上一节分析了Dispatcher中的init（）初始化相应的配置信息，只是简单的分析了一下，现在重点分析一下怎么加载的struts.xml文件，更重点是struts.xml中action标签是怎么加载？

   init_TraditionalXmlConfigurations()代码：

private static final String DEFAULT_CONFIGURATION_PATHS = "struts-default.xml,struts-plugin.xml,struts.xml";private void init_TraditionalXmlConfigurations() {        String configPaths = initParams.get("config");        if (configPaths == null) {            configPaths = DEFAULT_CONFIGURATION_PATHS;        }        String[] files = configPaths.split("\\s*[,]\\s*");        for (String file : files) {            if (file.endsWith(".xml")) {                if ("xwork.xml".equals(file)) {                    configurationManager.addContainerProvider(createXmlConfigurationProvider(file, false));                } else {                    configurationManager.addContainerProvider(createStrutsXmlConfigurationProvider(file, false, servletContext));                }            } else {                throw new IllegalArgumentException("Invalid configuration file name");            }        }    }

注释：（1） 首先读取web.xml中的config初始参数值，如果没有配置就使用默认的DEFAULT_CONFIGURATION_PATHS:"struts-default.xml,struts-plugin.xml,struts.xml"，看到这，笔者想起以前写代码把struts.xml没有放到源文件的根下，报错了，然后在web.xml配置了config初始参数值的相应文件路径，就对了，原来是在这搞的鬼啊!

(2)XmlConfigurationProvider负责解析xwork.xml  

(3)其它xml都是由StrutsXmlConfigurationProvider来解析

对于其它配置文件只用StrutsXmlConfigurationProvider，此类继承XmlConfigurationProvider，而XmlConfigurationProvider又实现ConfigurationProvider接口。

类XmlConfigurationProvider负责配置文件的读取和解析.

1、XmlConfigurationProvider中init()方法：

public void init(Configuration configuration) {        this.configuration = configuration;        this.includedFileNames = configuration.getLoadedFileNames();        loadDocuments(configFileName);    }

注释：（1）configuration赋值

（2）配置文件里包含文件

（3）加载配置。

2、loadDocuments(configFileName)代码：

private void loadDocuments(String configFileName) {        try {            loadedFileUrls.clear();            documents = loadConfigurationFiles(configFileName, null);        } catch (ConfigurationException e) {            throw e;        } catch (Exception e) {            throw new ConfigurationException("Error loading configuration file " + configFileName, e);        }    }

注释：清空loadedFileUrls数据，并且调用 loadConfigurationFiles（）方法

3、loadConfigurationFiles(configFileName, null)代码：

private List
    
      loadConfigurationFiles(String fileName, Element includeElement) {        List
     
       docs = new ArrayList
      
       ();//        if (!includedFileNames.contains(fileName)) {//（1）检查时候已经加载过这个文件            if (LOG.isDebugEnabled()) {                LOG.debug("Loading action configurations from: " + fileName);            }            //（2）把filename添加到includedFileNames中            includedFileNames.add(fileName);            Iterator
       
         urls = null;            Document doc = null;            InputStream is = null;            IOException ioException = null;            try {                urls = getConfigurationUrls(fileName);//（3）加载这个文件的路径。            } catch (IOException ex) {                ioException = ex;            }            //（4）如果urls为空或者没有值，errorIfMissing为true报错，否则直接返回。errorIfMissing为true                                                                                         if (urls == null || !urls.hasNext()) {                if (errorIfMissing) {                    throw new ConfigurationException("Could not open files of the name " + fileName, ioException);                } else {                    LOG.info("Unable to locate configuration files of the name "                            + fileName + ", skipping");                    return docs;                }            }            URL url = null;            while (urls.hasNext()) {                try {                    url = urls.next();                    is = FileManager.loadFile(url);//（5）加载文件，并且返回流                 InputSource in = new InputSource(is);                    in.setSystemId(url.toString());                    doc = DomHelper.parse(in, dtdMappings);//(6)将configFileName配置文件通过SAX解析方式按照DtdMappings解析成Document对象. } catch (XWorkException e) {                    if (includeElement != null) {                        throw new ConfigurationException("Unable to load " + url, e, includeElement);                    } else {                        throw new ConfigurationException("Unable to load " + url, e);                    }                } catch (Exception e) {                    final String s = "Caught exception while loading file " + fileName;                    throw new ConfigurationException(s, e, includeElement);                } finally {                    if (is != null) {                        try {                            is.close();                        } catch (IOException e) {                            LOG.error("Unable to close input stream", e);                        }                    }                }                Element rootElement = doc.getDocumentElement();                NodeList children = rootElement.getChildNodes();                int childSize = children.getLength();                for (int i = 0; i < childSize; i++) {                    Node childNode = children.item(i);                    if (childNode instanceof Element) {                        Element child = (Element) childNode;                        final String nodeName = child.getNodeName();                    //（7）判断这个配置文件里是否包含“include”标签，并且把这个子文件转成Document对象添加到docs中                                                                                                                                                //解析每个action配置是，对于include文件可以使用通配符*来进行配置                        //如Struts.xml中可配置成
         if ("include".equals(nodeName)) {                            String includeFileName = child.getAttribute("file");                            if (includeFileName.indexOf('*') != -1) {                                // handleWildCardIncludes(includeFileName, docs, child);                                ClassPathFinder wildcardFinder = new ClassPathFinder();                                wildcardFinder.setPattern(includeFileName);                                Vector
        
          wildcardMatches = wildcardFinder.findMatches();                                for (String match : wildcardMatches) {                                    docs.addAll(loadConfigurationFiles(match, child));                                }                            } else {                                docs.addAll(loadConfigurationFiles(includeFileName, child));                            }                        }                    }                }                docs.add(doc);                loadedFileUrls.add(url.toString());            }            if (LOG.isDebugEnabled()) {                LOG.debug("Loaded action configuration from: " + fileName);            }        }        return docs;    }
        
       
      
     
    

4、loadPackages()加载package及package中的属性

loadPackages()代码：

public void loadPackages() throws ConfigurationException {        List
    
      reloads = new ArrayList
     
      ();        for (Document doc : documents) {            Element rootElement = doc.getDocumentElement();            NodeList children = rootElement.getChildNodes();            int childSize = children.getLength();            for (int i = 0; i < childSize; i++) {                Node childNode = children.item(i);                if (childNode instanceof Element) {                    Element child = (Element) childNode;                    final String nodeName = child.getNodeName();                    if ("package".equals(nodeName)) {                        PackageConfig cfg = addPackage(child);                        if (cfg.isNeedsRefresh()) {                            reloads.add(child);                        }                    }                }            }            loadExtraConfiguration(doc);        }        if (reloads.size() > 0) {            reloadRequiredPackages(reloads);        }        for (Document doc : documents) {            loadExtraConfiguration(doc);        }        documents.clear();        configuration = null;    }
     
    

注释：遍历每个节点，判断节点名称是否是"package"，如果是，通过addPackage(child)返回PackageConfig

5、addPackage(child)代码：

/**     * Create a PackageConfig from an XML element representing it.     */    protected PackageConfig addPackage(Element packageElement) throws ConfigurationException {        PackageConfig.Builder newPackage = buildPackageContext(packageElement);        if (newPackage.isNeedsRefresh()) {            return newPackage.build();        }        if (LOG.isDebugEnabled()) {            LOG.debug("Loaded " + newPackage);        }        // add result types (and default result) to this package        addResultTypes(newPackage, packageElement);        // load the interceptors and interceptor stacks for this package        loadInterceptors(newPackage, packageElement);        // load the default interceptor reference for this package        loadDefaultInterceptorRef(newPackage, packageElement);        // load the default class ref for this package        loadDefaultClassRef(newPackage, packageElement);        // load the global result list for this package        loadGlobalResults(newPackage, packageElement);        // load the global exception handler list for this package        loadGobalExceptionMappings(newPackage, packageElement);        // get actions        NodeList actionList = packageElement.getElementsByTagName("action");        for (int i = 0; i < actionList.getLength(); i++) {            Element actionElement = (Element) actionList.item(i);            addAction(actionElement, newPackage);        }        // load the default action reference for this package        loadDefaultActionRef(newPackage, packageElement);        PackageConfig cfg = newPackage.build();        configuration.addPackageConfig(cfg.getName(), cfg);        return cfg;    }

注释：（1）buildPackageContext(packageElement)创建Package 上下文，设置属性name,namespace,abstract,extends。如果没有parents没有值，就把这个 Package 上下文设置根Package 。

/**     * This method builds a package context by looking for the parents of this new package.     * 
     * If no parents are found, it will return a root package.     */    protected PackageConfig.Builder buildPackageContext(Element packageElement) {        String parent = packageElement.getAttribute("extends");        String abstractVal = packageElement.getAttribute("abstract");        boolean isAbstract = Boolean.valueOf(abstractVal).booleanValue();        String name = TextUtils.noNull(packageElement.getAttribute("name"));        String namespace = TextUtils.noNull(packageElement.getAttribute("namespace"));        if (TextUtils.stringSet(packageElement.getAttribute("externalReferenceResolver"))) {            throw new ConfigurationException("The 'externalReferenceResolver' attribute has been removed.  Please use " +                    "a custom ObjectFactory or Interceptor.", packageElement);        }        PackageConfig.Builder cfg = new PackageConfig.Builder(name)                .namespace(namespace)                .isAbstract(isAbstract)                .location(DomHelper.getLocationObject(packageElement));        if (TextUtils.stringSet(TextUtils.noNull(parent))) { // has parents, let's look it up            List
    
      parents = ConfigurationUtil.buildParentsFromString(configuration, parent);            if (parents.size() <= 0) {                cfg.needsRefresh(true);            } else {                cfg.addParents(parents);            }        }        return cfg;    }
    

下面会加载其他的类型，有兴趣的自己看看，很简单。

下面详细解释addAction(actionElement, newPackage)，创建ActionConfig，并且给name,class,method赋值。

protected void addAction(Element actionElement, PackageConfig.Builder packageContext) throws ConfigurationException {        String name = actionElement.getAttribute("name");        String className = actionElement.getAttribute("class");        String methodName = actionElement.getAttribute("method");        Location location = DomHelper.getLocationObject(actionElement);        if (location == null) {            LOG.warn("location null for " + className);        }        //methodName should be null if it's not set        methodName = (methodName.trim().length() > 0) ? methodName.trim() : null;//判断方法名称是否为空        // if there isnt a class name specified for an 
     then try to        // use the default-class-ref from the 
            if (!TextUtils.stringSet(className)) {            // if there is a package default-class-ref use that, otherwise use action support           /* if (TextUtils.stringSet(packageContext.getDefaultClassRef())) {                className = packageContext.getDefaultClassRef();            } else {                className = ActionSupport.class.getName();            }*/        } else {            if (!verifyAction(className, name, location)) {                return;            }        }        Map
    
      results;        try {            results = buildResults(actionElement, packageContext);//解析出result标签的name，类型，返回值        } catch (ConfigurationException e) {            throw new ConfigurationException("Error building results for action " + name + " in namespace " + packageContext.getNamespace(), e, actionElement);        }        List
     
       interceptorList = buildInterceptorList(actionElement, packageContext);//拦截器配置        List
      
        exceptionMappings = buildExceptionMappings(actionElement, packageContext);        ActionConfig actionConfig = new ActionConfig.Builder(packageContext.getName(), name, className)                .methodName(methodName)                .addResultConfigs(results)                .addInterceptors(interceptorList)                .addExceptionMappings(exceptionMappings)                .addParams(XmlHelper.getParams(actionElement))                .location(location)                .build();        packageContext.addActionConfig(name, actionConfig);        if (LOG.isDebugEnabled()) {            LOG.debug("Loaded " + (TextUtils.stringSet(packageContext.getNamespace()) ? (packageContext.getNamespace() + "/") : "") + name + " in '" + packageContext.getName() + "' package:" + actionConfig);        }    }
      
     
    

注释：（1）解析出action标签的name，class，method属性值

（2）verifyAction（）验证这个action是否合法

（3）buildResults（）方法解析出action返回类型，因为result标签可以有多个，所以这里使用 Map<String, ResultConfig>保存result相关信息。

buildResults（）源码：

protected Map
    
      buildResults(Element element, PackageConfig.Builder packageContext) {        NodeList resultEls = element.getElementsByTagName("result");//获取result标签        Map
     
       results = new LinkedHashMap
      
       ();//遍历每一个result标签，并且获取属性值        for (int i = 0; i < resultEls.getLength(); i++) {            Element resultElement = (Element) resultEls.item(i);            if (resultElement.getParentNode().equals(element) || resultElement.getParentNode().getNodeName().equals(element.getNodeName())) {                String resultName = resultElement.getAttribute("name");//获取name属性                String resultType = resultElement.getAttribute("type");//获取type属性                // if you don't specify a name on 
       , it defaults to "success"                    //如果name属性为空，默认“success”                if (!TextUtils.stringSet(resultName)) {                    resultName = Action.SUCCESS;                }                // there is no result type, so let's inherit from the parent package                if (!TextUtils.stringSet(resultType)) {                    resultType = packageContext.getFullDefaultResultType();                    // now check if there is a result type now                    if (!TextUtils.stringSet(resultType)) {                        // uh-oh, we have a problem                        throw new ConfigurationException("No result type specified for result named '"                                + resultName + "', perhaps the parent package does not specify the result type?", resultElement);                    }                }            //获取type的处理类的相关信息                ResultTypeConfig config = packageContext.getResultType(resultType);                if (config == null) {                    throw new ConfigurationException("There is no result type defined for type '" + resultType                            + "' mapped with name '" + resultName + "'."                            + "  Did you mean '" + guessResultType(resultType) + "'?", resultElement);                }                //处理类的类名                String resultClass = config.getClazz();                                // invalid result type specified in result definition                if (resultClass == null) {                    throw new ConfigurationException("Result type '" + resultType + "' is invalid");                }                //key表示name属性，值表示是result标签的值                Map
       
         resultParams = XmlHelper.getParams(resultElement);                if (resultParams.size() == 0) // maybe we just have a body - therefore a default parameter                {                    // if 
        
         something
         then we add a parameter of 'something' as this is the most used result param                    if (resultElement.getChildNodes().getLength() >= 1) {                        resultParams = new LinkedHashMap
        
         ();                        String paramName = config.getDefaultResultParam();                        if (paramName != null) {                            StringBuilder paramValue = new StringBuilder();                            for (int j = 0; j < resultElement.getChildNodes().getLength(); j++) {                                if (resultElement.getChildNodes().item(j).getNodeType() == Node.TEXT_NODE) {                                    String val = resultElement.getChildNodes().item(j).getNodeValue();                                    if (val != null) {                                        paramValue.append(val);                                    }                                }                            }                            String val = paramValue.toString().trim();                            if (val.length() > 0) {                                resultParams.put(paramName, val);                            }                        } else {                            LOG.warn("no default parameter defined for result of type " + config.getName());                        }                    }                }                // create new param map, so that the result param can override the config param                Map
         
           params = new LinkedHashMap
          
           (); Map
           
             configParams = config.getParams(); if (configParams != null) { params.putAll(configParams); } params.putAll(resultParams);                //根据上面获得name，type相应的处理类，还有参数创建ResultConfig对象 ResultConfig resultConfig = new ResultConfig.Builder(resultName, resultClass) .addParams(params) .location(DomHelper.getLocationObject(element)) .build(); results.put(resultConfig.getName(), resultConfig); } } return results; }
           
          
         
        
       
      
     
    

注释：这里很重要的是解析出result标签的name，type属性，以及每个标签对应的值。默认的type类型是 “dispatcher”，为什么是他，请看struts-default.xml中这一行代码：

            
                 
                  
      。。。。
     
    

总结：

首先通过init()中的loadDocuments(configFileName);利用DomHelper中的parse(InputSource inputSource, Map<String, String> dtdMappings) 将configFileName配置文件通过SAX解析方式按照DtdMappings解析成Document对象.

然后通过Provider的register()方法加载"bean"和"constant"属性,再通过loadPackages()加载package及package中的属性addAction()方法负责读取<action>标签，并将数据保存在ActionConfig中；addResultTypes()方法负责将<result-type>标签转化为ResultTypeConfig对象；loadInterceptors()方法负责将<interceptor>标签转化为InterceptorConfi对象；loadInterceptorStack()方法负责将<interceptor-ref>标签转化为InterceptorStackConfig对象；loadInterceptorStacks()方法负责将<interceptor-stack>标签转化成InterceptorStackConfig对象。而上面的方法最终会被addPackage()方法调用,addPackage又会被Provider的loadPackages()调用，将所读取到的数据汇集到PackageConfig对象中。

再说句大实话把配置文件转成Document对象，然后就是对这个对象进行遍历节点，根据节点名称进行相应转换成相应的Config