Dynamic Placeholder substitution in properties in java

user_263791 0
Viewed 63798

I wanted to substitute the placeholder dynamically in properties in a java application. Like 

 WelcomeMessage=Welcome Mr. {firstName} {lastName} !!!

These firstName and LastName variable needs to be substituted dynamically. Should we use velocity template engine for the same? Or are there any other opensource frameworks for the same?

Thanks, Manish

placeholder properties java
6 Answers

You can use the MessageFormat class of Java SE. It allows you to do exactly what you ask for.

In your case the below code snippet must do the trick, assuming props contains all the properties loaded from your file.

MessageFormat.format((String) props.get("WelcomeMessage"), "First", "Last");

Note that your properties files should have index of parameters instead of named parameters as below.

WelcomeMessage=Welcome Mr. {0} {1} !!!
user_1951300

Velocity is rather old and unpleasant, in my opinion, there are nicer ways to do this:

  • StringTemplate is the simplest of the template engines, and good enough for what you need (see syntax examples here).
  • If you're already using Spring 3, it has the PropertyPlaceholderHelper class which can do this also, but I wouldn't use Spring just to get hold of this one class.
user_212340

Another option is adding Apache FreeMarker with no dependencies and define template as:

Welcome Mr. ${firstName} ${lastName} !!!

Apache FreeMarker™ is a template engine: a Java library to generate text output (HTML web pages, e-mails, configuration files, source code, etc.) based on templates and changing data. Templates are written in the FreeMarker Template Language (FTL), which is a simple, specialized language

You can use StringTemplateLoader to load template using String

you can create a StringTemplateLoader and add each template to it:

user_72949000

velocity is the best tool as of now. But it depends on what file type you want to use as a template.

For example, if you want to use MS word docs as template, then you have to extend velocity classess and write your own implementation.

user_1184740
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