Arouter source code analysis (I)

arouter-api version : 1.4.1

Preface

Previous pair ActivityRouter I did an analysis of the source code of , I believe you have a general understanding of the routing framework .

And today I'll give you an analysis ARouter . Everyone is in the process of Componentization of the project , Probably most developers will use ARouter As the routing framework of the project . After all ARouter It's made by Ali , Naturally, there is no need to say more about the advantages .

So in the process of ordinary use , Not just to be able to use , We need to know more about it ARouter Internal principle .

This time ARouter The analysis of is divided into three parts ：

1. Yes IRouteRoot Page Jump for source code analysis ;
2. Yes IInterceptorGroup Interceptor for source code analysis ;
3. Yes IProviderGroup Source code analysis of service components ;

This is ARouter The first in the series , Now it's right IRouteRoot Page Jump for detailed analysis .

ARouter Source code

Use ARouter When , All need to be initialized

if (isDebug()) {          
    ARouter.openLog();
    ARouter.openDebug();
}
ARouter.init(mApplication);

Copy

The entrance of source code analysis , It's just ARouter.init in

public static void init(Application application) {
    if (!hasInit) {
        logger = _ARouter.logger;
        _ARouter.logger.info(Consts.TAG, "ARouter init start.");
        hasInit = _ARouter.init(application);

        if (hasInit) {
            _ARouter.afterInit();
        }

        _ARouter.logger.info(Consts.TAG, "ARouter init over.");
    }
}

Copy

You can see from the source code ,ARouter The inside of is actually _ARouter It's working ,ARouter Just put _ARouter Another layer of packaging . Then we will follow up _ARouter Of init Method .

protected static synchronized boolean init(Application application) {
    mContext = application;
    LogisticsCenter.init(mContext, executor);
    logger.info(Consts.TAG, "ARouter init success!");
    hasInit = true;
    mHandler = new Handler(Looper.getMainLooper());

    return true;
}

Copy

The most important code is LogisticsCenter.init(mContext, executor) , among executor Thread pool .

So here comes the question , LogisticsCenter What is it for ？

* LogisticsCenter contains all of the map.
* 
* 1. Creates instance when it is first used.
* 2. Handler Multi-Module relationship map(*)
* 3. Complex logic to solve duplicate group definition

Copy

According to official notes ,LogisticsCenter It contains all the mappings , Deal with cross module mapping and matching routes .

So according to the previous ActivityRouter Experience guessed ,LogisticsCenter Of init Method inside , I will definitely load the route , And build relationships .

public synchronized static void init(Context context, ThreadPoolExecutor tpe) throws HandlerException {
    mContext = context;
    executor = tpe;

    try {
        long startInit = System.currentTimeMillis();
        //billy.qi modified at 2017-12-06
        //load by plugin first
        loadRouterMap();
        if (registerByPlugin) {
            logger.info(TAG, "Load router map by arouter-auto-register plugin.");
        } else {
            Set<String> routerMap;

            //  If it is debug Or the new version , Will reload the routing map 
            if (ARouter.debuggable() || PackageUtils.isNewVersion(context)) {
                logger.info(TAG, "Run with debug mode or new install, rebuild router map.");
                //  Load routing map 
                routerMap = ClassUtils.getFileNameByPackageName(mContext, ROUTE_ROOT_PAKCAGE);
                //  Save all route mappings to  SharedPreferences
                if (!routerMap.isEmpty()) {
                    context.getSharedPreferences(AROUTER_SP_CACHE_KEY, Context.MODE_PRIVATE).edit().putStringSet(AROUTER_SP_KEY_MAP, routerMap).apply();
                }
                //  Save the new version number to  sharedpreference
                PackageUtils.updateVersion(context);    // Save new version name when router map update finishes.
            } else {
                //  Otherwise, it will be from  SharedPreferences  Read all previously saved route maps in 
                logger.info(TAG, "Load router map from cache.");
                routerMap = new HashSet<>(context.getSharedPreferences(AROUTER_SP_CACHE_KEY, Context.MODE_PRIVATE).getStringSet(AROUTER_SP_KEY_MAP, new HashSet<String>()));
            }

            logger.info(TAG, "Find router map finished, map size = " + routerMap.size() + ", cost " + (System.currentTimeMillis() - startInit) + " ms.");
            startInit = System.currentTimeMillis();

            //  According to ClassName Divided into three , Register separately 
            // IRouteRoot  Page Jump 
            // IInterceptorGroup  Interceptor 
            // IProviderGroup  Service components 
            for (String className : routerMap) {
                if (className.startsWith(ROUTE_ROOT_PAKCAGE + DOT + SDK_NAME + SEPARATOR + SUFFIX_ROOT)) {
                    // This one of root elements, load root.
                    ((IRouteRoot) (Class.forName(className).getConstructor().newInstance())).loadInto(Warehouse.groupsIndex);
                } else if (className.startsWith(ROUTE_ROOT_PAKCAGE + DOT + SDK_NAME + SEPARATOR + SUFFIX_INTERCEPTORS)) {
                    // Load interceptorMeta
                    ((IInterceptorGroup) (Class.forName(className).getConstructor().newInstance())).loadInto(Warehouse.interceptorsIndex);
                } else if (className.startsWith(ROUTE_ROOT_PAKCAGE + DOT + SDK_NAME + SEPARATOR + SUFFIX_PROVIDERS)) {
                    // Load providerIndex
                    ((IProviderGroup) (Class.forName(className).getConstructor().newInstance())).loadInto(Warehouse.providersIndex);
                }
            }
        }

        ...
        
    } catch (Exception e) {
        throw new HandlerException(TAG + "ARouter init logistics center exception! [" + e.getMessage() + "]");
    }
}

Copy

LogisticsCenter Of init Basically, the code of the method can be understood , among ClassUtils.getFileNameByPackageName It's something we need to explore . The main thing this code does is start from dex Middle traversal class find arouter-compiler Generated class collection . We will talk about the specific analysis later , Here is a foreshadowing .

So let's look down , We know ,routerMap Medium className All are arouter-compiler Generated at compile time , Let's first see what the generated class looks like

/**
 * DO NOT EDIT THIS FILE!!! IT WAS GENERATED BY AROUTER. */
public class ARouter$$Root$$app implements IRouteRoot {
  @Override
  public void loadInto(Map<String, Class<? extends IRouteGroup>> routes) {
    routes.put("test", ARouter$$Group$$test.class);
    routes.put("yourservicegroupname", ARouter$$Group$$yourservicegroupname.class);
  }
}

Copy

ARouter The route of will be loaded in groups , For example, there is /test/abc and /test/def Two routes , Then they all belong to /test This group . So in Warehouse.groupsIndex Stored in key Is the routing group name ,value Is the corresponding group routing class . The route is also found according to the group name key , Then find the group routing class value Find the matching route in .

/**
 * DO NOT EDIT THIS FILE!!! IT WAS GENERATED BY AROUTER. */
public class ARouter$$Group$$test implements IRouteGroup {
  @Override
  public void loadInto(Map<String, RouteMeta> atlas) {
    atlas.put("/test/activity1", RouteMeta.build(RouteType.ACTIVITY, Test1Activity.class, "/test/activity1", "test", new java.util.HashMap<String, Integer>(){{put("ser", 9); put("ch", 5); put("fl", 6); put("dou", 7); put("boy", 0); put("url", 8); put("pac", 10); put("obj", 11); put("name", 8); put("objList", 11); put("map", 11); put("age", 3); put("height", 3); }}, -1, -2147483648));
    atlas.put("/test/activity2", RouteMeta.build(RouteType.ACTIVITY, Test2Activity.class, "/test/activity2", "test", new java.util.HashMap<String, Integer>(){{put("key1", 8); }}, -1, -2147483648));
    atlas.put("/test/activity3", RouteMeta.build(RouteType.ACTIVITY, Test3Activity.class, "/test/activity3", "test", new java.util.HashMap<String, Integer>(){{put("name", 8); put("boy", 0); put("age", 3); }}, -1, -2147483648));
    atlas.put("/test/activity4", RouteMeta.build(RouteType.ACTIVITY, Test4Activity.class, "/test/activity4", "test", null, -1, -2147483648));
    atlas.put("/test/fragment", RouteMeta.build(RouteType.FRAGMENT, BlankFragment.class, "/test/fragment", "test", null, -1, -2147483648));
    atlas.put("/test/webview", RouteMeta.build(RouteType.ACTIVITY, TestWebview.class, "/test/webview", "test", null, -1, -2147483648));
  }
}

Copy

You can see that the route related parameter configuration is constructed into a RouteMeta object .RouteMeta Class is as follows ：

public class RouteMeta {
    private RouteType type;         // Type of route
    private Element rawType;        // Raw type of route
    private Class<?> destination;   // Destination
    private String path;            // Path of route
    private String group;           // Group of route
    private int priority = -1;      // The smaller the number, the higher the priority
    private int extra;              // Extra data
    private Map<String, Integer> paramsType;  // Param type
    private String name;

    private Map<String, Autowired> injectConfig;  // Cache inject config.

    ...
}

Copy

Come here , The part of loading routes is finished , The rest is to jump the route .

The usual operation of jump route ：

ARouter.getInstance().build("/test/abc").navigation();

Copy

Let's have a look ARouter Of build Method

 public Postcard build(String path) {
    return _ARouter.getInstance().build(path);
}

Copy

It calls _ARouter Of build Method .

protected Postcard build(String path) {
    if (TextUtils.isEmpty(path)) {
        throw new HandlerException(Consts.TAG + "Parameter is invalid!");
    } else {
        //  obtain  PathReplaceService  example , If it's not empty , Will deal with  path
        PathReplaceService pService = ARouter.getInstance().navigation(PathReplaceService.class);
        if (null != pService) {
            path = pService.forString(path);
        }
        return build(path, extractGroup(path));
    }
}

/**
 *  Intercept the first segment in the jump path as the group name 
 */
private String extractGroup(String path) {
    if (TextUtils.isEmpty(path) || !path.startsWith("/")) {
        throw new HandlerException(Consts.TAG + "Extract the default group failed, the path must be start with '/' and contain more than 2 '/'!");
    }

    try {
        String defaultGroup = path.substring(1, path.indexOf("/", 1));
        if (TextUtils.isEmpty(defaultGroup)) {
            throw new HandlerException(Consts.TAG + "Extract the default group failed! There's nothing between 2 '/'!");
        } else {
            return defaultGroup;
        }
    } catch (Exception e) {
        logger.warning(Consts.TAG, "Failed to extract default group! " + e.getMessage());
        return null;
    }
}

Copy

PathReplaceService It's the opening reserved by the government for us , Used to correct path Preprocessing . If you have a need, come to path Do unified pretreatment , Then directly realize PathReplaceService that will do .

Let's follow up , look down _ARouter.build(String path, String group) Method

protected Postcard build(String path, String group) {
    if (TextUtils.isEmpty(path) || TextUtils.isEmpty(group)) {
        throw new HandlerException(Consts.TAG + "Parameter is invalid!");
    } else {
        PathReplaceService pService = ARouter.getInstance().navigation(PathReplaceService.class);
        if (null != pService) {
            path = pService.forString(path);
        }
        return new Postcard(path, group);
    }
}

Copy

Found in build(String path, String group) Created directly in Postcard Object and return .Postcard Class inherits RouteMeta , Some additional information has been added .

With Postcard after , Call directly navigation To jump .

public Object navigation(Context context, NavigationCallback callback) {
    return ARouter.getInstance().navigation(context, this, -1, callback);
}

public void navigation(Activity mContext, int requestCode, NavigationCallback callback) {
    ARouter.getInstance().navigation(mContext, this, requestCode, callback);
}

Copy

Postcard All of the navigation Methods will eventually call ARouter Of navigation This method .

public Object navigation(Context mContext, Postcard postcard, int requestCode, NavigationCallback callback) {
    return _ARouter.getInstance().navigation(mContext, postcard, requestCode, callback);
}

Copy

And then it does _ARouter.navigation

protected Object navigation(final Context context, final Postcard postcard, final int requestCode, final NavigationCallback callback) {
    try {
        //  take  postcard  Match with the routing table , And fill in  postcard  The data of 
        LogisticsCenter.completion(postcard);
    } catch (NoRouteFoundException ex) {
        logger.warning(Consts.TAG, ex.getMessage());
        //  If  debug , It shows a matching error 
        if (debuggable()) {
            // Show friendly tips for user.
            runInMainThread(new Runnable() {
                @Override
                public void run() {
                    Toast.makeText(mContext, "There's no route matched!\n" +
                            " Path = [" + postcard.getPath() + "]\n" +
                            " Group = [" + postcard.getGroup() + "]", Toast.LENGTH_LONG).show();
                }
            });
        }
        //  Callback route matching failed 
        if (null != callback) {
            callback.onLost(postcard);
        } else {    
            // No callback for this invoke, then we use the global degrade service.
            //  If there is no callback , Call the strategy of global degradation 
            DegradeService degradeService = ARouter.getInstance().navigation(DegradeService.class);
            if (null != degradeService) {
                degradeService.onLost(context, postcard);
            }
        }

        return null;
    }

    //  Callback route matching succeeded 
    if (null != callback) {
        callback.onFound(postcard);
    }
    //  If it's not the green channel , Just call the interceptor , Interceptors will be discussed separately later , I won't talk about it here 
    if (!postcard.isGreenChannel()) {   // It must be run in async thread, maybe interceptor cost too mush time made ANR.
        interceptorService.doInterceptions(postcard, new InterceptorCallback() {
            /**
             * Continue process
             *
             * @param postcard route meta
             */
            @Override
            public void onContinue(Postcard postcard) {
                _navigation(context, postcard, requestCode, callback);
            }

            /**
             * Interrupt process, pipeline will be destory when this method called.
             *
             * @param exception Reson of interrupt.
             */
            @Override
            public void onInterrupt(Throwable exception) {
                if (null != callback) {
                    callback.onInterrupt(postcard);
                }

                logger.info(Consts.TAG, "Navigation failed, termination by interceptor : " + exception.getMessage());
            }
        });
    } else {
        //  Otherwise, call  _navigation  To jump 
        return _navigation(context, postcard, requestCode, callback);
    }

    return null;
}

private Object _navigation(final Context context, final Postcard postcard, final int requestCode, final NavigationCallback callback) {
    final Context currentContext = null == context ? mContext : context;

    switch (postcard.getType()) {
        case ACTIVITY: //  If it is  activity  Of , Perform jump 
            // Build intent
            final Intent intent = new Intent(currentContext, postcard.getDestination());
            intent.putExtras(postcard.getExtras());

            // Set flags.
            int flags = postcard.getFlags();
            if (-1 != flags) {
                intent.setFlags(flags);
            } else if (!(currentContext instanceof Activity)) {    // Non activity, need less one flag.
                intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
            }

            // Set Actions
            String action = postcard.getAction();
            if (!TextUtils.isEmpty(action)) {
                intent.setAction(action);
            }

            // Navigation in main looper.
            runInMainThread(new Runnable() {
                @Override
                public void run() {
                    startActivity(requestCode, currentContext, intent, postcard, callback);
                }
            });

            break;
        case PROVIDER: //  If it is a service component , Then return to the component directly 
            return postcard.getProvider();
        case BOARDCAST:
        case CONTENT_PROVIDER:
        case FRAGMENT: //  If it is  fragment  Words , Return to the  fragment  Example 
            Class fragmentMeta = postcard.getDestination();
            try {
                Object instance = fragmentMeta.getConstructor().newInstance();
                if (instance instanceof Fragment) {
                    ((Fragment) instance).setArguments(postcard.getExtras());
                } else if (instance instanceof android.support.v4.app.Fragment) {
                    ((android.support.v4.app.Fragment) instance).setArguments(postcard.getExtras());
                }

                return instance;
            } catch (Exception ex) {
                logger.error(Consts.TAG, "Fetch fragment instance error, " + TextUtils.formatStackTrace(ex.getStackTrace()));
            }
        case METHOD:
        case SERVICE:
        default:
            return null;
    }

    return null;
}

Copy

The above code is basically annotated , You should be able to read this .

Let's focus on LogisticsCenter.completion(postcard);

public synchronized static void completion(Postcard postcard) {
    if (null == postcard) {
        throw new NoRouteFoundException(TAG + "No postcard!");
    }
    //  First, according to  path  To get  RouteMeta
    RouteMeta routeMeta = Warehouse.routes.get(postcard.getPath());
    if (null == routeMeta) {    //  If  routeMeta  It's empty , It may not exist or it may not be loaded 
        Class<? extends IRouteGroup> groupMeta = Warehouse.groupsIndex.get(postcard.getGroup());  //  Load the routing map under the packet 
        //  If it doesn't exist , Just report a mistake 
        if (null == groupMeta) {
            throw new NoRouteFoundException(TAG + "There is no route match the path [" + postcard.getPath() + "], in group [" + postcard.getGroup() + "]");
        } else {
            // Load route and cache it into memory, then delete from metas.
            try {
                if (ARouter.debuggable()) {
                    logger.debug(TAG, String.format(Locale.getDefault(), "The group [%s] starts loading, trigger by [%s]", postcard.getGroup(), postcard.getPath()));
                }
                //  Implement on-demand loading 
                IRouteGroup iGroupInstance = groupMeta.getConstructor().newInstance();
                iGroupInstance.loadInto(Warehouse.routes);
                //  remove  groupsIndex ,  Otherwise, it will cause a dead cycle 
                Warehouse.groupsIndex.remove(postcard.getGroup());

                if (ARouter.debuggable()) {
                    logger.debug(TAG, String.format(Locale.getDefault(), "The group [%s] has already been loaded, trigger by [%s]", postcard.getGroup(), postcard.getPath()));
                }
            } catch (Exception e) {
                throw new HandlerException(TAG + "Fatal exception when loading group meta. [" + e.getMessage() + "]");
            }
            //  Reload 
            completion(postcard);   // Reload
        }
    } else {
        //  Find the corresponding  routeMeta,  fill  postcard  data 
        postcard.setDestination(routeMeta.getDestination());
        postcard.setType(routeMeta.getType());
        postcard.setPriority(routeMeta.getPriority());
        postcard.setExtra(routeMeta.getExtra());

        Uri rawUri = postcard.getUri();
        //  If  rawUri  Not empty , It is  uri  Jump . Just analyze  rawUri  Parameters in , Put in  bundle  in 
        if (null != rawUri) {   // Try to set params into bundle.
            Map<String, String> resultMap = TextUtils.splitQueryParameters(rawUri);
            Map<String, Integer> paramsType = routeMeta.getParamsType();

            if (MapUtils.isNotEmpty(paramsType)) {
                // Set value by its type, just for params which annotation by @Param
                for (Map.Entry<String, Integer> params : paramsType.entrySet()) {
                    setValue(postcard,
                            params.getValue(),
                            params.getKey(),
                            resultMap.get(params.getKey()));
                }

                // Save params name which need auto inject.
                postcard.getExtras().putStringArray(ARouter.AUTO_INJECT, paramsType.keySet().toArray(new String[]{}));
            }

            // Save raw uri
            postcard.withString(ARouter.RAW_URI, rawUri.toString());
        }
        //  If it is  PROVIDER  and  FRAGMENT  Type of , Open green channel 
        switch (routeMeta.getType()) {
            case PROVIDER:  // if the route is provider, should find its instance
                // Its provider, so it must implement IProvider
                Class<? extends IProvider> providerMeta = (Class<? extends IProvider>) routeMeta.getDestination();
                IProvider instance = Warehouse.providers.get(providerMeta);
                if (null == instance) { // There's no instance of this provider
                    IProvider provider;
                    try {
                        provider = providerMeta.getConstructor().newInstance();
                        provider.init(mContext);
                        Warehouse.providers.put(providerMeta, provider);
                        instance = provider;
                    } catch (Exception e) {
                        throw new HandlerException("Init provider failed! " + e.getMessage());
                    }
                }
                postcard.setProvider(instance);
                postcard.greenChannel();    // Provider should skip all of interceptors
                break;
            case FRAGMENT:
                postcard.greenChannel();    // Fragment needn't interceptors
            default:
                break;
        }
    }
}

Copy

thus , The whole process of route jump is over , The general process can be divided into

1. Load routing map
2. according to path Construct out Postcard object
3. distinguish Postcard Of type To make a jump

Off the coast

As I said before ,ARouter Will be in dex Search for arouter-compiler The generated class . Let's finally see how it is achieved .

public static Set<String> getFileNameByPackageName(Context context, final String packageName) throws PackageManager.NameNotFoundException, IOException, InterruptedException {
    final Set<String> classNames = new HashSet<>();
    //  obtain  dex  Path of file storage 
    List<String> paths = getSourcePaths(context);
    final CountDownLatch parserCtl = new CountDownLatch(paths.size());
    //  Traverse all of  dex  Path to file 
    for (final String path : paths) {
        DefaultPoolExecutor.getInstance().execute(new Runnable() {
            @Override
            public void run() {
                DexFile dexfile = null;

                try {
                    //  Load according to the path  dex  file 
                    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);
                    }
                    //  Traverse  dexfile  All in  className  If it is  arouter  At the beginning of the registration , Join in  classNames  in 
                    Enumeration<String> dexEntries = dexfile.entries();
                    while (dexEntries.hasMoreElements()) {
                        String className = dexEntries.nextElement();
                        if (className.startsWith(packageName)) {
                            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.d(Consts.TAG, "Filter " + classNames.size() + " classes by packageName <" + packageName + ">");
    return classNames;
}

Copy

Let's see getSourcePaths Method , See how it finds dex File path

    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;

//         If VM Has supported MultiDex, Don't go Secondary Folder load  Classesx.zip 了 , There is no such thing as 
//         Through the existence of sp Medium multidex.version It's not accurate , Because users upgrading from a lower version , It includes this sp Configured 
        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() + "'");
                }
            }
        }

        //  If it is debug Of , Then load it extra  instant run  Medium dex File path 
        if (ARouter.debuggable()) { // Search instant run support only debuggable
            sourcePaths.addAll(tryLoadInstantRunDexFile(applicationInfo));
        }
        return sourcePaths;
    }

Copy

For more details, interested students can go back and see it by themselves , Because of the space, I don't want to talk more about this .

So that's the end of today , About ARouter Series of more source code analysis , You can see the next two blogs .

bye