Jemmy Walker

　　粉久沒再踹Struts 2了，web.xml可以設個Filter減少struts.xml的配置，其實就是用注釋替代。飯粒如下：

(web.xml)

<filter>
        <filter-name>action2</filter-name>
        <filter-class>org.apache.struts2.dispatcher.FilterDispatcher</filter-class>
        <init-param>
            <param-name>actionPackages</param-name>
            <param-value>com.fdar.apress.s2</param-value>
        </init-param>
</filter>
<filter-mapping>
        <filter-name>action2</filter-name>
        <url-pattern>/*</url-pattern>
</filter-mapping>

　　因此假設web cotnext root name叫app，而FooAction的package name是com.fdar.apress.s2.app，那FooAction的URL是http://localhost:8080/app/foo.action，若BarAction的package name是com.fdar.apress.s2.app.test.bar，則其URL為http://localhost:8080/app/test/bar/bar.action。而FooAction和BarAction在java怎麼使用注釋如下：

(FooAction.java in com.fdar.apress.s2)

package com.fdar.apress.s2.app;

import org.apache.struts2.config.Namespace;
import org.apache.struts2.config.Result;
import org.apache.struts2.dispatcher.ServletDispatcherResult;

@Namespace("/")
@Result(name="success", value="/jsp/success.jsp", type=ServletDispatcherResult.class)
public class FooAction {
    public String execute() {
        return "success";
    }
}

(BarAction.java in com.fdar.apress.s2.book.test)

package com.fdar.apress.s2.app.book.test;

import java.util.Random;

import org.apache.struts2.config.Namespace;
import org.apache.struts2.config.Result;
import org.apache.struts2.config.Results;
import org.apache.struts2.dispatcher.ServletDispatcherResult;

@Namespace("/book/test")
@Results({
    @Result(name="success", value="/jsp/success.jsp", type= ServletDispatcherResult.class),
    @Result(name="input", value="/jsp/input.jsp", type= ServletDispatcherResult.class)
})
public class BarAction {

    public String execute() {
        return new Random().nextBoolean() ? "success" : "input";
    }
}

　　由上例看，注釋主要是用@Results、@Result替代了struts.xml內<result>標籤。但要特別注意也得加Namespace，FooAction的URL是http://localhost:8080/app/foo.action，所以是"/"；而BarAction的URL則是把package的.book.test變成/book/test，是故@Namespace("/book/test")對映到http://localhost:8080/app/test/bar/bar.action。

P.S.在web.xml設了actionPackages之後，原本struts.xml裡有關action、result的標籤就完全失效了。