tapestry自定义基本IEngineService

                                      

 

   tapestry的SeviceLink组件能调用9种基本的service（ActionService, AssetService, DirectService, EngineServiceInnerProxy, EngineServiceOuterProxy, ExternalService, HomeService, PageService, ResetService, RestartService）。如果这9种基本service不能满足需求，那可以使用自定义service来代替基本service，下面将讲述如何创建自定义service：

   举例：有这样一个需求，要求用户对出的操作，会注销掉session中的数据，并且删除用户的cookie。
    首先，新建立一个类，实现IEngineService接口。

public class LogoutService implements IEngineService {
    /** @since 4.0 *hivemind注射基本服务/
    private Log _log;

    /** @since 4.0 *hivemind注射基本服务/
    private HttpServletRequest _request;

    /** @since 4.0 *hivemind注射基本服务/
    private HttpServletResponse _response;

    /** @since 4.0 *hivemind注射基本服务/
    private LinkFactory _linkFactory;

    /** @since 4.0 */
    private String _servletPath;
   
   
    @SuppressWarnings("unchecked")
    public ILink getLink(boolean post, Object parameter)
    {
        //该服务允许带参数，所以屏蔽以下两句，若不允许带参数取消注释
        // if (parameter != null)
        // throw new IllegalArgumentException(EngineMessages.serviceNoParameter(this));

        Map parameters = new HashMap();
        //key必须为ServiceConstants所指定的key，否则会有异常
        parameters.put(ServiceConstants.SERVICE, getName());
        //其中parameter参数为，@ServiceLink组件的parameters
        parameters.put(ServiceConstants.PARAMETER,parameter);
        return _linkFactory.constructLink(this, post, parameters, true);
    }

   
    public void service(IRequestCycle cycle) throws IOException
    {
        String serviceName = cycle.getParameter(ServiceConstants.SERVICE);
        System.out.println(serviceName);
        HttpSession session = _request.getSession(false);
       
        //注销清除cookie
        CookieSource cookieSource=cycle.getInfrastructure().getCookieSource();
        //获得@ServiceLink组件的parameters
        Object[] obj=_linkFactory.extractListenerParameters(cycle);
        for (Object object : obj) {
            cookieSource.removeCookieValue((String)object);
        }
       
        if (session != null)
        {
            try
            {
                session.invalidate();
            }
            catch (IllegalStateException ex)
            {
                _log.warn("Exception thrown invalidating HttpSession.", ex);

                // Otherwise, ignore it.
            }
        }

        String url = cycle.getAbsoluteURL(_servletPath);

        _response.sendRedirect(url);
    }

    //指定该service的名字
    public String getName()
    {
        return "logout";
    }

    /** @since 4.0 */
    public void setLog(Log log)
    {
        _log = log;
    }

    /** @since 4.0 */
    public void setRequest(HttpServletRequest request)
    {
        _request = request;
    }

    /** @since 4.0 */
    public void setResponse(HttpServletResponse response)
    {
        _response = response;
    }

    /** @since 4.0 */
    public void setLinkFactory(LinkFactory linkFactory)
    {
        _linkFactory = linkFactory;
    }

    /** @since 4.0 */
    public void setServletPath(String servletPath)
    {
        _servletPath = servletPath;
    }
}

hivemind配置如下：
      <service-point id="LogoutService" interface="org.apache.tapestry.engine.IEngineService">
        <invoke-factory service-id="hivemind.BuilderFactory" model="singleton" >
            <construct class="impl.FenixLogoutService" >
                <set-service property="request" service-id="tapestry.globals.HttpServletRequest" />
                <set-service property="response" service-id="tapestry.globals.HttpServletResponse" />
                <set-object property="servletPath" value="app-property:org.apache.tapestry.servlet-path" />
                <set-object property="linkFactory" value="infrastructure:linkFactory" />
            </construct>
        </invoke-factory>
    </service-point>

    <contribution configuration-id="tapestry.services.ApplicationServices">
        <service name="logout" object="service:LogoutService"/>
    </contribution>

使用就简单了:
<a jwcid="@ServiceLink" service="logout" parameters="ognl:cookieList">退出</a>