组件化学习-3-源码分析ARouter

之前我们学习了Arouter的使用,今天分析下源码实现原理。主要分3步

1. 生成路由表
2. 加载路由表
3. 使用路由表

生成路由表

RouteProcessor负责生产路由表

ARouter框架使用编译时注解工具(Annotation Processing Tool 简称APT),用来编译时扫描和处理注解。

编译时,编译器会检查AbstractProcessor的子类,并调用AbstractProcessor的子类的process()方法,然后把添加了注解的元素传到process()方法中,在process()函数中生成新的java类文件。

RouterProcessor是一个注解处理器,是AbstractProcessor的子类,在它的process()方法中,会调用parseRouter()方法,parseRouter()调用JavaPoet API生成java代码,参数注解处理器和拦截器注解处理器同理。

具体代码分析:

com.alibaba.android.arouter.compiler.processor.java 

@Override
    public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
        if (CollectionUtils.isNotEmpty(annotations)) {
            Set<? extends Element> routeElements = roundEnv.getElementsAnnotatedWith(Route.class);
            try {
                logger.info(">>> Found routes, start... <<<");
                this.parseRoutes(routeElements);//关键代码,得到所有带Route的类元素,进行解析处理

            } catch (Exception e) {
                logger.error(e);
            }
            return true;
        }

        return false;
    }


private void parseRoutes(Set<? extends Element> routeElements) throws IOException{
    ....
     if (types.isSameType(tm, iProvider)) {   // Its implements iProvider interface himself.
                                    // This interface extend the IProvider, so it can be used for mark provider
                                    loadIntoMethodOfProviderBuilder.addStatement(
                                            "providers.put($S, $T.build($T." + routeMeta.getType() + ", $T.class, $S, $S, null, " + routeMeta.getPriority() + ", " + routeMeta.getExtra() + "))",
                                            (routeMeta.getRawType()).toString(),
                                            routeMetaCn,
                                            routeTypeCn,
                                            className,
                                            routeMeta.getPath(),
                                            routeMeta.getGroup());
                                } else if (types.isSubtype(tm, iProvider)) {
                                    // This interface extend the IProvider, so it can be used for mark provider
                                    loadIntoMethodOfProviderBuilder.addStatement(
                                            "providers.put($S, $T.build($T." + routeMeta.getType() + ", $T.class, $S, $S, null, " + routeMeta.getPriority() + ", " + routeMeta.getExtra() + "))",
                                            tm.toString(),    // So stupid, will duplicate only save class name.
                                            routeMetaCn,
                                            routeTypeCn,
                                            className,
                                            routeMeta.getPath(),
                                            routeMeta.getGroup());
                                }
    ...
         loadIntoMethodOfGroupBuilder.addStatement(
                            "atlas.put($S, $T.build($T." + routeMeta.getType() + ", $T.class, $S, $S, " + (StringUtils.isEmpty(mapBody) ? null : ("new java.util.HashMap<String, Integer>(){{" + mapBodyBuilder.toString() + "}}")) + ", " + routeMeta.getPriority() + ", " + routeMeta.getExtra() + "))",
                            routeMeta.getPath(),
                            routeMetaCn,
                            routeTypeCn,
                            className,
                            routeMeta.getPath().toLowerCase(),
                            routeMeta.getGroup().toLowerCase());
    ...
        if (MapUtils.isNotEmpty(rootMap)) {
                // Generate root meta by group name, it must be generated before root, then I can find out the class of group.
                for (Map.Entry<String, String> entry : rootMap.entrySet()) {
                    loadIntoMethodOfRootBuilder.addStatement("routes.put($S, $T.class)", entry.getKey(), ClassName.get(PACKAGE_OF_GENERATE_FILE, entry.getValue()));
                }
            }
    ...
}

一顿操作猛如虎,找到所有带Route注解的页面,最终实际项目生产一些文件,同时生成路由表

在ARouter$$Group$$app中已经加载了全部的路由

package com.alibaba.android.arouter.routes;

import com.alibaba.android.arouter.facade.enums.RouteType;
import com.alibaba.android.arouter.facade.model.RouteMeta;
import com.alibaba.android.arouter.facade.template.IRouteGroup;
import com.sun.module_main.MainActivity;
import com.sun.module_main.arouter.RouterDataActivity;
import com.sun.module_main.arouter.RouterFragment;
import com.sun.module_main.arouter.RouterLoginActivity;
import com.sun.module_main.arouter.RouterMainActivity;
import java.lang.Override;
import java.lang.String;
import java.util.Map;

/**
 * DO NOT EDIT THIS FILE!!! IT WAS GENERATED BY AROUTER. */
public class ARouter$$Group$$app implements IRouteGroup {
  @Override
  public void loadInto(Map<String, RouteMeta> atlas) {
    atlas.put("/app/MainActivity", RouteMeta.build(RouteType.ACTIVITY, MainActivity.class, "/app/mainactivity", "app", null, -1, -2147483648));
    atlas.put("/app/RouterDataActivity", RouteMeta.build(RouteType.ACTIVITY, RouterDataActivity.class, "/app/routerdataactivity", "app", new java.util.HashMap<String, Integer>(){{put("BOOLEAN_KEY", 0); put("BOOLEAN_BEAN", 11); put("BOOLEAN_STRING", 8); put("BOOLEAN_INT", 3); }}, -1, -2147483648));
    atlas.put("/app/RouterFragment", RouteMeta.build(RouteType.FRAGMENT, RouterFragment.class, "/app/routerfragment", "app", null, -1, -2147483648));
    atlas.put("/app/RouterLoginActivity", RouteMeta.build(RouteType.ACTIVITY, RouterLoginActivity.class, "/app/routerloginactivity", "app", new java.util.HashMap<String, Integer>(){{put("message", 8); }}, -1, -2147483648));
    atlas.put("/app/RouterMainActivity", RouteMeta.build(RouteType.ACTIVITY, RouterMainActivity.class, "/app/routermainactivity", "app", null, -1, -2147483648));
  }
}

路由以map("路径",activity.class)全给保存好了,路由表生成完毕.

加载路由表

使用中先加载路由表,具体流程如下

Arouter使用了门面设计模式,所有明面上的操作类是ARouter.java,实际逻辑类是_ARouter.java

使用ARouter必须先初始化

ARouter.java

/**
     * Init, it must be call before used router.
     */
    public static void init(Application application) {
        if (!hasInit) {
            logger = _ARouter.logger;
            _ARouter.logger.info(Consts.TAG, "ARouter init start.");
            hasInit = _ARouter.init(application);//实际初始化操作

            if (hasInit) {
                _ARouter.afterInit();//初始化后处理拦截器功能
            }

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

主要实现为_Arouter.init()
_Arouter.java

   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;
    }  

主要实现功能的是LogisticsCenter.init(mContext, executor);
LogisticsCenter类的注释为:
LogisticsCenter contains all of the map.   //包含所有的集合
1,Creates instance when it is first used. //第一次使用时创建实例
2,Handler Multi-Module relationship map(*) //处理多模块组件间的对应关系
3,Complex logic to solve duplicate group definition//解决重复组定义的复杂逻辑

LogisticsCenter.java
 /**
     * LogisticsCenter init, load all metas in memory. Demand initialization 初始化 加载内存中全部的元素
     */
    public synchronized static void init(Context context, ThreadPoolExecutor tpe) throws HandlerException {
        mContext = context;
        executor = tpe;

        try {
            long startInit = System.currentTimeMillis();
            //load by plugin first
            loadRouterMap();//加载路由表
            if (registerByPlugin) {
                logger.info(TAG, "Load router map by arouter-auto-register plugin.");//插件主动加载
            } else {
                Set<String> routerMap;


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

                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() + "]");
        }
    }

遍历所有的路由集合,通过反射+loadInfo(上面生成的文件就有这个方法),将所有的路由放到仓库中Warehouse,这样就实现了路由的加载.

使用路由表

使用过程路由跳转时

1,    ARouter.getInstance().build("/module_a/ARouterOneActivity")//看这一句关键代码
                .withString("From", "hello,I'm from app module")
                .navigation();
主要分析build("xx")

2,  ARouter.java

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

3,_ARouter.java

  /**
     * Build postcard by path and default group
     */
    protected Postcard build(String path) {
        if (TextUtils.isEmpty(path)) {
            throw new HandlerException(Consts.TAG + "Parameter is invalid!");
        } else {
            PathReplaceService pService = ARouter.getInstance().navigation(PathReplaceService.class);//看这一句关键代码
            if (null != pService) {
                path = pService.forString(path);
            }
            return build(path, extractGroup(path), true);
        }
    }

4, ARouter不干活,直接去_ARouter类中

  /**
     * Launch the navigation by type
     *
     * @param service interface of service
     * @param <T>     return type
     * @return instance of service
     */
    public <T> T navigation(Class<? extends T> service) {
        return _ARouter.getInstance().navigation(service);//看这一句关键代码
    }

5,_ARouter.java

    protected <T> T navigation(Class<? extends T> service) {
        try {
            Postcard postcard = LogisticsCenter.buildProvider(service.getName());//这一句关键代码

            // Compatible 1.0.5 compiler sdk.
            // Earlier versions did not use the fully qualified name to get the service
            if (null == postcard) {
                // No service, or this service in old version.
                postcard = LogisticsCenter.buildProvider(service.getSimpleName());
            }

            if (null == postcard) {
                return null;
            }

            // Set application to postcard.
            postcard.setContext(mContext);

            LogisticsCenter.completion(postcard);
            return (T) postcard.getProvider();
        } catch (NoRouteFoundException ex) {
            logger.warning(Consts.TAG, ex.getMessage());
            return null;
        }
    }


6,去仓库里找路由,组装成postcard
LogisticsCenter.java
 public static Postcard buildProvider(String serviceName) {
        RouteMeta meta = Warehouse.providersIndex.get(serviceName);

        if (null == meta) {
            return null;
        } else {
            return new Postcard(meta.getPath(), meta.getGroup());
        }
    }

这是执行ARouter.getInstance().build("xx/xx")执行的查找路由的过程,最终还是去路由表中查找

当执行到navigation()方法时,一路跟踪,最终到达_ARouter.java中的_navigation(final Postcard postcard, final int requestCode, final NavigationCallback callback()方法

private Object _navigation(final Postcard postcard, final int requestCode, final NavigationCallback callback) {
        final Context currentContext = postcard.getContext();

        switch (postcard.getType()) {
            case ACTIVITY:
                // Build intent
                final Intent intent = new Intent(currentContext, postcard.getDestination());
                intent.putExtras(postcard.getExtras());

                // Set flags.
                int flags = postcard.getFlags();
                if (0 != flags) {
                    intent.setFlags(flags);
                }

                // Non activity, need FLAG_ACTIVITY_NEW_TASK
                if (!(currentContext instanceof Activity)) {
                    intent.addFlags(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:
                return postcard.getProvider();
            case BOARDCAST:
            case CONTENT_PROVIDER:
            case FRAGMENT:
                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;
    }

根据postcard的类型,找到Activity,新建Intent,设置页面,最终在主线程完成页面跳转,至此,Arouter的整个流程分析完成。

SerializationService

之前有写到"传递对象时需做特殊序列化处理",为什么要重新实现SerializationService

package com.sun.commonlibrary.util;

import android.content.Context;

import com.alibaba.android.arouter.facade.annotation.Route;
import com.alibaba.android.arouter.facade.service.SerializationService;
import com.google.gson.Gson;

import java.lang.reflect.Type;

@Route(path = "/service/json")
public class JsonServiceImpl implements SerializationService {

    private Gson mGson;

    @Override
    public void init(Context context) {
        mGson = new Gson();

    }

    @Override
    public <T> T json2Object(String text, Class<T> clazz) {
        checkJson();
        return mGson.fromJson(text, clazz);
    }

    @Override
    public String object2Json(Object instance) {
        checkJson();
        return mGson.toJson(instance);
    }

    @Override
    public <T> T parseObject(String input, Type clazz) {
        checkJson();
        return mGson.fromJson(input, clazz);
    }

    public void checkJson() {
        if (mGson == null) {
            mGson = new Gson();
        }
    }
}

其实道理很简单

 public Postcard withObject(@Nullable String key, @Nullable Object value) {
        serializationService = ARouter.getInstance().navigation(SerializationService.class);
        mBundle.putString(key, serializationService.object2Json(value));
        return this;
    }

执行withObject()方法时,需要个SerializationService对象将对象转为json数据,所以必须实现个SerializationService(),同时用Router注解标识

至此,ARouter框架初步深入研究完成,感觉还是比较多懵懂的,后续再深入分析。

组件化学习代码位置:GitHub - xingzhesun215/Android_Componentized: 安卓组件化学习