开始struts2(运行)

struts2和struts1差距太大，差不多应该换一个名字了，struts2更好用，更简单。效率我没测试过，没有发言权。

首先得运行起来，我在网络上看了很多关于struts2运行的错误信息：

严重: Error filterStart java.lang.UnsupportedClassVersionError: org/apache/struts2/dispatcher/FilterDispatcher (Unsupported major.minor version 49.0) 2010-02-05 23:07:55 StandardContext[/myweb]Exception starting filter struts2 javax.xml.transform.TransformerFactoryConfigurationError: Provider org.apache.xalan.processor.TransformerFactoryImpl not found

其实是最简单的解决问题方式就是用jdk1.5+tomcat5.5以上的版本就可以了。

问题出在tomcat5.0以前的版本jar包比较旧，缺少一些类文件，可以将新的jar库文件拷贝到tomcat5.0的对应目录来解决。

 

从apache.ora上下载struts2的示例struts-2.0.14-apps.zip。解压之后看到一些war文件。

直接把其中一个war文件struts2-blank-2.0.14.war拷贝到webapps目录下，运行tomcat，用ie打开http://127.0.0.1:8088/struts2-blank-2.0.14/，得到输出界面。ok，运行成功。

 

运行jar -xvf struts2-blank-2.0.14.war命令，将其中一个war包解压。

可以看看目录下有些什么东西。

一个文件index.html

三个目录WEB-INF、META-INF、example。

META-INF目录不管，example下面是放的jsp文件。

WEB-INF目录下有一个web.xml和两个目录(lib,class)。

web.xml内容如下：

<?xml version="1.0" encoding="UTF-8"?> <web-app id="WebApp_9" version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"> <display-name>Struts Blank</display-name> <filter> <filter-name>struts2</filter-name> <filter-class>org.apache.struts2.dispatcher.FilterDispatcher</filter-class> </filter> <filter-mapping> <filter-name>struts2</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <welcome-file-list> <welcome-file>index.html</welcome-file> </welcome-file-list> </web-app>

看看内容，差异和struts1太大了，根据配置应该知道，struts2配置了一个filter来处理所有的http请求。

欢迎页面是根目录下的index.html。

 

lib目录是5个基础的jar文件，这儿不在一一描述。

class目录下有一个struts.xml,struts2用来配置struts2的规则，对struts2来说，struts.xml文件必须存在，内容如下：

<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN" "http://struts.apache.org/dtds/struts-2.0.dtd"> <struts> <constant name="struts.enable.DynamicMethodInvocation" value="false" /> <constant name="struts.devMode" value="false" /> <include file="example.xml"/> <!-- Add packages here --> </struts>

根据上面的内容，这个文件包含了example.xml文件，本身没有配置对应的控制规则，这和struts1一样，可以铜鼓哦多个struts-config.xml来配置页面规则。

 

再看看example.xml的内容：

<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN" "http://struts.apache.org/dtds/struts-2.0.dtd"> <struts> <package name="example" namespace="/example" extends="struts-default"> <action name="HelloWorld" class="example.HelloWorld"> <result>/example/HelloWorld.jsp</result> </action> <action name="Login_*" method="{1}" class="example.Login"> <result name="input">/example/Login.jsp</result> <result type="redirect-action">Menu</result> </action> <action name="*" class="example.ExampleSupport"> <result>/example/{1}.jsp</result> </action> <!-- Add actions here --> </package> </struts>

配置了一些如struts1的action，感觉比struts1简单。程序内容我就不在描述了，搞web开发的一看就明白。

 

package标签中的name和和namespace属性定义了包内所有action路径名，如果两个都存在，以namespace为准，如果没有namespace，那么以name为准。按照上面的配置，访问helloworld标签的时候，路径必须是example.helloword.action，在所有的struts2的访问uri都必须加上action作为后缀。

 

在struts.xml中有设置了两个常量值，如:

<constant name="struts.enable.DynamicMethodInvocation" value="false" /> <constant name="struts.devMode" value="false" />

 这些常量定义在一个properties文件中，我在struts2的文档中说明在struts-default.properties中定义，但我打开struts2-core-2.0.14.jar文件，发现这些长岭一个定义在default.properties文件中，default.properties的内容我也贴出来，如下：

# $Id: Action.java 502296 2007-02-01 17:33:39Z niallp $ # # Licensed to the Apache Software Foundation (ASF) under one # or more contributor license agreements. See the NOTICE file # distributed with this work for additional information # regarding copyright ownership. The ASF licenses this file # to you under the Apache License, Version 2.0 (the # "License"); you may not use this file except in compliance # with the License. You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, # software distributed under the License is distributed on an # "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY # KIND, either express or implied. See the License for the # specific language governing permissions and limitations # under the License. ### START SNIPPET: complete_file ### Struts default properties ###(can be overridden by a struts.properties file in the root of the classpath) ### ### Specifies the Configuration used to configure Struts ### one could extend org.apache.struts2.config.Configuration ### to build one's customize way of getting the configurations parameters into Struts # struts.configuration=org.apache.struts2.config.DefaultConfiguration ### This can be used to set your default locale and encoding scheme # struts.locale=en_US struts.i18n.encoding=UTF-8 ### if specified, the default object factory can be overridden here ### Note: short-hand notation is supported in some cases, such as "spring" ### Alternatively, you can provide a com.opensymphony.xwork2.ObjectFactory subclass name here # struts.objectFactory = spring ### specifies the autoWiring logic when using the SpringObjectFactory. ### valid values are: name, type, auto, and constructor (name is the default) struts.objectFactory.spring.autoWire = name ### indicates to the struts-spring integration if Class instances should be cached ### this should, until a future Spring release makes it possible, be left as true ### unless you know exactly what you are doing! ### valid values are: true, false (true is the default) struts.objectFactory.spring.useClassCache = true ### if specified, the default object type determiner can be overridden here ### Note: short-hand notation is supported in some cases, such as "tiger" or "notiger" ### Alternatively, you can provide a com.opensymphony.xwork2.util.ObjectTypeDeterminer implementation name here ### Note: By default, com.opensymphony.xwork2.util.DefaultObjectTypeDeterminer is used which handles type detection ### using generics. com.opensymphony.xwork2.util.GenericsObjectTypeDeterminer was deprecated since XWork 2, it's ### functions are integrated in DefaultObjectTypeDeterminer now. ### To disable tiger support use the "notiger" property value here. #struts.objectTypeDeterminer = tiger #struts.objectTypeDeterminer = notiger ### Parser to handle HTTP POST requests, encoded using the MIME-type multipart/form-data # struts.multipart.parser=cos # struts.multipart.parser=pell struts.multipart.parser=jakarta # uses javax.servlet.context.tempdir by default struts.multipart.saveDir= struts.multipart.maxSize=2097152 ### Load custom property files (does not override struts.properties!) # struts.custom.properties=application,org/apache/struts2/extension/custom ### How request URLs are mapped to and from actions #struts.mapper.class=org.apache.struts2.dispatcher.mapper.DefaultActionMapper ### Used by the DefaultActionMapper ### You may provide a comma separated list, e.g. struts.action.extension=action,jnlp,do struts.action.extension=action ### Used by FilterDispatcher ### If true then Struts serves static content from inside its jar. ### If false then the static content must be available at <context_path>/struts struts.serve.static=true ### Used by FilterDispatcher ### This is good for development where one wants changes to the static content be ### fetch on each request. ### NOTE: This will only have effect if struts.serve.static=true ### If true -> Struts will write out header for static contents such that they will ### be cached by web browsers (using Date, Cache-Content, Pragma, Expires) ### headers). ### If false -> Struts will write out header for static contents such that they are ### NOT to be cached by web browser (using Cache-Content, Pragma, Expires ### headers) struts.serve.static.browserCache=true ### Set this to false if you wish to disable implicit dynamic method invocation ### via the URL request. This includes URLs like foo!bar.action, as well as params ### like method:bar (but not action:foo). ### An alternative to implicit dynamic method invocation is to use wildcard ### mappings, such as <action name="*/*" method="{2}" class="actions.{1}"> struts.enable.DynamicMethodInvocation = true ### Set this to true if you wish to allow slashes in your action names. If false, ### Actions names cannot have slashes, and will be accessible via any directory ### prefix. This is the traditional behavior expected of WebWork applications. ### Setting to true is useful when you want to use wildcards and store values ### in the URL, to be extracted by wildcard patterns, such as ### <action name="*/*" method="{2}" class="actions.{1}"> to match "/foo/edit" or ### "/foo/save". struts.enable.SlashesInActionNames = false ### use alternative syntax that requires %{} in most places ### to evaluate expressions for String attributes for tags struts.tag.altSyntax=true ### when set to true, Struts will act much more friendly for developers. This ### includes: ### - struts.i18n.reload = true ### - struts.configuration.xml.reload = true ### - raising various debug or ignorable problems to errors ### For example: normally a request to foo.action?someUnknownField=true should ### be ignored (given that any value can come from the web and it ### should not be trusted). However, during development, it may be ### useful to know when these errors are happening and be told of ### them right away. struts.devMode = false ### when set to true, resource bundles will be reloaded on _every_ request. ### this is good during development, but should never be used in production struts.i18n.reload=false ### Standard UI theme ### Change this to reflect which path should be used for JSP control tag templates by default struts.ui.theme=xhtml struts.ui.templateDir=template #sets the default template type. Either ftl, vm, or jsp struts.ui.templateSuffix=ftl ### Configuration reloading ### This will cause the configuration to reload struts.xml when it is changed struts.configuration.xml.reload=false ### Location of velocity.properties file. defaults to velocity.properties struts.velocity.configfile = velocity.properties ### Comma separated list of VelocityContext classnames to chain to the StrutsVelocityContext struts.velocity.contexts = ### Location of the velocity toolbox struts.velocity.toolboxlocation= ### used to build URLs, such as the UrlTag struts.url.http.port = 80 struts.url.https.port = 443 ### possible values are: none, get or all struts.url.includeParams = get ### Load custom default resource bundles # struts.custom.i18n.resources=testmessages,testmessages2 ### workaround for some app servers that don't handle HttpServletRequest.getParameterMap() ### often used for WebLogic, Orion, and OC4J struts.dispatcher.parametersWorkaround = false ### configure the Freemarker Manager class to be used ### Allows user to plug-in customised Freemarker Manager if necessary ### MUST extends off org.apache.struts2.views.freemarker.FreemarkerManager #struts.freemarker.manager.classname=org.apache.struts2.views.freemarker.FreemarkerManager ### Enables caching of FreeMarker templates ### Has the same effect as copying the templates under WEB_APP/templates struts.freemarker.templatesCache=false ### See the StrutsBeanWrapper javadocs for more information struts.freemarker.wrapper.altMap=true ### configure the XSLTResult class to use stylesheet caching. ### Set to true for developers and false for production. struts.xslt.nocache=false ### A list of configuration files automatically loaded by Struts struts.configuration.files=struts-default.xml,struts-plugin.xml,struts.xml ### Whether to always select the namespace to be everything before the last slash or not struts.mapper.alwaysSelectFullNamespace=false ### END SNIPPET: complete_file

这个文件中对每一个常量值都作了说明。

有人对一些常量的说明做了中文注释，间文章http://hi.baidu.com/rcda/blog/item/fc967e36549ae7d5a3cc2bba.html

我就不抄袭别的的成果了。

 

设置常量可以在struts.xml或者web.xml中进行定义。

struts.xml中的

<constant name="struts.enable.DynamicMethodInvocation" value="false" /> <constant name="struts.devMode" value="false" />

可以在web.xml中定义成

<filter> <filter-name>struts</filter-name> <filter-class>org.apache.struts2.dispatcher.FilterDispatcher</filter-class> <init-param> <param-name>struts.devMode</param-name> <param-value>true</param-value> </init-param> <init-param> <param-name>struts.enable.DynamicMethodInvocation</param-name> <param-value>false</param-value> </init-param> </filter>

 

 

根据上面的运行结果和配置情况来说，struts2比struts1简单很多了。

 

代码解读和运行结果

首页：

在ie上输入http://127.0.0.1:8088/struts2-blank-2.0.14/，根据web.xml的配置，会显示欢迎页面index.html。

index.html文件的内容：

<html> <head> <META HTTP-EQUIV="Refresh" CONTENT="0;URL=example/HelloWorld.action"> </head> <body> <p>Loading ...</p> </body> </html>

在页面上显示"Loading ...",根据里面的meta内容，2秒以后，转跳到页面example/HelloWorld.action。

根据example.xml中的配置，显示页面HelloWorld.jsp，页面上有些使用了strut2标签，显示两个url连接“English”和“Espanol”，文本内容如下：

<li> <a href="/myweb/example/HelloWorld.action?request_locale=en" mce_href="myweb/example/HelloWorld.action?request_locale=en">English</a> </li> <li> <a href="/myweb/example/HelloWorld.action?request_locale=es" mce_href="myweb/example/HelloWorld.action?request_locale=es">Espanol</a> </li>

分别有两个不同的参数es和en，选择不同的连接，标题显示不同的语言的标题，但是根据action的配置，选择不同的url的时候，都是请求同一个action，即HelloWorld，在HelloWorld.execute中，只有一条语句setMessage(getText(MESSAGE))，我们没有处理request_locale参数啊，为什么会有不同的显示结果呢？

原来在Struts 2.0中，通过ActionContext.getContext().setLocale(Locale arg)可以设置用户的默认语言。
Struts 2.0为您提供了一个名i18n的拦截器（Interceptor），并在默认情况下将其注册到拦截器链（Interceptor chain）中。
它的原理为在执行Action方法前，i18n拦截器查找请求中的一个名为"request_locale"的参数。

果其存在，拦截器就将其作为参数实例化Locale对象，并将其设为用户默认的区域（Locale），最后，将此Locale对象保存在session的名为“WW_TRANS_I18N_LOCALE”的属性中。

 

有了这个Locale属性之后，HelloWorld.java中的getText方法会根据不同的值，分别选选择目录下的配置文件package.properties和package_es.properties，取出文件中HelloWorld.message对应的配置字符串。

所以显示就不同了。

 

2.登陆页面

 在示例struts2-blank-2.0.14.war中还有一些页面怎么显示呢，好像通过首页连不过去，只能在ie上直接输入url。

在ie上输入ulr=http://127.0.0.1:8088/myweb/example/Welcome.action,其实Welcome只是个jsp，但是这里必须输入Welcome.action，否则struts 2不认识，和输入Welcome.jsp一样的。

根据Welcome.jsp中的url标签，显示两个连接的内容如下：

<ul> <li><a href="/myweb/example/Login_input.action" mce_href="myweb/example/Login_input.action">Sign On</a></li> <li><a href="/myweb/example/Register.action" mce_href="myweb/example/Register.action">Register</a></li> </ul>

根据Login.java中的代码，由于没有username和password参数，最后选择了重定向到页面example/Login.jsp显示登陆操作。

在Login.jsp页面中输入username和password，选择提交,login.java中会返回SUCCESS，直接重定向到Menu.action，其实Menu.action就是Menu.jsp。

如果在界面上不输入就直接提交呢？

登陆页面如果不输入，Struts 2回自动调用/classes/example/Login-validation.xml验证合法性。
采用stuts 2的校验框架时，只需要为Aciton按-validation.xml提供一个校验文件即可，该文件放在Acion class相同路径下。
哦，原来是Struts 2.0为您提供了一个名validation的拦截器（Interceptor），并在默认情况下包含在defaultStack中了，直接用就行了。