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Apache Shiro part 1 – selecting a Java security framework

Apache Shiro part 1 – selecting a Java security framework

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What is Shiro?
Apache Shiro is an open source Java security framework which makes authentication, authorization and cryptography very easy to use with a simple and small configuration. It is very portable because of its independence from the used application frameworks and covers all kinds of scenarios from console over desktop client to web applications.

Why Shiro?
I searched for a security solution (authorization and authentication) which I plan to reuse in multiple “pet projects” without having to think about the same problem over and over again. My actual project is a web project based on Java EE 7 and has at the moment a JSF/Primefaces frontend. I plan to extend the application with a REST interface and an alternative UI technology for personal testing/learning and research purposes. Maybe there will also be an iOS app later on which should use the then existent REST endpoint. With that in mind I need a flexible framework to support securing JAX-RS endpoints as well as my actual JSF UI.
I previously had some experience with the Java EE standard solution JAAS as well as the JBoss project Picketlink. Additional to that I’ve worked in projects using Spring Security (but had not much to do with it) which seems to be the industry standard nowadays but besides that I did a little research about possible alternatives I wasn’t aware of and came up with Apache Shiro and Keycloak.
This four/five tools and frameworks were the solutions I considered and researched which would be the best fit for me. …

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Don’t rely on Java finalizers

Don’t rely on Java finalizers

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Recently I was facing a problem where a Java application should persist a part of its state when it was closed. This was already implemented but seemed to work just unreliably and it was not clearly reproducible when it worked properly and when it failed. After analyzing the existing source code I figured out that finalizers were used to implement the functionality by delegating the call of the persist logic to the garbage collector. This seems like a very good idea at first but lacks in reliability. As a short note up front don’t use finalizers for important things.

A finalizer is a method which represents the opposite of a constructor. It is a method with the purpose to do some cleanup work, free up some memory and so on which gets called by the garbage collector before the object gets collected. A simple example would look like this
[java]
protected void finalize() {
logger.info(“start important work before GC”);
fooBar.persist(this.getDataMap());
}
[/java]
…

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Removing Excel rows with POI

Removing Excel rows with POI

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https://poi.apache.org
https://poi.apache.org

When generating Excel Sheets it is sometimes necessary to remove rows which match a given criteria afterwards. The first idea for this would be to use removeRow(Row row) but this has the problem that it deletes all the row contents and leaves the empty row in your sheet which is probably not what you want. To remove the rows as a whole the shiftRows(int startRow, int endRow, int n) is needed.
Lets say we have a xls file with column A being the title which is always filled but we want to remove every row in which the data column B is not filled. For this case the following snippet would be appropriate …

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Book review: Becoming a Better Programmer

Book review: Becoming a Better Programmer

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Becoming a Better Programmer
Becoming a Better Programmer

This is a book I wish I had read when starting my career as a professional developer because I would have had a head start about many of the things everybody takes for granted but at as a student nobody tells you about.
Don’t get me wrong I don’t say that I couldn’t get anything out of the book because I have already known it all but as it tries to cover nearly everything that is important for a professional developer there are naturally some things I already was aware about.

This book is not about telling you which patterns to use or how to solve specific problems but covers more the everyday life of a developer and how to become better in getting the right behavior, communicating with colleagues and customers, important general concepts in programming, a bit of tooling hints, basics of agile development and how to learn and what to read.

Positive: …

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