Mit ‘Google’ getaggte Beiträge

So,

it was quite for some time now. (12 days :)) My vacations are over and I have to develop GAB (Automatic Binding for Guice) in my spare time, but no problem so far. This means my evenings will be longer. 🙂

First good news: GAB is now listed as official 3rd-Party Extension for Google Guice!
Second good news: I release v0.7! 🙂

The blog was quite, but github was under fire 🙂

So what’s changed so far?

Summary:

  • Added Automatic Binding of AOP Interceptors
  • Added Automatic Binding Configurations for java.util.Properties
  • Added Automatic Binding Configurations Apache Commons Configurations
  • Added rocoto (Simple Configuration) to the Integrations
  • Improved JavaDoc, JUnit-Tests and Examples

Added Automatic Binding of AOP Interceptors

This Feature is one of the coolest things. 🙂 You can use your existing AOP-Alliance compatible MethodInterceptors. Just annotate them with @Interceptor and they will be bound automatically.
But Guice needs some more Informations:

  • Which Classes should be monitored
  • Which Methods of this Class should be intercepted

Normally you would pass a Matcher-Object to the Guice-Binder. Due the fact that this should happen automatically, I introduced two Annotations, which will mark the Methods, which returns the Matcher-Object. @ClassMatcher and @MethodMatcher

@Interceptor
public class AnnotatedMethodInterceptor{
    @Invoke
    public Object invoke(MethodInvocation invocation) throws Throwable {
	return invocation.proceed();
    }

    @ClassMatcher
    public Matcher<? super Class<?>> getClassMatcher() {
	return Matchers.any();
    }

    @MethodMatcher
    public Matcher<? super Method> getMethodMatcher() {
	return Matchers.annotatedWith(Intercept.class);
    }
}

This Example is a complete Implementation of a MethodInterceptor. There are different ways you could go. Use your existing MethodInterceptors, which implement The MethodInterceptor Interface.
If you choose this way, you need to annotate at least two Methods for the Matchers.

The second way can be, that you extend my abstract GuiceMethodInterceptor Class, so you need no Annotations.

Or you are going the complete dynamic way, like the one displayed above. Just annotate the Matcher-Methods and the Method which should be invoked, if a monitored Method matches the Criterias.

Added Automatic Binding Configurations for java.util.Properties

GAB is now able, to bind your needed Configurations automatically. 🙂

You just need one annotation, which informs GAB, if you want a Named- and/or Lazy-Binding and where it find the Configuration File (Classpath, File, URL)

@Configuration(name="config", path="/configuration.properties", pathType=PathType.CLASSPATH)
public class Example{
    @Inject @Named("config")
    private Properties config;
...
}

Added Automatic Binding Configurations Apache Commons Configurations

Or are you more a Friend of Apache Commons Configurations?

@Configuration(name="config", bind=PropertyListConfiguration.class, path="http://devsurf.de/guice/configuration.plist", pathType=PathType.URL)
public class Example{
    @Inject @Named("config")
    private PropertyListConfiguration config;

...or...

    @Inject @Named("config")
    private Configuration config;
}

Added rocoto (Simple Configuration) to the Integrations

So you don’t want a Properties or Configuration-Object? You could use the rocoto-Extension (rocoto-googlecode and homepage). This allows you to direct inject your values into an Object. GAB will do the Rest for your. (Automatically Binding/Installation of rocoto-Features)

@Configuration(path="/configuration.properties", pathType=PathType.CLASSPATH)
public class ExampleImpl implements Example {
    @Inject @Named("message")
    private String message;
    
    @Override
    public String sayHello() {
	return "sayHello() - "+message;
    }
}

No boilerplates anymore! 🙂

Checkout the Examples

So I just can say, check out the Examples and JUnit-Test! You will find several Examples, how to use the different Modules.

Straight to v1.0

The Release of the v1.0 is not so far away. At the moment it is planned for the End of October. Why so long? I’ll make sure that it is not only tested on Windows. I’m going to create a Web Application for Remote Configurations. So you can keep the Customer specific Things out of your Applications. This one will be tested at least under Windows/Linux and Tomcat/Glassfish.

After finishing that, I’ll release! Promised! 🙂

Btw: I tested the last release with the Google Guice 3.0-Branch. Works like a charm! Using only JSR330-Annotations leads to no heavy dependencies to Guice. (and if you want to remove all Source Code-Dependencies – checkout the JNDI-Example for Guice)

		<dependency>
			<groupId>de.devsurf.injection.guice.integrations</groupId>
			<artifactId>de.devsurf.injection.guice.integrations.guicyfruit</artifactId>
			<version>0.6.2-SNAPSHOT</version>
		</dependency>

This will add the JSR250Module of the GuicyFruit-Extension to your Classpath and the Scanner will find the Module, because it is marked with @GuiceModule.
So you can annotate your Classes with @PostConstruct, @PreDestroy and/or @Resource.

In my git-Repository you will also find an Example-Folder, where all Features are used. From automatic Binding of Classes, over automatic installation of Modules, to using JNDI and/or Multiple-Bindings.

I’ll show it in the next Example how to use it.

In our Example we have one Interface „Example“ 🙂 :

public interface Example {
    String sayHello(); //will be called in our Application
    void inform(); //will be called through @PostConstruct
}

Our Implementation is as easy and boring as you would expect it 🙂 :

public class ExampleImpl implements Example {  
    @PostConstruct  
    public void inform(){  
	System.out.println("inform about post construction!");  
    }  
    
    @Override  
    public String sayHello() {  
	return "yeahhh!!!";  
    }  
}

and for completeness a Module, which will be installed automatically which will bind our Interfact to the Implementation:

@GuiceModule
public class ExampleModule extends AbstractModule {   
    @Override
    protected void configure() {  
	bind(Example.class).to(ExampleImpl.class);
    }
}

You see how difficult it is? 🙂

Oh and I forgot our Application. We will use the StartupModule, which only wants to know about the ClasspathScanner-Implementation and which Packages should be scanned.
After creating an Injector, we will retrieve an Instance of our DynamicModule, which is bound to the ScannerModule.
Last but not least, this Module can be used to create a new Injector.

public static void main(String[] args) throws IOException {  
	StartupModule startupModule = StartupModule.create(VirtualClasspathReader.class, ExampleApp.class.getPackage().getName(), JSR250Module.class.getPackage().getName());  
	Injector injector = Guice.createInjector(startupModule);  
  
	Module m = Modules.combine(startupModule, injector.getInstance(DynamicModule.class));  
	injector = Guice.createInjector(m); 

	System.out.println(injector.getInstance(Example.class).sayHello());  
}

Attention: At the Moment there is something I don’t understand. When I use my original Injector to create a ChildInjector, all Interface-to-Class-Bindings work like a charm. But I install a Module, which will bind a TypeListener or something else, they are not recognized.
I’m not sure if this is a Bug or a wanted behavior. So we are only able to use GuicyFruit, if we create a new Injector with the Help of the DynamicModule.

Guicefy JNDI

If you are working a lot with JNDI and/or JavaEE you often have to work with a Context. A good description about the Use Case can be found on the GuicyFruit Wiki. I’ll only describe how you can use it with my Extension.

First of all you will need a „jndi.properties“ with the ContextFactory, our Class for the ClasspathScanner and which Packages should be scanned. (sounds familiar? :))

java.naming.factory.initial = ...integrations.guicyfruit.GuicyInitialContextFactory
guice.classpath.scanner = ...scanner.asm.VirtualClasspathReader
guice.classpath.packages = ...

After that you need to create a new Context and lookup your Instances with the help of it. The Rest is magic. 🙂 (behind the scene there is the normal automatic binding and installation of modules/beans)

public static void main(String[] args) throws Exception {  
	InitialContext context = new InitialContext();  
	Example example = (Example) context.lookup(Example.class.getName());  
  	
	System.out.println(example.sayHello());  
}

On the road to Version 1.0 I have to invest a little bit in the rocoto-Integration and further Tests/Documentation.

On Monday I released my „Automatic Injection for Guice„, which should help to automatically create Bean bindings and install Guice Modules.
This is done, due using Implementations of Classpath Scanners. At the moment there is my own pure Implementation, which uses ASM to inspect the classes. You can also choose between the Reflections-API or a Guice Extensions which was created by Sonatype.

Reflections has the biggest advantage at the moment, because it scans the classpath in parallel if you have multiple Cores/CPUs. One Problem I figured out is, that the Binder of Guice is not threadsafe. So if you are want to use it in parallel, make sure that you synchronize it.

In the last stage, my extension added the GuiceModule- and AutoBind-Feature by default. Due the fact, that this can have bad behaviors you can now overwrite it. The „bad“ behaviors can result of multiple bindings. If you for example have an automatic installed Guice-Module which binds your class and if the class is annotated with @AutoBind, which would lead to another binding.

The default StartupModule still uses both Features. Create it like that:

StartupModule.create(VirtualClasspathReader.class, "de.devsurf", "net.java.dev.webdav.jaxrs")

StartupModule is an abstract Class, which should be used, if you want to overwrite the used Features. It therefore declares an abstract method „bindAnnotationListeners“.
To bind multiple Implementations we are using the Multibindings Extension for Guice.

So if you only want the automatic Module installation, just bind the GuiceModuleListener:

public class ExampleStartupModule extends StartupModule {
    public ExampleStartupModule(Class<? extends ClasspathScanner> scanner, String... packages) {
        super(scanner, packages);
    }

    @Override
    protected void bindAnnotationListeners() {
        Multibinder<AnnotationListener> listeners = Multibinder.newSetBinder(binder(), AnnotationListener.class);
        listeners.addBinding().to(GuiceModule.GuiceModuleListener.class);
        //listeners.addBinding().to(AutoBind.AutoBindListener.class); //used for Automatic Bean Binding
    }
}

I extended the Examples which can be found on Github Automatic Guice Injection.

Still to go:

  • Maven Release
  • JUnit Tests
  • GIN Release (if possible :)) – Research has to be done.

Today I wanted to share a new Proof-of-Concept of mine.

I’m working for an ECM company, which often faces to create new Integration for customers or in other products. Some months ago I created a http-based Interfaces for a customer. To give it a general touch, I decided to make it highly configurable, so it can be used for more projects.

This led me to the Command- and Chain of Responsibility-Pattern. I created a mechanism to configure the steps, which are taken when a new document should be archived. These Plugins (Java Classes) are annotated, so I can find them at runtime.

You ask yourself now, what does it have to do with Google Guice?

I started the project without Dependency Injection and used Reflections (http://code.google.com/p/reflections/), to scan my Classpath for my plugins. Due the fact that I have vacations and have to look after my son (15 months), I started to investigate a little bit to learn GWT and Guice.

I really like the idea of the Guice ESL to bind all my stuff, but for a project like mine where I need configurable bindings, this doesn’t fit. So I started to search for Classpath Scanners for Guice and found a project created by Sonatype.

This project did exactly what I want. It scans my classpath and informs me about Classes and its annotations. The problem was that just for scanning the footprint was to much and there were some design decisions which I don’t like.

So I created the „Guice Automatic Injection“-Project, with a small Classpath Scanner which uses ASM to load and inspect classes. I also created some interfaces, so I can use Reflections or Sonatype as a Scanner, too.

After a lot of experiments, I found my way how to do it. I created some listeners.

Number 1: Installs all Google Guice Modules, which are annotated with @GuiceModule (mehr …)