Spring5参考指南:Environment

public interface Environment extends PropertyResolver {

  /**
   * Return the set of profiles explicitly made active for this environment. Profiles
   * are used for creating logical groupings of bean definitions to be registered
   * conditionally, for example based on deployment environment. Profiles can be
   * activated by setting {@linkplain AbstractEnvironment#ACTIVE_PROFILES_PROPERTY_NAME
   * "spring.profiles.active"} as a system property or by calling
   * {@link ConfigurableEnvironment#setActiveProfiles(String...)}.
   * <p>If no profiles have explicitly been specified as active, then any
   * {@linkplain #getDefaultProfiles() default profiles} will automatically be activated.
   * @see #getDefaultProfiles
   * @see ConfigurableEnvironment#setActiveProfiles
   * @see AbstractEnvironment#ACTIVE_PROFILES_PROPERTY_NAME
   */
  String[] getActiveProfiles();

  /**
   * Return the set of profiles to be active by default when no active profiles have
   * been set explicitly.
   * @see #getActiveProfiles
   * @see ConfigurableEnvironment#setDefaultProfiles
   * @see AbstractEnvironment#DEFAULT_PROFILES_PROPERTY_NAME
   */
  String[] getDefaultProfiles();

  /**
   * Return whether one or more of the given profiles is active or, in the case of no
   * explicit active profiles, whether one or more of the given profiles is included in
   * the set of default profiles. If a profile begins with '!' the logic is inverted,
   * i.e. the method will return {@code true} if the given profile is <em>not</em> active.
   * For example, {@code env.acceptsProfiles("p1", "!p2")} will return {@code true} if
   * profile 'p1' is active or 'p2' is not active.
   * @throws IllegalArgumentException if called with zero arguments
   * or if any profile is {@code null}, empty, or whitespace only
   * @see #getActiveProfiles
   * @see #getDefaultProfiles
   * @see #acceptsProfiles(Profiles)
   * @deprecated as of 5.1 in favor of {@link #acceptsProfiles(Profiles)}
   */
  @Deprecated
  boolean acceptsProfiles(String... profiles);

  /**
   * Return whether the {@linkplain #getActiveProfiles() active profiles}
   * match the given {@link Profiles} predicate.
   */
  boolean acceptsProfiles(Profiles profiles);

}

public interface PropertyResolver {

  /**
   * Return whether the given property key is available for resolution,
   * i.e. if the value for the given key is not {@code null}.
   */
  boolean containsProperty(String key);

  /**
   * Return the property value associated with the given key,
   * or {@code null} if the key cannot be resolved.
   * @param key the property name to resolve
   * @see #getProperty(String, String)
   * @see #getProperty(String, Class)
   * @see #getRequiredProperty(String)
   */
  @Nullable
  String getProperty(String key);

  /**
   * Return the property value associated with the given key, or
   * {@code defaultValue} if the key cannot be resolved.
   * @param key the property name to resolve
   * @param defaultValue the default value to return if no value is found
   * @see #getRequiredProperty(String)
   * @see #getProperty(String, Class)
   */
  String getProperty(String key, String defaultValue);

  /**
   * Return the property value associated with the given key,
   * or {@code null} if the key cannot be resolved.
   * @param key the property name to resolve
   * @param targetType the expected type of the property value
   * @see #getRequiredProperty(String, Class)
   */
  @Nullable
  <T> T getProperty(String key, Class<T> targetType);

  /**
   * Return the property value associated with the given key,
   * or {@code defaultValue} if the key cannot be resolved.
   * @param key the property name to resolve
   * @param targetType the expected type of the property value
   * @param defaultValue the default value to return if no value is found
   * @see #getRequiredProperty(String, Class)
   */
  <T> T getProperty(String key, Class<T> targetType, T defaultValue);

  /**
   * Return the property value associated with the given key (never {@code null}).
   * @throws IllegalStateException if the key cannot be resolved
   * @see #getRequiredProperty(String, Class)
   */
  String getRequiredProperty(String key) throws IllegalStateException;

  /**
   * Return the property value associated with the given key, converted to the given
   * targetType (never {@code null}).
   * @throws IllegalStateException if the given key cannot be resolved
   */
  <T> T getRequiredProperty(String key, Class<T> targetType) throws IllegalStateException;

  /**
   * Resolve ${...} placeholders in the given text, replacing them with corresponding
   * property values as resolved by {@link #getProperty}. Unresolvable placeholders with
   * no default value are ignored and passed through unchanged.
   * @param text the String to resolve
   * @return the resolved String (never {@code null})
   * @throws IllegalArgumentException if given text is {@code null}
   * @see #resolveRequiredPlaceholders
   * @see org.springframework.util.SystemPropertyUtils#resolvePlaceholders(String)
   */
  String resolvePlaceholders(String text);

  /**
   * Resolve ${...} placeholders in the given text, replacing them with corresponding
   * property values as resolved by {@link #getProperty}. Unresolvable placeholders with
   * no default value will cause an IllegalArgumentException to be thrown.
   * @return the resolved String (never {@code null})
   * @throws IllegalArgumentException if given text is {@code null}
   * or if any placeholders are unresolvable
   * @see org.springframework.util.SystemPropertyUtils#resolvePlaceholders(String, boolean)
   */
  String resolveRequiredPlaceholders(String text) throws IllegalArgumentException;

}

@Configuration
@Profile("development")
public class StandaloneDataConfig {

    @Bean
    public DataSource dataSource() {
        return new EmbeddedDatabaseBuilder()
                .setType(EmbeddedDatabaseType.HSQL)
                .addScript("classpath:com/bank/config/sql/schema.sql")
                .addScript("classpath:com/bank/config/sql/test-data.sql")
                .build();
    }
}

@Configuration
@Profile("production")
public class JndiDataConfig {

    @Bean(destroyMethod="")
    public DataSource dataSource() throws Exception {
        Context ctx = new InitialContext();
        return (DataSource) ctx.lookup("java:comp/env/jdbc/datasource");
    }
}

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Profile("production")
public @Interface Production {
}

@Configuration
public class AppConfig {

    @Bean("dataSource")
    @Profile("development") 
    public DataSource standaloneDataSource() {
        return new EmbeddedDatabaseBuilder()
            .setType(EmbeddedDatabaseType.HSQL)
            .addScript("classpath:com/bank/config/sql/schema.sql")
            .addScript("classpath:com/bank/config/sql/test-data.sql")
            .build();
    }

    @Bean("dataSource")
    @Profile("production") 
    public DataSource jndiDataSource() throws Exception {
        Context ctx = new InitialContext();
        return (DataSource) ctx.lookup("java:comp/env/jdbc/datasource");
    }
}

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:jdbc="http://www.springframework.org/schema/jdbc"
    xmlns:jee="http://www.springframework.org/schema/jee"
    xsi:schemaLocation="...">

    <!-- other bean definitions -->

    <beans profile="development">
        <jdbc:embedded-database id="dataSource">
            <jdbc:script location="classpath:com/bank/config/sql/schema.sql"/>
            <jdbc:script location="classpath:com/bank/config/sql/test-data.sql"/>
        </jdbc:embedded-database>
    </beans>

    <beans profile="production">
        <jee:jndi-lookup id="dataSource" jndi-name="java:comp/env/jdbc/datasource"/>
    </beans>
</beans>

public static void main(String[] args) {
        AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
        ctx.getEnvironment().setActiveProfiles("development");
        ctx.register(AppConfig.class, StandaloneDataConfig.class, JndiDataConfig.class);
        ctx.refresh();
    }

@Configuration
@Profile("default")
public class DefaultDataConfig {

    @Bean
    public DataSource dataSource() {
        return new EmbeddedDatabaseBuilder()
            .setType(EmbeddedDatabaseType.HSQL)
            .addScript("classpath:com/bank/config/sql/schema.sql")
            .build();
    }
}

public static void main(String[] args) {
        ApplicationContext ctx = new GenericApplicationContext();
        Environment env = ctx.getEnvironment();
        boolean containsMyProperty = env.containsProperty("my-property");
        System.out.println("Does my environment contain the 'my-property' property? " + containsMyProperty);
    }

/** System environment property source name: {@value}. */
  public static final String SYSTEM_ENVIRONMENT_PROPERTY_SOURCE_NAME = "systemEnvironment";

  /** JVM system properties property source name: {@value}. */
  public static final String SYSTEM_PROPERTIES_PROPERTY_SOURCE_NAME = "systemProperties";

@Configuration
@PropertySource("classpath:app.properties")
public class PropertiesConfig {


    @Autowired
    Environment env;

    @Bean
    public TestBean testBean() {
        TestBean testBean = new TestBean();
        testBean.setName(env.getProperty("testbean.name"));
        return testBean;
    }
}

@PropertySource("classpath:/com/${my.placeholder:default/path}/app.properties")