| // Copyright 2016 The Bazel Authors. All rights reserved. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| package com.google.devtools.build.android; |
| |
| import java.io.IOException; |
| import java.lang.reflect.Field; |
| import java.net.URL; |
| import java.net.URLClassLoader; |
| import java.nio.file.Path; |
| import java.util.LinkedHashMap; |
| import java.util.Map; |
| |
| /** |
| * Loads android.R.attr resource IDs from an android jar. An alternative may be to parse the |
| * res/values/public.xml from the SDK, but the class loading approach is ~20ms, right now. |
| */ |
| public class AndroidFrameworkAttrIdJar implements AndroidFrameworkAttrIdProvider { |
| |
| private static final String ANDROID_ATTR_CLASS = "android.R$attr"; |
| private final Path androidJar; |
| private Map<String, Integer> cachedFields; |
| |
| public AndroidFrameworkAttrIdJar(Path androidJar) { |
| this.androidJar = androidJar; |
| } |
| |
| @Override |
| public int getAttrId(String fieldName) throws AttrLookupException { |
| // Lazily load the ANDROID_ATTR_CLASS from the androidJar, to save time if never end up |
| // needing the android framework attributes. This provider can only work for one given |
| // androidJar path, since we never invalidate the lazily filled cache. |
| if (cachedFields == null) { |
| cachedFields = getAttrFields(); |
| } |
| Integer result = cachedFields.get(fieldName); |
| if (result == null) { |
| throw new AttrLookupException("Android attribute not found: " + fieldName); |
| } |
| return result; |
| } |
| |
| private Map<String, Integer> getAttrFields() throws AttrLookupException { |
| try (URLClassLoader urlClassLoader = |
| new URLClassLoader(new URL[] {androidJar.toUri().toURL()})) { |
| Class<?> attrClass = urlClassLoader.loadClass(ANDROID_ATTR_CLASS); |
| Map<String, Integer> attributeIds = new LinkedHashMap<>(); |
| for (Field field : attrClass.getFields()) { |
| attributeIds.put(field.getName(), field.getInt(null)); |
| } |
| return attributeIds; |
| } catch (IOException | ClassNotFoundException | IllegalAccessException e) { |
| throw new AttrLookupException(e); |
| } |
| } |
| } |