windows form窗体应用程序，建一个记事本参考代码，重点是打开，保存，另存为...

  //当点击打开的时候private string files;  //建一个成员变量，用来存储打开的路径private void 打开OToolStripMenuItem_Click(object sender, EventArgs e){//openFileDialog1.Filter = "文本文件|*txt|视频文件|*avi;*jpg"; //filter建立一个筛选器//openFileDialog1.ShowDialog();DialogResult isok = openFileDialog1.ShowDialog();if (isok == DialogResult.OK) //判断是否点击的打开按钮{string filename = openFileDialog1.FileName;//获取文件路径,文件路径存在FileName里//使用流进行文件读取StreamReader sr = new StreamReader(filename); //构建一个streamreader类的对象sr ,文件路径作为参数textBox1.Text = sr.ReadToEnd();   //readtoend方法，把文件完全读出sr.Close();  //流用完一定关闭files = filename;}
//当点击另存为按钮的时候private void 保存sToolStripMenuItem_Click(object sender, EventArgs e){saveFileDialog1.Filter = "文本文件|*.txt";   //要保存的文件格式。Filter文件筛选器DialogResult isok = saveFileDialog1.ShowDialog();  //是否点击保存按钮if (isok==DialogResult .OK){string filename = saveFileDialog1.FileName;StreamWriter sw = new StreamWriter(filename);sw.Write(textBox1.Text);sw.Close(); //流用完一定要关闭}MessageBox.Show(saveFileDialog1 .FileName );}//当点击保存按钮的时候private void 另存为AToolStripMenuItem_Click(object sender, EventArgs e){if (files == null){DialogResult baocun = saveFileDialog1.ShowDialog();if (baocun == DialogResult.OK){string filename = saveFileDialog1.FileName;StreamWriter sw = new StreamWriter(filename);sw.Write(textBox1.Text);sw.Close();}}else{StreamWriter sw = new StreamWriter(files);sw.Write(textBox1.Text);sw.Close();}}//当点击颜色的时候private void 颜色ToolStripMenuItem_Click(object sender, EventArgs e){//colorDialog1.ShowDialog();//显示颜色对话框，要显示对话框都有showdialog这个共同属性。。 colorDialog1.ShowDialog()会有一个返回值，用dialogresult这个枚举类型来接受DialogResult dr = colorDialog1.ShowDialog();if (dr==DialogResult .OK)  //判断是否点击的确定按钮{this.BackColor = colorDialog1.Color;  //如果仅仅写这一句代码，在选完颜色之后点取消，会默认系统里的一个黑色}}//点击文件浏览器获取路径private void 文件浏览器ToolStripMenuItem_Click(object sender, EventArgs e){DialogResult dr = folderBrowserDialog1.ShowDialog();   //接受打卡文件路径时的返回值if (dr==DialogResult .OK){MessageBox.Show(folderBrowserDialog1.SelectedPath );  //selectedpath获取路径的属性}}//当点击新建的时候private void 新建NToolStripMenuItem_Click(object sender, EventArgs e){if (textBox1 .Text .Length>0){saveFileDialog1.ShowDialog();DialogResult dr = new DialogResult();if (dr == DialogResult.OK){string filename = saveFileDialog1.FileName;StreamWriter sw = new StreamWriter(filename);sw.Write(textBox1.Text);sw.Close();}else{textBox1.Text = "";}}}