I wanted to use JET (Java Emitter Templates)
in my Netbeans projects, but had to find out that JET
heavily depends on Eclipse libraries.
Is there something similar to JET, but as a standalone project?
Something which is open source and well maintained?
Futhermore, is "code generation" the common term for such tools?
If you are using Maven, you can use JET templates with the maven-jet-plugin.
This seems to be the source code. And here the documentation.
It is not actively maintained but works pretty well and follows the JET spec.
I've used it with templates and skeletons.
It's self contained, doesn't depend on Eclipse, and doesn't introduce any transitive dependencies to your project.
Indeed JET is very tied with Eclipse.
If you want to generate code without Eclipse you should use another solution.
You can choose another template engine like Velocity (https://velocity.apache.org/) or FreeMarker (https://freemarker.apache.org/).
Or you can choose a code generator working by itself independently of any IDE.
For example "Telosys Command Line Interface" : http://www.telosys.org/
From what I know, JET is something like JSP, no?
Java Emitter Templates are very similar to Java Server Pages (JSPs). Both JETs and JSPs use the same syntax, and are compiled to Java behind the scenes. Both are used to separate the responsibility for rendering pages from the model and controller. Both accept objects passed into them as an input argument, both allow inserting string values within code ("expressions"), and allow direct use of Java code to perform loops, declare variable, or perform logical flows ("scriptlets"). Both are good ways of representing the structure of a generated object (web page, Java class, or file) while supporting customization of the details.
JETs differ from JSPs in a few key ways. In a JET, the structure of the markup may be changed to support generating code in different languages. Typically the input to a JET will be a configuration file and not user input (though there is nothing forbidding this). And also typically, JET processing will take place only once for a given workflow. These are not technical limitations, and you may find uses for JETs which are quite different...
ibm.com
Here are a few links to get you started on JSP, if that sounds like what you need:
sun.com
netbeans.org
Look for "template engine" for these types of tools.
A couple you might want to look at:
Apache Velocity (http://velocity.apache.org/)
StringTemplate (http://stringtemplate.org/)
I ended up using ERB (Ruby's template engine).
Works great in Netbeans!
I define custom ant task which generates source files by calling ERB (whose results are placed inside a non-versioned special directory).
The ant task is overriding Netbeans' "-pre-compile" task.
Related
I've been working on a Maven project consisting entirely of Java, and lately started to mix Scala code into it.
I'm amazed by the great expressiveness Scala offers, the easy use of scala-maven-plugin, and especially the incredible interoperability between Java and Scala.
However, I hit one inconvenience; according to the Maven's convention, Java's source code goes into src/main/java, whereas Scala's into src/main/scala. I found it quite cumbersome because I have to frequently go back and forth Java and Scala source files and every time I have to traverse the deep hierarchy of package directories (I often close tabs to keep my editor from cluttered).
So the question is: Is it recommended to maintain separate directories src/main/java and src/main/scala? If so, why?
To add more background, I've been working on the web application framework Wicket, whose convention is to put the HTML files alongside with their corresponding Java files. If we keep the directories separated, naturally the HTML files are separated as well (I don't think putting Scala files and corresponding HTML files in different directories makes sense). And then it goes "why I can't find Foo.html? Oh, I was looking for the wrong directory."
The source files themselves are very easy to distinguish both by humans and by machines by inspecting their extensions. I configured pom.xml to handle both Java and Scala put together in src/main/java and it worked (compiles and runs). On the other hand, separating directories poses a risk of defining conflicting classes in Java and in Scala, a careless mistake.
Well, I don't want to name a directory java if it contained not only Java's but also Scala's. But this is the only point I can come up with for separating directories.
(Edit: I've come up with a workaround-interpretation; let us think java stands for Java Virtual Machine. In this way, having src/main/c doesn't contradict if we ever decided to use JNI because C doesn't run on JVM.)
Oh, and one more point; my project is not intended as an open-source project; development convenience is preferred than trying hard to follow conventions.
This question is inspired by this answer.
I'd say yes, re-use code as much as possible. Maybe in future you can use this Java piece somewhere else...
As you probably know, you can use Java in Scala projects but not Scala in Java projects. So in this specific example it will help you with (future?) Java projects. If you want to re-use a piece of your Java code you can do that in either Java projects as well as Scala projects.
So i.m.h.o. it doesn't stop at the src/main/... but you should really put them even in different components.
Btw, little side note: if I'm correct, Wicket allows you to put the html somewhere else too, even in a different project... I saw it being handy (only) once, where we had to create different frontend for different clients of us. The java code stayed the same, the wicket-id's as well, but the html changed everywhere. Though it did give us some problems as well using the Qwicky plugin, as it could not find the html files in our IDE anymore.
In Android applications, resources are specified in xml documents, which automatically are built into the R class, readily accessible within the source code as strongly typed.
Is there any way I could use a similar approach for a regular Java desktop application?
What I'd like to accomplish, is both the removal of strings from the code (as a separation of "layers", more or less) and to make it easy to add support for localization, by simply telling the program to choose the xml file corresponding to the desired language.
I've googled around a bit, but the things I'm looking for seem to be drowning in results about parsing or outputting xml, rather than tools utilizing xml to generate code.
Eclipse's message bundle implementation (used by plugins for example) integrates with the Externalize Strings feature and generates both a static class and a resource properties file for your strings:
http://www.eclipse.org/eclipse/platform-core/documents/3.1/message_bundles.html
For this integration to work Eclipse needs to see org.eclipse.osgi.util.NLS on the class path. From memory, the dependencies of the libraries it was available in were a little tricky for the project I used this approach in, so I just got the source and have it as a stand-alone class in my core module (see the comments for more on that).
It provides the type safety you're looking for and the IDE features save a lot of time. I've found no downsides to the approach so far.
Edit: this is actually what ghostbust555 mentioned in the comments, but not clear in that article that this isn't limited to Eclipse plugins and you refer to your resources via static members of a messages class.
I haven't seen any mention of others using this approach with their own applications, but to me it makes complete sense given the IDE integration and type safety.
I'm not sure if this is what you mean but check out internationalization- http://netbeans.org/kb/docs/java/gui-automatic-i18n.html
Are you looking for something that parses XML files and generates Java instances of similar "struct-like" objects, like JAXP, and JAXB?
I came across ResGen which, given resource bundle XML files generates Java files that can be used to access the resources in a type-safe way.
http://eigenbase.sourceforge.net/resgen/
Suppose I have a bunch of (very simple) HTML pages, that I want to apply a common 'theme".
These files are downloaded using various Groovy scripts, and I would like to apply to them this styling during a maven build. How could I do that ?
Using which framework/library could I do that ?
Furthermore notice I want to do that in a static fashion, that's to say I want to have the following process to occur
Files are downloaded by Groovy scripts
They are processed (in a "magical" fashion) by this library
They may be sent by FTP/SCP to an hosting server
Do you know such an easy to use library ?
Depends on the details of the task but having in mind the steps you've described you can consider using velocity templates.
I would suggest using sitemesh decorator. I am a user of old version but a new release is being worked on that allows you to do exactly what you are asking for. Do a google search on sitemesh and you should find lots of examples.
In a nutshell sitemesh decoration: basic html + template = decorated page.
We want to design a simple domain specific language for writing test scripts to automatically test a XML-based interface of one of our applications. A sample test would be:
Get an input XML file from network shared folder or subversion repository
Import the XML file using the interface
Check if the import result message was successfull
Export the XML corresponding to the object that was just imported using the interface and check if it correct.
If the domain specific language can be declarative and its statements look as close as my sentences in the sample above as possible, it will be awesome because people won't necessarily have to be programmers to understand/write/maintain the tests. Something like:
newObject = GET FILE "http://svn/repos/template1.xml"
reponseMessage = IMPORT newObject
newObjectID = GET PROPERTY '/object/id/' FROM responseMessage
(..)
But then I'm not sure how to implement a simple parser for that languange in Java. Back in school, 10 years ago, I coded a language parser using Lex and Yacc for the C language. Maybe an approach would be to use some equivalent for Java?
Or, I could give up the idea of having a declarative language and choose an XML-based language instead, which would possibly be easier to create a parser for? What approach would you recommend?
You could try JavaCC or Antlr for creating a parser for your domain specific language. If the editors of that file are not programmers, I would prefer this approach over XML.
Take a look at Xtext - it will take a grammar definition and generate a parser as well as a fully-featured eclipse editor pluging with syntax highlighting and -checking.
ANTLR should suffice
ANTLR, ANother Tool for Language Recognition, is a language tool that provides a framework for constructing recognizers, interpreters, compilers, and translators from grammatical descriptions containing actions in a variety of target languages. ANTLR provides excellent support for tree construction, tree walking, translation, error recovery, and error reporting.
Look at Antlr library. You'll have to use EBNF grammatic to describe your language and then use Antlr to make java classes from your grammatic.
Have a look at how Cucumber defines its test cases:
(source: cukes.info)
http://cukes.info/ - can run in JRuby.
Or, I could give up the idea of having a declarative language and
choose an XML-based language instead,
which would possibly be easier to
create a parser for? What approach
would you recommend?
This could be easily done using XML to describe your test scenarios.
< GETFILE object="newObject" file="http://svn/repos/template1.xml"/ >
Since your example of syntax is quite simple, it should also be possible to simply use StringTokenizer to tokenize and parse these kind of scripts.
If you want to introduce more complex expressions or control structures you probably better choose ANTLR
I realize this thread is 3 years old but still feel prompted to offer my take on it. The questioner asked if Java could be used for a DSL to look as closely as possible like
Get an input XML file from network shared folder or subversion repository
Import the XML file using the interface
Check if the import result message was successfull
Export the XML corresponding to the object that was just imported
using the interface and check if it correct.
The answer is yes it can be done, and has been done for similar needs. Many years ago I built a Java DSL framework that - with simple customization - could allow the following syntax to be used for compilable, runnable code:
file InputFile
message Message
get InputFile from http://<....>
import Message from InputFile
if validate Message export Message
else
begin
! Signal an error
end
In the above, the keywords file, message, get, import, validate and export are all custom keywords, each one requiring two simple classes of less than a page of code to implement their compiler and runtime functions. As each piece of functionality is completed it is dropped into the framework, where it is immediately available to do its job.
Note that this is just one possible form; the exact syntax can be freely chosen by the implementor. The system is effectively a DIY high-level assembly language, using pre-written Java classes to perform all the functional blocks, both for compiling and for the runtime. The framework defines where these bits of functionality have to be placed, and provides the necessary abstract classes and interfaces to be implemented.
The system meets the primary need of clarity, where non-programmers can easily see what's happening. Changes can be made quickly and run immediately as compilation is almost instantaneous.
Complete (open) source code is available on request. There's a generic Java version and also one for Android.
For C#, I have often used CodeSmith and lately the T4 generator which is part of Visual Studio.
I'm looking for something similar for Java, in particular an Eclipse add-in since I do all my Java development using the Eclipse IDE.
I've found that freemarker does a pretty good job for generating any type of code. From the website:
FreeMarker is a "template engine"; a generic tool to generate text output (anything from HTML to autogenerated source code) based on templates. It's a Java package, a class library for Java programmers. It's not an application for end-users in itself, but something that programmers can embed into their products.
It is used by struts2 a lot. The website has a long list of other products that use freemarker.
I have worked with both Velocity and StringTemplate. Velocity is a bit more conventional (think JSP/ASP concepts), while StringTemplate seems a bit cleaner. in a sense described in this Artima interview. Both are pure templating engines, and will require you to write some code around them, if you want to do full-blown code generation from a model.
StringTemplate is used internally by ANTLR, which may be useful to your effort.
As an alternative approach, you could go with Eclipse, using EMF and JET.
You should try Telosys Tools, an Eclipse plugin for code generation working from an existing database with customizable Velocity templates
See: http://www.telosys.org/
Eclipse Marketplace : http://marketplace.eclipse.org/content/telosys-tools
The tutorials are here : https://sites.google.com/site/telosystutorial/
See this other question about CodeSmith : Is there any freeware tool available which is like Codesmith?
I use JavaForger to generate code from templates. It parses existing classes so that you can use that class-data inside your templates. It can both create new classes or insert code into existing classes. You can determine where generated code will be inserted based on a string conversion rule (e.g. myProject/dao/ProductDao.java => myProject/service/ProductService.java).
JavaForger is open source and uses FreeMarker as template engine and JavaParser as parser.
This is an old question but the only thing that comes close (for Java) to do what CodeSmith Generator does is Spring Roo.
The reason is that Java does not have Partial Classes like C# does. Spring Roo gets around this by using AspectJ ITDs.
My answer is to use StringTemplate, but there is a bit more to it than just what tool to use.
Is it the issue to generate java code? Or is it to use java tools? Programmers would be normally very comfortable writing code. Therefore, it would not be a leap to write some java classes and write a walk that would generate code using StringTemplate. I personally think it is a good exercise to create example models, generate your java code from the models. And depending on your use case you could end up writing JSON models by hand and never having to write any java code to produce the java code. Or you could end up writing Java classes that produce equivalent models.
You could use the StringTemplate based STST, which reads JSON. STST is command line based, and I am sure you could hook it to both eclipse and/or Visual Studio.
I personally think about portability, JSON is an extremely simple language. And almost every language has libraries that support it.
I'm not a C# man so I don't know what the equivalents would be, however I've found xdoclet to be very good in the past. I don't think it integrates with eclipse as such but you can run it from an ant script. Does things like generating Hibernate mapping files from annotated Java classes. Useful if that's what you're looking for :)
eclipse has a built-in template system.
look in window -> preferences -> java -> code style -> code templates
You might look at my plugin : http://fast-code.sourceforge.net/. It allows one to select multiple fields and generate code using user specified velocity templates.
Take a look at my project https://github.com/karajdaar/templator and see if that helps.
I wrote a simple web based application for my use.
its available at https://github.com/harish2704/templates
and a demo is available at http://templates-harish2704.rhcloud.com/
Its language independent tool. GUI supports several languages ( highlighting, snippet completion ect )