I'm using javax.xml.xpath to read nodes out of a XML-DOM and to create Java-Objects from the read data.
After changing the data of these objects and perhaps creating new objects, I would like to write them back to the XML-DOM.
So I was wondering if it is possible to use xpath to also create nodes at specific positions in the XML-DOM. I am not sure if xpath is designed to write to DOM because its a "Query"-Language. But on the other hand SQL is also a query-language and is able to write data to databases.
So my general question is: Is it possible to create DOM-Nodes with XPaths?
No, you will need to use low-level DOM methods to create new nodes.
Are you sure you are using the right approach? Could the whole application be written more easily in XSLT? Even if you want to use a Java tree-based API, why DOM, which is so slow and unwieldy compared with subsequent tree models such as JDOM and XOM?
No that is not possible as far as I know. But the elements returned are 'live' which means any change made on them is directly reflected in the dom.
Related
I have an XML file with a stable tree structure and more than 5000 elements.
A fraction of it is below:
<Companies>
<Offices>
<RevenueInfo>
<TransactionId>14042015014606877</TransactionId>
<Company>
<Identification>
<GlobalId>25142400905</GlobalId>
<BranchId>373287734</BranchId>
<GeoId>874</GeoId>
<LastUpdated>2015-04-14T01:46:06.940</LastUpdated>
<RecordType>7785</RecordType>
</Identification>
<Info>
<DataEntry>
<EntryId>12345</EntryId>
</DataEntry>
<DataEntry>
<EntryId>34567</EntryId>
</DataEntry>
<DataEntry>
<EntryId>89076</EntryId>
</DataEntry>
<DataEntry>
<EntryId>13211</EntryId>
</DataEntry>
</Info>
...more elements
</Company>
</RevenueInfo>
</Offices>
</Companies>
I need to be able to update any of the values in the document based on user input and create a new XML file with the updated information. User will pass BranchId, the name of the element to update and it's number of order if multiple occurring element ( for example, for EntryId 12345 the user will pass 373287734 EntryId=1 010101 )
I've been looking at JAXB but it seems like a considerable effort to create the model classes for this kind of XML but it also seems like it would make printing to file and locating the element to update a lot easier.
Dom4j seems to have good performance results too, but not sure how parsing will be.
My question is, is JAXB the best approach in this case or can you suggest a better way to parse this type of XML?
In my experience JAXB only works well when the schema is simple and stable. In other cases you are better off using a generic tree model. The main generic models in the Java world are DOM, JDOM2, DOM4J, XOM, AXIOM. My own preferences are JDOM2 and XOM; DOM4J seems to me overcomplex, and somewhat old-fashioned. But it depends what you are looking for.
But then, the application you describe looks an ideal candidate for an "XML end-to-end" or XRX approach - XForms, XSLT, XQuery, XProc. You don't need Java at all.
Leaving performance and memory requirements aside, I would recommend trying XPath together with DOM4J (or JDOM, or even plain DOM). To select the company you could use an XPath expression like this:
"//Company[Identification/BranchId = '373287734']"
Then, using the returned company element as context, you can get the element to be updated with another XPath expression:
"//EntryId[position() = 1]"
I'm using the Java Scripting API which is working quite well. Now I have a function where I want to get all <a> tags from a String and then add/remove attributes before returning the manipulated String. The problem of course is, that I can't just use document.getElementsByTagName. Is there any easy option that comes to your mind without going through regex-hell?
Please note that I'm currently running on Java 7 (with Rhino), planning to update to Java 8 (with Nashorn), so I don't want to use any Rhino specific APIs.
In the book "Learning JavaScript Design Patterns" by Addi Osmani, author mentions 3 alternatives to a similar problem, obviously being getElementById() the fastest.
Excerpt from book:
Imagine that we have a script where for each DOM element found on page
with class "foo," we wish to increment a counter. What's the most
efficient way to query for this collection of elements? Well, there
are a few different ways this problem could be tackled:
Select all of the elements in the page and then store references to them. Next, filter this collection and use regular expressions (or
another means) to store only those with the class "foo."
Use a modern native browser feature such as querySelectorForAll() to select all of the elements with the class "foo."
Use a netive feature such as getElementsByClassName() to similarly...
Another way is, since you're using Nashorn/Rhino, you could use the Java implementation of the Xerces library to manipulate the DOM.
Hope this helps you find out the solution.
If one needed to be able to display certain elements that contain some certain data and then sort them based on this data.
Which would be a better choice for a XML parser, DOM or SAX?
Also can either of these achieve sorting of XML data without the need of storing the data first?
Sorting will require you to read in all of the XML document to memory. So working with a DOM will probably be easier. There are good libraries available that make working with a DOM easier:
dom4j
JDOM
It would be a better to use STAX (Streaming API for XML), because it is universal solution for tiny or large files, but if your XML files isn't bigger you could use DOM, because it will be easier. Also you could make xpath query when using DOM, that could be helpful for you.
Woodstox
Aalto XML processor
I am new to this validation process in Java...
-->XML file named Validation Limits
-->Structure of the XML
parameter /parameter
lowerLimit /lowerLimit
upperLimit /upperLimit
enable /enable
-->Depending the the enable status, 'true or false', i must perform the validation process for the respective parameter
--> what could be the best possible method to perform this operation...
I have parsed the xml (DOM) [forgot this to mention earlier] and stored the values in the arrays but is complicated with lot of referencing that take place from one array to another. If any better method that could replace array procedure will be helpful
Thank you in advance.
Try using a DOM or SAX parser, they will do the parsing for you. You can find some good, free tutorials in the internet.
The difference between DOM and SAX is as follows: DOM loads the XML into a tree structure which you can browse through (i.e. the whole XML is loaded), whereas SAX parses the document and triggers events (calls methods) in the process. Both have advantages and disadvantages, but personally, for reasonably sized XML files, I would use DOM.
So, in your case: use DOM to get a tree of your XML document, locate the attribute, see other elements depending on it.
Also, you can achieve this in pure XML, using XML Schema, although this might be too much for simple needs.
I am creating a JTree from an xml file.
Q: I have to implement a search functionality .
I have done it using JTree and I have observed that its too slow and my tree is quite heavy.
Q. Please suggest if I can implement using xml file
I always suggest UI programmers to avoid creating huge user interface widgets such as trees and lists.
The best solution is to parse your XML file, keep it in memory if it's size allows it, perform the search in the memory and then display ONLY the result of the search !!!
If the file can't fit into memory, then you should have a look on XML Sax parser and look forward to allow your end users to navigate in the data represented by your XML file.
Manu
I hope I understand correctly :)
If You need to query collections of XML data then use XQuery / XPath (wich especially designed for XML processing).
Best Regards, Gedevan