Android如何设置默认的Launcher

问题
机器装有多个launcher，第一次开机，系统会弹出让用户选择哪个作为默认launcher的对话框，但是客户不希望看到这个框，默认使用其中的一个launcher

涉及代码
frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java
frameworks/base/services/core/java/com/android/server/pm/PackageManagerService.java

修改方法
在ActivityManagerService中的startHomeActivityLocked之前，将客户希望的launcher设置到系统的addPreferredActivity(mPreferredActivities)当中，对应的xml配置文件在/data/system/users/0/package-restrictions.xml 当中，例如

<preferred-activities>
    <item name="com.test.touch.homescreen/.MainActivity" match="100000" always="true" set="2">
        <set name="com.test.touch.homescreen/.MainActivity" />
        <set name="com.android.launcher3/.Launcher" />
        <filter>
            <action name="android.intent.action.MAIN" />
            <cat name="android.intent.category.HOME" />
            <cat name="android.intent.category.DEFAULT" />
        </filter>
    </item>
</preferred-activities>

修改方法
svn diff

• //if no preferered launcher activity exist, set the default one
• private void setDefaultLauncher(int userId) {

•    // get default component
  

•    String packageName = "com.test.touch.homescreen";
  

•    String className = "com.test.touch.homescreen.MainActivity";
  

•    IPackageManager pm = ActivityThread.getPackageManager();
  

•    //判断指定的launcher是否存在
  

•           Slog.i(TAG, "setDefaultLauncher packageName " + packageName + " className " + className);
  

•    if (hasApkInstalled(packageName)) {
  

•        Slog.i(TAG, "default packageName = " + packageName + ", default className = " + className);
  

•        ArrayList<IntentFilter> intentList = new ArrayList<IntentFilter>();
  

•        ArrayList<ComponentName> cnList = new ArrayList<ComponentName>();
  

•        mContext.getPackageManager().getPreferredActivities(intentList, cnList, null);
  

•        IntentFilter dhIF = null;
  

•        for (int i = 0; i < cnList.size(); i++) {
  

•            dhIF = intentList.get(i);
  

•            if (dhIF.hasAction(Intent.ACTION_MAIN) && dhIF.hasCategory(Intent.CATEGORY_HOME)) {
  

•                Slog.i(TAG, "default launcher exist = " + cnList.get(i).getPackageName());
  

•                return;
  

•            }
  

•        }
  

•        //获取所有launcher activity
  

•        Intent intent = new Intent(Intent.ACTION_MAIN);
  

•        intent.addCategory(Intent.CATEGORY_HOME);
  

•        intent.addCategory(Intent.CATEGORY_DEFAULT);            
  

•                   List<ResolveInfo> list = new ArrayList<ResolveInfo>();
  

•        try {
  

•            list = pm.queryIntentActivities(intent,
  

•            intent.resolveTypeIfNeeded(mContext.getContentResolver()),
  

•            STOCK_PM_FLAGS, userId);
  

•        } catch (RemoteException e) {
  

•            throw new RuntimeException("Package manager has died", e);
  

•        }
  

•        // get all components and the best match
  

•        IntentFilter filter = new IntentFilter();
  

•        filter.addAction(Intent.ACTION_MAIN);
  

•        filter.addCategory(Intent.CATEGORY_HOME);
  

•        filter.addCategory(Intent.CATEGORY_DEFAULT);
  

•        final int N = list.size();
  

•        //设置默认launcher
  

•        ComponentName launcher = new ComponentName(packageName, className);
  

•        ComponentName[] set = new ComponentName[N];
  

•        ComponentName[] setLauncher = new ComponentName[2];
  

•        int defaultMatch = 0;
  

•        for (int i = 0; i < N; i++) {
  

•            ResolveInfo r = list.get(i);
  

•            set[i] = new ComponentName(r.activityInfo.packageName, r.activityInfo.name);
  

•            Slog.d(TAG, "r.activityInfo.packageName======= " + r.activityInfo.packageName);
  

•            Slog.d(TAG, "r.activityInfo.name========= " + r.activityInfo.name);
  

•            //if (launcher.getClassName().equals(r.activityInfo.name)) {
  

•            if(r.activityInfo.name.indexOf("com.android.settings.CryptKeeper") != -1) {
  

•                     continue;
  

•             }
  

•           if(r.activityInfo.name.indexOf("com.android.provision.DefaultActivity") != -1) {
  

•                   continue;
  

•            }
  

•             if (r.activityInfo.name.indexOf(launcher.getClassName()) != -1) {                 
  

•             		defaultMatch = r.match;
  

•              	setLauncher[0] = new ComponentName(r.activityInfo.packageName, r.activityInfo.name);
  

•            } else {
  

•                   setLauncher[1] = new ComponentName(r.activityInfo.packageName, r.activityInfo.name);
  

•             }
  

•        }
  

•        Slog.w(TAG, "defaultMatch = " + defaultMatch);
  

•        try {
  

•            pm.addPreferredActivity(filter, defaultMatch, setLauncher, launcher, getCurrentUserIdLocked());
  

•        } catch (RemoteException e) {
  

•            throw new RuntimeException("Package manager has died", e);
  

•        }
  

•    }
  

• }
• private boolean hasApkInstalled(String packageName) {

•    if (packageName == null || "".equals(packageName)) {
  

•                   return false;
  

•           }
  

•    android.content.pm.ApplicationInfo info = null;
  

•    try {
  

•        info = mContext.getPackageManager().getApplicationInfo(packageName, 0);
  

•       Slog.i(TAG, "packageName found " + info);
  

•        return info != null;
  

•    } catch (NameNotFoundException e) {
  

•       Slog.i(TAG, "packageName not found " + packageName + " " + e);
  

•        return false;
  

•    }
  

• }
• //end
• boolean startHomeActivityLocked(int userId, String reason) {

•    if (mFactoryTest == FactoryTest.FACTORY_TEST_LOW_LEVEL
  

•     setDefaultLauncher(userId);
  

遇到的坑
String className = “com.test.touch.homescreen.MainActivity”;
此处的className要是完整的名字，不能是.MainActivity，否则PackageManagerService会打印
Removing dangling preferred activity:xxxxxxx
1
将我们原本设置的preferred activity删除掉。

queryIntentActivities
此处query出来的launcher的activities，有多个launcher，与PackageManagerService当中识别到的launcher数量不一致，导致打印：
Result set changed, dropping preferred activity for xxxx
1
同样会删除我们之前设置的preferred activity.
所以采用了恶心的代码，删除掉其他多的activity，与PackageManagerService保持一致