Three kinds of configuration mode (006) AnnotationConfigApplicationContext of the spring

　　AnnotationConfigApplicationContext spring is constructed in the context of the spring utilized for annotation class configuration.

　　The first way: constructor passing one or more classes. Annotations can be a class, can also be a general category, the incoming class will be included in the spring container. as follows:

　　pom.xml

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.edu.spring</groupId>
    <artifactId>spring</artifactId>
    <version>1.0.0</version>

    <name>spring</name>
    <!-- FIXME change it to the project's website -->
    <url>http://www.example.com</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>
    
    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>4.3.2.RELEASE</version>
        </dependency>
    </dependencies>

</project>

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　　User.java、Cat.java、Dog.java、UserDao.java、UserService.java、MyConfig.java如下：

package com.edu.spring;

public class User {

}


package com.edu.spring;

public class Cat {

}


package com.edu.spring;

public class Dog {

}


package com.edu.spring;

import org.springframework.stereotype.Component;

@Component
public class UserDao {

}


package com.edu.spring;

import org.springframework.context.annotation.Bean;
import org.springframework.stereotype.Service;

@Service
public class UserService {
    
    @Bean
    public Cat createCat(){
        return new Cat();
    }
}


package com.edu.spring;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class MyConfig {
    
    @Bean
    public Dog createDog(){
        return new Dog();
    }
}

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　　App.java

package com.edu.spring;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;


public class App 
{
    public static void main( String[] args )
    {
        AnnotationConfigApplicationContext context=new AnnotationConfigApplicationContext(User.class,UserDao.class,UserService.class,MyConfig.class);
        System.out.println(context.getBean(User.class));
        System.out.println(context.getBean(Cat.class));
        System.out.println(context.getBean(Dog.class));
        System.out.println(context.getBean(UserDao.class));
        System.out.println(context.getBean(UserService.class));
        System.out.println(context.getBean(MyConfig.class));
        context.close();
        
    }
}

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　　Results are as follows:

 　　The second way: the constructor pass a package name, the class will be created under the package bean, the container and into the spring

　　App.java, User.class not annotated, does not create bean

package com.edu.spring;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;


public class App 
{
    public static void main( String[] args )
    {
        AnnotationConfigApplicationContext context=new AnnotationConfigApplicationContext("com.edu.spring");
       // System.out.println(context.getBean(User.class));
        System.out.println(context.getBean(Cat.class));
        System.out.println(context.getBean(Dog.class));
        System.out.println(context.getBean(UserDao.class));
        System.out.println(context.getBean(UserService.class));
        System.out.println(context.getBean(MyConfig.class));
        context.close();
        
    }
}

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　　Results are as follows:

 　　The third way: passing a constructor added @ComponentScan annotated class, which indicates the scanning annotation packages and classes excluded

　　AnnotationScan.java

package com.edu.spring;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.ComponentScan.Filter;
import org.springframework.context.annotation.FilterType;

@ComponentScan(basePackages="com.edu.spring",
               excludeFilters=@Filter(type=FilterType.ASSIGNABLE_TYPE,classes={MyConfig.class,UserService.class}))
public class AnnotationScan {

}

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　　App.java code written off classes are not created bean, since ruled out

package com.edu.spring;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;


public class App 
{
    public static void main( String[] args )
    {
        AnnotationConfigApplicationContext context=new AnnotationConfigApplicationContext(AnnotationScan.class);
        //System.out.println(context.getBean(User.class));
        //System.out.println(context.getBean(Cat.class));
        //System.out.println(context.getBean(Dog.class));
        System.out.println(context.getBean(UserDao.class));
        //System.out.println(context.getBean(UserService.class));
        //System.out.println(context.getBean(MyConfig.class));
        context.close();
        
    }
}

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　　Results are as follows: