近期在做船仅仅识别方面的事情，须要大量的正样本来训练adaboost分类器。
于是到marinetraffic这个站点上下载船仅仅图片。写个爬虫来自己主动下载显然非常方便。
站点特点
在介绍爬虫之前首先了解一下marinetraffic这个站点的一些特点：
1. 会定期检測爬虫行为。假设觉得有爬虫大量下载图片。
会把该连接增加黑名单，后几天都没办法下载。
2. 船仅仅图片资源差异大。有的船仅仅有1000多张图，有的船仅仅没有一张图，我们须要的是非常多船仅仅的非常多张图。所以须要对下载的船仅仅按优先级排序。
3. 用来训练分类器的正样本要求检測对象的分辨率一样。而marinetraffic站点下载的图片能够设置下在的图片的宽度，站点依据长宽比，生成对应的高度。所以。不同图片高度不一样。须要自己后期处理。
解决方式
- 针对爬虫检測。设置一个随机等待时间，10s左右。能够绕过站点爬虫行为检測。
- 对船仅仅依照图片熟练排序，先下载图片数量多的，而且每一个船仅仅不用下载太多。保证图片的差异性。比如
- 在下载的时候使用统一的宽度。
后期处理从图片中抠出分辨率一样的船仅仅
爬虫源代码
using System;
using System.Collections.Generic;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Net;
using System.Runtime.Serialization.Formatters.Binary;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading;
using System.Threading.Tasks;
namespace 船仅仅图像爬虫
{
class Program
{
static void download_all_shipid(List<string> shipid_list)
{
try
{
WebClient MyWebClient = new WebClient();
MyWebClient.Headers["User-Agent"] = "blah";
MyWebClient.Credentials = CredentialCache.DefaultCredentials;//获取或设置用于向Internet资源的请求进行身份验证的网络凭据;
//Console.WriteLine("here1");
//http://www.marinetraffic.com/en/photos/of/ships/shipid:281519/
//http://www.marinetraffic.com/en/ais/index/ships/all
//http://www.marinetraffic.com/ais/index/ships/all/page:2/sort:COUNT_PHOTOS/direction:desc;
for (int pageNum = 1; pageNum < 100; pageNum++)
{
Console.WriteLine("開始分析第" + pageNum + "张网页");
MyWebClient.Credentials = CredentialCache.DefaultCredentials;//获取或设置用于向Internet资源的请求进行身份验证的网络凭据;
MyWebClient.Headers["User-Agent"] = "blah";
try
{
//Console.WriteLine("here0");
Byte[] pageData = MyWebClient.DownloadData(@"http://www.marinetraffic.com/en/ais/index/ships/all/page:" + pageNum + "/sort:COUNT_PHOTOS/direction:desc/per_page:50"); //从指定站点下载数据
//pageHtml = Encoding.Default.GetString(pageData); //假设获取站点页面採用的是GB2312，则使用这句;
string pageHtml = Encoding.UTF8.GetString(pageData); //假设获取站点页面採用的是UTF-8。则使用这句;
//Console.WriteLine(pageHtml);//在控制台输入获取的内容;
//Console.WriteLine("here1");
int urlindex = -1;
string org_label = "shipid:";
urlindex = pageHtml.IndexOf(org_label, urlindex + 1);
while (urlindex != -1)
{
int endOfUrl = pageHtml.IndexOf("/", urlindex + org_label.Length);
//Console.WriteLine("here2");
string shipid = pageHtml.Substring(urlindex + org_label.Length, endOfUrl - urlindex - org_label.Length);
if (!shipid_list.Contains(shipid))
{
Console.WriteLine("新增id:" + shipid);
shipid_list.Add(shipid);
}
//Console.WriteLine("已有id:" + shipid);
urlindex = pageHtml.IndexOf(org_label, urlindex + 1);
}
///保存网页
//using (StreamWriter sw = new StreamWriter("ouput.html"))//将获取的内容写入文本
//{
// sw.Write(pageHtml);
//}
Console.WriteLine("完毕第" + pageNum + "页分析");
}
catch (WebException webEx)
{
Console.WriteLine(webEx.Message.ToString());
}
//以下是一个随机数的方法保证10秒后再下载。以绕过违规检測。
Console.Write("绕开站点爬虫行为检測中......");
Random rd = new Random();
int time_sleep = rd.Next() % 10 + 10;
Thread.Sleep(time_sleep * 1000);
Console.WriteLine();
}
Console.WriteLine("分析结束");
//以下把list内容保存进文件,使用序列化的方法;
string file = @"C:UsersdragonfiveDesktop爬虫获得船仅仅图片第三批 _100page_shipid.txt";
using (FileStream fsWriter = new FileStream(file, FileMode.OpenOrCreate, FileAccess.Write))
{
//以下对stu进行序列化。
BinaryFormatter bf = new BinaryFormatter();
bf.Serialize(fsWriter, shipid_list);
}
}
catch (WebException webEx)
{
Console.WriteLine(webEx.Message.ToString());
}
}
/// <summary>
/// 依据得到的ship_id获得该ship_id的全部图片;
/// </summary>
/// <param name="ship_id"></param>
static void download_jpg(string ship_id)
{
try
{
Console.WriteLine("開始下载shipid为："+ship_id+"的图片");
WebClient MyWebClient = new WebClient();
MyWebClient.Credentials = CredentialCache.DefaultCredentials;//获取或设置用于向Internet资源的请求进行身份验证的网络凭据
MyWebClient.Headers["User-Agent"] = "blah";
//http://www.marinetraffic.com/en/photos/of/ships/shipid:281519/
//http://www.marinetraffic.com/en/photos/of/ships/shipid:371668/per_page:1000/page:1
Byte[] pageData = MyWebClient.DownloadData(@"http://www.marinetraffic.com/en/photos/of/ships/shipid:" + ship_id + @"/per_page:100/page:1"); //从指定站点下载数据
//string pageHtml = Encoding.Default.GetString(pageData); //假设获取站点页面採用的是GB2312。则使用这句
string pageHtml = Encoding.UTF8.GetString(pageData); //假设获取站点页面採用的是UTF-8，则使用这句
//Console.WriteLine(pageHtml);//在控制台输入获取的内容
Console.WriteLine("元网页已下载");
//using (StreamWriter sw = new StreamWriter("ouput.html"))//将获取的内容写入文本
//{
// sw.Write(pageHtml);
//}
int urlindex = -1;
string org_label = "data-original='";
urlindex = pageHtml.IndexOf(org_label, urlindex + 1);
int i = 0;
//Directory.CreateDirectory(@"./" );
while (urlindex != -1)
{
int endOfUrl = pageHtml.IndexOf("'", urlindex + org_label.Length);
string url = pageHtml.Substring(urlindex + org_label.Length, endOfUrl - urlindex - org_label.Length);
////以下是unicode编码转换为string的方式;
//MatchCollection mc = Regex.Matches(strName, @"\u([w]{2})([w]{2})", RegexOptions.Compiled | RegexOptions.IgnoreCase);
//byte[] bts = new byte[2];
//foreach (Match m in mc)
//{
// bts[0] = (byte)int.Parse(m.Groups[2].Value, NumberStyles.HexNumber);
// bts[1] = (byte)int.Parse(m.Groups[1].Value, NumberStyles.HexNumber);
// musicName += Encoding.Unicode.GetString(bts);
//}
//Console.WriteLine("接下来下载的是:" + musicName);
//以下是一个随机数的方法保证10秒后再下载。以绕过违规检測。
Console.Write("绕过站点爬虫行为检測中......");
Random rd = new Random();
int time_sleep = rd.Next() % 10 + 10;
Thread.Sleep(time_sleep * 1000);
Console.WriteLine();
try
{
//这是下载的命令；
Console.WriteLine(url);
MyWebClient.Credentials = CredentialCache.DefaultCredentials;//获取或设置用于向Internet资源的请求进行身份验证的网络凭据
MyWebClient.Headers["User-Agent"] = "blah";
Byte[] jpgdata = MyWebClient.DownloadData(url); //从指定网页下载数据;
//把下载的内容保存在一个地方;
using (FileStream fs = new FileStream(@"C:UsersdragonfiveDesktop爬虫获得船仅仅图片第三批" + ship_id + "_" + i + ".jpg", FileMode.OpenOrCreate, FileAccess.Write))
{
fs.Write(jpgdata, 0, jpgdata.Length);
}
}
catch (WebException webEx)
{
Console.WriteLine("被捕获了吗?");
Console.WriteLine(webEx.Message.ToString());
}
Console.WriteLine("成功下载第" + (i ++) + "张图片");
urlindex = pageHtml.IndexOf(org_label, urlindex + 1);
}
///保存网页
//using (StreamWriter sw = new StreamWriter("ouput.html"))//将获取的内容写入文本
//{
// sw.Write(pageHtml);
//}
Console.WriteLine("*****************************************");
Console.WriteLine("下载"+i+"张ship_id为"+ship_id+"的图片");
Console.WriteLine("*****************************************");
//Console.ReadLine(); //让控制台暂停,否则一闪而过了
}
catch (WebException webEx)
{
Console.WriteLine(webEx.Message.ToString());
}
}
static void Main(string[] args)
{
List<string> shipid_list = new List<string>();
//shipid_list.Add("371681");//临时高速产生图片用这个;
download_all_shipid(shipid_list);
//string file = @"C:UsersdragonfiveDesktop爬虫获得船仅仅图片第三批 _100page_shipid.txt";
//using (FileStream fsReader = new FileStream(file, FileMode.Open, FileAccess.Read))
//{
// //以下进行反序列话;
// BinaryFormatter bf = new BinaryFormatter();
// shipid_list = (List<string>)bf.Deserialize(fsReader);
// Console.WriteLine("成功加载" + shipid_list.Count + "个shipid");
//}
////371652 371668 371681 1252401
//shipid_list.Remove("371652");
//shipid_list.Remove("371668");
//shipid_list.Remove("371681");
//shipid_list.Remove("1252401");
////132264
//shipid_list.Remove("371077");
//shipid_list.Remove("132264");
//shipid_list.Remove("224871");
//shipid_list.Remove("279923");
//shipid_list.Remove("369163");
//shipid_list.Remove("266342");
//shipid_list.Remove("371216");
//shipid_list.Remove("368174");
//shipid_list.Remove("369163");
foreach (var ship_id in shipid_list)
{
download_jpg(ship_id);
}
Console.ReadLine(); //让控制台暂停,否则一闪而过了
}
}
}