使用WebClient类对网页下载源码,对文件下载保存及异步下载并报告下载进度

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" alt="" />

private void button1_Click(object sender, EventArgs e)
        {
            WebClient webclient = new WebClient();
            webclient.Proxy = null;
            webclient.Encoding = Encoding.UTF8;
            richTextBox1.AppendText(webclient.DownloadString(textBox1.Text.Trim()));
            webclient.Dispose();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            WebClient webclient = new WebClient();
            webclient.Proxy = null;
            webclient.DownloadFile(textBox2.Text, textBox3.Text);
            MessageBox.Show("成功！");
            webclient.Dispose();

        }

        private void button3_Click(object sender, EventArgs e)
        {
            WebClient webclient = new WebClient();
            webclient.Proxy = null;
            webclient.DownloadProgressChanged += webclient_DownloadProgressChanged;
            webclient.DownloadDataCompleted += webclient_DownloadDataCompleted;
            webclient.DownloadFileAsync(new Uri(textBox2.Text), textBox3.Text);
            webclient.Dispose();
        }

        void webclient_DownloadDataCompleted(object sender, DownloadDataCompletedEventArgs e)
        {
            MessageBox.Show("成功");
        }

        void webclient_DownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e)
        {
            progressBar1.Value = e.ProgressPercentage;
        }