Spring - 注解驱动开发三切换环境Profile

@Profile注解

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。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。

接口类如下：

• 看一下Javadoc，什么都明白了。

/**
 * Indicates that a component is eligible for registration when one or more
 * {@linkplain #value specified profiles} are active.//看这句看这句看这句看这句
 *
 * 
A profile is a named logical grouping that may be activated
 * programmatically via {@link ConfigurableEnvironment#setActiveProfiles} or declaratively
 * by setting the {@link AbstractEnvironment#ACTIVE_PROFILES_PROPERTY_NAME
 * spring.profiles.active} property as a JVM system property, as an
 * environment variable, or as a Servlet context parameter in {@code web.xml}
 * for web applications. Profiles may also be activated declaratively in
 * integration tests via the {@code @ActiveProfiles} annotation.//这里说了四种方式
 *
 * 
The {@code @Profile} annotation may be used in any of the following ways:
 * 

 * 
as a type-level annotation on any class directly or indirectly annotated with
 * {@code @Component}, including {@link Configuration @Configuration} classes
 * 
as a meta-annotation, for the purpose of composing custom stereotype annotations
 * 
as a method-level annotation on any {@link Bean @Bean} method
 * 
 *
 * 
If a {@code @Configuration} class is marked with {@code @Profile}, all of the
 * {@code @Bean} methods and {@link Import @Import} annotations associated with that class
 * will be bypassed unless one or more of the specified profiles are active. This is
 * analogous to the behavior in Spring XML: if the {@code profile} attribute of the
 * {@code beans} element is supplied e.g., {@code }, the
 * {@code beans} element will not be parsed unless at least profile 'p1' or 'p2' has been
 * activated. Likewise, if a {@code @Component} or {@code @Configuration} class is marked
 * with {@code @Profile({"p1", "p2"})}, that class will not be registered or processed unless
 * at least profile 'p1' or 'p2' has been activated.
 *
 * 
If a given profile is prefixed with the NOT operator ({@code !}), the annotated
 * component will be registered if the profile is not active — for example,
 * given {@code @Profile({"p1", "!p2"})}, registration will occur if profile 'p1' is active
 * or if profile 'p2' is not active.
 *
 * 
If the {@code @Profile} annotation is omitted, registration will occur regardless
 * of which (if any) profiles are active.
 *
 * 
NOTE: With {@code @Profile} on {@code @Bean} methods, a special scenario may
 * apply: In the case of overloaded {@code @Bean} methods of the same Java method name
 * (analogous to constructor overloading), an {@code @Profile} condition needs to be
 * consistently declared on all overloaded methods. If the conditions are inconsistent,
 * only the condition on the first declaration among the overloaded methods will matter.
 * {@code @Profile} can therefore not be used to select an overloaded method with a
 * particular argument signature over another; resolution between all factory methods
 * for the same bean follows Spring's constructor resolution algorithm at creation time.
 * Use distinct Java method names pointing to the same {@link Bean#name bean name}
 * if you'd like to define alternative beans with different profile conditions;
 * see {@code ProfileDatabaseConfig} in {@link Configuration @Configuration}'s javadoc.
 *
 * 
When defining Spring beans via XML, the {@code "profile"} attribute of the
 * {@code } element may be used. See the documentation in the
 * {@code spring-beans} XSD (version 3.1 or greater) for details.
 *
 * @author Chris Beams
 * @author Phillip Webb
 * @author Sam Brannen
 * @since 3.1
 * @see ConfigurableEnvironment#setActiveProfiles
 * @see ConfigurableEnvironment#setDefaultProfiles
 * @see AbstractEnvironment#ACTIVE_PROFILES_PROPERTY_NAME
 * @see AbstractEnvironment#DEFAULT_PROFILES_PROPERTY_NAME
 * @see Conditional
 * @see org.springframework.test.context.ActiveProfiles
 */
@Target({ElementType.TYPE, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Conditional(ProfileCondition.class)
public @interface Profile {

	/**
	 * The set of profiles for which the annotated component should be registered.
	 */
	String[] value();

}

---

总结如下：

① 如果不加@Profile注解，则该bean在任何环境下都被注入；

	@Bean
	public Yellow yellow(){
		return new Yellow();
	}

---

② 如果指定了@Profile，则只有该环境被激活的时候bean才会被注入；

	@Profile("dev")
	@Bean("devDataSource")
	public DataSource dataSourceDev(@Value("${db.password}")String pwd) throws Exception{
		ComboPooledDataSource dataSource = new ComboPooledDataSource();
		dataSource.setUser(user);
		dataSource.setPassword(pwd);
		dataSource.setJdbcUrl("jdbc:mysql://localhost:3306/xian");
		dataSource.setDriverClass(driverClass);
		return dataSource;
	}

---

③ 如果指定了@Profile(“default”)，那么默认环境下bean会被注入；

	@Profile("default")
	@Bean("testDataSource")
	public DataSource dataSourceTest(@Value("${db.password}")String pwd) throws Exception{
		ComboPooledDataSource dataSource = new ComboPooledDataSource();
		dataSource.setUser(user);
		dataSource.setPassword(pwd);
		dataSource.setJdbcUrl("jdbc:mysql://localhost:3306/test");
		dataSource.setDriverClass(driverClass);
		return dataSource;
	}

---

④ 如果@Profile配置于类上，则该类下的bean想起作用，Spring激活的环境首先要与类配置@Profile指定的环境一致，其次再看类中方法上的@Profile注解配置。

@PropertySource("classpath:/dbconfig.properties")
@Profile("dev")
@Configuration
public class MainConfigOfProfile implements EmbeddedValueResolverAware{
	
	@Value("${db.user}")
	private String user;
	
	private StringValueResolver valueResolver;
	
	private String  driverClass;
	
	@Bean
	public Yellow yellow(){
		return new Yellow();
	}
	
	@Profile("default")
//	@Profile("test")
	@Bean("testDataSource")
	public DataSource dataSourceTest(@Value("${db.password}")String pwd) throws Exception{
		ComboPooledDataSource dataSource = new ComboPooledDataSource();
		dataSource.setUser(user);
		dataSource.setPassword(pwd);
		dataSource.setJdbcUrl("jdbc:mysql://localhost:3306/test");
		dataSource.setDriverClass(driverClass);
		return dataSource;
	}
	
	@Profile("dev")
	@Bean("devDataSource")
	public DataSource dataSourceDev(@Value("${db.password}")String pwd) throws Exception{
		ComboPooledDataSource dataSource = new ComboPooledDataSource();
		dataSource.setUser(user);
		dataSource.setPassword(pwd);
		dataSource.setJdbcUrl("jdbc:mysql://localhost:3306/xian");
		dataSource.setDriverClass(driverClass);
		return dataSource;
	}
}

---

激活环境的几种方式

① 虚拟机参数

---

② 代码激活

@Test
	public void test01(){
		//1、创建一个applicationContext
		AnnotationConfigApplicationContext applicationContext = 
				new AnnotationConfigApplicationContext();
		//2、设置需要激活的环境
		applicationContext.getEnvironment().setActiveProfiles("dev");
		//3、注册主配置类
		applicationContext.register(MainConfigOfProfile.class);
		//4、启动刷新容器
		applicationContext.refresh();
		
		String[] namesForType = applicationContext.getBeanNamesForType(DataSource.class);
		for (String string : namesForType) {
			System.out.println(string);
		}
		
		Yellow bean = applicationContext.getBean(Yellow.class);
		System.out.println(bean);
		applicationContext.close();
	}

---

③ web.xml

 
  
       spring.profiles.default
       dev
   

 
       appServlet
       org.springframework.web.servlet.DispatcherServlet
       
       
	       spring.profiles.default
	       dev
       
       1