学Struts2从HelloWorld示例开始

介绍

    当提交一个Html的Form给Struts2框架时，数据不再是提交给服务器端的某一个JSP页面，而是提交给一个Action类。而框架根据配置文件 把与该Action类对应的页面（这个页面可以是JSP页面，也可以是PDF、Excel或Applet）返回给客户端。

写一个Struts2的HelloWorld ， 我们需要做三件事：

1. 创建一个显示信息的JSP文件

2. 创建一个生成信息的Action类

3. 建立JSP页面和Action的mapping（映射）

创建HelloWorld.jsp文件 
 

<!-- 

Code highlighting produced by Actipro CodeHighlighter (freeware)

http://www.CodeHighlighter.com/

-->

<


%...@ taglib 


prefix


="s"


 uri


="/struts-tags"


 %


>









<


html


>






    





<


head


>






        





<


title


>


Hello World!


</


title


>






    





</


head


>






    





<


body


>






        





<


h2


><


s:property 


value


="message"


 


/></


h2


>






    





</


body


>









</


html


>

HelloWorld.jsp存放在war目录下面

创建Action类HelloWorld.java
 

<!-- 

Code highlighting produced by Actipro CodeHighlighter (freeware)

http://www.CodeHighlighter.com/

-->package tutorial;
import com.opensymphony.xwork2.ActionSupport;



public


 


class





 HelloWorld extends ActionSupport ...{



public


 


static


 final String MESSAGE 


=


 


"


Struts is up and running ...


"





;



public





 String execute() throws Exception ...{
setMessage(MESSAGE);



return





 SUCCESS;
}



private





 String message;



public


 


void





 setMessage(String message)...{



this


.message 


=





 message;
}



public





 String getMessage() ...{



return





 message;
}
}

HelloWorld.java存放在src/tutorial下面
在struts.xml建立映射

<!-- 

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http://www.CodeHighlighter.com/

--><!





DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
"http://struts.apache.org/dtds/struts-2.0.dtd"


>









<


struts


>






    





<


package 


name


="tutorial"


 extends


="struts-default"


>






        





<


action 


name


="HelloWorld"


 class


="tutorial.HelloWorld"


>






            





<


result


>


/HelloWorld.jsp


</


result


>









</


action


>






        





<!--


 Add your actions here 


-->






    





</


package


>









</


struts


>

 
    此文件存放在classes下面，同时还要建一个struts.properties的属性文件放在这个目录下，这个文件可以是空的，什么都不写
创建web.xml

<!-- 

Code highlighting produced by Actipro CodeHighlighter (freeware)

http://www.CodeHighlighter.com/

--><?


xml version="1.0" encoding="UTF-8"


?>









<


web-app


>









<


display-name


>


Struts2 Hello World!


</


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


>









</


web-app


>

 
web.xml毫无疑问放在WEB-INF下

 
创建build.xml

<!-- 

Code highlighting produced by Actipro CodeHighlighter (freeware)

http://www.CodeHighlighter.com/

--><?


xml version="1.0"


?>









<


project 


name


="struts2app"


 basedir


="."


 default


="usage"


>






    





<


property 


file


="build.properties"


/>






    





<


property 


name


="src.dir"


 value


="src"


/>






    





<


property 


name


="web.dir"


 value


="war"


/>






    





<


property 


name


="build.dir"


 value


="${web.dir}/WEB-INF/classes"


/>






    





<


property 


name


="name"


 value


="struts2app"


/>






    





<


path 


id


="master-classpath"


>






        





<


fileset 


dir


="${web.dir}/WEB-INF/lib"


>






            





<


include 


name


="*.jar"


/>






        





</


fileset


>






        





<!--


 We need the servlet API classes:        


-->






        





<!--


   for Tomcat 4.1 use servlet.jar        


-->






        





<!--


   for Tomcat 5.0 use servlet-api.jar    


-->






        





<!--


   for Other app server - check the docs 


-->






        





<


fileset 


dir


="${appserver.home}/common/lib"


>






            





<


include 


name


="servlet*.jar"


/>






        





</


fileset


>






        





<


pathelement 


path


="${build.dir}"


/>






    





</


path


>






    





<


target 


name


="usage"


>






        





<


echo 


message


=""


/>






        





<


echo 


message


="${name} build file"


/>






        





<


echo 


message


="-----------------------------------"


/>






        





<


echo 


message


=""


/>






        





<


echo 


message


="Available targets are:"


/>






        





<


echo 


message


=""


/>






        





<


echo 


message


="build     --> Build the application"


/>






        





<


echo 


message


="deploy    --> Deploy application as directory"


/>






        





<


echo 


message


=""


/>






    





</


target


>






    





<


target 


name


="build"


 description


="Compile main source tree java files"


>






        





<


mkdir 


dir


="${build.dir}"


/>






        





<


javac 


destdir


="${build.dir}"


 target


="1.3"


 debug


="true"






               deprecation





="false"


 optimize


="false"


 failonerror


="true"


>






            





<


src 


path


="${src.dir}"


/>






            





<


classpath 


refid


="master-classpath"


/>






        





</


javac


>






    





</


target


>






    





<


target 


name


="deploy"


 depends


="build"


 description


="Deploy application"


>






        





<


copy 


todir


="${deploy.path}/${name}"


 preservelastmodified


="true"


>






            





<


fileset 


dir


="${web.dir}"


>






                





<


include 


name


="**/*.*"


/>






            





</


fileset


>






        





</


copy


>






    





</


target


>









</


project


>

 
build.xml放在struts2app目录下，再在这个目录下建一个build.properties文件，内容如下:

按照build.properties配置你的tomcat位置。在struts2app目录下运行ant build ，ant deploy ，程序就发布到tomcat的webapps下

# Ant properties for building the springapp
appserver.home=d:/tomcat5.5
deploy.path=${appserver.home}/webapps

tomcat.manager.url=http://localhost:8080/manager
tomcat.manager.username=admin
tomcat.manager.password=admin
 

运行
现在，启动tomcat，访问 http://localhost:8080/tutorial/HelloWorld.action ，能看到页面的title为"Hello World!" ，页面上显示"Struts is up and running!".

它们怎么运行的
1、       struts2容器收到HelloWorld.action请求，从web.xml获取设置，org.apache.struts2.dispatcher.FilterDispatcher是所有应用（包括*.action）的入口点。
2、       struts2在struts.xml中找到HelloWorld类（Action），并调用它的execute方法。
3、       execute方法给message变量赋值，并返回SUCCESS，struts2收到SUCCESS标志，按照映射关系，把HelloWorld.jsp返回客户端。
4、       当HelloWorld.jsp开始运行，<s:property value="message" />会调用HelloWorld类getMessage方法，把结果显示在页面上。

 

 

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