先貼兩段程式碼，在慢慢解釋

(1)struts-user.xml

1.<struts>

2.    <package name="struts-user" extends="struts-default">

3.       
4.        <global-results>

5.            <result type="redirect-action">UserAction_queryAll</result>

6.        </global-results>

7.       
8.        <action name="UserAction_login" class="userAction" method="login"></action>

9.        <action name="UserAction_insert" class="userAction" method="insert"></action>

10.        <action name="UserAction_update" class="userAction" method="update"></action>

11.        <action name="UserAction_delete" class="userAction" method="delete"></action>

12.        <action name="UserAction_queryById" class="userAction" method="queryById"></action>
13.        <action name="UserAction_queryByLike" class="userAction" method="queryByLike"></action>

14.        <action name="UserAction_queryAll" class="userAction" method="queryAll">

15.            <result>/user/user_list.jsp</result>

16.        </action>

17.       
18.    </package>

19.</struts>

(2)struts.xml(引入了struts-user.xml)

1.<struts>

2.

3.    <include file="struts-user.xml"></include>

4.    <package name="struts" extends="struts-default"></package>

5.   
6.</struts>

1. 使用<include>標籤重用配置檔案

(1)在Struts2中提供了一個預設的struts.xml檔案，但如果package、action、interceptors等配置比較多時，都放到一個struts.xml檔案不太容易維護。因此，就需要將struts.xml檔案分成多個配置檔案，然後在struts.xml檔案中使用<include>標籤引用這些配置檔案。如上面的程式碼。

注意：用<include>引用的xml檔案也必須是完成的struts2的配置。實際上<include>在引用時是單獨解析的xml檔案，而不是將被引用的檔案插入到struts.xml檔案中。

注意：struts.xml和struts-user.xml中<package></package>標籤中的name屬性不能相同。道理很簡單，<struts></struts>標籤中可以有多個<package></package>標籤，要通過name屬性以示區別。

(2)Apache Struts 2 Documentation: Can we break up a large struts.xml file into smaller pieces --> Yes, there are two approaches. We can include other struts.xml file from a bootstrap, or we can package a struts.xml files in a JAR. Or both.

<1>By Include：A typical struts.xml files will have one or more include elements:

1.<struts>

2.    <include file="struts-default.xml"/>

3.    <include file="config-browser.xml"/>

4.    <package name="default" extends="struts-default">

5.    ....
6.    </package>

7.    <include file="other.xml"/>

8.</struts>

The first include element tells the framework to load the struts-default.xml, which it will find in the struts2.jar file. The struts-default.xml file defines the "standard" interceptor and result definitions. You can put your own <include> elements in your struts.xml interchangeably with <package> elements. The configuration objects will be loaded in the order of appearance. The framework reads the configuration from top to bottom and adds objects as they are referenced.

<2>By JAR

A "module" can be added to an application by placing a struts.xml and related classes into a JAR on the classpath. FreeMarker and Velocity templates can also be provided by JAR, making it possible to distribution a module in a single, self-contained JAR that is automatically configured on startup.

2. 全域性result(global-results)

(1)有很多時候一個<result>可供很多<action>使用，這時可以使用<global-results>標籤來定義全域性的<result>，程式碼見struts-user.xml。執行順序：當一個Action返回的String沒有相應的<result>與之對應，Struts2就會查詢全域性的<result>。

(2)Apache Struts 2 Documentation: Global Results

Most often, results are nested with the action element. But some results apply to multiple actions. In a secure application, a client might try to access a page without being authorized, and many actions may need access to a "logon" result. If actions need to share results, a set of global results can be defined for each package. The framework will first look for a local result nested in the action. If a local match is not found, then the global results are checked.

1.<!-- Defining global results -->

2.<global-results>

3.    <result name="error">/Error.jsp</result>

4.    <result name="invalid.token">/Error.jsp</result>

5.    <result name="login" type="redirectAction">Logon!input</result>

6.</global-results>

3. <include>標籤和<global-results>標籤結合

(1)<global-results>標籤的作用域只是當前<struts></struts>，也可以說是當前的xml檔案；struts2不允許把struts-user.xml(通過<include>引入到struts.xml)中的<global-results>標籤寫在struts.xml中。

(2)如果struts-user.xml中的package繼承自struts.xml中的package，則可以將struts-user.xml中的<global-results>放在struts.xml中。然後struts-user.xml將此<global-results>從struts.xml中繼承過來。例如(將上面的兩段程式碼簡單修改)：

(1)struts-user.xml

1.<struts>

2.    <!-- 這裡struts-user繼承(extends)的是struts, 即struts.xml中package的name屬性值 -->

3.    <package name="struts-user" extends="struts">

4.       
5.        <action name="UserAction_login" class="userAction" method="login"></action>

6.        <action name="UserAction_insert" class="userAction" method="insert"></action>

7.        <action name="UserAction_update" class="userAction" method="update"></action>

8.        <action name="UserAction_delete" class="userAction" method="delete"></action>

9.        <action name="UserAction_queryById" class="userAction" method="queryById"></action>
10.        <action name="UserAction_queryByLike" class="userAction" method="queryByLike"></action>

11.        <action name="UserAction_queryAll" class="userAction" method="queryAll">

12.            <result>/user/user_list.jsp</result>

13.        </action>

14.       
15.    </package>

16.</struts>

(2)struts.xml(引入了struts-user.xml)

1.<struts>

2.

3.    <include file="struts-user.xml"></include>

4.    <package name="struts" extends="struts-default">

5.        <global-results>

6.            <result type="redirect-action">UserAction_queryAll</result>

7.        </global-results>

8.    </package>

9.   
10.</struts>