org.impalaframework.extension.mvc.flash.FlashHelper.java Source code

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Here is the source code for org.impalaframework.extension.mvc.flash.FlashHelper.java

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/*
 * Copyright 2009-2010 the original author or authors.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package org.impalaframework.extension.mvc.flash;

import java.util.HashMap;
import java.util.Map;
import java.util.Set;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

import org.springframework.ui.ModelMap;

/**
 * Class with responsibilities for flash-scope specific request and model management operations.
 * @author Phil Zoio
 */
@SuppressWarnings("unchecked")
public class FlashHelper {

    private String sessionPrefix;

    public FlashHelper() {
        this.sessionPrefix = "";
    }

    public FlashHelper(String sessionPrefix) {
        super();
        this.sessionPrefix = sessionPrefix;
    }

    public void beforeHandleRequest(HttpServletRequest request) {
        //unpack flash state from session into request
        unpackFlashState(request);
    }

    public void afterHandleRequest(HttpServletRequest request, final ModelMap modelMap) {
        //merge in existing flash state from request
        mergeFlashState(request, modelMap);

        //outgoing flash parameters should be added to the session
        setFlashState(request, modelMap);
    }

    void unpackFlashState(HttpServletRequest request) {

        final HttpSession session = request.getSession(false);
        if (session != null) {
            final Map<String, Object> flashState = (Map<String, Object>) session
                    .getAttribute(sessionPrefix + "flashState");
            if (flashState != null) {
                request.setAttribute("flashState", flashState);
                session.removeAttribute(sessionPrefix + "flashState");

                Set<String> flashKeys = flashState.keySet();
                for (String flashKey : flashKeys) {
                    Object currentRequestAttribute = request.getAttribute(flashKey);
                    if (currentRequestAttribute == null) {
                        request.setAttribute(flashKey, flashState.get(flashKey));
                    }
                }
            }
        }
    }

    void mergeFlashState(HttpServletRequest request, ModelMap modelMap) {
        final Map<String, Object> flashState = (Map<String, Object>) request.getAttribute("flashState");
        if (flashState != null) {
            modelMap.mergeAttributes(flashState);
            request.removeAttribute("flashState");
        }
    }

    void setFlashState(HttpServletRequest request, Map modelMap) {

        final Set keys = modelMap.keySet();
        Map<String, Object> flashState = null;

        for (Object object : keys) {
            String key = object.toString();
            if (key.startsWith("flash:")) {
                String realKey = key.substring("flash:".length());
                if (flashState == null)
                    flashState = new HashMap<String, Object>();
                flashState.put(realKey, modelMap.get(key));
            }
        }

        if (flashState != null) {
            request.getSession().setAttribute(sessionPrefix + "flashState", flashState);
        }
    }

}