UiApplicationContextUtils：用于UI应用程序上下文实现的实用程序类。提供对名为’themeSource’ 的特殊Bean的支持，该Bean类型为 themeSource
/**
* Utility class for UI application context implementations.
* Provides support for a special bean named "themeSource",
* of type {@link org.springframework.ui.context.ThemeSource}.
* <p>用于UI应用程序上下文实现的实用程序类。提供对名为'themeSource'
* 的特殊Bean的支持，该Bean类型为 themeSource</p>
*
* @author Jean-Pierre Pawlak
* @author Juergen Hoeller
* @since 17.06.2003
*/
public abstract class UiApplicationContextUtils {
/**
* Name of the ThemeSource bean in the factory.
* If none is supplied, theme resolution is delegated to the parent.
* @see org.springframework.ui.context.ThemeSource
*/
public static final String THEME_SOURCE_BEAN_NAME = "themeSource";
private static final Log logger = LogFactory.getLog(UiApplicationContextUtils.class);
/**
* Initialize the ThemeSource for the given application context,
* autodetecting a bean with the name "themeSource". If no such
* bean is found, a default (empty) ThemeSource will be used.
* <p>初始化给定应用程序上下文的 ThemeSource,自动检查名为 'ThemeSource'的
* bean。如果没有找到这样的Bean，将使用默认的'空'主题源</p>
* @param context current application context -- 当前应用程序上下文
* @return the initialized theme source (will never be {@code null})
* -- 初始化的主题源文件(永远不会为 null )
* @see #THEME_SOURCE_BEAN_NAME
*/
public static ThemeSource initThemeSource(ApplicationContext context) {
//ThemeSource：接口，由能够解决主题的对象实现。这使得给定'Theme'的消息能够参数化和国际化
//如果context的BeanFactory包含'themeSource'的bean，忽略父工厂
if (context.containsLocalBean(THEME_SOURCE_BEAN_NAME)) {
//从beanFactory中获取名为 themeSource 的 ThemeSource 类型的Bean对象
ThemeSource themeSource = context.getBean(THEME_SOURCE_BEAN_NAME, ThemeSource.class);
// Make ThemeSource aware of parent ThemeSource.
// 使 ThemeSource 知道 父ThemeSource
// HierarchicalThemeSource:主题源的子接口，由能够分层解决主题消息的对象实现
//如果context的父级上下文是ThemeSource对象 && themeSource 是 HierarchicalThemeSource 对象
if (context.getParent() instanceof ThemeSource && themeSource instanceof HierarchicalThemeSource) {
//将themeSource强转为 HierarchicalThemeSource 对象
HierarchicalThemeSource hts = (HierarchicalThemeSource) themeSource;
//如果 hts 的父级ThemeSource为null
if (hts.getParentThemeSource() == null) {
// Only set parent context as parent ThemeSource if no parent ThemeSource
// registered already.
// 如果没有父ThemeSource已经注册，只能将父上下文设置为父主题资源
//将父级上下文作为hts的父级ThemeSource
hts.setParentThemeSource((ThemeSource) context.getParent());
}
}
//如果当前日志级别是调试
if (logger.isDebugEnabled()) {
// 打印调试日志：使用 ThemeSource [ themeSource ]
logger.debug("Using ThemeSource [" + themeSource + "]");
}
//将 themeSource 返回出去
return themeSource;
}
else {
// Use default ThemeSource to be able to accept getTheme calls, either
// delegating to parent context's default or to local ResourceBundleThemeSource.
// 使用默认的ThemeSource能够接受getTheme调用，或者委托给父上下文的默认值，或者委托给本地的
// ResourceBundleThemeSource
HierarchicalThemeSource themeSource = null;
//如果context的父级上下文是ThemeSource对象
if (context.getParent() instanceof ThemeSource) {
// DeletgatingThemeSource : 清空委托所有调用父ThemeSource的ThemeSource。如果没有可用的父元
// 素，他就不能解决任何 主题
//新建一个DelegatingThemeSource对象
themeSource = new DelegatingThemeSource();
//将父级上线问作为themeSource的父级ThemeSource
themeSource.setParentThemeSource((ThemeSource) context.getParent());
}
else {
//ResourceBundleThemeSource：查找个人信息的资源实现 java.util.ResourceBundle 每个主题。主题 名称被解释为
// ResourceBundle basename ,支持所有主题的公共 basename 前缀
//新建一个 ResourceBundleThemeSource 对象
themeSource = new ResourceBundleThemeSource();
}
//如果当前日志级别是调试
if (logger.isDebugEnabled()) {
//打印调试日志：无法找到带有名称'themeSource'的数据源：使用默认 [ themeSource ]
logger.debug("Unable to locate ThemeSource with name '" + THEME_SOURCE_BEAN_NAME +
"': using default [" + themeSource + "]");
}
//返回themeSource
return themeSource;
}
}
}