Android 路由实践（二）-白红宇

前言

继上一篇之后，断更已经差不多一个月，毕竟是年前的最后一个月，各种事情扎堆，直到近几天才稍微闲下来，于是有了此文。简单回顾下，上一篇文章中简单介绍了三种实现路由的方式，分别是：隐式的Intent、通过初始化路由表的方式实现、通过注解。最后总结了下优缺点，建议使用第二种，今天我们讲下第四种，为啥单开一篇文章呢？因为第四种涉及到知识点有点多，并且参考ButterKbife以及部分阿里巴巴ARouter的实现。

大体思路

通过 annotationProcessor处理编译期注解，在编译的时候给路由表注入数据，这样在运行时通过annotationProcessor生成java代码并编译class文件。以下代码部分参考了Butterknife的实现：

/** * 自定义的编译期Processor，用于生成xxx$$Router.java文件 */@AutoService(Processor.class)public class RouterProcessor extends AbstractProcessor {    /**     * 文件相关的辅助类     */    private Filer mFiler;    /**     * 元素相关的辅助类     */    private Elements mElementUtils;    /**     * 日志相关的辅助类     */    private Messager mMessager;    /**     * 解析的目标注解集合     */    @Override    public synchronized void init(ProcessingEnvironment processingEnv) {        super.init(processingEnv);        mElementUtils = processingEnv.getElementUtils();        mMessager = processingEnv.getMessager();        mFiler = processingEnv.getFiler();    }    @Override    public Set
    
      getSupportedAnnotationTypes() {        Set
     
       types = new LinkedHashSet<>();        types.add(RouterTarget.class.getCanonicalName());        return types;    }    @Override    public SourceVersion getSupportedSourceVersion() {        return SourceVersion.latestSupported();    }    @Override    public boolean process(Set
       annotations, RoundEnvironment roundEnv) {        mMessager.printMessage(Diagnostic.Kind.WARNING, "processprocessprocessprocess");        Set
       routeElements = roundEnv.getElementsAnnotatedWith(RouterTarget.class);        for (Element element : routeElements) {            String packageName = element.getEnclosingElement().toString();            String fullClassName = element.toString();            String className = fullClassName.substring(fullClassName.indexOf(packageName) + packageName.length() + 1, fullClassName.length());            /**             //             * 构建类             //             */            try {                RouterTarget annotation = element.getAnnotation(RouterTarget.class);                RouterByAnnotationManager.getInstance().addRouter(annotation.value(), element.toString());                mMessager.printMessage(Diagnostic.Kind.WARNING, RouterByAnnotationManager.getInstance().getRouter(annotation.value()) + RouterByAnnotationManager.getInstance());                FieldSpec routerKey = FieldSpec.builder(String.class, "routerKey", Modifier.FINAL, Modifier.PRIVATE).initializer("$S", annotation.value()).build();                FieldSpec clazz = FieldSpec.builder(String.class, "fullClassName", Modifier.FINAL, Modifier.PRIVATE).initializer("$S", fullClassName).build();                /**                 * 构建方法                 */                MethodSpec methodSpec = MethodSpec.methodBuilder("injectRouter")                        .addModifiers(Modifier.PUBLIC)                        .addAnnotation(Override.class)                        .addCode("com.example.commonlib.RouterByAnnotationManager.getInstance().addRouter($L,$L);", "routerKey", "fullClassName")                        .build();                TypeSpec finderClass = TypeSpec.classBuilder(className + "$$Router")                        .addModifiers(Modifier.PUBLIC)                        .addMethod(methodSpec)                        .addField(routerKey)                        .addField(clazz)                        .addSuperinterface(RouterInjector.class)                        .build();                JavaFile.builder(packageName, finderClass).build().writeTo(mFiler);            } catch (Exception e) {                error("processBindView", e.getMessage());            }        }        return true;    }    public String getPackageName(TypeElement type) {        return mElementUtils.getPackageOf(type).getQualifiedName().toString();    }    private void error(String msg, Object... args) {        mMessager.printMessage(Diagnostic.Kind.ERROR, String.format(msg, args));    }    private void info(String msg, Object... args) {        mMessager.printMessage(Diagnostic.Kind.NOTE, String.format(msg, args));    }}复制代码

注意getSupportedAnnotationTypes()，如果你要对那些类进行处理，就要把Class的类名加入到Set中并且返回。然后看下process()方法，里面利用javaPoet生成java文件，文件形如UserInfoActivity$$Router,内容如下：

import java.lang.Override;import java.lang.String;public class UserInfoActivity$$Router implements RouterInjector {  private final String routerKey = "android.intent.action.USERINFO";  private final String fullClassName = "com.example.userlib.UserInfoActivity";  @Override  public void injectRouter() {    com.example.commonlib.RouterByAnnotationManager.getInstance().addRouter(routerKey,fullClassName);}}复制代码

那么相信重点来了，怎么去调用injectRouter()方法，将数据注入到路由表中，到这里的时候

差点因为这个问题前功尽弃，最后祭出了阿里大法，参考了ARouter的实现。具体如下：

通过Application对Router进行初始化：

public class RouterApplication extends Application {    @Override    public void onCreate() {        super.onCreate();        //初始化路由        Router.init(this);    }}复制代码

Router初始化的时候通过反射将数据注入到路由表

public static void init(Application application) {    try {        Set
    
      classNames = ClassUtils.getFileNameByPackageName(application, ActionConstant.SUFFIX);        for (String className : classNames) {            RouterFinder.bind(className);        }    } catch (PackageManager.NameNotFoundException e) {        e.printStackTrace();    } catch (IOException e) {        e.printStackTrace();    } catch (InterruptedException e) {        e.printStackTrace();    }}复制代码

来看下阿里ARouter的反射帮助类：

** 这个类是从alibaba的ARouter复制过来的用来扫描所有的类等 */public class ClassUtils {    private static final String EXTRACTED_NAME_EXT = ".classes";    private static final String EXTRACTED_SUFFIX = ".zip";    private static final String SECONDARY_FOLDER_NAME = "code_cache" + File.separator + "secondary-dexes";    private static final String PREFS_FILE = "multidex.version";    private static final String KEY_DEX_NUMBER = "dex.number";    private static final int VM_WITH_MULTIDEX_VERSION_MAJOR = 2;    private static final int VM_WITH_MULTIDEX_VERSION_MINOR = 1;    private static SharedPreferences getMultiDexPreferences(Context context) {        return context.getSharedPreferences(PREFS_FILE, Build.VERSION.SDK_INT < Build.VERSION_CODES.HONEYCOMB ? Context.MODE_PRIVATE : Context.MODE_PRIVATE | Context.MODE_MULTI_PROCESS);    }    /**     * 通过指定包名，扫描包下面包含的所有的ClassName     *     * @param context     U know     * @param suffix 包名     * @return 所有class的集合     */    public static Set
    
      getFileNameByPackageName(Context context, final String suffix) throws PackageManager.NameNotFoundException, IOException, InterruptedException {        final Set
     
       classNames = new HashSet<>();        List
      
        paths = getSourcePaths(context);        final CountDownLatch parserCtl = new CountDownLatch(paths.size());        for (final String path : paths) {            RouterPoolExecutor.getInstance().execute(new Runnable() {                @Override                public void run() {                    DexFile dexfile = null;                    try {                        if (path.endsWith(EXTRACTED_SUFFIX)) {                            //NOT use new DexFile(path), because it will throw "permission error in /data/dalvik-cache"                            dexfile = DexFile.loadDex(path, path + ".tmp", 0);                        } else {                            dexfile = new DexFile(path);                        }                        Enumeration
       
         dexEntries = dexfile.entries();                        while (dexEntries.hasMoreElements()) {                            String className = dexEntries.nextElement();                            if (className.endsWith(suffix)) {                                classNames.add(className);                            }                        }                    } catch (Throwable ignore) {                        Log.e("ARouter", "Scan map file in dex files made error.", ignore);                    } finally {                        if (null != dexfile) {                            try {                                dexfile.close();                            } catch (Throwable ignore) {                            }                        }                        parserCtl.countDown();                    }                }            });        }        parserCtl.await();        Log.e("getFileNameByPackage", "Filter " + classNames.size() + " classes by packageName <" + suffix + ">");        return classNames;    }    /**     * get all the dex path     *     * @param context the application context     * @return all the dex path     * @throws PackageManager.NameNotFoundException     * @throws IOException     */    public static List
        
          getSourcePaths(Context context) throws PackageManager.NameNotFoundException, IOException {        ApplicationInfo applicationInfo = context.getPackageManager().getApplicationInfo(context.getPackageName(), 0);        File sourceApk = new File(applicationInfo.sourceDir);        List
         
           sourcePaths = new ArrayList<>(); sourcePaths.add(applicationInfo.sourceDir); //add the default apk path //the prefix of extracted file, ie: test.classes String extractedFilePrefix = sourceApk.getName() + EXTRACTED_NAME_EXT;// 如果VM已经支持了MultiDex，就不要去Secondary Folder加载 Classesx.zip了，那里已经么有了// 通过是否存在sp中的multidex.version是不准确的，因为从低版本升级上来的用户，是包含这个sp配置的 if (!isVMMultidexCapable()) { //the total dex numbers int totalDexNumber = getMultiDexPreferences(context).getInt(KEY_DEX_NUMBER, 1); File dexDir = new File(applicationInfo.dataDir, SECONDARY_FOLDER_NAME); for (int secondaryNumber = 2; secondaryNumber <= totalDexNumber; secondaryNumber++) { //for each dex file, ie: test.classes2.zip, test.classes3.zip... String fileName = extractedFilePrefix + secondaryNumber + EXTRACTED_SUFFIX; File extractedFile = new File(dexDir, fileName); if (extractedFile.isFile()) { sourcePaths.add(extractedFile.getAbsolutePath()); //we ignore the verify zip part } else { throw new IOException("Missing extracted secondary dex file '" + extractedFile.getPath() + "'"); } } } sourcePaths.addAll(tryLoadInstantRunDexFile(applicationInfo)); return sourcePaths; } /** * Get instant run dex path, used to catch the branch usingApkSplits=false. */ private static List
          
            tryLoadInstantRunDexFile(ApplicationInfo applicationInfo) { List
           
             instantRunSourcePaths = new ArrayList<>(); if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP && null != applicationInfo.splitSourceDirs) { // add the split apk, normally for InstantRun, and newest version. instantRunSourcePaths.addAll(Arrays.asList(applicationInfo.splitSourceDirs)); Log.d("tryLoadInstantRunDex", "Found InstantRun support"); } else { try { // This man is reflection from Google instant run sdk, he will tell me where the dex files go. Class pathsByInstantRun = Class.forName("com.android.tools.fd.runtime.Paths"); Method getDexFileDirectory = pathsByInstantRun.getMethod("getDexFileDirectory", String.class); String instantRunDexPath = (String) getDexFileDirectory.invoke(null, applicationInfo.packageName); File instantRunFilePath = new File(instantRunDexPath); if (instantRunFilePath.exists() && instantRunFilePath.isDirectory()) { File[] dexFile = instantRunFilePath.listFiles(); for (File file : dexFile) { if (null != file && file.exists() && file.isFile() && file.getName().endsWith(".dex")) { instantRunSourcePaths.add(file.getAbsolutePath()); } } Log.d("tryLoadInstantRunDex", "Found InstantRun support"); } } catch (Exception e) { Log.d("tryLoadInstantRunDex", "InstantRun support error, " + e.getMessage()); } } return instantRunSourcePaths; } /** * Identifies if the current VM has a native support for multidex, meaning there is no need for * additional installation by this library. * * @return true if the VM handles multidex */ private static boolean isVMMultidexCapable() { boolean isMultidexCapable = false; String vmName = null; try { if (isYunOS()) { // YunOS需要特殊判断 vmName = "'YunOS'"; isMultidexCapable = Integer.valueOf(System.getProperty("ro.build.version.sdk")) >= 21; } else { // 非YunOS原生Android vmName = "'Android'"; String versionString = System.getProperty("java.vm.version"); if (versionString != null) { Matcher matcher = Pattern.compile("(\\d+)\\.(\\d+)(\\.\\d+)?").matcher(versionString); if (matcher.matches()) { try { int major = Integer.parseInt(matcher.group(1)); int minor = Integer.parseInt(matcher.group(2)); isMultidexCapable = (major > VM_WITH_MULTIDEX_VERSION_MAJOR) || ((major == VM_WITH_MULTIDEX_VERSION_MAJOR) && (minor >= VM_WITH_MULTIDEX_VERSION_MINOR)); } catch (NumberFormatException ignore) { // let isMultidexCapable be false } } } } } catch (Exception ignore) { } Log.i("isVMMultidexCapable", "VM with name " + vmName + (isMultidexCapable ? " has multidex support" : " does not have multidex support")); return isMultidexCapable; } /** * 判断系统是否为YunOS系统 */ private static boolean isYunOS() { try { String version = System.getProperty("ro.yunos.version"); String vmName = System.getProperty("java.vm.name"); return (vmName != null && vmName.toLowerCase().contains("lemur")) || (version != null && version.trim().length() > 0); } catch (Exception ignore) { return false; } }}复制代码

注意看tryLoadInstantRunDexFile()这个方法，记得在上一篇文章中说到资源路径获得DexFile,注意5.0以上版本要求关掉instant run 方法否则会自动拆包遍历不到所有activity类，导致有些加了RouterTarget注解的Activity扫描不到，Arouter在tryLoadInstantRunDexFile()解决了这个问题，如果不调用这个方法的话，，只有如下图的apk:

base.apk一般是不包括我们自己写的代码，这个方法调用之后结果如下：

可以扫描到所有的apk，之后接下来我们就可以解压出项目里面所有的类，通过找出类名后缀为$$Router的类进行发射，代码如下：

/** * 通过指定包名，扫描包下面包含的所有的ClassName * * @param context     U know * @param suffix 包名 * @return 所有class的集合 */public static Set
    
      getFileNameByPackageName(Context context, final String suffix) throws PackageManager.NameNotFoundException, IOException, InterruptedException {    final Set
     
       classNames = new HashSet<>();    List
      
        paths = getSourcePaths(context);    final CountDownLatch parserCtl = new CountDownLatch(paths.size());    for (final String path : paths) {        RouterPoolExecutor.getInstance().execute(new Runnable() {            @Override            public void run() {                DexFile dexfile = null;                try {                    if (path.endsWith(EXTRACTED_SUFFIX)) {                        //NOT use new DexFile(path), because it will throw "permission error in /data/dalvik-cache"                        dexfile = DexFile.loadDex(path, path + ".tmp", 0);                    } else {                        dexfile = new DexFile(path);                    }                    Enumeration
       
         dexEntries = dexfile.entries();                    while (dexEntries.hasMoreElements()) {                        String className = dexEntries.nextElement();                        if (className.endsWith(suffix)) {                            classNames.add(className);                        }                    }                } catch (Throwable ignore) {                    Log.e("ARouter", "Scan map file in dex files made error.", ignore);                } finally {                    if (null != dexfile) {                        try {                            dexfile.close();                        } catch (Throwable ignore) {                        }                    }                    parserCtl.countDown();                }            }        });    }    parserCtl.await();    Log.e("getFileNameByPackage", "Filter " + classNames.size() + " classes by packageName <" + suffix + ">");    return classNames;}复制代码

注意这里：

dexfile = new DexFile(path);复制代码

我们上一篇文章中建议不要使用，因为安卓8.0已经打上了废弃标志

但是既然阿里爸爸这么用了，相信以后也会有相应的解决办法，我们及时跟进，如果读者有好的方法，欢迎提出，大家一起研究研究，接下来就是反射调用injectRouter() ，

public class RouterFinder {    public RouterFinder() {        throw new AssertionError("No .instances");    }    private static Map
    
      FINDER_MAP = new HashMap<>();    /**     * 获取目标类     *     * @param className     */    public static void inject(String  className) {        try {            Log.e("inject",className);            RouterInjector injector = FINDER_MAP.get(className);            if (injector == null) {                Class
      finderClass = Class.forName(className);                injector = (RouterInjector) finderClass.newInstance();                FINDER_MAP.put(className, injector);            }            injector.injectRouter();        } catch (Exception e) {        }    }}复制代码

到此完成了路由表的数据填充，具体使用如下：

new Router.Builder(this, RouterByAnnotationManager.getInstance().getRouter(ActionConstant.ACTION_USER_INFO)).        addParams(ActionConstant.KEY_USER_NAME, etUserName.getText().toString())        .addParams(ActionConstant.KEY_PASS_WORD, etPassWord.getText().toString()).go();复制代码

到此完成了编译期路由的实现，牵扯的东西还是挺多，历经千辛万苦。,喜欢的给个星吧！