1.装配进阶
1)environment-specific bean
@profile
@Configuration
public class DataSourceConfig {
@Bean(destroyMethod="shutdown")
@Profile("dev")
public DataSource embeddedDataSource() {
return new EmbeddedDatabaseBuilder()
.setType(EmbeddedDatabaseType.H2)
.addScript("classpath:schema.sql")
.addScript("classpath:test-data.sql")
.build();
}
@Bean
@Profile("prod")
public DataSource jndiDataSource() {
JndiObjectFactoryBean jndiObjectFactoryBean =
new JndiObjectFactoryBean();
jndiObjectFactoryBean.setJndiName("jdbc/myDS");
jndiObjectFactoryBean.setResourceRef(true);
jndiObjectFactoryBean.setProxyInterface(javax.sql.DataSource.class);
return (DataSource) jndiObjectFactoryBean.getObject();
}
}
2）conditioinal beans
@Conditional
@Bean
@Conditional(MagicExistsCondition.class)
public MagicBean magicBean() {
return new MagicBean();
}
3）ambiguity in autowiring
autowiring works when exactly one bean matches the disired result.
@ Primary--- designating a primary bean
@Qualifier("beanid")
4)Scoping beans
在spring的应用上下文中，所有的bean都是单例的
@Scope(ConfigurableBeanFactory.SCOPE_PROTOTYPE)
? Singleton—One instance of the bean is created for the entire application.
? Prototype—One instance of the bean is created every time the bean is injected
into or retrieved from the Spring application context.
? Session—In a web application, one instance of the bean is created for each session.
? Request—In a web application, one instance of the bean is created for each
request.
5）runtime value injection
@Configuration
@PropertySource("classpath:/com/soundsystem/app.properties")
public class ExpressiveConfig {
@Autowired
Environment env;
@Bean
public BlankDisc disc() {
return new BlankDisc(
env.getProperty("disc.title"),
env.getProperty("disc.artist"));
}}
6) wiring with Spring Expression Language(SpEL)
#{}