn.filter = "图片文件(*.jpg*.png)\0*.jpg;*.png";
        ofn.file = new string(new char[256]);
        ofn.maxFile = ofn.file.Length;
        ofn.fileTitle = new string(new char[64]);
        ofn.maxFileTitle = ofn.fileTitle.Length;
        string path = Application.streamingAssetsPath;
        path = path.Replace('/', '\\');
        //默认路径
        ofn.initialDir = path;
        ofn.title = "Open Project";

        ofn.defExt = "JPG";//显示文件的类型
                           //注意 以下项目不一定要全选 但是0x00000008项不要缺少
        ofn.flags = 0x00080000 | 0x00001000 | 0x00000800 | 0x00000200 | 0x00000008;//OFN_EXPLORER|OFN_FILEMUSTEXIST|OFN_PATHMUSTEXIST| OFN_ALLOWMULTISELECT|OFN_NOCHANGEDIR

        if (WindowDll.GetOpenFileName(ofn))
        {
            //  Debug.Log("Selected file with full path: {0}" + ofn.file);
            StartCoroutine(Load(ofn.file));
        }

        //}
    }
    IEnumerator Load(string path)
    {
        double startTime = (double)Time.time;
        WWW www = new WWW("file:///" + path);
        yield return www;
        if (www != null && string.IsNullOrEmpty(www.error))
        {
            //获取Texture
            Texture2D texture = www.texture;
            //直接将选择图保存
            byte[] bytes = texture.EncodeToJPG(100);
            string filename = PublicStaticTools.ReadFile(2);
            File.WriteAllBytes(PublicStaticTools.ReadFile(2) + @"\" + string.Format("{0:F0}", Time.realtimeSinceStartup * 10f) + ".jpg", bytes);
            Sprite sprite = Sprite.Create(texture, new Rect(0, 0, texture.width, texture.height), new Vector2(0.5f, 0.5f));
            this.sprite = sprite;
            startTime = (double)Time.time - startTime;
            UnityEngine.Debug.Log("WWW加载用时:" + startTime);
        }
    }
}