public void init() throws ServletException {
final String configPrefix = "config/";
final int configPrefixLength = configPrefix.length() - 1;
// Wraps the entire initialization in a try/catch to better handle
// unexpected exceptions and errors to provide better feedback
// to the developer
try {
initInternal();
initOther();
initServlet();
initChain();
getServletContext().setAttribute(Globals.ACTION_SERVLET_KEY, this);
initModuleConfigFactory();
// 初始化模块配置
ModuleConfig moduleConfig = initModuleConfig("", config);
initModuleMessageResources(moduleConfig);
initModulePlugIns(moduleConfig);
initModuleFormBeans(moduleConfig);
initModuleForwards(moduleConfig);
initModuleExceptionConfigs(moduleConfig);
initModuleActions(moduleConfig);
moduleConfig.freeze();
Enumeration names = getServletConfig().getInitParameterNames();
while (names.hasMoreElements()) {
String name = (String) names.nextElement();
if (!name.startsWith(configPrefix)) {
continue;
}
String prefix = name.substring(configPrefixLength);
moduleConfig =
initModuleConfig(prefix,
getServletConfig().getInitParameter(name));
initModuleMessageResources(moduleConfig);
initModulePlugIns(moduleConfig);
initModuleFormBeans(moduleConfig);
initModuleForwards(moduleConfig);
initModuleExceptionConfigs(moduleConfig);
initModuleActions(moduleConfig);
moduleConfig.freeze();
}
this.initModulePrefixes(this.getServletContext());
this.destroyConfigDigester();
} catch (UnavailableException ex) {
throw ex;
} catch (Throwable t) {
// The follow error message is not retrieved from internal message
// resources as they may not have been able to have been
// initialized
log.error("Unable to initialize Struts ActionServlet due to an "
+ "unexpected exception or error thrown, so marking the "
+ "servlet as unavailable. Most likely, this is due to an "
+ "incorrect or missing library dependency.", t);
throw new UnavailableException(t.getMessage());
}
}initModuleConfigFactory方法（初始化模块配置工厂？）
protected void initModuleConfigFactory() {
String configFactory =
getServletConfig().getInitParameter("configFactory");
if (configFactory != null) {
//设置class类名，当ModuleConfigFactory调用createFactory时，会拿到当前线程的classloader去加载这个类，并且返回一个实例。
ModuleConfigFactory.setFactoryClass(configFactory);
}
}初始化模块配置代码
ModuleConfig moduleConfig = initModuleConfig("", config);
//config就是struts-config路径，默认/WEB-INF/struts-config.xmlinitModuleConfig代码
protected ModuleConfig initModuleConfig(String prefix, String paths)
throws ServletException {
//在这里创建了一个ModuleConfigFactory，如果用户没有配置configFactory，name这个工厂类是org.apache.struts.config.impl.DefaultModuleConfigFactory
ModuleConfigFactory factoryObject = ModuleConfigFactory.createFactory();
//创建一个配置，默认是new ModuleConfigImpl(prefix)
ModuleConfig config = factoryObject.createModuleConfig(prefix);
//又要解析xml了，其中用到ConfigRuleSet来作为解析规则。也可以自己定义RuleSet来解析
//如果自定义的话，参数名实rulesets，多个RuleSet类名用逗号分隔
//自定义ruleset相关代码在initConfigDigester中的addRuleSets中
Digester digester = initConfigDigester();
List urls = splitAndResolvePaths(paths);
URL url;
for (Iterator i = urls.iterator(); i.hasNext();) {
url = (URL) i.next();
digester.push(config);
//解析每个url，并且处理解析异常。处理解析异常的时候就用到了internal
this.parseModuleConfigFile(digester, url);
}
getServletContext().setAttribute(Globals.MODULE_KEY
+ config.getPrefix(), config);
return config;
}ConfigRuleSet代码
public class ConfigRuleSet extends RuleSetBase {
public void addRuleInstances(Digester digester) {
ClassLoader cl = digester.getClassLoader();
digester.addRule("struts-config/action-mappings",
new SetActionMappingClassRule());
digester.addFactoryCreate("struts-config/action-mappings/action",
new ActionMappingFactory(cl));
digester.addSetProperties("struts-config/action-mappings/action");
digester.addSetNext("struts-config/action-mappings/action",
"addActionConfig", "org.apache.struts.config.ActionConfig");
digester.addRule("struts-config/action-mappings/action/set-property",
new BaseConfigSetPropertyRule());
digester.addObjectCreate("struts-config/action-mappings/action/exception",
"org.apache.struts.config.ExceptionConfig", "className");
digester.addSetProperties(
"struts-config/action-mappings/action/exception");
digester.addSetNext("struts-config/action-mappings/action/exception",
"addExceptionConfig", "org.apache.struts.config.ExceptionConfig");
digester.addRule("struts-config/action-mappings/action/exception/set-property",
new BaseConfigSetPropertyRule());
digester.addFactoryCreate("struts-config/action-mappings/action/forward",
new ActionForwardFactory(cl));
digester.addSetProperties(
"struts-config/action-mappings/action/forward");
digester.addSetNext("struts-config/action-mappings/action/forward",
"addForwardConfig", "org.apache.struts.config.ForwardConfig");
digester.addRule("struts-config/action-mappings/action/forward/set-property",
new BaseConfigSetPropertyRule());
digester.addObjectCreate("struts-config/controller",
"org.apache.struts.config.ControllerConfig", "className");
digester.addSetProperties("struts-config/controller");
digester.addSetNext("struts-config/controller", "setControllerConfig",
"org.apache.struts.config.ControllerConfig");
digester.addRule("struts-config/controller/set-property",
new BaseConfigSetPropertyRule());
digester.addRule("struts-config/form-beans",
new SetActionFormBeanClassRule());
digester.addFactoryCreate("struts-config/form-beans/form-bean",
new ActionFormBeanFactory(cl));
digester.addSetProperties("struts-config/form-beans/form-bean");
digester.addSetNext("struts-config/form-beans/form-bean",
"addFormBeanConfig", "org.apache.struts.config.FormBeanConfig");
digester.addObjectCreate("struts-config/form-beans/form-bean/form-property",
"org.apache.struts.config.FormPropertyConfig", "className");
digester.addSetProperties(
"struts-config/form-beans/form-bean/form-property");
digester.addSetNext("struts-config/form-beans/form-bean/form-property",
"addFormPropertyConfig",
"org.apache.struts.config.FormPropertyConfig");
digester.addRule("struts-config/form-beans/form-bean/form-property/set-property",
new BaseConfigSetPropertyRule());
digester.addRule("struts-config/form-beans/form-bean/set-property",
new BaseConfigSetPropertyRule());
digester.addObjectCreate("struts-config/global-exceptions/exception",
"org.apache.struts.config.ExceptionConfig", "className");
digester.addSetProperties("struts-config/global-exceptions/exception");
digester.addSetNext("struts-config/global-exceptions/exception",
"addExceptionConfig", "org.apache.struts.config.ExceptionConfig");
digester.addRule("struts-config/global-exceptions/exception/set-property",
new BaseConfigSetPropertyRule());
digester.addRule("struts-config/global-forwards",
new SetActionForwardClassRule());
digester.addFactoryCreate("struts-config/global-forwards/forward",
new GlobalForwardFactory(cl));
digester.addSetProperties("struts-config/global-forwards/forward");
digester.addSetNext("struts-config/global-forwards/forward",
"addForwardConfig", "org.apache.struts.config.ForwardConfig");
digester.addRule("struts-config/global-forwards/forward/set-property",
new BaseConfigSetPropertyRule());
digester.addObjectCreate("struts-config/message-resources",
"org.apache.struts.config.MessageResourcesConfig", "className");
digester.addSetProperties("struts-config/message-resources");
digester.addSetNext("struts-config/message-resources",
"addMessageResourcesConfig",
"org.apache.struts.config.MessageResourcesConfig");
digester.addRule("struts-config/message-resources/set-property",
new BaseConfigSetPropertyRule());
digester.addObjectCreate("struts-config/plug-in",
"org.apache.struts.config.PlugInConfig");
digester.addSetProperties("struts-config/plug-in");
digester.addSetNext("struts-config/plug-in", "addPlugInConfig",
"org.apache.struts.config.PlugInConfig");
digester.addRule("struts-config/plug-in/set-property",
new PlugInSetPropertyRule());
// PluginConfig does not extend BaseConfig, at least for now.
}
}
final class PlugInSetPropertyRule extends Rule {
public PlugInSetPropertyRule() {
super();
}
public void begin(String namespace, String names, Attributes attributes)
throws Exception {
PlugInConfig plugInConfig = (PlugInConfig) digester.peek();
plugInConfig.addProperty(attributes.getValue("property"),
attributes.getValue("value"));
}
}
final class SetActionFormBeanClassRule extends Rule {
public SetActionFormBeanClassRule() {
super();
}
public void begin(String namespace, String name, Attributes attributes)
throws Exception {
String className = attributes.getValue("type");
if (className != null) {
ModuleConfig mc = (ModuleConfig) digester.peek();
mc.setActionFormBeanClass(className);
}
}
}
final class BaseConfigSetPropertyRule extends SetPropertyRule {
public BaseConfigSetPropertyRule() {
super("property", "value");
}
public void begin(Attributes attributes)
throws Exception {
if (attributes.getIndex("key") == -1) {
super.begin(attributes);
return;
}
if (attributes.getIndex("property") != -1) {
throw new IllegalArgumentException(
"<set-property> accepts only one of 'key' or 'property' attributes.");
}
Object topOfStack = digester.peek();
if (topOfStack instanceof BaseConfig) {
BaseConfig config = (BaseConfig) topOfStack;
config.setProperty(attributes.getValue("key"),
attributes.getValue("value"));
} else {
throw new IllegalArgumentException(
"'key' attribute of <set-property> only applicable to subclasses of BaseConfig; "
+ "object on top of stack is " + topOfStack + " [key: "
+ attributes.getValue("key") + ", value: "
+ attributes.getValue("value") + "]");
}
}
}
final class ActionFormBeanFactory extends AbstractObjectCreationFactory {
private ClassLoader cl;
public ActionFormBeanFactory(ClassLoader cl) {
super();
this.cl = cl;
}
public Object createObject(Attributes attributes) {
// Identify the name of the class to instantiate
String className = attributes.getValue("className");
if (className == null) {
ModuleConfig mc = (ModuleConfig) digester.peek();
className = mc.getActionFormBeanClass();
}
// Instantiate the new object and return it
Object actionFormBean = null;
try {
actionFormBean = RequestUtils.applicationInstance(className, cl);
} catch (Exception e) {
digester.getLogger().error("ActionFormBeanFactory.createObject: ", e);
}
return actionFormBean;
}
}
final class SetActionMappingClassRule extends Rule {
public SetActionMappingClassRule() {
super();
}
public void begin(String namespace, String name, Attributes attributes)
throws Exception {
String className = attributes.getValue("type");
if (className != null) {
ModuleConfig mc = (ModuleConfig) digester.peek();
mc.setActionMappingClass(className);
}
}
}
final class ActionMappingFactory extends AbstractObjectCreationFactory {
private ClassLoader cl;
public ActionMappingFactory(ClassLoader cl) {
super();
this.cl = cl;
}
public Object createObject(Attributes attributes) {
// Identify the name of the class to instantiate
String className = attributes.getValue("className");
if (className == null) {
ModuleConfig mc = (ModuleConfig) digester.peek();
className = mc.getActionMappingClass();
}
// Instantiate the new object and return it
Object actionMapping = null;
try {
actionMapping = RequestUtils.applicationInstance(className, cl);
} catch (Exception e) {
digester.getLogger().error("ActionMappingFactory.createObject: ", e);
}
return actionMapping;
}
}
final class SetActionForwardClassRule extends Rule {
public SetActionForwardClassRule() {
super();
}
public void begin(String namespace, String name, Attributes attributes)
throws Exception {
String className = attributes.getValue("type");
if (className != null) {
ModuleConfig mc = (ModuleConfig) digester.peek();
mc.setActionForwardClass(className);
}
}
}
final class GlobalForwardFactory extends AbstractObjectCreationFactory {
private ClassLoader cl;
public GlobalForwardFactory(ClassLoader cl) {
super();
this.cl = cl;
}
public Object createObject(Attributes attributes) {
// Identify the name of the class to instantiate
String className = attributes.getValue("className");
if (className == null) {
ModuleConfig mc = (ModuleConfig) digester.peek();
className = mc.getActionForwardClass();
}
// Instantiate the new object and return it
Object globalForward = null;
try {
globalForward = RequestUtils.applicationInstance(className, cl);
} catch (Exception e) {
digester.getLogger().error("GlobalForwardFactory.createObject: ", e);
}
return globalForward;
}
}
final class ActionForwardFactory extends AbstractObjectCreationFactory {
private ClassLoader cl;
public ActionForwardFactory(ClassLoader cl) {
super();
this.cl = cl;
}
public Object createObject(Attributes attributes) {
// Identify the name of the class to instantiate
String className = attributes.getValue("className");
if (className == null) {
ModuleConfig mc = (ModuleConfig) digester.peek(1);
className = mc.getActionForwardClass();
}
// Instantiate the new object and return it
Object actionForward = null;
try {
actionForward = RequestUtils.applicationInstance(className, cl);
} catch (Exception e) {
digester.getLogger().error("ActionForwardFactory.createObject: ", e);
}
return actionForward;
}
}
