pagehelper.java

这个weblogging 设计得比较精巧

package org.roller.presentation.velocity;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.struts.Globals;
import org.apache.struts.util.RequestUtils;
import org.apache.velocity.VelocityContext;
import org.apache.velocity.app.Velocity;
import org.apache.velocity.context.Context;
import org.roller.RollerException;
import org.roller.pojos.RefererData;
import org.roller.pojos.UserData;
import org.roller.pojos.WeblogEntryData;
import org.roller.presentation.LanguageUtil;
import org.roller.presentation.RollerContext;
import org.roller.presentation.RollerRequest;
import org.roller.presentation.tags.calendar.CalendarModel;
import org.roller.presentation.tags.calendar.CalendarTag;
import org.roller.presentation.tags.menu.EditorNavigationBarTag;
import org.roller.presentation.tags.menu.MenuTag;
import org.roller.presentation.weblog.tags.BigWeblogCalendarModel;
import org.roller.presentation.weblog.tags.WeblogCalendarModel;
import org.roller.util.StringUtils;

import java.io.StringWriter;
import java.net.MalformedURLException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.List;
import java.util.Locale;
import java.util.Vector;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.jsp.PageContext;

/**
 * Provides assistance to VelociMacros, filling in where Velocity falls.
 * 
 * @author llavandowska
 * @author David M Johnson
 * 
 */
public class PageHelper
{
    private static Log mLogger = 
       LogFactory.getFactory().getInstance(PageHelper.class);
    
    private Context              mVelocityContext = null;
    private PageContext          mPageContext = null;
    private HttpServletResponse  mResponse = null;     
    private RollerRequest        mRollerReq = null;
    private String               mUsername = null;
    private Collection           mPagePlugins = new ArrayList();
    private boolean              mSkipFlag = false;
    
    //------------------------------------------------------------------------
    
    /**
     * Initialize VelocityHelper, setting the variables it will be hiding from
     * the Velocimacros.
     */
    public PageHelper(
            RollerRequest rreq, HttpServletResponse response, Context ctx)
    {
        mVelocityContext = ctx;
        mRollerReq = rreq;
        mResponse = response;
        if (rreq != null) 
        {
            mPageContext = rreq.getPageContext();
            UserData user = null;
            if ( rreq.getRequest().getAttribute(RollerRequest.OWNING_USER) != null)
            {
                user = (UserData)
                    rreq.getRequest().getAttribute(RollerRequest.OWNING_USER);
            }
            else if ( rreq.getUser() != null )
            {
                user = rreq.getUser();
            }
            if ( user != null )
            {       
                mUsername = user.getUserName();       
            }
        }
        
        if (mVelocityContext == null) mVelocityContext = new VelocityContext();
    }
    
    //------------------------------------------------------------------------
    
    /**
     * Initialized VelocityHelper without a Velocity Context.
     */
    public PageHelper(RollerRequest rreq, HttpServletResponse response)
    {
        this(rreq, response, null);
    }

    //------------------------------------------------------------------------
    /**
     * Return a PageHelper with a new VelocityContext.
     */
    public static PageHelper createPageHelper(
        HttpServletRequest request, HttpServletResponse response)
    {
        Context ctx = (Context)(new VelocityContext());
        RollerRequest rreq = RollerRequest.getRollerRequest(request);
        PageHelper pageHelper = new PageHelper(rreq, response, ctx);
        pageHelper.initializePlugins(ContextLoader.getPagePlugins());

        return pageHelper;
    }

    //------------------------------------------------------------------------
    /**
     * Create individual instances of the PagePlugins for use by this PageHelper.
     */
    protected void initializePlugins(Collection pluginClasses) 
    {
        Iterator it = pluginClasses.iterator();
        while (it.hasNext()) 
        {
            try
            {
                PagePlugin plugin = (PagePlugin)it.next();
                plugin.init(mRollerReq, mVelocityContext);
                mPagePlugins.add(plugin);
            }
            catch (RollerException e)
            {
                mLogger.warn("Unable to init() PagePlugin: ", e    );
            }
        }
    }

    //------------------------------------------------------------------------
    /**
     * This is a quasi-hack: there are places we don't want to render the
     * ReadMore Plugin in particular (I cannot think of other plugins
     * which warrant this treatment).  The "skip flag" will be made
     * available to the Plugin if it wants to check to see if it should
     * be skipped.
     */
    public void setSkipFlag(boolean skip) 
    {
        mSkipFlag = skip;
    }
    
    //------------------------------------------------------------------------
    
    /**
     * Another stupid helper method to make up for the shortcomings of Velocity.
     * @return HashMap
     */
    public Hashtable addParam(String key, String value, Hashtable map)
    {
        if (map == null) map = new Hashtable();
        if (key != null && value != null)
            map.put(key, value);
        return map;
    }
        
    //------------------------------------------------------------------------
    
    /**
     * Evaluates the String as a Velocimacro, returning the results.
     * 
     * @param str String
     * @return String
     */
    public String evaluateString(String str)
    {
        if (mVelocityContext == null) return str;
        
        StringWriter sw = new StringWriter();
        try
        {
            Velocity.evaluate( mVelocityContext, sw, "evalStr", str );
            return sw.toString();
        }
        catch (Exception e)
        {
            mLogger.warn("VelocityHelper.evaluateString()", e);
        }
        return "";
    }
   
    /** Build the URL for editing an WeblogEntry **/
    public String getEntryEditUrl(WeblogEntryData entry)
    {
        Hashtable params = new Hashtable();
        params.put( RollerRequest.WEBLOGENTRYID_KEY, entry.getId());
        params.put( RollerRequest.ANCHOR_KEY,        entry.getAnchor());
        if (mUsername != null)
        {    
            params.put( RollerRequest.USERNAME_KEY,  mUsername);
        }
        try
        {
            return RequestUtils.computeURL( mPageContext,
                "weblogEdit", null, null, null, params, null, false);
        }
        catch (MalformedURLException mue)
        {
            mLogger.warn("RollerRequest.editEntryUrl exception: ", mue);
        }
        return 
           mRollerReq.getRequest().getContextPath() + "edtior/weblog.do?method=edit";
    }
    
    //-------------------------------------------------------------------------
    public String getToggleLinkbackDisplayHTML(RefererData referer)
    {
        String ret = "";
        String link = null;
        try
        {
            if ( mRollerReq.isUserAuthorizedToEdit() )
            {
                Hashtable params = new Hashtable();
                params.put( RollerRequest.REFERERID_KEY, referer.getId());
                params.put( RollerRequest.USERNAME_KEY, mUsername);
                link = RequestUtils.computeURL( mPageContext,
                    "toggleLinkback", null, null, null, params,null,false);
                    
                StringBuffer sb = new StringBuffer();
                sb.append("[<a href=\"");
                sb.append(link);
                if ( referer.getVisible().booleanValue() )
                {
                    sb.append("\">Visible</a>] ");
                }
                else
                {
                    sb.append("\">Hidden</a>] ");
                }
                ret = sb.toString();
            }
        }
        catch (Exception e)
        {
           // should never happen, but if it does:
           mLogger.error("ERROR creating toggle-linkback URL",e);
        }
        
        return ret;
    }
    
    //------------------------------------------------------------------------
    
    public boolean isUserAuthorizedToEdit()
    {
        try
        {
            return mRollerReq.isUserAuthorizedToEdit();
        }
        catch (Exception e)
        {
            mLogger.warn("PageHelper.isUserAuthorizedToEdit)", e);
        }
        return false;
    }
    
    //------------------------------------------------------------------------
    public void setContentType( String type )
    {
        mResponse.setContentType(type);
    }

    //------------------------------------------------------------------------
    /** 
     * Display big weblog calendar, well suited for an archive page.
     * @return HTML for calendar.
     */
    public String showBigWeblogCalendar()
    {
        return showWeblogCalendar(true, null);
    }
        
    //------------------------------------------------------------------------
    
    /** 
     * Call hybrid EditorNavBarTag to render editor navbar.
     * @param vertical True for vertical navbar.
     * @return String HTML for navbar.
     */
    public String showEditorNavBar(boolean vertical)
    {
        EditorNavigationBarTag editorTag = new EditorNavigationBarTag();
        editorTag.setPageContext(mPageContext);
        if ( vertical )
        {
            editorTag.setView("/navbar-vertical.vm");
        }
        else
        {