Java, Query a series of .HTML Help - java

I'm trying to figure out what is nessary to preform what I belive to be a somewhat simple task, but it seems its execution is a bit advance.
Can someone provide an example that might help me figure out the following goal?
Check various known .html files on local server for a string
If string is Que_for_board the preform a parse of other strings that will be in file
Example: Release data, Author, Program etc
Else (if Que_for_board not found) go to next HTML
Takes results in and print to a file
Is this is hard as it seems? I've looked into HTMLCleaner parser but not sure I need to clean up the HTML into XML, and Im finding it hard to find a query code that has the next step in detail.

I would not describe this as a truly hard task, in that it's really a matter of using a number of techniques that are "out there", but I can see that it could be intimidating.
A technique I find useful is to decompose the overall task into small problems, and teach myself to think only about one problem at a time, having faith that I can assemble the overall solution eventually.
So here you have perhaps
get a list of files from somewhere (where? directory listing, a document?)
Open each file in a list in turn
parse an html file
find a specific string in the parsed file
Of these parsing html files is potentially very easy or not so easy. Can you trust the file to be well-formed or was it written by a human? Humans simply don't make good HTML files and browsers are very tolerant of missing </P> etc.
If these are very simple html files you can fake this by using simple String searching, regex and so on. Otherwise you need a proper parser, and maybe a clean up first.
My first step would be to understand how to process a single HTML file.

Related

Is it possible to do this type of search in Java

I am stuck on a project at work that I do not think is really possible and I am wondering if someone can confirm my belief that it isn't possible or at least give me new options to look at.
We are doing a project for a client that involved a mass download of files from a server (easily did with ftp4j and document name list), but now we need to sort through the data from the server. The client is doing work in Contracts and wants us to pull out relevant information such as: Licensor, Licensee, Product, Agreement date, termination date, royalties, restrictions.
Since the documents are completely unstandardized, is that even possible to do? I can imagine loading in the files and searching it but I would have no idea how to pull out information from a paragraph such as the licensor and restrictions on the agreement. These are not hashes but instead are just long contracts. Even if I were to search for 'Licensor' it will come up in the document multiple times. The documents aren't even in a consistent file format. Some are PDF, some are text, some are html, and I've even seen some that were as bad as being a scanned image in a pdf.
My boss keeps pushing for me to work on this project but I feel as if I am out of options. I primarily do web and mobile so big data is really not my strong area. Does this sound possible to do in a reasonable amount of time? (We're talking about at the very minimum 1000 documents). I have been working on this in Java.
I'll do my best to give you some information, as this is not my area of expertise. I would highly consider writing a script that identifies the type of file you are dealing with, and then calls the appropriate parsing methods to handle what you are looking for.
Since you are dealing with big data, python could be pretty useful. Javascript would be my next choice.
If your overall code is written in Java, it should be very portable and flexible no matter which one you choose. Using a regex or a specific string search would be a good way to approach this;
If you are concerned only with Licensor followed by a name, you could identify the format of that particular instance and search for something similar using the regex you create. This can be extrapolated to other instances of searching.
For getting text from an image, try using the API's on this page:
How to read images using Java API?
Scanned Image to Readable Text
For text from a PDF:
https://www.idrsolutions.com/how-to-search-a-pdf-file-for-text/
Also, PDF is just text, so you should be able to search through it using a regex most likely. That would be my method of attack, or possibly using string.split() and make a string buffer that you can append to.
For text from HTML doc:
Here is a cool HTML parser library: http://jericho.htmlparser.net/docs/index.html
A resource that teaches how to remove HTML tags and get the good stuff: http://www.rgagnon.com/javadetails/java-0424.html
If you need anything else, let me know. I'll do my best to find it!
Apache tika can extract plain text from almost any commonly used file format.
But with the situation you describe, you would still need to analyze the text as in "natural language recognition". Thats a field where; despite some advances have been made (by dedicated research teams, spending many person years!); computers still fail pretty bad (heck even humans fail at it, sometimes).
With the number of documents you mentioned (1000's), hire a temp worker and have them sorted/tagged by human brain power. It will be cheaper and you will have less misclassifications.
You can use tika for text extraction. If there is a fixed pattern, you can extract information using regex or xpath queries. Other solution is to use Solr as shown in this video.You don't need solr but watch the video to get idea.

Is there a clean way to to transform text files that are not the same into a standard format

I'm pretty sure the answer i'm going to get is: "why don't you just have the text files all be the same or follow some set format". Unfortunately i do not have this option but, i was wondering if there is a way to take any text file and translate it over to another text or xml file that will always look the same?
The text files pretty much have the same data just arranged differently.
The closest i can come up with is to have an XSLT sheet for each text file but, then i have to turn around and read the file that was just created, delete it, and repeat for each text file.
So, is there a way to grab the data off text files that essentially have the same data just stored differently; and store this data in an object that i could then re-use later on in some process?
If it was up to me, i would push for every text file to follow some predefined format since they all pretty much contain the same data but, it's not up to me.
Odd question... You say they are text files yet mention XSLT as a possible solution. XSLT will only work if the source is XML, if that is so, please redefine the question. If you say text files I assume delimiter separated (e.g. csv), fixed length,...
There are some parsers (like smooks) out there that allow you to parse multiple formats, but it will still require you to perform the "mapping" yourself of course.
This is a typical problem in the integration world so any integration tool should offer you a solution (e.g. wso2, fuse,...).

Extracting webpage information based on a template in Java

Right now I use Jsoup to extract certain information (not all the text) from some third party webpages, I do it periodically. This works fine until the HTML of certain webpage changes, this change leads to a change in the existing Java code, this is a tedious task, because these webpage change very frequently. Also it requires a programmer to fix the Java code. Here is an example of HTML code of my interest on a webpage:
<div>
<p><strong>Score:</strong>2.5/5</p>
<p><strong>Director:</strong> Bryan Singer</p>
</div>
<div>some other info which I dont need</div>
Now here is what I want to do, I want to save this webpage (an HTML file) locally and create a template out of it, like:
<div>
<p><strong>Score:</strong>{MOVIE_RATING}</p>
<p><strong>Director:</strong>{MOVIE_DIRECTOR}</p>
</div>
<div>some other info which I dont need</div>
Along with the actual URLs of the webpages these HTML templates will be the input to the Java program which will find out the location of these predefined keywords (e.g. {MOVIE_RATING}, {MOVIE_DIRECTOR}) and extract the values from the actual webpages.
This way I wouldn't have to modify the Java program every time a webpage changes, I will just save the webpage's HTML and replace the data with these keywords and rest will be taken care by the program. For example in future the actual HTML code may look like this:
<div>
<div><b>Rating:</b>**1/2</div>
<div><i>Director:</i>Singer, Bryan</div>
</div>
and the corresponding template will look like this:
<div>
<div><b>Rating:</b>{MOVIE_RATING}</div>
<div><i>Director:</i>{MOVIE_DIRECTOR}</div>
</div>
Also creating these kind of templates can be done by a non-programmer, anyone who can edit a file.
Now the question is, how can I achieve this in Java and is there any existing and better approach to this problem?
Note: While googling I found some research papers, but most of them require some prior learning data and accuracy is also a matter of concern.
The approach you gave is pretty much similar to the Gilbert's except
the regex part. I don't want to step into the ugly regex world, I am
planning to use template approach for many other areas apart from
movie info e.g. prices, product specs extraction etc.
The template you describe is not actually a "template" in the normal sense of the word: a set static content that is dumped to the output with a bunch of dynamic content inserted within it. Instead, it is the "reverse" of a template - it is a parsing pattern that is slurped up & discarded, leaving the desired parameters to be found.
Because your web pages change regularly, you don't want to hard-code the content to be parsed too precisely, but want to "zoom in" on its' essential features, making the minimum of assumptions. i.e. you want to commit to literally matching key text such as "Rating:" and treat interleaving markup such as"<b/>" in a much more flexible manner - ignoring it and allowing it to change without breaking.
When you combine (1) and (2), you can give the result any name you like, but IT IS parsing using regular expressions. i.e. the template approach IS the parsing approach using a regular expression - they are one and the same. The question is: what form should the regular expression take?
3A. If you use java hand-coding to do the parsing then the obvious answer is that the regular expression format should just be the java.util.regex format. Anything else is a development burden and is "non-standard" and will be hard to maintain.
3B. If you use want to use an html-aware parser, then jsoup is a good solution. Problem is you need more text/regular expression handling and flexibility than jsoup seems to provide. It seems too locked into specific html tags and structures and so breaks when pages change.
3C. You can use a much more powerful grammar-controlled general text parser such as ANTLR - a form of backus-naur inspired grammar is used to control the parsing and generator code is inserted to process parsed data. Here, the parsing grammar expressions can be very powerful indeed with complex rules for how text is ordered on the page and how text fields and values relate to each other. The power is beyond your requirements because you are not processing a language. And there's no escaping the fact that you still need to describe the ugly bits to skip - such as markup tags etc. And wrestling with ANTLR for the first time involves educational investment before you get productivity payback.
3D. Is there a java tool that just uses a simple template type approach to give a simple answer? Well a google search doesn't give too much hope https://www.google.com/search?q=java+template+based+parser&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-GB:official&client=firefox-a. I believe that any attempt to create such a beast will degenerate into either basic regex parsing or more advanced grammar-controlled parsing because the basic requirements for matching/ignoring/replacing text drive the solution in those directions. Anything else would be too simple to actually work. Sorry for the negative view - it just reflects the problem space.
My vote is for (3A) as the simplest, most powerful and flexible solution to your needs.
Not really a template-based approach here, but jsoup can still be a workable solution if you just externalize your Selector queries to a configuration file.
Your non-programmer doesn't even have to see HTML, just update the selectors in the configuration file. Something like SelectorGadget will make it easier to pick out what selector to actually use.
How can I achieve this in Java and is there any existing and better approach to this problem?
The template approach is a good approach. You gave all of the reasons why in your question.
Your templates would consist of just the HTML you want to process, and nothing else. Here's my example based on your example.
<div>
<p><strong>Score:</strong>{MOVIE_RATING}</p>
<p><strong>Director:</strong>{MOVIE_DIRECTOR}</p>
</div>
Basically, you would use Jsoup to process your templates. Then, as you use Jsoup to process the web pages, you check all of your processed templates to see if there's a match.
On a template match, you find the keywords in the processed template, then you find the corresponding values in the processed web page.
Yes, this would be a lot of coding, and more difficult than my description indicates. Your Java programmer will have to break this description down into simpler and simpler tasks until she or he can code the tasks.
If the web page changes frequently, then you'll probably want to confine your search for the fields like MOVIE_RATING to the smallest possible part of the page, and ignore everything else. There are two possibilities: you could either use a regular expression for each field, or you could use some kind of CSS selector. I think either would work and either "template" can consist of a simple list of search expressions, regex or css, that you would apply. Just roll through the list and extract what you can, and fail if some particular field isn't found because the page changed.
For example, the regex could look like this:
"Score:"(.)*[0-9]\.[0-9]\/[0-9]
(I haven't tested this.)
Or you can try different approach, using what i would call 'rules' instead of templates: for each piece of information that you need from the page, you can define jQuery expression(s) that extracts the text. Often when page change is small, the same well written jQuery expressions would still give the same results.
Then you can use Jerry (jQuery in Java), with the almost the same expressions to fetch the text you are looking for. So its not only about selectors, but you also have other jQuery methods for walking/filtering the DOM tree.
For example, rule for some Director text would be (in sort of sudo-java-jerry-code):
$.find("div#movie").find("div:nth-child(2)")....text();
There could be more (and more complex) expressions in the rule, spread across several lines, that for example iterate some nodes etc.
If you are OO person, each rule may be defined in its own implementation. If you are groovy person, you can even rewrite rules when needed, without recompiling your project, and still being in java. Etc.
As you see, the core idea here is to define rules how to find your text; and not to match to patterns as that may be fragile to minor changes - imagine if just a space has been added between two divs:). In this example of mine, I've used jQuery-alike syntax (actually, it's Jerry-alike syntax, since we are in Java) to define rules. This is only because jQuery is popular and simple, and known by your web developer too; at the end you can define your own syntax (depending on parsing tool you are using): for example, you may parse HTML into DOM tree and then write rules using your helper methods how to traverse it to the place of interest. Jerry also gives you access to underlaying DOM tree, too.
Hope this helps.
I used the following approach to do something similar in a personal project of mine that generates a RSS feed out of here the leading real estate website in spain.
Using this tool I found the rented place I'm currently living in ;-)
Get the HTML code from the page
Transform the HTML into XHTML. I used this this library I guess there might be today better options available
Use XPath to navigate the XHTML to the information you're interesting in
Of course every time they change the original page you will have to change the XPath expression. The other approach I can think of -semantic analysis of the original HTML source- is far, far beyond my humble skills ;-)

XSLT extraction of all input possible xpaths

I have really complex xsl (20 000 rows xsl file!) file which processes input file XML and makes output XML file.
I would like to extract all input file xpaths which are possible processed in the xsl. So I would like somehow to have a extraction of all (input)xpaths which are concerned in the XSL.
For that purpose I would like to find java API or tool which is able to give me this information with single passing of the XSL file. Are there such APIs or tools?
Regards
Aurel
Technically, that's easy- every node's processed in some way. I'm guessing what you really want is "what's specifically processed by a template that's defined in the stylesheet."
To do that, just add the identity template to the very bottom of your stylesheet- anything which hasn't already been processed already will be processed by that, and you can add in an <xsl:message> instruction to output whatever you need there. I'm fairly sure you'll find examples of how to generate the XPath of the context node around, that's been asked a few times.
EDIT: I forgot to mention- technically this will give you the inverse of what you asked for, it'll tell you what nodes are NOT processed. Hopefully you'll be able to use that to achieve the same goal though.

java - analyzing big text files

I need to analyze a log file at runtime with Java.
What I need is, to be able to take a big text file, and search for a certain string or regex within a certain range of lines.
The range itself is deduced by another search.
For example, I want to search the string "operation ended with failure" in the file, but not the whole file, only starting with the line which says "starting operation".
Of course I can do this with plain InputStream and file reading, but is there a library or a tool that will help do it more conveniently?
If the file is really huge, then in your case either good written java or any *nix tool solution will be almost equally slow (it will be bound to IO). In such a case you won't avoid reading the whole file line-by-line.... And in this case few lines of java code would do the job ... But rather than once-off search I'd think about splitting the file at generation time, which might be much more efficient. You could redirect the log file to another program/script (either awk or python would be perfect for it) and split the file on-line/when generated rather than post-factum.
Check this one out - http://johannburkard.de/software/stringsearch/
Hope that helps ;)

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