爬虫简单案例
1.概念:
是一种按照一定的规则，自动地抓取万维网信息的程序或者脚本;
2.案例:
一: 爬虫抓取信息
界面:
3.引用名称空间:
using System.Net;
4.代码:
private void button1_Click(object sender, EventArgs e)
{
if (this.txtUrl.Text.Trim().Length == 0)
{
MessageBox.Show("URL地址不能为空!");
}
WebClient wc = new WebClient();
//上载或下载当页的编码
wc.Encoding = Encoding.Default;
//下载
this.txtContent.Text = wc.DownloadString(this.txtUrl.Text.Trim());
}
二: 爬虫抓取指定信息
界面:
引用空间:
using System.Net.Http;
using HtmlAgilityPack;
代码:
//抓取页面内容
private void button1_Click(object sender, EventArgs e)
{
//httpClient模拟提交访问请求类
var httpClient = new HttpClient();
string url = this.txtUrl.Text.Trim();
//模拟提交访问请求并得到整页HTML
HttpResponseMessage http = httpClient.GetAsync(url).Result;
//如果访问成功
if (http.IsSuccessStatusCode)
{
//分析内容
//第三方分析HTML的组件
HtmlAgilityPack.HtmlDocument doc = new HtmlAgilityPack.HtmlDocument();
HtmlNode node = doc.DocumentNode;
//把HTML字符串变成对象
doc.LoadHtml(http.Content.ReadAsStringAsync().Result);
//查找需要的节点内容
this.txtContent.Text = node.SelectNodes("//div[@class='info-cont']")[0].SelectNodes("//ul[@class='info-list']") [0].InnerText.Replace("\r\n ", "").Replace(" ", "");
}
else
{
this.txtContent.Text = "未抓取到内容";
}
}
结果:
三: 爬虫分页
界面:
代码:
private void btnCrawl_Click(object sender, EventArgs e)
{
List
film ns;
string url = this.txtUrl.Text.Trim();
//HtmlWeb类是一个从网络上获取一个HTML文档的类
HtmlAgilityPack.HtmlWeb htmlWeb = new HtmlAgilityPack.HtmlWeb();
//定义网页解析对象
HtmlAgilityPack.HtmlDocument document = htmlWeb.Load(url);
////html/body/div[4]/div[3]/a[7]
HtmlNode pagenode = document.DocumentNode.SelectSingleNode("//html/body/div[3]/div[3]/a[7]");
//得到总页数
int pageCount = int.Parse(pagenode.InnerText);
if (pageCount > 2)
pageCount = 2;//页多太慢，人工改成3页
//循环每一页
for (int i = 1; i <= pageCount; i++)
{
if (i != 1) //非第一页的话，将采集下一页
{
url = "http://www.360kan.com/dianshi/list.php?year=all&area=all&act=all&cat=all&pageno=" + i;
document = htmlWeb.Load(url);
}
//Xpath /html/body/div[4]/div[2]/div/div[2]
//HtmlNode node = document.DocumentNode.SelectSingleNode("//html//body//div[3]//div[2]//div//div[2]");
//HtmlNodeCollection htmlNodes = node.SelectNodes("ul//li");
HtmlNodeCollection htmlNodes = document.DocumentNode.SelectNodes("//html//body//div[3]//div[2]//div//div[2]//ul//li");
//nd 现在代表的是 li
int j = 1;
foreach (var nd in htmlNodes)
{
try
{
//电视剧的名字所在标签的 Xpath
var vName = nd.SelectSingleNode("a//div[2]//p[1]//span").InnerText;
//var yName = nd.SelectSingleNode("a//div[2]//p[2]").InnerText;
//HtmlNode imgNode = nd.SelectSingleNode("a/div[1]/img");
//var imgsrc = imgNode.Attributes["src"].Value;
//获取该部电视剧详情地址
// Xpath如下： /html/body/div[4]/div[2]/div/div[2]/ul/li[1]/a
HtmlNode aNode = nd.SelectSingleNode("a");
string aurl = aNode.Attributes["href"].Value;
//加载详情页
document = htmlWeb.Load("http://www.360kan.com/" + aurl);
//html/body/div[3]/div/div/div
HtmlNode node = document.DocumentNode.SelectSingleNode("//html//body//div[3]//div//div//div");
//获取电视剧图片：/html/body/div[3]/div/div/div/div[1]/div/a/img
HtmlNode node01 = node.SelectSingleNode("div[1]//div//a//img");
string picture = node01.Attributes["src"].Value;
//获取电视剧名称：/html/body/div[3]/div/div/div/div[2]/div[1]/div[1]/div[1]/h1
HtmlNode node02 = node.SelectSingleNode("div[2]//div[1]//div[1]//div[1]//h1");
string tvName = node02.InnerText;
//获取电视剧集数：/html/body/div[3]/div/div/div/div[2]/div[1]/div[1]/div[1]/p
HtmlNode node03 = node.SelectSingleNode("div[2]//div[1]//div[1]//div[1]//p");
string setNumber = node03.InnerText;
//获取电视类型，多个 /html/body/div[3]/div/div/div/div[2]/div[1]/div[2]/div[1]/p[1]/a
HtmlNodeCollection node04 = node.SelectNodes("div[2]//div[1]//div[2]//div[1]//p[1]//a");
string tvType = "";
foreach (var nd04 in node04)
{
tvType += nd04.InnerText + ",";
}
tvType = tvType.TrimEnd(',');
//获取电视年代 /html/body/div[4]/div/div/div/div[2]/div[1]/div[2]/div[1]/p[2]
HtmlNode node05 = node.SelectSingleNode("div[2]//div[1]//div[2]//div[1]//p[2]");
string years = node05.InnerText;
//获取电视地区 /html/body/div[3]/div/div/div/div[2]/div[1]/div[2]/div[1]/p[3]/span
HtmlNode node06 = node.SelectSingleNode("div[2]//div[1]//div[2]//div[1]//p[3]");
string region = node06.InnerText;
//获取电视剧导演 /html/body/div[4]/div/div/div/div[2]/div[1]/div[2]/div[1]/p[5]/a[1]
HtmlNodeCollection node07 = node.SelectNodes("div[2]//div[1]/div[2]//div[1]//p[5]//a");
string director = "";
foreach (var no07 in node07)
{
director += no07.InnerText + ",";
}
director = director.TrimEnd(',');
//获取电视剧演员 /html/body/div[4]/div/div/div/div[2]/div[1]/div[2]/div[1]/p[6]/a[1]
HtmlNodeCollection node08 = node.SelectNodes("div[2]//div[1]/div[2]//div[1]//p[6]//a");
string performer = "";
foreach (var no08 in node08)
{
performer += no08.InnerText + ",";
}
performer = performer.TrimEnd(',');
//获取电视剧描述 /html/body/div[4]/div/div/div/div[2]/div[1]/div[2]/div[3]/p
HtmlNode node09 = node.SelectSingleNode("div[2]//div[1]//div[2]//div[3]//p");
string miaoshu = node09.InnerText;
ns = new film();
ns.picture = picture;
ns.tvName = tvName;
ns.setNumber = setNumber;
ns.tvType = tvType;
ns.years = years;
ns.region = region;
ns.director = director;
ns.performer = performer;
ns.miaoshu = miaoshu;
ls.Add(ns);
}
catch (Exception ex)
{
}
// Thread.Sleep(random.Next(50));
j++;
}
// Thread.Sleep(random.Next(50));
}
this.dataGridView1.DataSource = ls;
}