403禁止使用Java但不禁用Web浏览器? [英] 403 Forbidden with Java but not web browser?
问题描述
我正在编写一个小型Java程序来获取给定Google搜索字词的结果数量。出于某种原因,在Java中我得到403 Forbidden但我在Web浏览器中得到了正确的结果。代码:
I am writing a small Java program to get the amount of results for a given Google search term. For some reason, in Java I am getting a 403 Forbidden but I am getting the right results in web browsers. Code:
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;
public class DataGetter {
public static void main(String[] args) throws IOException {
getResultAmount("test");
}
private static int getResultAmount(String query) throws IOException {
BufferedReader r = new BufferedReader(new InputStreamReader(new URL("https://www.google.com/search?q=" + query).openConnection()
.getInputStream()));
String line;
String src = "";
while ((line = r.readLine()) != null) {
src += line;
}
System.out.println(src);
return 1;
}
}
错误:
Exception in thread "main" java.io.IOException: Server returned HTTP response code: 403 for URL: https://www.google.com/search?q=test
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source)
at sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(Unknown Source)
at DataGetter.getResultAmount(DataGetter.java:15)
at DataGetter.main(DataGetter.java:10)
为什么这样做?
推荐答案
你只需要设置用户代理头让它工作:
You just need to set user agent header for it to work:
URLConnection connection = new URL("https://www.google.com/search?q=" + query).openConnection();
connection.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.95 Safari/537.11");
connection.connect();
BufferedReader r = new BufferedReader(new InputStreamReader(connection.getInputStream(), Charset.forName("UTF-8")));
StringBuilder sb = new StringBuilder();
String line;
while ((line = r.readLine()) != null) {
sb.append(line);
}
System.out.println(sb.toString());
从您的异常堆栈跟踪可以看出,SSL是透明处理的。
The SSL was transparently handled for you as could be seen from your exception stacktrace.
获取结果数量实际上并不是那么简单,在此之后你必须通过获取cookie并解析重定向令牌链接来假装你是浏览器。
Getting the result amount is not really this simple though, after this you have to fake that you're a browser by fetching the cookie and parsing the redirect token link.
String cookie = connection.getHeaderField( "Set-Cookie").split(";")[0];
Pattern pattern = Pattern.compile("content=\\\"0;url=(.*?)\\\"");
Matcher m = pattern.matcher(response);
if( m.find() ) {
String url = m.group(1);
connection = new URL(url).openConnection();
connection.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.95 Safari/537.11");
connection.setRequestProperty("Cookie", cookie );
connection.connect();
r = new BufferedReader(new InputStreamReader(connection.getInputStream(), Charset.forName("UTF-8")));
sb = new StringBuilder();
while ((line = r.readLine()) != null) {
sb.append(line);
}
response = sb.toString();
pattern = Pattern.compile("<div id=\"resultStats\">About ([0-9,]+) results</div>");
m = pattern.matcher(response);
if( m.find() ) {
long amount = Long.parseLong(m.group(1).replaceAll(",", ""));
return amount;
}
}
运行完整代码我得到了 2930000000L
。
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