Jerry Examples

Here are some examples of Jerry usages on some live pages.

Following examples depend on content of live web pages. At some point in time pages may change in such way that the examples stop working.

New music releases from allmusic.com

Site allmusic.com shows new music releases in the right column. Here is a simple code that downloads the page, parse it and displays all releases in console:

    public class AllMusicNewReleases {

        public static void main(String[] args) throws IOException {

            // download the page super-efficiently
            File file = new File(SystemUtil.getTempDir(), "allmusic.html");
            NetUtil.downloadFile("http://allmusic.com", file);

            // create Jerry, i.e. document context
            Jerry doc = Jerry.jerry(FileUtil.readString(file));

            // parse
            doc.$("div#new_releases div.list_item").each(new JerryFunction() {
                public boolean onNode(Jerry $this, int index) {
                    System.out.println("-----");
                    System.out.println($this.$("div.album_title").text());
                    System.out.println($this.$("div.album_artist").text().trim());
                    return true;
                }
            });
        }
    }

Nice :)

Change Google page

Let's remove toolbar from Google page and remove Google logo image with simple HTML text.

    public class ChangeGooglePage {

        public static void main(String[] args) throws IOException {

            // download the page super-efficiently
            File file = new File(SystemUtil.getTempDir(), "google.html");
            NetUtil.downloadFile("http://google.com", file);

            // create Jerry, i.e. document context
            Jerry doc = Jerry.jerry(FileUtil.readString(file));

            // remove div for toolbar
            doc.$("div#mngb").detach();
            // replace logo with html content
            doc.$("div#lga").html("<b>Google</b>");

            // produce clean html...
            String newHtml = doc.html();
            // ...and save it to file system
            FileUtil.writeString(
                new File(SystemUtil.getTempDir(), "google2.html"),
                newHtml);
        }
    }

Easy!

Facebook bot

To demonstrate the power of Jerry, we created a little Facebook bot just for fun:) The task was to create a bot that will login to Facebook account, list friends proposals and send a few "Add friend" requests. To see how, read it here.

Next example is similar, it uses Jerry and Http to login to facebook. This time everything is done with Jodd, no need for 3rd party libs. Take a look.

Jerry parses POM XML (too)!

Jerry can be used to parse XML files, too! We needed to parse Maven POM files, in order to display dependencies on our download page. First, we had to enable the XML mode of Lagarto parser:

    Jerry.JerryParser jerryParser = new Jerry.JerryParser();
    jerryParser.enableXmlMode();
    Jerry doc = jerryParser.parse(FileUtil.readString(pomFile));

and then we can access the content via CSS selectors, for example:

    Jerry dependencies = doc.$("dependencies dependency");

    dependencies.each(new JerryFunction() {
        @Override
        public boolean onNode(Jerry $this, int index) {
            // skip test dependencies
            if ($this.$("scope").text().equals("test")) {
                return true;
            }

            String artifactId = $this.$("artifactId").text();
            String optionalStr = $this.$("optional").text();

            // process

            return true;
        }
    });

Complete code you can find here.

Jerry on Groovy!

Jerry can be used very nicely in Groovy! Rob Flatcher uses it in Groovy tests like this (snippet):

    import static jodd.jerry.Jerry.jerry as $

    def dom = $(output)

    def labels = dom.find('label')
    labels*.attr('for') == ['foo_hours', 'foo_minutes', 'foo_seconds']
    labels*.text() == ['\u00a0hours ', '\u00a0minutes ', '\u00a0seconds ']
    labels.every {
        it.find(':input').attr('id') == it.attr('for')
    }

For more details, check unit tests in grails-joda-time.

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