001 // Copyright 2005 The Apache Software Foundation 002 // 003 // Licensed under the Apache License, Version 2.0 (the "License"); 004 // you may not use this file except in compliance with the License. 005 // You may obtain a copy of the License at 006 // 007 // http://www.apache.org/licenses/LICENSE-2.0 008 // 009 // Unless required by applicable law or agreed to in writing, software 010 // distributed under the License is distributed on an "AS IS" BASIS, 011 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 012 // See the License for the specific language governing permissions and 013 // limitations under the License. 014 015 package org.apache.tapestry.services.impl; 016 017 import org.apache.tapestry.IMarkupWriter; 018 import org.apache.tapestry.IPage; 019 import org.apache.tapestry.IRender; 020 import org.apache.tapestry.IRequestCycle; 021 022 /** 023 * Contains code needed to render the <base> tag for pages. The <base> tag ensures that 024 * the base URL for the rendered page matches the location of the page template in the servlet 025 * context, so that relative URLs to static assets (images, stylesheets, etc.) will be processed 026 * correctly. This is important starting with release 4.0, where HTML templates are no longer 027 * restricted to the servlet root. 028 * <p> 029 * Note that pages outside of the application namespace (provided by the framework itself, or in a 030 * library) are "virtually located" in the application root. 031 * 032 * @author Howard M. Lewis Ship 033 * @since 4.0 034 */ 035 public class BaseTagWriter implements IRender 036 { 037 038 public void render(IMarkupWriter writer, IRequestCycle cycle) 039 { 040 IPage page = cycle.getPage(); 041 042 StringBuffer sb = new StringBuffer(); 043 sb.append("/"); 044 045 if (page.getNamespace().getId() == null) 046 { 047 String name = page.getPageName(); 048 int slashx = name.lastIndexOf('/'); 049 050 // Include the directory and trailing slash. 051 if (slashx > 0) 052 sb.append(name.substring(0, slashx + 1)); 053 } 054 055 String url = cycle.getAbsoluteURL(sb.toString()); 056 057 writer.beginEmpty("base"); 058 writer.attribute("href", url); 059 writer.printRaw("<!--[if IE]></base><![endif]-->"); 060 061 writer.println(); 062 } 063 064 }