接下来第三步:init_LegacyStrutsProperties()
调用的是调用的是LegacyPropertiesConfigurationProvider
通过比较前面DefaultPropertiesProvider与调用的是LegacyPropertiesConfigurationProvider.
发现DefaultPropertiesProvider继承自后者,但重写了register()方法,主要是生成PropertiesSetting的不同,前者是根据org/apache/struts2/default.properties
后者是根据struts.properties

我们展开register()中的Settings.getInstance(),最后是调用getDefaultInstance()

private static Settings getDefaultInstance() {     if (defaultImpl == null) {     // Create bootstrap implementation     
//不带参数的DefaultSettings(),区别与DefaultPropertiesProvider中直接带default.properties参数     
//不带参数就是默认为struts.propertes,并且加载struts.custom.properties所定义的properties文件     defaultImpl = new DefaultSettings();     // Create default implementation     try {     //STRUTS_CONFIGURATION为:struts.configuration     //在struts.proterties中查找struts.configuration的值,这个值必须是org.apache.struts2.config.Configuration接口的实现类     //所以我有个困惑就是在下面的转换当中怎么将Configuration转换成Setting类型的...     //这一点先放下了,有时间再研究     String className = get(StrutsConstants.STRUTS_CONFIGURATION);     if (!className.equals(defaultImpl.getClass().getName())) {     try {     // singleton instances shouldn't be built accessing request or session-specific context data     defaultImpl = (Settings) ObjectFactory.getObjectFactory().buildBean(Thread.currentThread().getContextClassLoader().loadClass(className), null);     } catch (Exception e) {     LOG.error("Settings: Could not instantiate the struts.configuration object, substituting the default implementation.", e);     }     }     } catch (IllegalArgumentException ex) {     // ignore     }  

在2.1.6中去掉了第四步:init_ZeroConfiguration(); 
第五步是自定义的configProviders

private void init_CustomConfigurationProviders() {     //从这里可以看到可以将自定义的Provider定义在web.xml中FilterDispatcher的param中:configProviders     String configProvs = initParams.get("configProviders");     if (configProvs != null) {     String[] classes = configProvs.split("//s*[,]//s*");     for (String cname : classes) {     try {     Class cls = ClassLoaderUtils.loadClass(cname, this.getClass());     ConfigurationProvider prov = (ConfigurationProvider)cls.newInstance();     configurationManager.addConfigurationProvider(prov);     }      
...     }     }     
}   

第六步:init_FilterInitParameters

//从这里可以看出struts.properties中的属性不仅可以在struts.xml中以constant形式定义,而且可以在FilterDispatcher的param中定义       private void init_FilterInitParameters() {     configurationManager.addConfigurationProvider(new ConfigurationProvider() {     public void destroy() {}     public void init(Configuration configuration) throws ConfigurationException {}     public void loadPackages() throws ConfigurationException {}     public boolean needsReload() { return false; }     public void register(ContainerBuilder builder, LocatableProperties props) throws ConfigurationException {     props.putAll(initParams);//在这里实现滴~     }     });     }  

第七步:init_AliasStandardObjects,使用BeanSelectionProvider
这是将配置文件中定义的<bean>与实际的类相映射,就是注入bean的依赖关系,这部分以后有时候再研究Container
 
接下来是看怎样调用这些ConfigurationProviders
展开init_PreloadConfiguration()

private Container init_PreloadConfiguration() {     Configuration config = configurationManager.getConfiguration();     Container container = config.getContainer();     boolean reloadi18n = Boolean.valueOf(container.getInstance(String.class, StrutsConstants.STRUTS_I18N_RELOAD));     LocalizedTextUtil.setReloadBundles(reloadi18n);     return container;     }     //再看getConfiguration()     public synchronized Configuration getConfiguration() {     if (configuration == null) {     setConfiguration(new DefaultConfiguration(defaultFrameworkBeanName));     try {     
//重点就是这个reloadContainer     configuration.reloadContainer(getContainerProviders());     } catch (ConfigurationException e) {     setConfiguration(null);     throw new ConfigurationException("Unable to load configuration.", e);     }     } else {     conditionalReload();     }     return configuration;     } 

展开DefaultConfiguration中的reloadContainer

public synchronized List<PackageProvider> reloadContainer(List<ContainerProvider> providers) throws ConfigurationException {     packageContexts.clear();     loadedFileNames.clear();     List<PackageProvider> packageProviders = new ArrayList<PackageProvider>();     //Struts2(xwork2)用Container来完成依赖注入的功能     
//首先初始化一个ContainerBuilder,再由builder来保存接口与实现类或工厂类的对应关系     
//然后通过builder.create(boolean)方法产生container     
//由container.getInstance(Class);就可以得到接口的实现实例了     
//这一部分比较复杂,后面研究完成了,会单独拿出来讲,这里先弄清楚Xwork依赖注入的实现步骤就可以了     ContainerProperties props = new ContainerProperties();     ContainerBuilder builder = new ContainerBuilder();     for (final ContainerProvider containerProvider : providers)     {     //循环调用ConfigurationProvider的init和register方法,明白了吧,在这里统一循环调用     containerProvider.init(this);     containerProvider.register(builder, props);     }     props.setConstants(builder);     //注入依赖关系,在这里并不产生实例     builder.factory(Configuration.class, new Factory<Configuration>() {     public Configuration create(Context context) throws Exception {     return DefaultConfiguration.this;     }     });     ActionContext oldContext = ActionContext.getContext();     try {     // Set the bootstrap container for the purposes of factory creation     Container bootstrap = createBootstrapContainer();     setContext(bootstrap);     //create已经注入依赖关系的Container     container = builder.create(false);     setContext(container);     objectFactory = container.getInstance(ObjectFactory.class);     // Process the configuration providers first     for (final ContainerProvider containerProvider : providers)     {     if (containerProvider instanceof PackageProvider) {     container.inject(containerProvider);     //调用PackageProvider的loadPackages()方法,这里主要是针对XmlConfigurationProvider和StrutsXmlConfigurationProvider     ((PackageProvider)containerProvider).loadPackages();     packageProviders.add((PackageProvider)containerProvider);     }     }     // Then process any package providers from the plugins     Set<String> packageProviderNames = container.getInstanceNames(PackageProvider.class);     if (packageProviderNames != null) {     for (String name : packageProviderNames) {     PackageProvider provider = container.getInstance(PackageProvider.class, name);     provider.init(this);     provider.loadPackages();     packageProviders.add(provider);     }     }     rebuildRuntimeConfiguration();     } finally {     if (oldContext == null) {     ActionContext.setContext(null);     }     }     return packageProviders;     }