Tapestry4 Spring

How  can  you  reference  Spring  beans  from  Tapestry  4?  In  earlier  versions  of  Tapestry,  
the  most  common  method  was  to  extend  the  BaseEngine  class.  However,  in  Tapestry  4  the  BaseEngine  class  is  deprecated,  and  we  now  need  to  extend  SpringBeanFactoryHolder.  

(Basic  knowledge  of  Java,  Tapestry,  and  Spring  assumed.)  

Step  1:  Hivemind  Configuration
Note:  You  can  skip  this  step  by  downloading  tapestry-spring.jar  from    http://sourceforge.net/projects/diaphragma  and  placing  it  on  your  classpath.  

Continue  reading,  if  you're  interested  in  how  it  works...  

Tapestry  uses  Hivemind,  behind  the  scenes,  for  dependency-injection.  Hivemind's  XML  configuration  is  similar  to  Spring.  The  easiest  way  to  contribute  to  the  whole  Hivemind  registry  is  by  creating  hivemodule.xml  in  your  WEB-INF  directory.  

Here  is  what  you  need  in  this  project  to  provide  a  new  implementation  of  the  DefaultSpringBeanFactoryHolder:  

<form accept-charset="UNKNOWN" enctype="application/x-www-form-urlencoded" method="get"></form>

程序代码：

<?xml version="1.0"?>

<module id="diaphragma.tapspr" version="1.0.0">
    <implementation
        service-id="hivemind.lib.DefaultSpringBeanFactoryHolder">
        <invoke-factory>
            <construct autowire-services="false"
                class="diaphragma.tapspr.XSpringBeanFactoryHolderImpl">
                <event-listener
                    service-id="hivemind.ShutdownCoordinator" />
                <set-object property="context"
                    value="service:tapestry.globals.WebContext" />
            </construct>
        </invoke-factory>
    </implementation>
</module>

Next  job  is  to  create  XSpringBeanFactoryHolderImpl.java.  It  look  like  this:  

<form accept-charset="UNKNOWN" enctype="application/x-www-form-urlencoded" method="get"></form>

程序代码：

package diaphragma.tapspr;

import java.io.PrintStream;
import org.apache.hivemind.events.RegistryShutdownListener;
import org.apache.hivemind.lib.impl.SpringBeanFactoryHolderImpl;
import org.apache.tapestry.web.WebContext;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.context.ConfigurableApplicationContext;


public class XSpringBeanFactoryHolderImpl extends SpringBeanFactoryHolderImpl
    implements RegistryShutdownListener
{
    private WebContext context;

    public XSpringBeanFactoryHolderImpl()
    {
    }

    public void setContext(WebContext webcontext)
    {
        context = webcontext;
    }

    public WebContext getContext()
    {
        return context;
    }

    public BeanFactory getBeanFactory()
    {
        if(super.getBeanFactory() == null)
            super.setBeanFactory(XWebApplicationContextUtils.getWebApplicationContext(getContext()));
        return super.getBeanFactory();
    }

    public void registryDidShutdown()
    {
        ((ConfigurableApplicationContext)super.getBeanFactory()).close();
    }

}

As  we  can  see,  this  class  extends  the  default  SpringBeanFactoryHolder.  The  important  thing  is  what  you  see  in  getBeanFactory()  method,  there  you  define  where  our  BeanFactory  located.  In  this  example,  I  use  WebApplicationContextUtils.getRequiredWebApplicationContext()  method.  There  is  another  method  which  doesn't  throw  exception  WebApplicationContextUtils.getWebApplicationContext().  

Next,  we  implement  XWebApplicationContextUtils.java  

<form accept-charset="UNKNOWN" enctype="application/x-www-form-urlencoded" method="get"></form>

程序代码：

package diaphragma.tapspr;

import org.apache.tapestry.web.WebContext;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;

public class XWebApplicationContextUtils extends WebApplicationContextUtils
{

    public XWebApplicationContextUtils()
    {
    }

    public static WebApplicationContext getWebApplicationContext(WebContext webcontext)
    {
        Object obj = webcontext.getAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE);
        if(obj == null)
            return null;
        if(obj instanceof RuntimeException)
            throw (RuntimeException)obj;
        if(obj instanceof Error)
            throw (Error)obj;
        if(!(obj instanceof WebApplicationContext))
            throw new IllegalStateException((new StringBuilder()).append("Root context attribute is not of type WebApplicationContext: ").append(obj).toString());
        else
            return (WebApplicationContext)obj;
    }

    public static WebApplicationContext getRequiredWebApplicationContext(WebContext webcontext)
        throws IllegalStateException
    {
        WebApplicationContext webapplicationcontext = getWebApplicationContext(webcontext);
        if(webapplicationcontext == null)
            throw new IllegalStateException("No WebApplicationContext found: no ContextLoaderListener registered?");
        else
            return webapplicationcontext;
    }
}

Step  2:  Spring  Configuration
Spring  in  servlet  mode  need  two  things,  it  needs  the  XML  file  for  bean  configuration  and  also  a  filter  in  web.xml.  In  web.xml,  you  will  have  to  add  this:  

<form accept-charset="UNKNOWN" enctype="application/x-www-form-urlencoded" method="get"></form>

程序代码：

<context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/applicationContext.xml</param-value>
</context-param>
<listener>
        <listener-class>
                org.springframework.web.context.ContextLoaderListener
        </listener-class>
</listener>

And  now  let  us  try  a  simple  XML  file  (place  it  under  WEB-INF/  as  applicationContext.xml).  

<form accept-charset="UNKNOWN" enctype="application/x-www-form-urlencoded" method="get"></form>

程序代码：

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE beans public "-//SPRING//DTD BEAN//EN" 
        "http://www.springframework.org/dtd/spring-beans.dtd">

<beans>
        <bean id="person" class="com.example.model.Person">
        <property name="name">
                <value>Nanda Firdausi</value>
        </property>
        </bean>
</beans>

It  defines  one  object  with  one  property.  

Step  3:  Access  Spring  property  from  Tapestry  page  specification
Now  time  to  see  whether  our  bean  can  be  accessed  from  a  Tapestry  page.  First,  let  us  create  the  page  specification  (Home.page).  

<form accept-charset="UNKNOWN" enctype="application/x-www-form-urlencoded" method="get"></form>

程序代码：

<?xml version="1.0" encoding="UTF-8"?>
        
<!DOCTYPE page-specification PUBLIC
        "-//Apache Software Foundation//Tapestry Specification 4.0//EN"
        "http://jakarta.apache.org/tapestry/dtd/Tapestry_4_0.dtd">
        
<page-specification class="org.apache.tapestry.html.BasePage">
        <inject property="person" object="spring:person" />
</page-specification>
The page template is trivial, one super-simple-example is like this (Home.html). 

<span jwcid="@Insert" value="ognl:person.name" /> 
Please make comments, suggestions, and any other things related to this tutorial. 

--------------------------------------------------------------------------------

This  information  was  originally  written  in  an  email  to  the  Tapestry  User's  List  on  March  7,  2005  by  Nanda  Firdausi  

HowardLewisShip:  This  is  pretty  much  overkill,  since  you  can  just  acquire  your  AC  and  store  it  into  the  DefaultSpringBeanFactoryHolder  service  with  no  additional  work.  I  do  like  that  you  have  a  shutdown  option,  though.  I'm  putting  together  a  proper  implementation  for  Tapestry  @  JavaForge.  

HowardLewisShip:  I've  put  together  a  basic  Spring  integration  module:    tapestry-spring.  The  solution  on  this  page  is  a  little  more  flexible,  however  (at  least  for  the  moment).  

NandaFirdausi:  I've  seen  your  implementation,  and  I  like  it  too,  just  like  your  other  code  ;).  I  thing  your  implementation  doesn't  need  spring  listener  anymore,  am  I  right?  If  so,  then  the  choice  to  the  user  is  if  they  do  have  another  spring  wep  application  with  nothing  to  do  with  tapestry,  it's  better  to  set  the  spring  listener  and  do  like  this  page  says.  If  your  web  application  is  all  tapestry  based  (with  spring  as  back-end  support),  then  your  code  looks  cleaner  for  me    

Tapestry  4  (another  solution)
JarekWoloszyn:  Here  is  another  solution  for  Tapestry4.  

We  need  a  helper  class  which  will  create  WebApplicationContext  for  the  ServletContext.  Hivemind  can't  call  factory  methods  (from  WebApplicationContextUtils),  so  we  create  a  POJO.  Spring  Context  is  re-created  everytime  we  change  ServletContext.  

<form accept-charset="UNKNOWN" enctype="application/x-www-form-urlencoded" method="get"></form>

程序代码：

package org.your.application;

import javax.servlet.ServletContext;

import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;


public class SpringContextFactory {
    private ServletContext servletContext;
    private WebApplicationContext appContext;
    
    public WebApplicationContext getAppContext() {
        return appContext;
    }    
    
    public ServletContext getServletContext() {
        return servletContext;
    }

    public void setServletContext(ServletContext servletContext) {
        this.servletContext = servletContext;
        appContext = WebApplicationContextUtils.getWebApplicationContext(getServletContext());
    }     
}

Tapestry  4  has  Spring  integration  out  of  the  box.  We  must  only  say  which  BeanFactory  should  be  used.  In  hivemind.xml,  we  define  a  service-point  for  our  helper  class.  This  class  takes  ServletContext  as  parameter.  We  configure  then  Hivemind  to  use  appContext  member  as  spring-bean  factory.  

<form accept-charset="UNKNOWN" enctype="application/x-www-form-urlencoded" method="get"></form>

程序代码：

<?xml version="1.0"?>
<module id="app" version="1.0.0" package="org.your.application">
  
  <contribution configuration-id="hivemind.ApplicationDefaults">
    <default symbol="hivemind.lib.spring-bean-factory" value="service-property:app.SpringContextFactory:appContext"/>
  </contribution>
  
    <service-point id="SpringContextFactory">        
        Create WebApplicatonContext for Spring
        <invoke-factory>
            <construct class="SpringContextFactory">
                <set-service property="servletContext" service-id="tapestry.globals.ServletContext"/>
            </construct>
        </invoke-factory>        
        
    </service-point>
    
</module>