Detailed explanation of @Profile annotation

package com.spring.config;
 
import java.beans.PropertyVetoException;
 
import javax.sql.DataSource;
 
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.EmbeddedValueResolverAware;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Profile;
import org.springframework.context.annotation.PropertySource;
import org.springframework.util.StringValueResolver;
 
import com.mchange.v2.c3p0.ComboPooledDataSource;
 
/**
 * Profile:
 * 		Spring为我们提供的可以根据当前环境，动态的激活和切换一系列组件的功能；
 * 
 * 开发环境develop、测试环境test、生产环境master
 * 数据源：(/dev) (/test) (/master)
 *
 * @Profile:指定组件在哪个环境的情况下才能被注册到容器中，不指定，任何环境下都能注册这个组件
 * 
 * 1) 加了环境标识的bean，只有这个环境被激活的时候才能注册到容器中。默认是default环境
 * 2) 写在配置类上，只有是指定的环境的时候，整个配置类里面的所有配置才能开始生效
 * 
 */
@PropertySource("classpath:/dbconfig.properties")
@Configuration
public class MainConfigOfProfile implements EmbeddedValueResolverAware{
	
	@Value("${db.user}")
	private String user;
	
	private String driverClass;
	
	@Profile("default")
	@Bean("test")
	public DataSource testDataSource(@Value("${db.password}")String password) throws PropertyVetoException {
		ComboPooledDataSource dataSource = new ComboPooledDataSource();
		dataSource.setUser(user);
		dataSource.setPassword(password);
		dataSource.setDriverClass(driverClass);
		return dataSource;
	}
	
	@Profile("dev")
	@Bean("dev")
	public DataSource devDataSource(@Value("${db.password}")String password) throws PropertyVetoException {
		ComboPooledDataSource dataSource = new ComboPooledDataSource();
		dataSource.setUser(user);
		dataSource.setPassword(password);
		dataSource.setDriverClass(driverClass);
		return dataSource;
	}
	
	@Profile("master")
	@Bean("master")
	public DataSource masterDataSource(@Value("${db.password}")String password) throws PropertyVetoException {
		ComboPooledDataSource dataSource = new ComboPooledDataSource();
		dataSource.setUser(user);
		dataSource.setPassword(password);
		dataSource.setDriverClass(driverClass);
		return dataSource;
	}
 
	public void setEmbeddedValueResolver(StringValueResolver resolver) {
		String driverClass = resolver.resolveStringValue("${db.driverClass}");
		this.driverClass = driverClass;
	}
 
}

package com.spring.test;
 
import java.util.Arrays;
 
import javax.sql.DataSource;
 
import org.junit.Test;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 
import com.spring.config.MainConfigOfProfile;
 
 
public class IOCTestProfile {
	//1. 使用命令行动态参数：在虚拟机参数位置加载 -Dspring.profiles.active=test
	//2. 使用代码的方式激活某种环境；
	@Test
	public void test01() {
		AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(MainConfigOfProfile.class);
		//1. 创建一个applicationContext
		//2. 设置需要激活的环境
		applicationContext.getEnvironment().setActiveProfiles("dev","master");
		//3. 注册主配置类
		applicationContext.register(MainConfigOfProfile.class);
		//4. 启动刷新容器
		applicationContext.refresh();
		
		String[] beanNamesForType = applicationContext.getBeanNamesForType(DataSource.class);
		System.out.println(Arrays.toString(beanNamesForType));
		
		applicationContext.close();
	}
 
 
        @Test
	public void test02() {
		AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(MainConfigOfProfile.class);
		
		String[] beanNamesForType = applicationContext.getBeanNamesForType(DataSource.class);
		System.out.println(Arrays.toString(beanNamesForType));
		
		applicationContext.close();
	}
}