Java Expression Language : Interpolation?

Question

Greetings,

In the webapplication I am developing , I want to do something like follows:

I Have a Bean like

class Gene{
String geneid;
String sequence;
..
}

// EL expression (sometimes should be simple as "${geneid}" without URL pattern)
String exp="<a> href='http://www.ncbi.nlm.nih.gov/pubmed?term=${geneid}' />";
String outputString=someframeworkobject.somemethod(exp,aGeneInstance);

So the outputString is interpolated like : http://www.ncbi.nlm.nih.gov/pubmed?term=gene19191X

Is there any lightweight EL frameworks that I can use for this?

To add my own question: Can the JSP EL (which would be a fit here) be called from Java code? — Thilo
– Thilo, Commented Jan 20, 2010 at 3:32
I came across with Apache Common JEXL and Commons EL.But not sure how I can solve this — Ashika Umanga Umagiliya
– Ashika Umanga Umagiliya, Commented Jan 20, 2010 at 3:35

Thilo · Accepted Answer · 2010-01-20 04:03:24Z

4

Maybe MVEL would work for you.

With a template like

 Hello, @{person.getSex() == 'F' ? 'Ms.' : 'Mr.'} @{person.name}

you can do

 context.put("person", personBean);
 String output = (String) TemplateRuntime.eval(template, context);

Check out this tutorial (where I read about this, I have no experience with MVEL).

answered Jan 20, 2010 at 4:03

Thilo

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Chris Dail · Accepted Answer · 2010-01-20 03:48:33Z

3

It sounds like all you need is the core Java library class MessageFormat. It is pretty easy to use and allows you to do replacement of templates in a string.

String outputString = MessageFormat.format("<a> href='http://www.ncbi.nlm.nih.gov/pubmed?term={0}' />", "gene19191X");

You can also create an instance of MessageFormat and reuse that with different values.

Other options you could also try are:

Apache Commons EL - This is built for expressions in web applications.
Groovy GStrings - I use this sometimes to evaluate a 'script'. This has the advantage of allowing more complex logic.

answered Jan 20, 2010 at 3:48

Chris Dail

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2 Comments

Thilo Over a year ago

MessageFormat does not do expressions, though. I suppose you could combine MessageFormat with an expression language, like JUEL.

Ashika Umanga Umagiliya Over a year ago

i need more dynamic solution,because above 'Gene' bean is just an example.I use many Bean classes and need something like BeanUtils to process the field values.

mernst · Accepted Answer · 2023-08-05 17:15:14Z

1

You can use Java's String Templates feature. It is described in JEP 430, and it appears in JDK 21 as a preview feature. Here is an example use:

String outputString = STR."<a href='http://www.ncbi.nlm.nih.gov/pubmed?term=\{someframeworkobject.geneid}' />";

answered Aug 5, 2023 at 17:15

mernst

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