public class PropertySourcesPropertyResolver extends AbstractPropertyResolver {

    ...

    @Nullable

    private final PropertySources propertySources; //内部持有一组PropertySource

​

    // 由此可以看出propertySources的顺序很重要~~~

    // 并且还能处理占位符~~~~~ resolveNestedPlaceholders支持内嵌、嵌套占位符

    @Nullable

    protected <T> T getProperty(String key, Class<T> targetValueType, boolean resolveNestedPlaceholders) {

        if (this.propertySources != null) {

            for (PropertySource<?> propertySource : this.propertySources) {

                Object value = propertySource.getProperty(key);

                if (value != null) {

                    if (resolveNestedPlaceholders && value instanceof String) {

                        value = resolveNestedPlaceholders((String) value);

                    }

                    logKeyFound(key, propertySource, value);

                    return convertValueIfNecessary(value, targetValueType);

                }

            }

        }

        return null;

    }

    ...

}

​

public abstract class AbstractPropertyResolver implements ConfigurablePropertyResolver {

    ...

​

    @Nullable

    private volatile ConfigurableConversionService conversionService;

​

    @Nullable

    private PropertyPlaceholderHelper nonStrictHelper;

​

    @Nullable

    private PropertyPlaceholderHelper strictHelper;

​

    private boolean ignoreUnresolvableNestedPlaceholders = false;

​

    private String placeholderPrefix = SystemPropertyUtils.PLACEHOLDER_PREFIX;

​

    private String placeholderSuffix = SystemPropertyUtils.PLACEHOLDER_SUFFIX;

​

    @Nullable

    private String valueSeparator = SystemPropertyUtils.VALUE_SEPARATOR;

​

    private final Set<String> requiredProperties = new LinkedHashSet<>();

    ...

}

​

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 true if the given profile is <em>not</em> active.

     * For example, <pre class="code">env.acceptsProfiles("p1", "!p2")</pre> 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

     */

    boolean acceptsProfiles(String... profiles);

​

}

public interface ConfigurableEnvironment extends Environment, ConfigurablePropertyResolver {

    // 指定该环境下的 profile 集

    void setActiveProfiles(String... profiles);

    // 增加此环境的 profile

    void addActiveProfile(String profile);

    // 设置默认的 profile

    void setDefaultProfiles(String... profiles);

    // 返回此环境的 PropertySources

    MutablePropertySources getPropertySources();

    // 尝试返回 System.getenv() 的值，若失败则返回通过 System.getenv(string) 的来访问各个键的映射

    Map<String, Object> getSystemEnvironment();

    // 尝试返回 System.getProperties() 的值，若失败则返回通过 System.getProperties(string) 的来访问各个键的映射

    Map<String, Object> getSystemProperties();

    void merge(ConfigurableEnvironment parent);

}

public abstract class AbstractEnvironment implements ConfigurableEnvironment {

    public static final String IGNORE_GETENV_PROPERTY_NAME = "spring.getenv.ignore";

​

    // 请参考：ConfigurableEnvironment#setActiveProfiles

    public static final String ACTIVE_PROFILES_PROPERTY_NAME = "spring.profiles.active";

    // 请参考：ConfigurableEnvironment#setDefaultProfiles

    public static final String DEFAULT_PROFILES_PROPERTY_NAME = "spring.profiles.default";

​

​

    private final Set<String> defaultProfiles = new LinkedHashSet<>(getReservedDefaultProfiles());

    // 默认的profile名称

    protected static final String RESERVED_DEFAULT_PROFILE_NAME = "default";

    ...

​

​

    protected Set<String> doGetActiveProfiles() {

        synchronized (this.activeProfiles) {

            if (this.activeProfiles.isEmpty()) {

                String profiles = getProperty(ACTIVE_PROFILES_PROPERTY_NAME);

                if (StringUtils.hasText(profiles)) {

                    setActiveProfiles(StringUtils.commaDelimitedListToStringArray(

                            StringUtils.trimAllWhitespace(profiles)));

                }

            }

            return this.activeProfiles;

        }

    }

    ...

}

@Target({ElementType.TYPE, ElementType.METHOD})

@Retention(RetentionPolicy.RUNTIME)

@Documented

@Conditional(ProfileCondition.class)

public @interface Profile {

​

    String[] value();

​

}

class ProfileCondition implements Condition {

​

    @Override

    public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {

        // 因为value值是个数组，所以此处有多个值 用的MultiValueMap

        MultiValueMap<String, Object> attrs = metadata.getAllAnnotationAttributes(Profile.class.getName());

        if (attrs != null) {

            for (Object value : attrs.get("value")) {

                // 多个值中，但凡只要有一个acceptsProfiles了，那就返回true~

                if (context.getEnvironment().acceptsProfiles(Profiles.of((String[]) value))) {

                    return true;

                }

            }

            return false;

        }

        return true;

    }

​

}