001// Copyright 2012, 2013 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 015package org.apache.tapestry5.internal.util; 016 017import org.apache.tapestry5.ioc.Resource; 018 019import java.io.ByteArrayInputStream; 020import java.io.IOException; 021import java.io.InputStream; 022import java.net.URL; 023import java.nio.charset.Charset; 024import java.util.Locale; 025 026/** 027 * Base class for virtual resources: resources that are not simply mapped to stored files, but are assembled, as necessary, 028 * on the fly. This is used inside Tapestry to expose the application's localized message catalog as a module. 029 * Subclasses should implement the {@link org.apache.tapestry5.ioc.Resource#openStream()} method to return a stream of 030 * the contents of the virtual resource. 031 * 032 * @see org.apache.tapestry5.services.javascript.ModuleManager 033 * @see org.apache.tapestry5.internal.services.javascript.ModuleDispatcher 034 * @since 5.4 035 */ 036public abstract class VirtualResource implements Resource 037{ 038 protected static final Charset UTF8 = Charset.forName("UTF-8"); 039 040 private <T> T unsupported(String name) 041 { 042 throw new UnsupportedOperationException(String.format("Method %s() is not supported for a VirtualResource.", name)); 043 } 044 045 public boolean exists() 046 { 047 048 return true; 049 } 050 051 public URL toURL() 052 { 053 return unsupported("toURL"); 054 } 055 056 public Resource forLocale(Locale locale) 057 { 058 return unsupported("forLocale"); 059 } 060 061 public Resource forFile(String relativePath) 062 { 063 return this; 064 } 065 066 public Resource withExtension(String extension) 067 { 068 return unsupported("withExtension"); 069 } 070 071 public String getFolder() 072 { 073 return unsupported("getFolder"); 074 } 075 076 public String getFile() 077 { 078 return unsupported("getFile"); 079 } 080 081 public String getPath() 082 { 083 return unsupported("getPath"); 084 } 085 086 protected InputStream toInputStream(String content) throws IOException 087 { 088 return toInputStream(content.getBytes(UTF8)); 089 } 090 091 protected InputStream toInputStream(byte[] content) throws IOException 092 { 093 return new ByteArrayInputStream(content); 094 } 095}