Android构建流程——篇四_build/generated/res/pngs

Task9 generateDebugResValues

1. input/ouput

taskName:generateDebugResValues
=========================================================
output:/Users/dingbaosheng/work/mockuai/project/AndroidGradleTaskDemo/app/build/generated/res/resValues/debug
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简单的说该任务就是生成一个generated.xml文件，里面包含了在build.gradle文件中自定义的资源属性

1. 配置自定义资源属性
   
2. 输出xml文件结构
   

2. 核心类(GenerateResValues)

public class GenerateResValues extends AndroidBuilderTask {
   
	@TaskAction
    void generate() throws IOException, ParserConfigurationException {
   
        File folder = getResOutputDir();
		
		//1. 读取build.gradle中自定义的资源配置数据项
        List<Object> resolvedItems = getItems();
		
		//2. 如果未自定义，清空旧数据
        if (resolvedItems.isEmpty()) {
   
            FileUtils.cleanOutputDir(folder);
        } else {
   
        	//如果自定义了，将自定义资源数据项交给资源值生成器对象
            ResValueGenerator generator = new ResValueGenerator(folder);
            generator.addItems(getItems());
			
			//3. 生成generated.xml
            generator.generate();
        }
    }
}
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代码看流程清晰明了，关键代码就是将自定义属性(支持12种类型属性哦)写入到xml文件中，其实现细节集中在类ResValueGenerator.generater中；内部主要使用DOM API来实现，具体不再详细说明，贴下实现代码

public class ResValueGenerator {
   

    public static final String RES_VALUE_FILENAME_XML = "generated.xml";

    private static final List<ResourceType> RESOURCES_WITH_TAGS = ImmutableList.of(
            ResourceType.ARRAY,
            ResourceType.ATTR,
            ResourceType.BOOL,
            ResourceType.COLOR,
            ResourceType.DECLARE_STYLEABLE,
            ResourceType.DIMEN,
            ResourceType.FRACTION,
            ResourceType.INTEGER,
            ResourceType.PLURALS,
            ResourceType.STRING,
            ResourceType.STYLE);
	/**
     * Generates the resource files
     */
    public void generate() throws IOException, ParserConfigurationException {
   
        File pkgFolder = getFolderPath();
        if (!pkgFolder.isDirectory()) {
   
            if (!pkgFolder.mkdirs()) {
   
                throw new RuntimeException("Failed to create " + pkgFolder.getAbsolutePath());
            }
        }

        File resFile = new File(pkgFolder, RES_VALUE_FILENAME_XML);

        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        factory.setNamespaceAware(true);
        factory.setValidating(false);
        factory.setIgnoringComments(true);
        DocumentBuilder builder;

        builder = factory.newDocumentBuilder();
        Document document = builder.newDocument();
		
		//创建根节点resources
        Node rootNode = document.createElement(TAG_RESOURCES);
        document.appendChild(rootNode);
		
		//添加子节点，此处就是添加些注释说明
        rootNode.appendChild(document.createTextNode("\n"));
        rootNode.appendChild(document.createComment("Automatically generated file. DO NOT MODIFY"));
        rootNode.appendChild(document.createTextNode("\n\n"));
		
		//遍历自定义资源属性
        for (Object item : mItems) {
   
            if (item instanceof ClassField) {
   
                ClassField field = (ClassField)item;

                ResourceType type = ResourceType.getEnum(field.getType());
				
				//判断是否是通用的11种类型中一种
                boolean hasResourceTag = (type != null && RESOURCES_WITH_TAGS.contains(type));
				
				//如果不是通用的资源类型，则生成<item>标签节点
                Node itemNode = document.createElement(hasResourceTag ? field.getType() : TAG_ITEM);
                Attr nameAttr = document.createAttribute(ATTR_NAME);

                nameAttr.setValue(field.getName());
                itemNode.getAttributes().setNamedItem(nameAttr);
				
				
                if (!hasResourceTag) {
   
                	//如果是item标签，需要设置其type、name属性值
                	//eg:<item type="id" name="button_ok" />
                    Attr typeAttr = document.createAttribute(ATTR_TYPE);
                    typeAttr.setValue(field.getType());
                    itemNode.getAttributes().setNamedItem(typeAttr);
                }

                if (type == ResourceType.STRING) {
   
                	//如果是string资源，添加traslatable属性，使其设备统一使用该字段，和系统语言等无关
                    Attr translatable = document.createAttribute(ATTR_TRANSLATABLE);
                    translatable.setValue(VALUE_FALSE);
                    itemNode.getAttributes().setNamedItem(translatable);
                }

                if (!field.getValue().isEmpty()) {
   
                    itemNode.appendChild(document.createTextNode(field.getValue()));
                }

                rootNode.appendChild(itemNode);
            } else if (item instanceof String) {
   
                rootNode.appendChild(document.createTextNode("\n"));
                rootNode.appendChild(document.createComment((String) item));
                rootNode.appendChild(document.createTextNode("\n"));
            }
        }

        String content;
        try {
   
            content = XmlPrettyPrinter.prettyPrint(document, true);
        } catch (Throwable t) {
   
            content = XmlUtils.toXml(document);
        }
		
		//写文件
        Files.write(content, resFile, Charsets.UTF_8);
    }
}    
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支持的自定义资源属性类型

Task10 generateDebugResources

属于空task直接忽略

Task11 mergeDebugResources

合并资源任务

1. input/ouput

taskName:mergeDebugResources
input:/Users/apple/.gradle/caches/transforms-1/files-1.1/aapt2-3.2.0-4818971-osx.jar/c5355294e416159d9559f45d46460f7d/aapt2-3.2.0-4818971-osx
input:/Users/apple/work/project/AndroidGradleTaskDemo/app/build/generated/res/resValues/debug
input:/Users/apple/.gradle/caches/transforms-1/files-1.1/appcompat-v7-26.1.0.aar/2774ea4f1cf1e83a6ad8e8d3c8b463b6/res
input:/Users/apple/.gradle/caches/transforms-1/files-1.1/constraint-layout-1.1.3.aar/f43c0ba95b6494825ed940fc4f04662b/res
input:/Users/apple/.gradle/caches/transforms-1/files-1.1/support-media-compat-26.1.0.aar/53ab5ad72634f3497309a8788f3ca200/res
input:/Users/apple/.gradle/caches/transforms-1/files-1.1/support-compat-26.1.0.aar/4ec3c1c46e5bad9ac3b91f45a2afec3e/res
input:/Users/apple/work/project/AndroidGradleTaskDemo/app/build/generated/res/rs/debug
input:/Users/apple/work/project/AndroidGradleTaskDemo/app/src/main/res
input:/Users/apple/work/project/AndroidGradleTaskDemo/app/src/debug/res
=========================================================
output:/Users/apple/work/project/AndroidGradleTaskDemo/app/build/intermediates/blame/res/debug
output:/Users/apple/work/project/AndroidGradleTaskDemo/app/build/generated/res/pngs/debug
output:/Users/apple/work/project/AndroidGradleTaskDemo/app/build/intermediates/incremental/mergeDebugResources
output:/Users/apple/work/project/AndroidGradleTaskDemo/app/build/intermediates/res/merged/debug
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先来一张总流程图吧，先把握主线；文字描述的不一定有图清楚

xml -> drawable 、string 、color、anim、layout、value
layout、generated
png
先看输入好了，可以很清楚看到输入都是项目依赖的库的res文件以及本身结构的res文件

app/build/intermediates/incremental/mergeDebugResources

1. merged.dir
2. stripped.dir
3. compile-file-map.properties
4. merger.xml

2. 核心类(MergeResources)

@CacheableTask
public class MergeResources extends IncrementalTask {
   
	
	@Override
    protected void doFullTaskAction() throws IOException, JAXBException {
   
        ResourcePreprocessor preprocessor = getPreprocessor();

        // this is full run, clean the previous outputs
        File destinationDir = getOutputDir();
        FileUtils.cleanOutputDir(destinationDir);
        if (dataBindingLayoutInfoOutFolder != null) {
   
            FileUtils.deleteDirectoryContents(dataBindingLayoutInfoOutFolder);
        }

        List<ResourceSet> resourceSets = getConfiguredResourceSets(preprocessor);

        // create a new merger and populate it with the sets.
        ResourceMerger merger = new ResourceMerger(minSdk.get());
        MergingLog mergingLog = null;
        if (blameLogFolder != null) {
   
            FileUtils.cleanOutputDir(blameLogFolder);
            mergingLog = new MergingLog(blameLogFolder);
        }

        try (ResourceCompilationService resourceCompiler =
                getResourceProcessor(
                        aaptGeneration,
                        getBuilder(),
                        aapt2FromMaven,
                        workerExecutorFacade,
                        crunchPng,
                        variantScope,
                        mergingLog,
                        flags,
                        processResources)) {
   

            for (ResourceSet resourceSet : resourceSets) {
   
                resourceSet.loadFromFiles(getILogger());
				//1. 添加资源
                merger.addDataSet(resourceSet);
            }

            MergedResourceWriter writer =
                    new MergedResourceWriter(
                            workerExecutorFacade,
                            destinationDir,
                            getPublicFile(),
                            mergingLog,
                            preprocessor,
                            resourceCompiler,
                            getIncrementalFolder(),
                            dataBindingLayoutProcessor,
                            mergedNotCompiledResourcesOutputDirectory,
                            pseudoLocalesEnabled,
                            getCrunchPng());
			//2. 执行资源合并操作
            merger.mergeData
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