Jsoup –リダイレクトURLの確認
この記事では、Jsoupを使用して、URLがリダイレクトされるかどうかを確認する方法を示します。
1. URLリダイレクト
通常、リダイレクトURLは301または307のHTTPコードを返し、ターゲットURLは応答ヘッダーの「location」フィールドに存在します。
HTTP応答ヘッダーのサンプルを確認する
HTTPコード：301は永久に移動しました
{
Location=http://example.com
Server=GSE,
Cache-Control=no-cache,
no-store,
max-age=0,
must-revalidate
}
2. Jsoupの例
2.1 By default, Jsoup will follow the redirect recursively and display the final URL.
RedirectExample.java
package com.example.crawler;
import java.io.IOException;
import org.jsoup.Connection.Response;
import org.jsoup.Jsoup;
public class RedirectExample {
public static void main(String[] args) throws IOException {
String url = "http://goo.gl/fb/gyBkwR";
Response response = Jsoup.connect(url).execute();
System.out.println(response.statusCode() + " : " + response.url());
}
}
出力
200 : http://www.example.com/mongodb/mongodb-remove-a-field-from-array-documents/
2.2 To test the URL redirection, set followRedirects to false.
Response response = Jsoup.connect(url).followRedirects(false).execute();
System.out.println(response.statusCode() + " : " + response.url());
//check if URL is redirect?
System.out.println("Is URL going to redirect : " + response.hasHeader("location"));
System.out.println("Target : " + response.header("location"));
出力
301 : http://goo.gl/fb/gyBkwR Is URL going to redirect : true Target : http://feeds.feedburner.com/~r/FeedForMkyong/~3/D_6Jqi4trqo/...
3. Jsoupの例、再び
3.1 This example will print out the redirect URLs recursively.
RedirectExample.java
package com.example.crawler;
import java.io.IOException;
import org.jsoup.Connection.Response;
import org.jsoup.Jsoup;
public class RedirectExample {
public static void main(String[] args) throws IOException {
String url = "http://goo.gl/fb/gyBkwR";
RedirectExample obj = new RedirectExample();
obj.crawl(url);
}
private void crawl(String url) throws IOException {
Response response = Jsoup.connect(url).followRedirects(false).execute();
System.out.println(response.statusCode() + " : " + url);
if (response.hasHeader("location")) {
String redirectUrl = response.header("location");
crawl(redirectUrl);
}
}
}
出力
301 : http://goo.gl/fb/gyBkwR 301 : http://feeds.feedburner.com/~r/FeedForMkyong/~3/D_6Jqi4trqo/... 200 : http://www.example.com/mongodb/mongodb-remove-a-field-from-array-documents/