Android R设置默认桌面

Posted 2021-11-10 虫师魁拔

一、launcher 启动过程

首先看下系统启动 Launcher 过程，主要涉及以下类和方法：

AMS ： 

systemReady -> mAtmInternal.startHomeOnAllDisplays(currentUserId, "systemReady");

ActivityTaskManagerInternal ：

startHomeOnAllDisplays -> mRootWindowContainer.startHomeOnAllDisplays(userId, reason);

RootWindowContainer ：

startHomeOnDisplay -> startHomeOnTaskDisplayArea -> mService.getActivityStartController().startHomeActivity(homeIntent, aInfo, myReason,
        taskDisplayArea);

ActivityStartController 中按照一般 activity 正常的启动。

二、修改默认 launcher 方案

设置默认应用方式有两种：

1、通过 RoleManager 接口设置

    setRoleHolderAsUser(RoleManager.ROLE_HOME, "com.android.launcher3", 0, Process.myUserHandle(), this);
    
    public void setRoleHolderAsUser(String roleName, String packageName,
            int flags, UserHandle user, Context context) {
        RoleManager roleManager = (RoleManager)context.getSystemService(Context.ROLE_SERVICE);
        Executor executor = context.getMainExecutor();
        Consumer<Boolean> callback = successful -> {
            if (successful) {
                Log.d(TAG, "Package added as role holder, role: " + roleName + ", package: " + packageName);
            } else {
                Log.d(TAG, "Failed to add package as role holder, role: " + roleName + ", package: "
                            + packageName);
            }
        };
        roleManager.addRoleHolderAsUser(roleName, packageName, flags, user, executor, callback);
    }

 这个是异步设置，需要在回调函数中进行监听判断。

2、通过 PackageManager 接口设置

        PackageManager pm = getPackageManager();

        Intent queryIntent = new Intent();
        queryIntent.addCategory(Intent.CATEGORY_HOME);
        queryIntent.setAction(Intent.ACTION_MAIN);

        List<ResolveInfo> homeActivities = pm.queryIntentActivities(queryIntent, 0);
        if(homeActivities == null) {
            return;
        }

        ComponentName defaultLauncher = new ComponentName("com.android.launcher3",
                "com.android.launcher3.Launcher");
        int activityNum = homeActivities.size();
        ComponentName[] set = new ComponentName[activityNum];
        int defaultMatch = -1;
        for(int i = 0; i < activityNum; i++){
            ResolveInfo info = homeActivities.get(i);
            set[i] = new ComponentName(info.activityInfo.packageName, info.activityInfo.name);
            if("com.android.launcher3.Launcher".equals(info.activityInfo.name)
                    && "com.android.launcher3".equals(info.activityInfo.packageName)){
                defaultMatch = info.match;
            }
        }

        //if Launcher3 is not found, do not set anything
        if(defaultMatch == -1){
            return;
        }
        IntentFilter filter = new IntentFilter();
        filter.addAction(Intent.ACTION_MAIN);
        filter.addCategory(Intent.CATEGORY_HOME);
        filter.addCategory(Intent.CATEGORY_DEFAULT);

        pm.addPreferredActivity(filter, defaultMatch, set, defaultLauncher);

这种方式需要注意 queryIntentActivities 查询不全的情况，参照上一篇记录说明。

第一种方案更适合 APP 运行中动态设置和监听。第二种适合系统默认设置，在AMS或者开机向导种添加此段代码。