Question

我正在制作一个简单的音乐播放器，实现WMPlib播放媒体文件.... 我正在尝试使用打开的文件对话框打开文件...对话框出现并且能够选择文件但是当我尝试将文件名分配给Player.URL时出现异常

在

行

Player.URL = openFileDialog1.FileName;

错误说

对象引用未设置为对象的实例。任何人都可以给我一个关于如何将文件名分配给player.URL

的线索

完整的代码如下....

using System;
    using System.Collections.Generic;
    using System.ComponentModel;
    using System.Data;
    using System.Drawing;
    using System.Linq;
    using System.Text;
    using System.Windows.Forms;

namespace WindowsFormsApplication2
{
    public partial class Form1 : Form
    {

        WMPLib.WindowsMediaPlayer Player;
        public Form1()
        {
            InitializeComponent();
        }




        private void PlayFile(String url)
        {
            Player = new WMPLib.WindowsMediaPlayer();
            Player.PlayStateChange +=
                new WMPLib._WMPOCXEvents_PlayStateChangeEventHandler(Player_PlayStateChange);
            Player.MediaError +=
                new WMPLib._WMPOCXEvents_MediaErrorEventHandler(Player_MediaError);
            Player.URL = url;
            Player.controls.play();
        }

        private void Player_PlayStateChange(int NewState)
        {
            if ((WMPLib.WMPPlayState)NewState == WMPLib.WMPPlayState.wmppsStopped)
            {
                this.Close();
            }
        }

        private void Player_MediaError(object pMediaObject)
        {
            MessageBox.Show("Cannot play media file.");
            this.Close();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            openFileDialog1.Filter = "(mp3,wav,mp4,mov,wmv,mpg)|*.mp3;*.wav;*.mp4;*.mov;*.wmv;*.mpg|all files|*.*";
            openFileDialog1.ShowDialog(); 



        }

        private void button2_Click(object sender, EventArgs e)
        {
            PlayFile(Player.URL);
        }

        private void openFileDialog1_FileOk(object sender, CancelEventArgs e)
        {
            MessageBox.Show(openFileDialog1.FileName);
            Player.URL = openFileDialog1.FileName;
        }
    }
}

Answer 1

尝试像这样使用openFileDialog1：

DialogResult result = openFileDialog1.ShowDialog();

if (result == DialogResult.OK)
{
   Player.URL = openFileDialog1.FileName;
}

在button1_Click（）

中

Answer 2

确保在使用之前创建 WMPLib.WindowsMediaPlayer 的实例。现在，您似乎正在单击“打开文件”按钮并尝试将返回的文件名分配给空对象。

如何从打开文件对话框中读取文件并添加到使用wmplib播放的URL？

2 个答案: