09 - Working with Java Based Configuration/001 Java Based Config_en.srt

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(gentle music)

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-: So till this point we were able to create a project,

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the spring project, with the help of XML configuration.

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So whatever beans we want Spring to manage,

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we were doing that in the XML file.

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And XML file was your spring.xml, right?

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Of course this name can change.

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The only thing you have to change then is this thing,

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you know in the ClassPathXmlApplicationContext,

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you have to mention that we are not working with spring.xml.

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We are working with some other name, but that's fine.

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We can go with a name.

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But now, let's say we don't want to use xml.

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A lot of people are not a big fan of XML,

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so they prefer to go for Java configuration.

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So yes, for the Spring you can do this configuration

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using Java code, that's right.

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So if you are happy with XML, continue with that.

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If you are not happy with XML,

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you can try out the Java based configuration.

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Sometime you don't have a choice when you join a project

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and if they're using XML, you have to use XML.

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If they're using Java based configuration,

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you have to use Java based.

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We have one more way,

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which is the annotation based configuration,

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which we'll do later.

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But let's see, how do you work

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with the Java based configuration?

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So what we do is the first thing if we change is

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we don't want to use the XML approach

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we want to use a Java approach.

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So of course for that you need a a file, a Java class.

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So what I'll do is in this package I will right click

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and I will say, hey, I want to create a new class.

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In fact, first let me create a new package called config.

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So the config file will go in this.

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And inside this config package,

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I will rightly can say new Java class

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and let me create a Java class as let's say AppConfig.

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Again, name doesn't matter, you can give any name.

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But let me go for AppConfig, user enter.

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So you can see we got AppConfig file here

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and now what we are going to do with this?

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So this is going to replace your XML configuration, right?

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So of course if you don't want to use this,

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I'm not going to delete this from the project.

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If you want to use it, I will just keep this file there.

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I will just close this or maybe I will just keep it open

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so that we can refer.

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Go back to your App.java. This is where things will change.

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So we don't want to go for this approach.

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What I will do is I will just comment everything here.

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In fact, first let me just uncomment this, yeah.

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So let me comment everything

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and let's do our coding on top here.

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So if I go back up, imagine we don't have any of this code,

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it's just that for your reference, I'm keeping it there.

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But here, let me create object of application context

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or the reference of application context,

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I would say context is equal to new.

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Now instead of using the XML approach,

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we are going for a Java based approach.

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For that we have to use a class

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which is called AnnotationConfigApplicationContext,

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let's go with this.

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And in this particular constructor

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you have to pass a name of your config file,

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which is AppConfig.class.

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The only thing is

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you have to basically import the package for this

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and package importing done.

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So, in both the cases, even if you're using XML,

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even if you're using a Java based configuration,

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you are basically using the same container,

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but the way you talk to a container changes.

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So here we were using XML way of talking to the containers,

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here we are using Java based configuration.

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Now how do we do the configuration? That's a real question.

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Okay, so what we will do is

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let's create the object or let's use the object for a class.

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Now let's not use Alien

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because Alien is dependent upon computers,

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so we have to do multiple things.

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Let's work with desktop because if you look at desktop,

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it's a independent class like laptop as well.

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So, let me create the instance for desktop.

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So I will say desktop, I will say des,

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or maybe I'll say dt is equal to,

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instead of saying new, I want to say context.getBean.

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And I want to say I want the object of the desktop.class.

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That's it.

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So I want this to work.

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And once you've got the object, I can also print something.

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I can call the method, which is compile.

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So it it should print something.

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If you run this code, let's see what happens.

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The moment you run this code, you got an error.

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The error is no qualifying bean of type desktop available.

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Of course, right?

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Now we are not using a XML configuration.

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We are using Java based configuration

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and in this file we did nothing.

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That's weird, right?

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So if you want to make this work,

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the first thing you will do is you will use annotation,

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which is called configuration.

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So if you want to configure your application

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or if you want to configure

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with the help of Java based configuration

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we have to make your config class

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with annotation called add configuration.

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That's one.

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What next?

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We have one more tag

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or one more annotation which we have to use, which is bean.

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So in the XML, we were using bean tag.

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Here we are going to use the bean annotation.

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Okay, so what do you want? You want desktops.

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I will just go back here, say desktop.

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I mean I want the object for desktops.

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I will say public, Desktop. And I will say desktop.

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I want the object for desktop, right?

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We have to import the package, let's do that, okay.

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Now since this is a Java based configuration,

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we have to manually create the object, okay?

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So you will say return new desktop, that's it.

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Now you'll be saying, hey, you know,

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by using new keyword, we are cutting the object.

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The thing about this, yes, we are writing this code here,

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but then we are not injecting the object, right?

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Spring is injecting it.

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So who will call this particular method? Spring.

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Who will manage the object? Spring.

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We are not doing it,

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we are just writing a code by saying new desktop.

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But all this thing will be created, injected,

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and managed by Spring framework.

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That's something you have to remember.

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Okay, so once we have done this,

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the only thing you have to do here

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is we have to add an annotation called bean.

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So if you want your spring framework to create the object,

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you have to use add bean.

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Now this is similar to what we have done in the XML.

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In the XML also we are reading bean tag, right?

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The same thing we have done here.

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We just shared using bean annotation.

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And now let's see if this works.

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Let's go back here, let's rerun and it works.

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You can see it says compiling using desktop.

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So what we have done is instead of using XML approach,

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we are using the Java approach.

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Even if we have this confusion still till now

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that we are creating our own object here.

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See we are just writing this code,

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but this will be executed by Spring,

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creating, injecting, managed by spring framework.

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So we are not manually doing it.

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Okay? So the approach which we have used here

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is we are looking for the desktop class.

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We are not specified the name of a bean,

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we are looking for the type of the bean, which is desktop.

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So it is looking for the desktop bean and it call it.

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That's how we use the Java based configuration

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with the help of this particular class here.

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Now what if you want to use a bean name?

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As of now you can see

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nowhere we have mentioned the be name.

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So what is a bean name and how do we change it?

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Let's see that in the next video.