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Use Spring’s JavaConfig

Swim, swim, swim

Java Spring configures the String Annotation XML Class Schema bean

Abstract: Previously we defined beans in XML files, such as: 1 2 3 4 5 6 7 8

Previously we defined beans in XML files, such as:

< beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd "> < bean id =" helloBean" class="com.mkyong.hello.impl.HelloWorldImpl"> </ beans>Copy the code

We can use annotations to do this, such as the following code, which does the same thing as the XML configuration above:

import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import com.mkyong.hello.HelloWorld; import com.mkyong.hello.impl.HelloWorldImpl; @Configuration public class AppConfig { @Bean(name= "helloBean") public HelloWorld helloWorld() { return new HelloWorldImpl(); }}Copy the code

Imagine a scenario where we have a large project and if all the beans were configured in an XML file, the file would be very large. So most of the time we split a large XML configuration file into several pieces. This will make it easier to manage. Finally, import into the overall XML file, such as:

< beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd "> < import resource =" XML config/customer. "/ > < import resource="config/scheduler.xml"/> </ beans>Copy the code

But now we can use JavaConfig to do the same thing:

                                                                            

                                                                                                

                                                                                                    

                                                                                                    import 
                                                                                                        org.springframework.context.annotation.Configuration;
                                                                                                    

                                                                                                    

                                                                                                    import 
                                                                                                        org.springframework.context.annotation.Import;
                                                                                                    

                                                                                                    

                                                                                                      

                                                                                                    
@Configuration

                                                                                                    

                                                                                                    @Import
                                                                                                        ({ CustomerConfig.class
                                                                                                            , SchedulerConfig.class 
                                                                                                                })
                                                                                                    

                                                                                                    

                                                                                                    public 
                                                                                                        class AppConfig {                                                                                                            

                                                                                                    

                                                                                                      

                                                                                                    
}

                                                                                                

                                                                                            

                                                                        Copy the code

Let’s take a look at a demo of this example:

CustomerBo.java

public class CustomerBo { public void printMsg(String msg) { System.out.println("CustomerBo : " + msg); }}Copy the code

SchedulerBo.java

public class SchedulerBo { public void printMsg(String msg) { System.out.println("SchedulerBo : " + msg); }}Copy the code

Now let’s use annotations:

@Configuration public class CustomerConfig { @Bean(name= "customer") public CustomerBo customerBo(){ return new CustomerBo(); }}Copy the code

@Configuration public class SchedulerConfig { @Bean(name= "scheduler") public SchedulerBo suchedulerBo(){ return new SchedulerBo(); }}Copy the code

AppConfig.java

                                                                            

                                                                                                

                                                                                                    

                                                                                                    import 
                                                                                                        org.springframework.context.annotation.Configuration;
                                                                                                    

                                                                                                    

                                                                                                    import 
                                                                                                        org.springframework.context.annotation.Import;
                                                                                                    

                                                                                                    

                                                                                                      

                                                                                                    
@Configuration

                                                                                                    

                                                                                                    @Import
                                                                                                        ({ CustomerConfig.class
                                                                                                            , SchedulerConfig.class 
                                                                                                                })
                                                                                                    

                                                                                                    

                                                                                                    public 
                                                                                                        class AppConfig {                                                                                                            

                                                                                                    

                                                                                                      

                                                                                                    
}

                                                                                                

                                                                                            

                                                                        Copy the code

Then run:

public class App { public static void main(String[] args) { ApplicationContext context = new AnnotationConfigApplicationContext( AppConfig.class ); CustomerBo customer = (CustomerBo) context.getBean("customer" ); customer.printMsg("Hello 1" ); SchedulerBo scheduler = (SchedulerBo) context.getBean("scheduler" ); scheduler.printMsg("Hello 2" ); }}Copy the code

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