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      1 /*
      2  * Copyright (C) 2010 Google Inc.
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  * http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.google.clearsilver.jsilver.resourceloader;
     18 
     19 import com.google.clearsilver.jsilver.exceptions.JSilverTemplateNotFoundException;
     20 
     21 import java.io.IOException;
     22 import java.io.InputStream;
     23 import java.io.InputStreamReader;
     24 import java.io.Reader;
     25 
     26 /**
     27  * Loads resources from classpath, alongside a given class.
     28  *
     29  * <p>For example, suppose the classpath contains:
     30  * <pre>
     31  * com/foo/SomeThing.class
     32  * com/foo/my-template.cs
     33  * com/foo/subdir/another-template.cs
     34  * </pre>
     35  *
     36  * <p>You can access the resources in the class's package like this:
     37  * <pre>
     38  * ResourceLoader loader = new ClassResourceLoader(SomeThing.class);
     39  * loader.open("my-template.cs");
     40  * loader.open("subdir/my-template.cs");
     41  * </pre>
     42  * Or by using a relative path:
     43  * <pre>
     44  * ResourceLoader loader = new ClassResourceLoader(Something.class, "subdir");
     45  * loader.open("my-template.cs");
     46  * </pre>
     47  *
     48  * @see ResourceLoader
     49  * @see ClassLoaderResourceLoader
     50  */
     51 public class ClassResourceLoader extends BufferedResourceLoader {
     52 
     53   private final Class<?> cls;
     54   private final String basePath;
     55 
     56   public ClassResourceLoader(Class<?> cls) {
     57     this.cls = cls;
     58     this.basePath = "/" + cls.getPackage().getName().replace('.', '/');
     59   }
     60 
     61   /**
     62    * Load resources from the given subdirectory {@code basePath},
     63    * relative to the .class file of {@code cls}.
     64    */
     65   public ClassResourceLoader(Class<?> cls, String basePath) {
     66     this.cls = cls;
     67     this.basePath = basePath;
     68   }
     69 
     70   @Override
     71   public Reader open(String name) throws IOException {
     72     InputStream stream = cls.getResourceAsStream(basePath + '/' + name);
     73     return stream == null ? null : buffer(new InputStreamReader(stream, getCharacterSet()));
     74   }
     75 
     76   @Override
     77   public Reader openOrFail(String name) throws JSilverTemplateNotFoundException, IOException {
     78     Reader reader = open(name);
     79     if (reader == null) {
     80       throw new JSilverTemplateNotFoundException("No '" + name + "' as class resource of "
     81           + cls.getName());
     82     } else {
     83       return reader;
     84     }
     85   }
     86 
     87 }
     88