前言
继上一篇Android 路由实践（一）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<String> getSupportedAnnotationTypes() {
Set<String> types = new LinkedHashSet<>();
types.add(RouterTarget.class.getCanonicalName());
return types;
}
@Override
public SourceVersion getSupportedSourceVersion() {
return SourceVersion.latestSupported();
}
@Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
mMessager.printMessage(Diagnostic.Kind.WARNING, "processprocessprocessprocess");
Set<? extends Element> 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));
}
}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);}
}
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);
}
}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<String> 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();
}
}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<String> getFileNameByPackageName(Context context, final String suffix) throws PackageManager.NameNotFoundException, IOException, InterruptedException {
final Set<String> classNames = new HashSet<>();
List<String> 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<String> 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<String> getSourcePaths(Context context) throws PackageManager.NameNotFoundException, IOException {
ApplicationInfo applicationInfo = context.getPackageManager().getApplicationInfo(context.getPackageName(), 0);
File sourceApk = new File(applicationInfo.sourceDir);
List<String> 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<String> tryLoadInstantRunDexFile(ApplicationInfo applicationInfo) {
List<String> 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;
}
}
}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<String> getFileNameByPackageName(Context context, final String suffix) throws PackageManager.NameNotFoundException, IOException, InterruptedException {
final Set<String> classNames = new HashSet<>();
List<String> 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<String> 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;
}注意这里：
dexfile = new DexFile(path);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<String, RouterInjector> 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) {
}
}
}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();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。代码github,喜欢的给个星吧！
