Spring scope MVC personalizzato

Vorrei creare il mio scope scope personalizzato che utilizzerà la sessione HTTP (tipo di ambito Flash).

Secondo Spring Manual ho bisogno di implementare l’interfaccia org.springframework.beans.factory.config.Scope

public class CustomScope implements Scope { @Override public Object get(String arg0, ObjectFactory arg1) { // TODO Auto-generated method stub return null; } @Override public String getConversationId() { // TODO Auto-generated method stub return null; } @Override public void registerDestructionCallback(String arg0, Runnable arg1) { // TODO Auto-generated method stub } @Override public Object remove(String arg0) { // TODO Auto-generated method stub return null; } @Override public Object resolveContextualObject(String arg0) { // TODO Auto-generated method stub return null; } } 

La mia domanda è come posso ottenere la sessione HTTP all’interno di questo bean? Capisco che se stavo creando bean in ambito ServletContext implementerei l’interfaccia ServletContextAware.

Per favore aiuto 🙂

Spero che possa essere utile per qualcuno in futuro, quindi mi piacerebbe condividerlo.

Ho fatto qualche ricerca e ho scoperto che sfortunatamente non è ansible ottenere HTTP Session per Spring MVC.

Il mio scopo era l’implementazione di Flash Scope per il mio controller Spring MVC che utilizzava il pattern PRG.

Fare ulteriori ricerche in Spring Forum Ho trovato il modo di farlo usando HandlerInterceptor.

 import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import java.util.*; import java.util.Map.Entry; import org.springframework.web.servlet.HandlerInterceptor; import org.springframework.web.servlet.ModelAndView; public class FlashScopeInterceptor implements HandlerInterceptor { public static final String DEFAULT_ATTRIBUTE_NAME = "flashScope"; public static final String DEFAULT_SESSION_ATTRIBUTE_NAME = FlashScopeInterceptor.class.getName(); public static final int DEFAULT_RETENTION_COUNT = 2; private String sessionAttributeName = DEFAULT_SESSION_ATTRIBUTE_NAME; private String attributeName = DEFAULT_ATTRIBUTE_NAME; private int retentionCount = DEFAULT_RETENTION_COUNT; /** * Unbinds current flashScope from session. Rolls request's flashScope to * the next scope. Binds request's flashScope, if not empty, to the session. * */ @Override public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception { if (request.getSession( false ) != null) { request.getSession().removeAttribute( this.sessionAttributeName ); } Object requestAttribute = request.getAttribute( this.attributeName ); if (requestAttribute instanceof MultiScopeModelMap) { MultiScopeModelMap attributes = (MultiScopeModelMap) requestAttribute; if (!attributes.isEmpty()) { attributes.next(); if (!attributes.isEmpty()) { request.getSession( true ).setAttribute( this.sessionAttributeName, attributes ); } } } } /** * merge modelAndView.model['flashScope'] to current flashScope */ @Override public void postHandle( HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception { if (modelAndView != null) { Map modelFlashScopeMap = null; for (Iterator> iterator = ((Map) modelAndView.getModel()).entrySet() .iterator(); iterator.hasNext();) { Entry entry = iterator.next(); if (this.attributeName.equals( entry.getKey() ) && entry.getValue() instanceof Map) { if (modelFlashScopeMap == null) { modelFlashScopeMap = (Map) entry.getValue(); } else { modelFlashScopeMap.putAll( (Map) entry.getValue() ); } iterator.remove(); } else if (entry.getKey().startsWith( this.attributeName + "." )) { String key = entry.getKey().substring( this.attributeName.length() + 1 ); if (modelFlashScopeMap == null) { modelFlashScopeMap = new HashMap(); } modelFlashScopeMap.put( key, entry.getValue() ); iterator.remove(); } } if (modelFlashScopeMap != null) { MultiScopeModelMap flashScopeMap; if (request.getAttribute( this.attributeName ) instanceof MultiScopeModelMap) { flashScopeMap = (MultiScopeModelMap) request.getAttribute( this.attributeName ); } else { flashScopeMap = new MultiScopeModelMap( this.retentionCount ); } flashScopeMap.putAll( modelFlashScopeMap ); request.setAttribute( this.attributeName, flashScopeMap ); } } } /** * binds session flashScope to current session, if not empty. Otherwise cleans up empty * flashScope */ @Override public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { HttpSession session = request.getSession( false ); if (session != null) { Object sessionAttribute = session.getAttribute( this.sessionAttributeName ); if (sessionAttribute instanceof MultiScopeModelMap) { MultiScopeModelMap flashScope = (MultiScopeModelMap) sessionAttribute; if (flashScope.isEmpty()) { session.removeAttribute( this.sessionAttributeName ); } else { request.setAttribute( this.attributeName, flashScope ); } } } return true; } } 

Ora MultiScopeModelMap.java

 import java.io.Serializable; import java.util.Collection; import java.util.HashMap; import java.util.LinkedList; import java.util.Map; import java.util.Set; import org.apache.commons.collections.map.CompositeMap; import org.apache.commons.collections.map.CompositeMap.MapMutator; public class MultiScopeModelMap extends CompositeMap implements Serializable, MapMutator { public MultiScopeModelMap(int num) { super(); setMutator( this ); for(int i = 0; i < num; ++i) { addComposited( new HashMap() ); } } /** Shadows composite map. */ private final LinkedList maps = new LinkedList(); @Override public synchronized void addComposited( Map map ) throws IllegalArgumentException { super.addComposited( map ); this.maps.addLast( map ); } @Override public synchronized Map removeComposited( Map map ) { Map removed = super.removeComposited( map ); this.maps.remove( map ); return removed; } /** * Starts a new scope. * All items added in the session before the previous session are removed. * All items added in the previous scope are still retrievable and removable. */ public void next() { removeComposited( this.maps.getFirst() ); addComposited( new HashMap() ); } public Object put( CompositeMap map, Map[] composited, Object key, Object value ) { if(composited.length < 1) { throw new UnsupportedOperationException("No composites to add elements to"); } Object result = map.get( key ); if(result != null) { map.remove( key ); } composited[composited.length-1].put( key, value ); return result; } public void putAll( CompositeMap map, Map[] composited, Map mapToAdd ) { for(Entry entry: (Set)mapToAdd.entrySet()) { put(map, composited, entry.getKey(), entry.getValue()); } } public void resolveCollision( CompositeMap composite, Map existing, Map added, Collection intersect ) { existing.keySet().removeAll( intersect ); } @Override public String toString() { return new HashMap(this).toString(); } } 

Uso:

 @RequestMapping(value="/login.do", method=RequestMethod.POST) public ModelAndView login(@Valid User user){ ModelAndView mv = new ModelAndView("redirect:result.html"); if (authService.authenticate(user.getUserName(), user.getPassword())) mv.addObject("flashScope.message", "Success"); //else mv.addObject("flashScope.message", "Login Failed"); return mv; } @RequestMapping(value ="/result.html", method=RequestMethod.GET) public ModelAndView result(){ ModelAndView mv = new ModelAndView("login/loginAction"); return mv; } 

In JSP l’utilizzo è molto semplice:

 ${flashScope.message} 

Inoltre, è necessario configurare la class FlashScopeInterceptor come interceptor.

       

Raccomando di dare un’occhiata al codice sorgente di org.springframework.web.context.request.SessionScope . Questo ambito deve aver risolto lo stesso problema in qualche modo.

Sembra che utilizzino: RequestContextHolder.currentRequestAttributes().getSessionId()

È ansible accedere agli attributi di sessione utilizzando il codice successivo all’interno dei metodi della class scope in Spring MVC (funziona in 3.2):

 RequestAttributes attributes = RequestContextHolder.currentRequestAttributes(); attributes.getAttribute("some key", NativeWebRequest.SCOPE_SESSION); attributes.setAttribute("some key", YouObject, NativeWebRequest.SCOPE_SESSION); 

L’implementazione RequestAttributes (ServletRequestAttributes) internamente chiamerà i metodi set / getAttribute () sull’object di sessione corrente.