[Translate]17-spring Java code-based configuration metadata

Spring also supports Java code-based configuration metadata. But this is a less common approach, but there are some people who use it. So it is necessary to introduce.

Spring is based on Java code Configuration metadata, which can be declared as a configuration class by @configuration annotations, and a new one through the @bean annotations

The classes that are created are managed by the spring container. In this configuration, we can assemble the beans manually, or we can assemble the beans automatically. I feel this way.

Use manual assembly in the same way, especially when there are multiple configuration classes.

Let's look at an example:

1. Create a new package Com.tutorialspoint.javacode and create a new Texteditor.java, Spellchecker.java, Highlighter.java in the package

//Texteditor.java PackageCom.tutorialspoint.javacode;ImportJavax.annotation.Resource; Public classTextEditor {Privatespellchecker spellchecker; Privatehighlighter highlighter; @Resource Public voidsethighlighter (highlighter highlighter) { This. Highlighter =highlighter; } @Resource Public voidSetspellchecker (spellchecker spellchecker) { This. Spellchecker =spellchecker; }         PublicTextEditor () {} PublicTextEditor (spellchecker spellchecker) { This. spellchecker=spellchecker; }     PublicTextEditor (highlighter highlighter) { This. highlighter=highlighter; }         Public voidinit () {System.out.println ("Init method invoked ..."); }     Public voiddestroy () {System.out.println ("Destroy method invoked ..."); }         Public voidprint () {System.out.println ("Spellchecker:" +spellchecker); System.out.println ("Highlighter:" +highlighter); }    }//Spellchecker.java PackageCom.tutorialspoint.javacode; Public classSpellchecker { Public voidCheckspell () {System.out.println ("Checking ..."); }}//Highlighter.java PackageCom.tutorialspoint.javacode; Public classHighlighter { Public voidHighlight () {System.out.println ("Highlighting ..."); }}

2. Create the following three configuration classes in package Com.tutorialspoint.javacode:

//Appconfig.java PackageCom.tutorialspoint.javacode;ImportOrg.springframework.context.annotation.Bean;Importorg.springframework.context.annotation.Configuration;ImportOrg.springframework.context.annotation.Import;/*** Use @Configuration annotations to indicate that a class belongs to a configuration class * You can introduce additional configuration classes through @import annotations. * */@Configuration @import (value={spellcheckerconfig.class, Highlighterconfig.class}) Public classAppConfig {/*** You can specify the bean's name in the spring container by using the Name property of the @bean annotation * Use the Initmethod property to specify the bean's initialization method * Use the Destroymethod property to specify the Bean's Destruction method */@Bean (Name= "TextEditor", initmethod= "Init", destroymethod= "destroy")     Publictexteditor TextEditor () {return NewTextEditor (); }    }//Highlighterconfig.java PackageCom.tutorialspoint.javacode;ImportOrg.springframework.context.annotation.Bean;Importorg.springframework.context.annotation.Configuration; @Configuration Public classhighlighterconfig {@Bean (name= "Highlighter")     PublicHighlighter highlighter () {return Newhighlighter (); }}//Spellcheckerconfig.java PackageCom.tutorialspoint.javacode;ImportOrg.springframework.context.annotation.Bean;Importorg.springframework.context.annotation.Configuration; @Configuration Public classspellcheckerconfig {@Bean (name= "Spellchecker")     Publicspellchecker spellchecker () {return Newspellchecker (); }        }

3. Create a new Mainapp.java in the package Com.tutorialspoint.javacode. The contents are as follows:

 PackageCom.tutorialspoint.javacode;ImportOrg.springframework.context.annotation.AnnotationConfigApplicationContext;ImportOrg.springframework.context.support.AbstractApplicationContext; Public classMainapp { Public Static voidMain (string[] args) {//Java code-based implementation class for a container to use AnnotationconfigapplicationcontextAbstractapplicationcontext CTX =NewAnnotationconfigapplicationcontext (AppConfig.class); TextEditor te= (TextEditor) Ctx.getbean (texteditor.class);                Te.print (); //registers the JVM's exit event in order for the Bean's Destroy method to workCtx.registershutdownhook (); }}

4. Run the program and check the results:

However, Java code-based configuration metadata does not support automatic dependency injection of constructor parameters, and constructor parameters must be assembled manually.

[Translate]17-spring Java code-based configuration metadata