Struts2開發自定義攔截器

Interceptor接口

public interface Interceptor extends Serializable {


/**
 * Called to let an interceptor clean up any resources it has allocated.
 */
void destroy();

/**
 * Called after an interceptor is created, but before any requests are processed using
 * {@link #intercept(com.opensymphony.xwork2.ActionInvocation) intercept} , giving
 * the Interceptor a chance to initialize any needed resources.
 */
void init();

/**
 * Allows the Interceptor to do some processing on the request before and/or after the rest of the processing of the
 * request by the {@link ActionInvocation} or to short-circuit the processing and just return a String return code.
 *
 * @param invocation the action invocation
 * @return the return code, either returned from {@link ActionInvocation#invoke()}, or from the interceptor itself.
 * @throws Exception any system-level error, as defined in {@link com.opensymphony.xwork2.Action#execute()}.
 */
String intercept(ActionInvocation invocation) throws Exception;

}</pre>

可以看出接口中只有三個方法需要實現。 

實現Interceptor接口 

public class MyInterceptor implements Interceptor {
    public void destroy() {
        System.out.println("destroy()----");
    }
    public void init() {
        System.out.println("init()----");
    }
    public String intercept(ActionInvocation invocation) throws Exception {
        System.out.println("在Action執行之前");
        String result = invocation.invoke();
        System.out.println("在Result執行之后");
        return result;
    }
}


我們需要在struts.xml文件中進行配置： 

<package name="helloworld" extends="struts-default">
        <interceptors>
            <interceptor name="MyInterceptor" class="com.lc.action.MyInterceptor" />
        </interceptors>
        <action name="loginAction" class="com.lc.action.LoginAction">
            <param name="account">test</param>
            <result>/welcome.jsp</result>
            <interceptor-ref name="MyInterceptor" />
            <interceptor-ref name="defaultStack" />
        </action>
    </package>


首先聲明一個自定義的攔截器： 

<interceptors>
            <interceptor name="MyInterceptor" class="com.lc.action.MyInterceptor" />
        </interceptors>


然后在action中引用： 

<interceptor-ref name="MyInterceptor" />


執行的結果可想而知： 

在Action執行之前
account=test,password=test,submitFlag=login
在Result執行之后