resourcemanager.java

Novocode的 SWT 控件框架 丰富了MDI功能

/*******************************************************************************
 * Copyright (c) 2004 Stefan Zeiger and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.novocode.com/legal/epl-v10.html
 * 
 * Contributors:
 *     Stefan Zeiger ([e-mail]) - initial API and implementation
 *******************************************************************************/

package com.novocode.naf.resource;

import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.*;
import javax.xml.parsers.*;
import javax.xml.transform.Transformer;

import org.w3c.dom.*;

import com.novocode.naf.app.*;
import com.novocode.naf.xml.DOMUtil;


/**
 * Reads NAF resource files and creates NGComponent objects from them.
 * 
 * @author Stefan Zeiger ([e-mail])
 * @since Nov 24, 2003
 */

public class ResourceManager
{
  public static final String NAF_NAMESPACE_URI = "http://www.novocode.com/namespaces/naf";

  private DocumentBuilder docbuilder;
  private Map<String, NGComponent> resources;
  private Map<String, Class> elementClasses;
  private StyleManager styleManager = new StyleManager();
  private NGComponent rootComponent;


  /**
   * Create a new ResourceManager.
   */

  public ResourceManager() throws NAFException
  {
    this.resources = new HashMap<String, NGComponent>();
    this.elementClasses = new HashMap<String, Class>();
    
    setElementClass("group",   NGGroup.class);
    setElementClass("include", NGInclude.class);

    try
    {
      DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
      factory.setNamespaceAware(true);
      factory.setIgnoringComments(true);
      this.docbuilder = factory.newDocumentBuilder();
    }
    catch(Exception ex) { throw new NAFException("Error creating ResourceManager", ex); }
  }


  public void setElementClass(String name, Class clazz)
  {
    if(clazz == null) elementClasses.remove(name);
    else elementClasses.put(name, clazz);
  }


  protected void setRootComponent(NGComponent c) { this.rootComponent = c; }


  private void readResource(URL resUrl) throws NAFException
  {
    InputStream in = null;
    try
    {
      in = resUrl.openStream();
      ArrayList<Transformer> trList = null;
      Document doc = docbuilder.parse(in);

      for(Node n = doc.getFirstChild(); n != null; n = n.getNextSibling())
      {
        if(n.getNodeType() == Node.PROCESSING_INSTRUCTION_NODE && "xml-stylesheet".equals(n.getNodeName()))
        {
          ProcessingInstruction pi = (ProcessingInstruction)n;
          Map<String, String> attrs = DOMUtil.parseProcessingInstructionAttributes(pi);
          if("text/xsl".equals(attrs.get("type")))
          {
            String href = attrs.get("href");
            if(href == null)
              throw new NAFException("Style sheet processing instructions must have an \"href\" attribute");
            try
            {
              Transformer t = styleManager.createTransformer(new URL(resUrl, href));
              if(trList == null) trList = new ArrayList<Transformer>();
              trList.add(t);
            }
            catch(Exception ex)
            {
              throw new NAFException("Error reading style sheet resource \""+href+"\"");
            }
          }
        }
      }
      
      if(trList != null)
      {
        for(Transformer t : trList)
        {
          doc = (Document)styleManager.transform(t, doc);
          if(LogSettings.RESOURCEMANAGER_DUMP_TRANSFORMED_STDOUT)
          {
            System.out.println("Transformed instance:");
            DOMUtil.dumpNode(doc, System.out);
            System.out.println();
          }
        }
      }

      Element rootE = doc.getDocumentElement();
      if(!NAF_NAMESPACE_URI.equals(rootE.getNamespaceURI()))
        throw new NAFException("Root element does not use the NAF namespace");

      String nafid = rootE.getAttribute("id");
      if(nafid != null && nafid.length() == 0) nafid = null;

      NGComponent comp = createComponent(rootE, nafid, resUrl, rootComponent);
      resources.put(resUrl.toExternalForm(), comp);
    }
    catch(Exception ex)
    {
      throw new NAFException("Error reading NAF resource \""+resUrl.toExternalForm()+"\"", ex);
    }
    finally
    {
      if(in != null) try { in.close(); } catch(Exception ignored) {}
    }
  }
  
  
  public NGComponent getResource(URL absUrl) throws NAFException
  {
    String urlStr = absUrl.toExternalForm();
    NGComponent comp = resources.get(urlStr);
    if(comp != null) return comp;

    String baseStr = urlStr;
    int sep = baseStr.indexOf('#');
    if(sep != -1) baseStr = baseStr.substring(0, sep);

    URL baseUrl;
    try
    {
      baseUrl = (baseStr == urlStr) ? absUrl : new URL(baseStr);
    }
    catch(MalformedURLException ex)
    {
      throw new NAFException("Error creating URL object for "+baseStr, ex);
    }
    readResource(baseUrl);

    comp = resources.get(urlStr);
    if(comp == null)
      throw new NAFException("NAF resource file "+baseStr+" doesn't contain resource \""+urlStr+"\"");

    return comp;
  }
  
  
  NGComponent createComponent(Element e, String id, URL resURL, NGComponent parent) throws NAFException
  {
    String name = e.getLocalName();

    Class<?> referencedClass = null;
    String using = null;
    {
      NGComponent c = parent;
      findComponentClassName: while(c != null)
      {
        List<Import> l = c.getImports();
        if(l != null)
        {
          for(Import im : l)
          {
            referencedClass = im.classFor(name);
            if(referencedClass != null)
            {
              using = im.getUsing();
              break findComponentClassName;
            }
          }
        }
        c = c.getParent();
      }
    }
    
    NGComponent ngc = null;

    if(referencedClass == null) referencedClass = elementClasses.get(name);
    if(referencedClass != null)
    {
      if(using == null) using = referencedClass.getName();
      try
      { 
        Class<?> componentClass = (using == null) ? referencedClass : Class.forName(using);
        ngc = (NGComponent)componentClass.newInstance();
      }
      catch(Exception ex)
      {
        throw new NAFException("Error instantiating element object from class "+using, ex);
      }
    }
    else throw new NAFException("Unknown element tag \""+name+"\"");
    ngc.init(referencedClass, e, resURL, id, this, parent);
    if(id != null)
    {
      String key = resURL.toExternalForm() + '#' + id;
      resources.put(key, ngc);
      if(LogSettings.RESOURCEMANAGER_DEBUG_STDOUT) System.out.println("Storing resource \""+key+"\" (class "+ngc.getClass().getName()+")");
    }
    return ngc;
  }
}