学步园

You can download this complete example, Basic_Struts2_Ant, from Google Code -
http://code.google.com/p/struts2-examples/downloads/list. Click on the link for Basic_Struts2_Ant.zip and save the file to your computer. Unzip the file and you should have a folder named Basic_Struts2_Ant. In that folder is a README.txt file with instruction
on how to build and run the application.

从上面的链接可以下载一上个Basic_Struts2_Ant示例，但是我对Ant的知识了解几乎为零，所以没有涉及到到Ant的我都忽略了。

This tutorial assumes you already know how to create a Java web application, use Ant to build the web application archive (war) file, and deploy the war file to a Servlet container such as Tomcat or Jetty.本教程假设你已经知道如何创建a Java web application，和布置a Java web application到一个servlet容器，比如Tomcat,Jetty

To create a Struts 2 web application with the Struts 2 artifacts added to the the application's class path manually you will need to download the Struts 2 distribution from the

Apache Struts website.

On the Struts 2 download page, click on the link for the current General Availability release. In that release's section you'll find several links. To get started with a basic Struts 2 web application you need to only download the Essential Dependencies
Only zip file, which is approximately 12mb.

After downloading this zip file, unzip it. You should have a folder named the same as the current general availability release and in that folder will be a lib folder. The lib folder contains the Struts 2 jar files (e.g. struts2-core-X.X.X.X.jar, where X.X.X.X
is the version) and other jar files Struts 2 requires (e.g. xwork-core.X.X.X.jar).

上面是说下载后，要加一些必要的Jar包，下面会有详细述说。

As we create our basic Struts 2 web application we will copy from the Struts 2 distribution lib folder just the jar files our application requires. As we add features to our application in future tutorials we will copy other jar files.

Step 1 - Create A Basic Java Web Application

In your Java IDE create a web application project named Basic_Struts2_Ant. To follow along with this tutorial your web application should have the following folder structure:

Remember Struts 2 requires Servlet API 2.4 or higher, JSP 2.0 or higher, and Java 5 or higher. The example project, Basic_Struts2_Ant, which you can download from Google code

http://code.google.com/p/struts2-examples/downloads/list was created using Eclipse 3.5 with Java 6.

告诉我们从哪下载和在Eclipse 3.5 with Java 6环境下运行

Step 2 - Add index.jsp and Ant Build File

Our next step is to add a simple index.jsp to this web application. Create an index.jsp under WebContent with a title of "Basic Struts 2 Application - Welcome" and in the body add an h1 heading of "Welcome to Struts 2!"

Next create an Ant build.xml file that will compile any Java classes and create the war file. The code example download, Basic_Struts2_Ant, includes an Ant build.xml.

Run the Ant target that creates the war file (in the example downloaded that is the archive target, which places the war file in the dist folder). Copy the war file into your Servlet container so that it will deploy the war file.

Start up your Servlet container and in a web browser go to
http://localhost:8080/Basic_Struts2_Ant/index.jsp. You should see the following:

这里使用到Ant知识，虽然简单，但是我还是忽略掉，计划找一个时间，再来补这方面知识。

Step 3 - Add Struts 2 Jar Files To Class Path

Now that we know we have a working Java web application, lets add the minimal required Struts 2 framework Jar files to our web application's class path. We'll copy these Jar files from the lib folder of the Struts 2 download to the WEB-INF/lib folder in
our web application.

下面是要运用到的一些jar包，其实下面三个，我也不知道有什么用，不过，用一个简单方法，就是到你下去的文件夹中找到apps目录下的struts2-blank.war，解压，然后到WEB-INF\lib目录下，把所有的jar包copy到你的项目下。

1. asm-x.x.jar
2. asm-commons-x.x.jar
3. asm-tree-x.x.jar

Find and copy to WEB-INF\lib these files (note X.X.X.X.jar refers to the version number):

1. asm-x.x.jar
2. asm-commons-x.x.jar
3. asm-tree-x.x.jar
4. commons-fileupload-X.X.X.jar
5. commons-io-X.X.X.jar
6. commons-lang-X.X.X.jar
7. commons-lang3-X.X.X.jar - as from version 2.3.3 Struts 2 bases on Commons Lang 3, but there are still external dependencies that base on Commons Lang.
8. freemarker-X.X.X.jar
9. javassist-X.X.X.jar
10. ognl-X.X.X.jar
11. struts2-core-X.X.X.X.jar
12. xwork-core-X.X.X.jar

You can see from the above that the Struts 2 core jar depends on several other artifacts. As we add additional Struts 2 features in future tutorials, we'll need to add additional Struts 2 jar files and other transitive dependencies.

上面是说，不要加多余的jar包，当需要额外的功能时，才加jar包。

Step 4 - Add Logging

To see what's happening under the hood, the example application for this tutorial uses log4j. You'll need to download the log4j jar file and copy it to WEB-INF/lib. The example application uses log4j-1.2.14.jar

http://archive.apache.org/dist/logging/log4j/1.2.14/.

Setup a log4j.xml configuration in the src folder. You can copy the one from the example application, which contains the following

这一步是加日志功能，对于初学者而言，我建议忽略这步，我们尽量在开始学习的时候简单化，以增加学习兴趣。

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration PUBLIC "-//log4j/log4j Configuration//EN" "log4j.dtd">

<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">
    
    <appender name="STDOUT" class="org.apache.log4j.ConsoleAppender">
       <layout class="org.apache.log4j.PatternLayout"> 
          <param name="ConversionPattern" value="%d %-5p %c.%M:%L - %m%n"/> 
       </layout> 
    </appender>
 
    <!-- specify the logging level for loggers from other libraries -->
    <logger name="com.opensymphony">
    	<level value="DEBUG" />
    </logger>

    <logger name="org.apache.struts2">
    	 <level value="DEBUG" />
    </logger>
  
   <!-- for all other loggers log only debug and above log messages -->
     <root>
        <priority value="INFO"/> 
        <appender-ref ref="STDOUT" /> 
     </root> 
    
</log4j:configuration> 

Step 5 - Add Struts 2 Servlet Filter

To enable the Struts 2 framework to work with your web application you need to add a Servlet filter class and filter mapping to web.xml. Below is the filter and filter-mapping nodes you should
add to web.xml.

为了使Struts2 能够在自己的web应用中起作用，需要添加Servlet filter和配置web.xml

                                                   web.xml Servlet Filter
<filter>
  <filter-name>struts2</filter-name>
  <filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>
</filter>

<filter-mapping>
  <filter-name>struts2</filter-name>
   <url-pattern>/*</url-pattern>
</filter-mapping>

Step 6 - Create struts.xml

Struts 2 can use either an XML configuration file or annotations (or both) to specify the relationship between a URL, a Java class, and a view page (such as index.jsp). For our basic Struts 2
application, we'll use a minimal xml configuration. Note the file name is struts.xml and it should be in the src folder (struts.xml must be on the web application's root class path).

主要意思是struts.xml应该放在src文件下，当编译整个项目时，会自动把它放到相应的classes目录下的。至于struts.xml有什么用，在最后总结时，我会述说整个过程的步骤。

                                                               struts.xml
<?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.devMode" value="true" />
                                                                 
	<package name="basicstruts2" extends="struts-default">

		<action name="index">
			<result>/index.jsp</result>
		</action>

	</package>

</struts>

struts.devMode开发模式，开发模式改为true之后，修改配置文件可以马上生效,不用重启服务器。

Step 7 - Build and Run the Application 
这一步可以忽略

With all of the above in place run the Ant target that creates the war file (in the example download that target is archive). Remove the previously created war file and exploded web application
folder from your Servlet container's webapps folder. Copy to your Servlet container's webapps folder the new war you just created.

Start up the Servlet container. View the console where you should see numerous debug messages that tell you the Struts 2 framework is being included in the Basic_Struts2_Ant web application.

Open a web browser and go to

http://localhost:8080/Basic_Struts2_Ant/index.action (note that's index.action not index.jsp at the end of the URL). You should see the same web page as when going to

http://localhost:8080/Basic_Struts2_Ant/index.jsp. View the log messages written to the console and you should find several that discuss index.action and index.jsp:

com.opensymphony.xwork2.DefaultActionProxy.debug:57 - Creating an DefaultActionProxy for namespace / and action name index
...
org.apache.struts2.dispatcher.ServletDispatcherResult.debug:57 - Forwarding to location /index.jsp

Note that the xwork2 artifact is one of the Jar files we copied over to WEB-INF lib and is used heavily by the Struts 2 framework.

<filter>
        <filter-name>struts2</filter-name>    
<filter-class>
org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>
  </filter>
  <filter-mapping>
        <filter-name>struts2</filter-name>
        <url-pattern>/*</url-pattern>
</filter-mapping>

<package name="basicstruts2" extends="struts-default">

		<action name="index">
			<result>/index.jsp</result>
		</action>

	</package>