Spring MVC自定义范围bean [英] Spring MVC custom scope bean

问题描述

我想创建自己的自定义范围bean，它将使用HTTP会话（一种Flash范围）。

I would like to create my own custom scope bean which will use HTTP session (kind of Flash scope).

根据Spring手册，我需要实现org.springframework.beans.factory.config.Scope接口

According to Spring Manual I need to implement org.springframework.beans.factory.config.Scope interface

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;
    }
}

我的问题是如何获取内部的HTTP会话这豆子？我理解如果我在ServletContext范围内创建bean，我会实现ServletContextAware接口。

My question is how can I obtain HTTP session inside of this bean? I understand that if I was creating bean in ServletContext scope I would implement ServletContextAware interface.

请帮助：）

推荐答案

我希望它对未来的人有用，所以我想分享一下。

I hope it will be useful for someone in the future, so I would like to share it.

我做了一些研究在它上面发现，遗憾的是，它无法获得Spring MVC的HTTP Session。

I made some reserch on it and have found that unfortunately, it is impossible to get HTTP Session for Spring MVC.

我的目的是使用PRG模式为我的Spring MVC控制器实现Flash Scope。

My purpose was Flash Scope implementation for my Spring MVC Controller using PRG pattern.

在Spring进行更多研究论坛我找到了使用HandlerInterceptor的方法。

Making more research in Spring Forum I've found the way to do it using 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<String, Object> modelFlashScopeMap = null;
            for (Iterator<Entry<String, Object>> iterator = ((Map<String, Object>) modelAndView.getModel()).entrySet()
                    .iterator(); iterator.hasNext();)
            {
                Entry<String, Object> 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<String, Object>();
                    }
                    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;
    }
}

现在MultiScopeModelMap.java

Now 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<Map> maps = new LinkedList<Map>();

    @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<Entry>)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();
    }


}

用法：

@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;
    }

在JSP中使用非常简单：

In JSP the usage is very simple:

${flashScope.message}

此外，您需要将FlashScopeInterceptor类配置为拦截器。

In addition you need to configure FlashScopeInterceptor class as interceptor.

<bean id="flashScopeInterceptor" class="x.y.z.FlashScopeInterceptor" />
<bean id="handlerMapping" class="org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping">
  <property name="interceptors">
    <list><ref bean="flashScopeInterceptor"/></list>
  </property>
</bean> 

这篇关于Spring MVC自定义范围bean的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！