198 Lotus blogs updated hourly. Who will post next? Home | Blogs | Search | About 
 
Latest 7 Posts
Go Evergreen
Tue, Oct 17th 2017 83
Change is in the Air
Fri, Sep 1st 2017 2
Open Source Contribution
Fri, Jun 16th 2017 3
Docker Quick Tips
Fri, Apr 28th 2017 3
Notes in 9: Dev Tools Grab Bg
Tue, Apr 4th 2017 1
Custom JSON Serialization With GSON
Mon, Jan 23rd 2017 6
Recapping 2016
Mon, Jan 16th 2017 7
Top 10
Go Evergreen
Tue, Oct 17th 2017 83
Manually Renewing HTTPS w/ Let's Encrypt
Wed, Jul 27th 2016 11
Building Java Objects From JSON
Thu, Jan 22nd 2015 10
Server REST Consumption with Authentication
Mon, Aug 18th 2014 8
Notes in 9: Docker + SonarQube
Wed, Feb 24th 2016 8
Using Node to Connect to ... Almost Anything
Mon, Apr 18th 2016 8
Rebirth: An App of Ice and Fire
Wed, Dec 14th 2016 8
A Few ConnectED Thoughts
Thu, Jan 29th 2015 7
Headless DDE Builds With Jenkins CI
Fri, Mar 25th 2016 7
SCM Survey Results
Tue, Apr 12th 2016 7


Building Java Objects From JSON
Twitter Google+ Facebook LinkedIn Addthis Email Gmail Flipboard Reddit Tumblr WhatsApp StumbleUpon Yammer Evernote Delicious
   

Intro

JSON, as previously mentioned, is a data format which has been exploding in web development since it was first introduced in the early 2000s. And whether or not you as a developer prefer XML (it’s okay, they’re just formats), there are some good reasons to use JSON data. Ultimately, I don’t really care about the “XML vs JSON” debate, because some services use XML and some use JSON, neither are going away anytime soon, and XML is more flexible than most people give it credit for.

Note: I am more of a JSON fan, but that should be immaterial to relevance. The biggest argument I see in favor of JSON as opposed to XML is file size.

JSON

To date, when I’ve shown examples on this blog of how to build JSON, I’ve generally used Google’s GSON library. I’ve also only shown it in a fashion (for simplicity’s sake) that I refer to as the “old” way (below), because it maps easily to converting to using the IBM Commons JSON library (more below). I try to add Gson to the server when possible, but often will end up importing the JAR to an NSF, should I not have administrator blessing. Gson is supported from Java 1.5 through 1.8, according to their pom file.

This is in contrast to the provided com.ibm.commons.util.io.json package, which is included and makes it a convenient option for many/most.

Be forewarned! To use com.google.gson, you will need to grant permission for it in your java.policy file; you can run into trouble if you don’t. This is probably the second best argument against using com.google.Gson, but I’m still a fan.

“Old” Way

Part of the reason com.ibm.commons.util.io.json is popular (aside that it comes with the server, a big plus) is that it maps well to how we think. Streaming in elements into an object tends to make sense to us, but there’s another way. Here’s what I’ll refer to as the “old” way (it works, it’s valid, but not ideal as I’ll show).


This will generate a resulting JSON string with an object, represented as such:


It may not be very exciting, but it sure gets the job done. Here’s what I’m excited about.

“New” Way

I first saw a technique in which a person used a Gson instance to generate, on the fly, application/json by merely calling the the Gson.toJson method. I thought this was cool, but it made good sense. The Java object already existed and inherited from a proper class, which can loosely map to the JavaScript prototypal elements (string, boolean, array, object, integer, etc.). Gson is not unique in this, as the IBM Commons JSON library can achieve the same thing, using a JsonGenerator. That’s the easy side of things, the tricky part is going backwards, consuming JSON into a Java Object (or just creating it from existing Java objects without being so linear in re-iterating properties just to change the format they’re stored in).

IBM Commons JSON

Using JsonParser, you can use fromJson, which returns a java.lang.Object. In other words, you need to do your tests and transforms to get a handle on its structure. This works, but takes more effort (I would be glad for someone to show me how to map the IBM Commons library to the approach I’ll show next).

Google Gson

The Gson approach is to take in a class definition (or type) as the second parameter in their fromJson method, immediately mapping your object to a well structured object that you can invoke for its properties. Here’s a quick demonstration.


Why The “New” Way?

It’s obviously more verbose up front, but done the “old” way, I didn’t show all the type checks and conversions I would have to do to keep things working as expected. The “new” way defines the data format and ensures consistently well-formed objects; they are POJO instances after all (beans, except for the implementing java.util.Serializable bit, as we are using getter/setter methods).

You’ve defined the format and instantiated data object, meaning that now all you need to do is use the standard EL get/set to interact with the data. That's it, you're done!



---------------------
https://edm00se.github.io/DevBlog/java/building-java-objects-from-json
Jan 22, 2015
11 hits



Recent Blog Posts
83
Go Evergreen
Tue, Oct 17th 2017 4:00p   Eric McCormick
Happy 🎂 Day IE 11! On the 17th of October in 2013, Internet Explorer 11 was released from Microsoft. That means that as of today, this popular* browser is now four years old and, with all respect to it, it really ought to go. Good day sir. I said good day! Evergreen Browsers What makes a browser, or any software for that matter, evergreen? Well, the basic requirements for a browser, or any piece of software for that matter, are specifically the support of automatic updates, that bring in:
2
Change is in the Air
Fri, Sep 1st 2017 1:00p   Eric McCormick
I’m Back What Can I Say? In Case You Missed It If you find yourself asking “where was Eric?”, this should summarize it all: Instead of trying to do everything all summer, I tend to take a break from blogging and a lot of open source endeavors over the summer. It means I can focus on family time along with yard and house projects. Ah... Summer That’s all paid off and, with fall fast approaching, I’ve found myself wanting to start those things back up; ramping up into winter when
3
Open Source Contribution
Fri, Jun 16th 2017 5:00p   Eric McCormick
Intro It’s time to clear some of the backlog. I started this post a few months back and it should probably be sent on its way to clear the pile of drafts I haven’t finished yet… 🤔 I have a bit of a passion for open source software. My preferred distribution of Linux has been Ubuntu since 4.10, the Warty Warthog (I was even a minor contributor on a short lived, wildly popular project that aimed at improving the Ubuntu experience early on), I’ve enjoyed most open source projects I’ve
3
Docker Quick Tips
Fri, Apr 28th 2017 3:00p   Eric McCormick
Docker If you have been living under a rock, Docker is pretty much amazing. If you haven’t been living under a rock, you may be getting used to the idea of Docker, but still have the occasional question. I’ve found myself using Docker in increasing amounts and complexity over the last year or so. I’ve recently decided to start recording some of the tasks I’ve found useful, some of which may be less familiar to a beginner. If you’re so inclined, check out the playlist, embedded here.
1
Notes in 9: Dev Tools Grab Bg
Tue, Apr 4th 2017 1:00p   Eric McCormick
Intro I’m on Notes in 9 again, with a “grab bag” of a couple of tools I’ve put together recently that may be of a varying degree of useful for other Domino + XPages developers. You don’t need these to do development, but for the right person, they may help with their development workflow. Also of note, with the upgrade to Swiper with the FP8 release of Notes + Domino Designer, the limitations previously mentioned are no longer there! This means that my second tool I talked about, node-
6
Custom JSON Serialization With GSON
Mon, Jan 23rd 2017 2:00p   Eric McCormick
Intro Here’s a curious one, in which I found myself with a limitation of not being able to output JSON with scientific notation values. wait, what? If you’re wondering why that is, since both JSON and JavaScript allow scientific notation of number values, you are absolutely correct and that’s a great question. The strange thing was that I found myself outputting perfectly valid JSON to be consumed by something specific which didn’t allow scientific notation. I’m not entirely sure wh
7
Recapping 2016
Mon, Jan 16th 2017 3:00p   Eric McCormick
Intro Per usual, I’ve had a little break between things and decided to catch up with a bit of a summary of some recent things that each didn’t necessitate their own post. 2017 IBM Champion For starters, I’m honored to be named an IBM Champion in Collaboration Solutions (/ Social Business) for the third time. This would be a hat trick in (ice) hockey 🏒. I’m happy to be recognized with a group of people, developers and more, who are passionate about both their work and the plat
8
Rebirth: An App of Ice and Fire
Wed, Dec 14th 2016 4:00p   Eric McCormick
Intro If you read my blog for any of the Saga of Servlets series, then I hope that you’re excited I’m returning to the application I put together for it. This time, it’s as a conversation piece in regards to some of the build process modernization I engaged in recently, in order to unify the code base in its git repository. In any case, it’s helping pave the way forward before I update some of the back-end elements, when it will again be a talking point for some additional rework and
2
Scripting Server Upgrades
Fri, Nov 11th 2016 2:00p   Eric McCormick
Intro This one might be slight departure from my usual, but those that have followed my blogging this past year will have noticed a bit more of a leaning towards DevOps in some of my posts. This echoes a lot of what I’ve been concluding as increasingly a necessary part of development; that we need to consider a picture large enough to encompass the themes surrounding development functions and, like any good developer (DRY ~= “lazy”), automate the heck out of it. Overview I had p
4
Everything Old is New Again
Mon, Oct 24th 2016 8:00p   Eric McCormick
Intro Every so often, it’s good to reassess one’s position. This is good from both a standpoint of being inquisitive and even interrogative, but when it comes to the ever changing landscape of the front-end development space, it’s not only inevitable, but must be embraced for what feels the need to “stay afloat”. I’m changing theme of my blog, hopefully for the better. The previous theme was good and did a great job of getting things started, but while I had forked a copy of a good




Created and Maintained by Yancy Lent - About - Planet Lotus Blog - Advertising - Mobile Edition