爬虫

private void Button1_Click(object sender, EventArgs e)
{
//接收通过url发送的请求数据
WebClient client = new WebClient();
//规范数据格式
client.Encoding = Encoding.UTF8;
//下载请求内容
var str = client.DownloadString(this.textBox1.Text);
//判断正则表达式是否为空
if (this.textBox2.Text == "")
{
//为空显示所有信息
this.textBox3.Text = str;
}
else
{
//自定义正则表达式
Regex regex = new Regex(this.textBox2.Text, RegexOptions.Multiline);
//根据正则表达式，筛选匹配数据
var matches = regex.Matches(str);
var strs = "";
//遍历数据
foreach (Match m in matches)
{
strs += m.Value;
}
//显示
this.textBox3.Text = strs;
}
}