Struts 源码学习之ActionServlet (三)

④ 调用 initChain(); 读取web.xml中命令链文件初始值chainConfig

protected String chainConfig = "org/apache/struts/chain/chain-config.xml";

// ④ initChain();

 

// 如没有chainConfig参数，则使用默认 "org/apache/struts/chain/chain-config.xml"

String value;

value = getServletConfig().getInitParameter("chainConfig");

if (value != null) {

    chainConfig = value;

}

 

ConfigParser parser = new ConfigParser();

List urls = splitAndResolvePaths(chainConfig);

URL resource;

 

// chainConfig 替换了原来传统的在 RequestProcessor 类中执行的 HTTP 请求处理

for (Iterator i = urls.iterator(); i.hasNext();) {

     resource = (URL) i.next();

     log.info("Loading chain catalog from " + resource);

     parser.parse(resource);

}

 

/************************************************************

// org.apache.struts.action. RequestProcessor .java 的process方法中，一些方法如

processLocale (request, response);

processContent (request, response);

processNoCache (request, response);

.......

被 "org/apache/struts/chain/chain-config.xml" 中下列配置所取代

<command

          className="org.apache.struts.chain.commands.servlet.SelectLocale"/>

<command

          className="org.apache.struts.chain.commands.servlet.SetContentType"/>

<command

          className="org.apache.struts.chain.commands.servlet.RequestNoCache"/>

.......

好处是充分降低了代码内部方法与方法之间的耦合度

************************************************************/

 

 

在④/⑤之间

// 把servlet对象存储到servletContext中，属性名为Globals.ACTION_SERVLET_KEY

（ " org.apache.struts.action.ACTION_SERVLET " ）

getServletContext().setAttribute(Globals.ACTION_SERVLET_KEY, this);

 

 

⑤ 调用 initModuleConfigFactory(); 和 initModuleConfig("", config); 创建 ModuleConfig 对象。Struts中的MessageResource、PlugIn、数据源等，都是通过ModuleConfig来实现的。

// 初始化ModuleConfig配置工厂

initModuleConfigFactory(); // ⑴

// 由配置工厂实例化一个ModuleConfig的对象

ModuleConfig moduleConfig = initModuleConfig("", config); // ⑵

 

⑴

initModuleConfigFactory(); 所做的工作：

// 得到web.xml中"configFactory"参数，如果找不到，则使用 默认工厂

String configFactory = getServletConfig().getInitParameter("configFactory");

if (configFactory != null) {

     ModuleConfigFactory.setFactoryClass(configFactory);

}

<servlet>

        <servlet-name>action</servlet-name>

        <servlet-class>org.apache.struts.action.ActionServlet</servlet-class>

        <init-param>

        <param-name>configFactory</param-name>   <!-- 得到"configFactory"参数-->

      <param-value>com.lively.base.webapp.UserModuleConfigFactory</param-value>

        </init-param>

        .......

    </servlet>

 

在ModuleConfigFactory.java中的setFactoryClass方法，

public static void setFactoryClass(String factoryClass) {

        ModuleConfigFactory.factoryClass = factoryClass;

        ModuleConfigFactory.clazz = null;

}

其中

protected static Class clazz = null;

protected static String factoryClass =

        "org.apache.struts.config.impl.DefaultModuleConfigFactory";

 

⑵

initModuleConfig ("", config); 所做的工作：

// Parse the configuration for this module

ModuleConfigFactory factoryObject = ModuleConfigFactory.createFactory(); // Ⅰ

ModuleConfig config = factoryObject.createModuleConfig(prefix); // Ⅱ

 

Ⅰ

ModuleConfigFactory.createFactory(); 方法中：

protected static Class clazz = null;

protected static String factoryClass =

        "org.apache.struts.config.impl.DefaultModuleConfigFactory";

if (clazz == null) {

     clazz = RequestUtils.applicationClass(factoryClass);

}

factory = (ModuleConfigFactory) clazz.newInstance();

 

而RequestUtils.applicationClass通过classLoader加载一个

org.apache.struts.config.impl.DefaultModuleConfigFactory

 

Ⅱ

ModuleConfig config = factoryObject.createModuleConfig(prefix); 方法中：

// 通过new ModuleConfigImpl(prefix);设置一些变量的初始值，在 initModuleConfig ("", config); 方法的最后会 把ModuleConfig对象放置到servletContext中 （参见 Ⅴ ）

protected String prefix = null;

protected HashMap actionConfigs = null;

protected List actionConfigList = null;

protected String actionFormBeanClass = "org.apache.struts.action.ActionFormBean";

protected String actionMappingClass = "org.apache.struts.action.ActionMapping";

protected String actionForwardClass = "org.apache.struts.action.ActionForward";

protected boolean configured = false;

protected ControllerConfig controllerConfig = null;

protected HashMap exceptions = null;

protected HashMap formBeans = null;

protected HashMap forwards = null;

protected HashMap messageResources = null;

protected ArrayList plugIns = null;

public ModuleConfigImpl(String prefix) {

        super();

        this.prefix = prefix;

        this.actionConfigs = new HashMap();

        this.actionConfigList = new ArrayList();

        this.actionFormBeanClass = "org.apache.struts.action.ActionFormBean";

        this.actionMappingClass = "org.apache.struts.action.ActionMapping";

        this.actionForwardClass = "org.apache.struts.action.ActionForward";

        this.configured = false;

        this.controllerConfig = null;

        this.exceptions = new HashMap();

        this.formBeans = new HashMap();

        this.forwards = new HashMap();

        this.messageResources = new HashMap();

        this.plugIns = new ArrayList();

}

 

Ⅲ

protected String config = "/WEB-INF/struts-config.xml"; // ② initOther(); ⑤ initModuleConfig ();

protected Digester configDigester = null; // ⑤ initModuleConfig ();

 

// 初始化Digester，

Digester digester = initConfigDigester();

 

initConfigDigester(); 所做的工作：

// Create a new Digester instance with standard capabilities

configDigester = new Digester();

configDigester.setNamespaceAware(true);

configDigester.setValidating(this.isValidating());

configDigester.setUseContextClassLoader(true);

// 解析struts配置文件之前，首先添加默认的解析规则

configDigester.addRuleSet(new ConfigRuleSet());

for (int i = 0; i < registrations.length; i += 2) {

    URL url = this.getClass().getResource(registrations[i + 1]);

    if (url != null) {

         configDigester.register(registrations[i], url.toString());

    }

}

// 通过getServletConfig().getInitParameter("rulesets");从web.xml中读取用户自定义的解析规则（用","分开的org.apache.commons.digester.RuleSet列表）

this.addRuleSets();

.......