[R0]设置默认Launcher - 《AOSP开发手记》

系统的选择弹窗是：
frameworks/base/core/java/com/android/internal/app/ResolverActivity.java

protected boolean onTargetSelected(TargetInfo target, boolean alwaysCheck) {
    ///......
        if (alwaysCheck) {
        final int userId = getUserId();
        final PackageManager pm = getPackageManager();
        android.util.Log.e("XShawn, "+TAG, "filter="+filter);                       // android.content.IntentFilter@3544861
        for(int i = 0 ; i < filter.countActions(); i++){
            android.util.Log.e("XShawn, "+TAG, "filter.getAction["+i+"]="+filter.getAction(i));
        }
        for(int i = 0 ; i < filter.countCategories(); i++){
            android.util.Log.e("XShawn, "+TAG, "filter.getCategory["+i+"]="+filter.getCategory(i));
        }
        android.util.Log.e("XShawn, "+TAG, "bestMatch="+bestMatch);                 // 1081344
        android.util.Log.e("XShawn, "+TAG, "set="+set);                             // [Landroid.content.ComponentName;@4f68f86
        android.util.Log.e("XShawn, "+TAG, "getComponent="+intent.getComponent());  // com.ordissimo.android.tablet.launcher/com.ordissimo.android.tablet.launcher.home.HomeActivity
        // Set the preferred Activity
        pm.addPreferredActivity(filter, bestMatch, set, intent.getComponent());
        if (ri.handleAllWebDataURI) {
            // Set default Browser if needed
            final String packageName = pm.getDefaultBrowserPackageNameAsUser(userId);
            if (TextUtils.isEmpty(packageName)) {
                pm.setDefaultBrowserPackageNameAsUser(ri.activityInfo.packageName, userId);
            }
        }
    } else {
        try {
            mMultiProfilePagerAdapter.getActiveListAdapter()
                    .mResolverListController.setLastChosen(intent, filter, bestMatch);
        } catch (RemoteException re) {
            Log.d(TAG, "Error calling setLastChosenActivity\n" + re);
        }
    }
    ///......
}

这里适合打印系统处理时产生的各种参数，进而拿到设置默认Launcher的关键参数。

尝试在SystemServer中 startSystemUI之后设置默认launcher，但首次开机时设置不上，可能是开机向导还没走完，系统没有初始化完的原因。
尝试在SystemServer中startOtherService之前设置，也不太理想。

设置默认Launcher，设置方法可参考PackageManagerService.setHomeActivity方法。
采用监听开机广播的方式处理：
MtkSettings\src\com\emdoor\customization\PreferredActivityReceiver.java

/*
 * ****** Copyright © 2015-2022 XShawn ********
 * Q Q：930226956 (请备注您的信息)
 * 邮箱：shawn.xiafei@foxmail.com
 * 语雀：https://www.yuque.com/xshawn
 * 更新：2022-03-31 10:21
 * ********** All Rights Reserved. ************
 */
package com.emdoor.customization;
import android.content.BroadcastReceiver;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.pm.PackageManager;
import android.content.pm.ResolveInfo;
import android.os.SystemProperties;
import android.provider.Settings;
import android.util.Log;
import java.util.ArrayList;
import java.util.List;
public class PreferredActivityReceiver extends BroadcastReceiver {
    private static final String TAG = "XShawn, PreferredActivityReceiver";
    private static final String KEY_ORDISSIMO_SUPPORT = "ro.com.ordissimo.support";
    private static final String KEY_ORDISSIMO_INIT = "ordissimo_init";
    @Override
    public void onReceive(Context context, Intent intent) {
        Log.w(TAG, "action: " + intent.getAction());
        if (SystemProperties.getBoolean(KEY_ORDISSIMO_SUPPORT, false)) {
            setDefaultHome(context);
        }
    }
    private static void setDefaultHome(Context context) {
        if (isOrdissimoInit(context)) {
            Log.w(TAG, "default home has already been set.");
            return;
        }
        Log.w(TAG, "try to set default home...");
        // target activity
        final ComponentName targetHome = new ComponentName(
                "com.ordissimo.android.tablet.launcher",
                "com.ordissimo.android.tablet.launcher.home.HomeActivity"
        );
        final PackageManager pm = context.getPackageManager();
        List<ResolveInfo> homeActivities = new ArrayList<>();
        ComponentName currentHome = pm.getHomeActivities(homeActivities);
        // pre-check status
        if (targetHome.equals(currentHome)) {
            Log.w(TAG, "default home has already been set.");
            setOrdissimoInit(context, true);
            return;
        }
        // available set
        ComponentName[] set = homeActivities.parallelStream()
                .map(resolveInfo -> resolveInfo.activityInfo.getComponentName())
                .toArray(ComponentName[]::new);
        // set default home
        context.getPackageManager().replacePreferredActivity(
                getHomeFilter(),
                IntentFilter.MATCH_CATEGORY_EMPTY,
                set,
                targetHome
        );
        // after-check status.
        currentHome = pm.getHomeActivities(homeActivities);
        if (targetHome.equals(currentHome)) {
            Log.w(TAG, "set default home success.");
            setOrdissimoInit(context, true);
        }
    }
    private static IntentFilter getHomeFilter() {
        IntentFilter filter = new IntentFilter(Intent.ACTION_MAIN);
        filter.addCategory(Intent.CATEGORY_HOME);
        filter.addCategory(Intent.CATEGORY_DEFAULT);
        return filter;
    }
    private static boolean isOrdissimoInit(Context context) {
        return Settings.Global.getInt(context.getContentResolver(), KEY_ORDISSIMO_INIT, 0) == 1;
    }
    private static void setOrdissimoInit(Context context, boolean done) {
        Settings.Global.putInt(context.getContentResolver(), KEY_ORDISSIMO_INIT, done ? 1 : 0);
    }
}

注册广播接收器：

<!-- START. For Ordissimo-Customization. By XShawn@20220331. -->
<receiver
    android:name="com.emdoor.customization.PreferredActivityReceiver"
    android:enabled="true"
    android:exported="true">
    <intent-filter>
        <action android:name="android.intent.action.BOOT_COMPLETED" />
        <action android:name="android.intent.action.LOCKED_BOOT_COMPLETED" />
        <action android:name="android.intent.action.USER_PRESENT" />
    </intent-filter>
</receiver>
<!-- END. For Ordissimo-Customization. By XShawn@20220331. -->

但开机广播是有延时性的，在有开机向导的前提下，能够成功设置默认launcher。
若没有开机向导，开机后直接就进了launcher，此时开机广播还没有发出来，所以默认不成功。

优化方案
找到安装APP的位置，安装完成，主动发广播去修改默认launcher，但这样每次安装都会自动默认上。

//frameworks\base\services\core\java\com\android\server\pm\PackageManagerService.java
try {
    PackageParser.Package newPackage = scanPackageTracedLI(pkg, policyFlags, scanFlags,
            System.currentTimeMillis(), user);
    updateSettingsLI(newPackage, installerPackageName, null, res, user);
    if (res.returnCode == PackageManager.INSTALL_SUCCEEDED) {
        prepareAppDataAfterInstallLIF(newPackage);
        //------------------------
        if (pkgName.equals("com.dianxinos.dxhome")){
            //发送广播
            Intent intent = new  Intent("emdoor.intent.action.UPDATE_LANUCHER_APPS");
            mContext.sendBroadcast(intent);
        }
        //------------------------
    } else {
    // Remove package from internal structures, but keep around any
    // data that might have already existed
    deletePackageLIF(pkgName, UserHandle.ALL, false, null,
            PackageManager.DELETE_KEEP_DATA, res.removedInfo, true, null);
    }
} catch (PackageManagerException e) {
    res.setError("Package couldn't be installed in " + pkg.codePath, e);
}