有一段时间，我一直在寻找一种使用Java程序搜索谷歌的方法。我很惊讶地看到谷歌有一个网络搜索API]，但它很早就被弃用了，现在没有标准的方法来实现这一点。Google搜索基本上是一个HTTP get请求，其中查询参数是URL的一部分，前面我们已经看到有不同的选项来执行此搜索，如Java HttpUrlConnection或[ApacheHttpClient Example to Send GET/POST HTTP Request.)。但问题更多地与解析HTML响应并从中获取有用信息有关。这就是为什么我选择使用[jsoup](/community/tutorials/jsoup-java-html-parser()，它是一个开源的HTML解析器，能够从给定的URL获取HTML.下面是一个简单的程序，它可以在Java程序中获取Google搜索结果，然后对其进行解析以找出搜索结果。
1package com.journaldev.jsoup;
2
3import java.io.IOException;
4import java.util.Scanner;
5
6import org.jsoup.Jsoup;
7import org.jsoup.nodes.Document;
8import org.jsoup.nodes.Element;
9import org.jsoup.select.Elements;
10
11public class GoogleSearchJava {
12
13 public static final String GOOGLE_SEARCH_URL = "https://www.google.com/search";
14 public static void main(String[] args) throws IOException {
15 //Taking search term input from console
16 Scanner scanner = new Scanner(System.in);
17 System.out.println("Please enter the search term.");
18 String searchTerm = scanner.nextLine();
19 System.out.println("Please enter the number of results. Example: 5 10 20");
20 int num = scanner.nextInt();
21 scanner.close();
22
23 String searchURL = GOOGLE_SEARCH_URL + "?q="+searchTerm+"&num="+num;
24 //without proper User-Agent, we will get 403 error
25 Document doc = Jsoup.connect(searchURL).userAgent("Mozilla/5.0").get();
26
27 //below will print HTML data, save it to a file and open in browser to compare
28 //System.out.println(doc.html());
29
30 //If google search results HTML change the <h3 class="r" to <h3 class="r1"
31 //we need to change below accordingly
32 Elements results = doc.select("h3.r > a");
33
34 for (Element result : results) {
35 String linkHref = result.attr("href");
36 String linkText = result.text();
37 System.out.println("Text::" + linkText + ", URL::" + linkHref.substring(6, linkHref.indexOf("&")));
38 }
39 }
40
41}
下面是上面程序的输出示例，我将HTML数据保存到文件中，并在浏览器中打开以确认输出，这是我们想要的。将输出与下图进行比较。
1Please enter the search term.
2journaldev
3Please enter the number of results. Example: 5 10 20
420
5Text::JournalDev, URL::=https://www.journaldev.com/
6Text::Java Interview Questions, URL::=https://www.journaldev.com/java-interview-questions
7Text::Java design patterns, URL::=https://www.journaldev.com/tag/java-design-patterns
8Text::Tutorials, URL::=https://www.journaldev.com/tutorials
9Text::Java servlet, URL::=https://www.journaldev.com/tag/java-servlet
10Text::Spring Framework Tutorial ..., URL::=https://www.journaldev.com/2888/spring-tutorial-spring-core-tutorial
11Text::Java Design Patterns PDF ..., URL::=https://www.journaldev.com/6308/java-design-patterns-pdf-ebook-free-download-130-pages
12Text::Pankaj Kumar (@JournalDev) | Twitter, URL::=https://twitter.com/journaldev
13Text::JournalDev | Facebook, URL::=https://www.facebook.com/JournalDev
14Text::JournalDev - Chrome Web Store - Google, URL::=https://chrome.google.com/webstore/detail/journaldev/ckdhakodkbphniaehlpackbmhbgfmekf
15Text::Debian -- Details of package libsystemd-journal-dev in wheezy, URL::=https://packages.debian.org/wheezy/libsystemd-journal-dev
16Text::Debian -- Details of package libsystemd-journal-dev in wheezy ..., URL::=https://packages.debian.org/wheezy-backports/libsystemd-journal-dev
17Text::Debian -- Details of package libsystemd-journal-dev in sid, URL::=https://packages.debian.org/sid/libsystemd-journal-dev
18Text::Debian -- Details of package libsystemd-journal-dev in jessie, URL::=https://packages.debian.org/jessie/libsystemd-journal-dev
19Text::Ubuntu – Details of package libsystemd-journal-dev in trusty, URL::=https://packages.ubuntu.com/trusty/libsystemd-journal-dev
20Text::libsystemd-journal-dev : Utopic (14.10) : Ubuntu - Launchpad, URL::=https://launchpad.net/ubuntu/utopic/%2Bpackage/libsystemd-journal-dev
21Text::Debian -- Details of package libghc-libsystemd-journal-dev in jessie, URL::=https://packages.debian.org/jessie/libghc-libsystemd-journal-dev
22Text::Advertise on JournalDev | BuySellAds, URL::=https://buysellads.com/buy/detail/231824
23Text::JournalDev | LinkedIn, URL::=https://www.linkedin.com/groups/JournalDev-6748558
24Text::How to install libsystemd-journal-dev package in Ubuntu Trusty, URL::=https://www.howtoinstall.co/en/ubuntu/trusty/main/libsystemd-journal-dev/
25Text::[global] auth supported = cephx ms bind ipv6 = true [mon] mon data ..., URL::=https://zooi.widodh.nl/ceph/ceph.conf
26Text::UbuntuUpdates - Package "libsystemd-journal-dev" (trusty 14.04), URL::=https://www.ubuntuupdates.org/libsystemd-journal-dev
27Text::[Journal]Dev'err - Cursus Honorum - Enjin, URL::=https://cursushonorum.enjin.com/holonet/m/23958869/viewthread/13220130-journaldeverr/post/last
这就是在Java程序中谷歌搜索的全部内容，谨慎使用它，因为如果你的电脑有异常流量，谷歌很有可能会屏蔽你。