Struts – Multiple configuration files example

最新推荐文章于 2020-04-14 08:54:38 发布

转载最新推荐文章于 2020-04-14 08:54:38 发布 · 349 阅读

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本文讨论了在大型Struts开发项目中，将所有Struts相关组件（action、form等）整合到单个配置文件的问题。这种做法虽便于初期开发，但不利于未来维护。文章建议将配置拆分到不同模块，利用Struts的多配置文件功能，通过示例展示了如何实现单个模块下的多个配置文件，并介绍了多模块环境下各自拥有独立配置文件的方法。同时，还提到了Struts2中Namespace的概念作为替代方案。

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Many developers like to put all Struts related stuff (action, form) into a single Struts configuration file. It’s fast for the initial development but bad for the future maintenance, and may be those developers are not aware of the Struts is allow multiple configuration files feature.
6 years ago, I had joined a large Struts development project which involve 20+ modules. Unfortunately, the prior developers put all the Struts related stuff (action, form and etc) into a single Struts configuration file (struts-config.xml). The struts-config.xml just keep growing extremely fast and finally hit 20++mb, every update to this configuration file will take few minutes, and even wait half an hour for a single debugging deployment in Eclipse IDE. This is a serious performance issue and causing the project keep delay the production date. What a good Struts development experience.

Please split the Struts configuration details into different modules, Struts can do it easily.
Struts multiple configuration files example

This is the sample project structure for the demonstration.
Struts-mutiple-configuration-file

1. Single module

A single module support multiple Struts configuration files.

page1.jsp

This is Page 1

page2.jsp

This is Page 2

struts-config-1.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts-config PUBLIC 
"-//Apache Software Foundation//DTD Struts Configuration 1.3//EN" 
"http://jakarta.apache.org/struts/dtds/struts-config_1_3.dtd">

<struts-config>

    <action-mappings>

        <action
            path="/Page1"
            type="org.apache.struts.actions.ForwardAction"
            parameter="/pages/page1.jsp"/>

    </action-mappings>

</struts-config>

struts-config-2.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts-config PUBLIC 
"-//Apache Software Foundation//DTD Struts Configuration 1.3//EN" 
"http://jakarta.apache.org/struts/dtds/struts-config_1_3.dtd">

<struts-config>

    <action-mappings>

        <action
            path="/Page2"
            type="org.apache.struts.actions.ForwardAction"
            parameter="/pages/page2.jsp"/>

    </action-mappings>

</struts-config>

In the web.xml, you can separate multiple Struts configure file by a comma “,“.

web.xml

<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
  <display-name>Maven Struts Examples</display-name>

  <servlet>
    <servlet-name>action</servlet-name>
    <servlet-class>
        org.apache.struts.action.ActionServlet
    </servlet-class>
    <init-param>
        <param-name>config</param-name>
        <param-value>
         /WEB-INF/struts-config-1.xml, /WEB-INF/struts-config-2.xml
        </param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
  </servlet>

  <servlet-mapping>
       <servlet-name>action</servlet-name>
       <url-pattern>*.do</url-pattern>
  </servlet-mapping>

</web-app>

Test it

    http://localhost:8080/StrutsExample/Page1.do
    It will display the page1.jsp
    http://localhost:8080/StrutsExample/common/Welcome.do
    It will display the page2.jsp

Both Struts configuration are loaded property.

2. Multiple modules

Multiple modules, each has own Struts configuration files.

admin/welcome.jsp

Welcome to admin page

common/welcome.jsp

Welcome to common page

Both “struts-config-admin.xml” and “struts-config-admin.xml” files contains the same settings, Struts is able to differential it via the “config” parameter value in web.xml.
In Struts 2, the “Namespace” is a more efficient way to replace this “config parameter” setting.

struts-config-admin.xml, struts-config-admin.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts-config PUBLIC 
"-//Apache Software Foundation//DTD Struts Configuration 1.3//EN" 
"http://jakarta.apache.org/struts/dtds/struts-config_1_3.dtd">

<struts-config>

    <action-mappings>

        <action
            path="/Welcome"
            type="org.apache.struts.actions.ForwardAction"
            parameter="/welcome.jsp"/>

    </action-mappings>

</struts-config>

web.xml

<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
  <display-name>Maven Struts Examples</display-name>

  <servlet>
    <servlet-name>action</servlet-name>
    <servlet-class>
        org.apache.struts.action.ActionServlet
    </servlet-class>
    <init-param>
        <param-name>config</param-name>
        <param-value>
         /WEB-INF/struts-config-1.xml, /WEB-INF/struts-config-2.xml
        </param-value>
    </init-param>
    <init-param>
        <param-name>config/admin</param-name>
        <param-value>
         /WEB-INF/struts-config-admin.xml
        </param-value>
    </init-param>
    <init-param>
        <param-name>config/common</param-name>
        <param-value>
         /WEB-INF/struts-config-common.xml
        </param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
  </servlet>

  <servlet-mapping>
       <servlet-name>action</servlet-name>
       <url-pattern>*.do</url-pattern>
  </servlet-mapping>

</web-app>

Test it

The “config/admin” will match to this URL pattern – http://localhost:8080/StrutsExample/admin/
The “config/common” will match to this URL pattern – http://localhost:8080/StrutsExample/common/

    http://localhost:8080/StrutsExample/admin/Welcome.do
    It will display the admin/welcome.jsp
    http://localhost:8080/StrutsExample/common/Welcome.do
    It will display the common/welcome.jsp

Each modules has own Struts configuration file.