Struts2-Dispatcher&ConfigurationProvider续

Struts2--Dispatcher&ConfigurationProvider续

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

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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); } ... } } }

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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~ } }); }

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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
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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; }

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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; }

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