struts 2

1. Struts2架构图
??????? 请求首先通过Filter chain，Filter主要包括ActionContextCleanUp，它主要清理当前线程的ActionContext和Dispatcher；FilterDispatcher主要通过AcionMapper来决定需要调用哪个Action。Java代码

1. //创—ispatcher，此类是一个Delegate，它是真正完成根据url解析，读取对应Action的地方public?void?init(FilterConfig?filterConfig)?throws?ServletException?{ ??
2. ????try?{ ??
3. ????????this.filterConfig?=?filterConfig; ??
4. ??
5. ????????initLogging(); ??
6. ??
7. ????????dispatcher?=?createDispatcher(filterConfig); ??
8. ????????dispatcher.init(); ??
9. ????????dispatcher.getContainer().inject(this); ??
10. ????????//读取初始参数pakages，调用parse()，解析成类似/org/apache/struts2/static,/template的数组"packages"); ??
11. ????????String?packages?=?"org.apache.struts2.static?template?org.apache.struts2.interceptor.debugging"; ??
12. ????????if?(param?!=?null)?{ ??
13. ????????????packages?=?param?+?"?"?+?packages; ??
14. ????????} ??
15. ????????this.pathPrefixes?=?parse(packages); ??
16. ????}?finally?{ ??
17. ????????ActionContext.setContext(null); ??
18. ????} ??
19. }??

Java代码

1. //创—ispatcher，此类是一个Delegate，它是真正完成根据url解析，读取对应Action的地方??
2. public?void?init(FilterConfig?filterConfig)?throws?ServletException?{??
3. ????try?{??
4. ????????this.filterConfig?=?filterConfig;??
5. ??
6. ????????initLogging();??
7. ??
8. ????????dispatcher?=?createDispatcher(filterConfig);??
9. ????????dispatcher.init();??
10. ????????dispatcher.getContainer().inject(this);??
11. ????????//读取初始参数pakages，调用parse()，解析成类似/org/apache/struts2/static,/template的数组??
12. ????????String?param?=?filterConfig.getInitParameter("packages");??
13. ????????String?packages?=?"org.apache.struts2.static?template?org.apache.struts2.interceptor.debugging";??
14. ????????if?(param?!=?null)?{??
15. ????????????packages?=?param?+?"?"?+?packages;??
16. ????????}??
17. ????????this.pathPrefixes?=?parse(packages);??
18. ????}?finally?{??
19. ????????ActionContext.setContext(null);??
20. ????}??
21. }??

???? 顺着流程我们看Disptcher的init方法。init方法里就是初始读取一些配置文件等，先看init_DefaultProperties，主要是读取properties配置文件。

Java代码

1. private?void?init_DefaultProperties()?{ ??
2. ????configurationManager.addConfigurationProvider(new?DefaultPropertiesProvider()); ??
3. }??

Java代码

1. private?void?init_DefaultProperties()?{??
2. ????configurationManager.addConfigurationProvider(new?DefaultPropertiesProvider());??
3. }??

??? 打开DefaultPropertiesProvider

Java代码

1. public?void?register(ContainerBuilder?builder,?LocatableProperties?props) ??
2. ?????????throws?ConfigurationException?{ ??
3. ????? ??
4. ?????Settings?defaultSettings?=?null; ??
5. ?????try?{ ??
6. ?????????defaultSettings?=?new?PropertiesSettings("org/apache/struts2/default"); ??
7. ?????}?catch?(Exception?e)?{ ??
8. ?????????throw?new?ConfigurationException("Could?not?find?or?error?in?org/apache/struts2/default.properties",?e); ??
9. ?????} ??
10. ????? ??
11. ?????loadSettings(props,?defaultSettings); ??
12. ?} ??
13. ??
14. ?//PropertiesSettings//读取org/apache/struts2/default.properties的配置信息，如果项目中需要覆盖，可以在classpath里的struts.properties里覆写public?PropertiesSettings(String?name)?{ ??
15. ????? ??
16. ?????URL?settingsUrl?=?ClassLoaderUtils.getResource(name?+?".properties",?getClass()); ??
17. ????? ??
18. ?????if?(settingsUrl?==?null)?{ ??
19. ?????????LOG.debug(name?+?".properties?missing"); ??
20. ?????????settings?=?new?LocatableProperties(); ??
21. ?????????return; ??
22. ?????} ??
23. ????? ??
24. ?????settings?=?new?LocatableProperties(new?LocationImpl(null,?settingsUrl.toString())); ??
25. ??
26. ?????//?Load?settingsnull; ??
27. ?????try?{ ??
28. ?????????in?=?settingsUrl.openStream(); ??
29. ?????????settings.load(in); ??
30. ?????}?catch?(IOException?e)?{ ??
31. ?????????throw?new?StrutsException("Could?not?load?"?+?name?+?".properties:"?+?e,?e); ??
32. ?????}?finally?{ ??
33. ?????????if(in?!=?null)?{ ??
34. ?????????????try?{ ??
35. ?????????????????in.close(); ??
36. ?????????????}?catch(IOException?io)?{ ??
37. ?????????????????LOG.warn("Unable?to?close?input?stream",?io); ??
38. ?????????????} ??
39. ?????????} ??
40. ?????} ??
41. ?}??

Java代码

1. public?void?register(ContainerBuilder?builder,?LocatableProperties?props)??
2. ?????????throws?ConfigurationException?{??
3. ???????
4. ?????Settings?defaultSettings?=?null;??
5. ?????try?{??
6. ?????????defaultSettings?=?new?PropertiesSettings("org/apache/struts2/default");??
7. ?????}?catch?(Exception?e)?{??
8. ?????????throw?new?ConfigurationException("Could?not?find?or?error?in?org/apache/struts2/default.properties",?e);??
9. ?????}??
10. ???????
11. ?????loadSettings(props,?defaultSettings);??
12. ?}??
13. ??
14. ?//PropertiesSettings??
15. ?//读取org/apache/struts2/default.properties的配置信息，如果项目中需要覆盖，可以在classpath里的struts.properties里覆写??
16. ?public?PropertiesSettings(String?name)?{??
17. ???????
18. ?????URL?settingsUrl?=?ClassLoaderUtils.getResource(name?+?".properties",?getClass());??
19. ???????
20. ?????if?(settingsUrl?==?null)?{??
21. ?????????LOG.debug(name?+?".properties?missing");??
22. ?????????settings?=?new?LocatableProperties();??
23. ?????????return;??
24. ?????}??
25. ???????
26. ?????settings?=?new?LocatableProperties(new?LocationImpl(null,?settingsUrl.toString()));??
27. ??
28. ?????//?Load?settings??
29. ?????InputStream?in?=?null;??
30. ?????try?{??
31. ?????????in?=?settingsUrl.openStream();??
32. ?????????settings.load(in);??
33. ?????}?catch?(IOException?e)?{??
34. ?????????throw?new?StrutsException("Could?not?load?"?+?name?+?".properties:"?+?e,?e);??
35. ?????}?finally?{??
36. ?????????if(in?!=?null)?{??
37. ?????????????try?{??
38. ?????????????????in.close();??
39. ?????????????}?catch(IOException?io)?{??
40. ?????????????????LOG.warn("Unable?to?close?input?stream",?io);??
41. ?????????????}??
42. ?????????}??
43. ?????}??
44. ?}??

??? 再来看init_TraditionalXmlConfigurations方法，这个是读取struts-default.xml和Struts.xml的方法。

Java代码

1. private?void?init_TraditionalXmlConfigurations()?{ ??
2. ????//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"struts-default.xml,struts-plugin.xml,struts.xml"，//这儿就可以看出为什么默认的配置文件必须取名为这三个名称了//如果不想使用默认的名称，直接在web.xml中配置config初始参数即可"config"); ??
3. ????if?(configPaths?==?null)?{ ??
4. ????????configPaths?=?DEFAULT_CONFIGURATION_PATHS; ??
5. ????} ??
6. ????String[]?files?=?configPaths.split("\\s*[,]\\s*"); ??
7. ????//依次解析配置文件，xwork.xml单独解析for?(String?file?:?files)?{ ??
8. ????????if?(file.endsWith(".xml"))?{ ??
9. ????????????if?("xwork.xml".equals(file))?{ ??
10. ????????????????configurationManager.addConfigurationProvider(new?XmlConfigurationProvider(file,?false)); ??
11. ????????????}?else?{ ??
12. ????????????????configurationManager.addConfigurationProvider(new?StrutsXmlConfigurationProvider(file,?false,?servletContext)); ??
13. ????????????} ??
14. ????????}?else?{ ??
15. ????????????throw?new?IllegalArgumentException("Invalid?configuration?file?name"); ??
16. ????????} ??
17. ????} ??
18. }??

Java代码

1. private?void?init_TraditionalXmlConfigurations()?{??
2. ????//首先读取web.xml中的config初始参数值??
3. ????//如果没有配置就使用默认的"struts-default.xml,struts-plugin.xml,struts.xml"，??
4. ????//这儿就可以看出为什么默认的配置文件必须取名为这三个名称了??
5. ????//如果不想使用默认的名称，直接在web.xml中配置config初始参数即可??
6. ????String?configPaths?=?initParams.get("config");??
7. ????if?(configPaths?==?null)?{??
8. ????????configPaths?=?DEFAULT_CONFIGURATION_PATHS;??
9. ????}??
10. ????String[]?files?=?configPaths.split("\\s*[,]\\s*");??
11. ????//依次解析配置文件，xwork.xml单独解析??
12. ????for?(String?file?:?files)?{??
13. ????????if?(file.endsWith(".xml"))?{??
14. ????????????if?("xwork.xml".equals(file))?{??
15. ????????????????configurationManager.addConfigurationProvider(new?XmlConfigurationProvider(file,?false));??
16. ????????????}?else?{??
17. ????????????????configurationManager.addConfigurationProvider(new?StrutsXmlConfigurationProvider(file,?false,?servletContext));??
18. ????????????}??
19. ????????}?else?{??
20. ????????????throw?new?IllegalArgumentException("Invalid?configuration?file?name");??
21. ????????}??
22. ????}??
23. }??

??? 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，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，将所读取到的数据汇集到PackageConfig对象中。来看XmlConfigurationProvider的源代码，详细的我自己也就大体浏览了一下，各位可以自己研读。

Java代码

1. protected?PackageConfig?addPackage(Element?packageElement)?throws?ConfigurationException?{ ??
2. ????PackageConfig.Builder?newPackage?=?buildPackageContext(packageElement); ??
3. ??
4. ????if?(newPackage.isNeedsRefresh())?{ ??
5. ????????return?newPackage.build(); ??
6. ????} ??
7. ????. ??
8. ??
9. ????addResultTypes(newPackage,?packageElement); ??
10. ????loadInterceptors(newPackage,?packageElement); ??
11. ????loadDefaultInterceptorRef(newPackage,?packageElement); ??
12. ????loadDefaultClassRef(newPackage,?packageElement); ??
13. ????loadGlobalResults(newPackage,?packageElement); ??
14. ????loadGobalExceptionMappings(newPackage,?packageElement); ??
15. ????NodeList?actionList?=?packageElement.getElementsByTagName("action"); ??
16. ??
17. ????for?(int?i?=?0;?i?<?actionList.getLength();?i++)?{ ??
18. ????????Element?actionElement?=?(Element)?actionList.item(i); ??
19. ????????addAction(actionElement,?newPackage); ??
20. ????} ??
21. ????loadDefaultActionRef(newPackage,?packageElement); ??
22. ????PackageConfig?cfg?=?newPackage.build(); ??
23. ????configuration.addPackageConfig(cfg.getName(),?cfg); ??
24. ????return?cfg; ??
25. }??

Java代码

1. protected?PackageConfig?addPackage(Element?packageElement)?throws?ConfigurationException?{??
2. ????PackageConfig.Builder?newPackage?=?buildPackageContext(packageElement);??
3. ??
4. ????if?(newPackage.isNeedsRefresh())?{??
5. ????????return?newPackage.build();??
6. ????}??
7. ????.??
8. ??
9. ????addResultTypes(newPackage,?packageElement);??
10. ????loadInterceptors(newPackage,?packageElement);??
11. ????loadDefaultInterceptorRef(newPackage,?packageElement);??
12. ????loadDefaultClassRef(newPackage,?packageElement);??
13. ????loadGlobalResults(newPackage,?packageElement);??
14. ????loadGobalExceptionMappings(newPackage,?packageElement);??
15. ????NodeList?actionList?=?packageElement.getElementsByTagName("action");??
16. ??
17. ????for?(int?i?=?0;?i?<?actionList.getLength();?i++)?{??
18. ????????Element?actionElement?=?(Element)?actionList.item(i);??
19. ????????addAction(actionElement,?newPackage);??
20. ????}??
21. ????loadDefaultActionRef(newPackage,?packageElement);??
22. ????PackageConfig?cfg?=?newPackage.build();??
23. ????configuration.addPackageConfig(cfg.getName(),?cfg);??
24. ????return?cfg;??
25. }??

??? 这儿发现一个配置上的小技巧，我的xwork2.0.*是没有的，但是看源码是看到xwork2.1.*是可以的。继续看XmlConfigurationProvider的源代码：

Java代码

1. private?List?loadConfigurationFiles(String?fileName,?Element?includeElement)?{ ??
2. ????List<Document>?docs?=?new?ArrayList<Document>(); ??
3. ????if?(!includedFileNames.contains(fileName))?{ ??
4. ???????????? ??
5. ????????????Element?rootElement?=?doc.getDocumentElement(); ??
6. ????????????NodeList?children?=?rootElement.getChildNodes(); ??
7. ????????????int?childSize?=?children.getLength(); ??
8. ??
9. ????????????for?(int?i?=?0;?i?<?childSize;?i++)?{ ??
10. ????????????????Node?childNode?=?children.item(i); ??
11. ??
12. ????????????????if?(childNode?instanceof?Element)?{ ??
13. ????????????????????Element?child?=?(Element)?childNode; ??
14. ??
15. ????????????????????final?String?nodeName?=?child.getNodeName(); ??
16. ????????????????????//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<include?file="actions_*.xml"/>if?(nodeName.equals("include"))?{ ??
17. ????????????????????????String?includeFileName?=?child.getAttribute("file"); ??
18. ????????????????????????if(includeFileName.indexOf('*')?!=?-1?)?{ ??
19. ????????????????????????????ClassPathFinder?wildcardFinder?=?new?ClassPathFinder(); ??
20. ????????????????????????????wildcardFinder.setPattern(includeFileName); ??
21. ????????????????????????????Vector<String>?wildcardMatches?=?wildcardFinder.findMatches(); ??
22. ????????????????????????????for?(String?match?:?wildcardMatches)?{ ??
23. ????????????????????????????????docs.addAll(loadConfigurationFiles(match,?child)); ??
24. ????????????????????????????} ??
25. ????????????????????????} ??
26. ????????????????????????else?{ ??
27. ???????????????????????????? ??
28. ????????????????????????????docs.addAll(loadConfigurationFiles(includeFileName,?child));???? ??
29. ????????????????????????}???? ??
30. ????????????????} ??
31. ????????????} ??
32. ????????????} ??
33. ????????????docs.add(doc); ??
34. ????????????loadedFileUrls.add(url.toString()); ??
35. ????????} ??
36. ????} ??
37. ????return?docs; ??
38. }??