1. 起动的时候会启动一个闪屏

见AppWindowContainerController.java中的addStartingWindow函数

刚启动程序时，会先弹出一个Activity，那个其实不是主Activity，是framework层创建的一个临时Activity

在开发手机应用时startingWindow是不能去掉的，所以现在一般采取的方案是启动透明窗体或者先启动一个图片闪屏界面

在开发定制系统时，可以去掉，但是点击按钮后过几百毫秒后才会显示Activity，去掉的方法：

在AppWindowContainerController.java中的addStartingWindow函数中提前return false

2. 匹配语言时速度很慢

见ResourceImpl.java中的updateConfiguration函数

如果你的应用只有中文，可以在AndroidManifest.xml中的Activity的节点中增加android:configChanges=”locale”以优化？

3. Choreographer.java中的doFrame函数

本文只是随手笔记，可能会有很多错误，仅供参考

基本Android8.1系统

一、healthd裁剪
1. system/core/rootdir/init.rc
屏蔽healthd服务
#service healthd /system/bin/healthd
# class core
# critical
# group root system wakelock

删除后系统没办法启动了

二、app删除
2. 启动模拟器看是否有Contacts和Email应用: 有
3. 去掉build/make/target/product/core.mk中PRODUCT_PACKAGES下的Emailt和Contacts并编译看系统中是否还这两个应用: 还有
4. 删除out下对应设备目录下的system/app/Email和system/priv-app/Contacts目录，并编译看系统中是否还这两个应用: 还有
5. 把out目录里的system.img删除掉，再试: 不行
6. 把out/target/common/obj/Apps目录下Email和Contacts相关目录删除再试: 还是有
7. 重启一下系统试试: 不行
8. 把修改core.mk中，把mmsservice也删除掉试试:不行
9. 把源码中packages/apps中的Contacts和Email目录删除，Email目录保留emailcommon目录：好了，这次没了
此阶段结论：其实第3步后make clean一下也可以，但是不想make clean
10. 把Calendar、ExactCalculator(calculator2)、Music、Gallery、Gallery2、SoundRecorder、TvSettings全删掉

三、mediaserver裁剪
在frameworks/av/media/mediaserver/mediaserver.rc中，将mediaserver启动项屏蔽掉
编译后系统可以启动，但是没有壁纸了，设置壁纸也没作用

四、framework服务删减
1、VibratorService删除
屏蔽掉SystemServer.java中启动这个服务的代码
//traceBeginAndSlog(“StartVibratorService”);
//vibrator = new VibratorService(context);
//ServiceManager.addService(“vibrator”, vibrator);
//traceEnd();
删除后，应用调用Vibrator时不会崩溃，log会提示no vibrator service

下面这一段也屏蔽掉：
/* by liuderu
traceBeginAndSlog(“MakeVibratorServiceReady”);
try {
vibrator.systemReady();
} catch (Throwable e) {
reportWtf(“making Vibrator Service ready”, e);
}
traceEnd(); */

2. ConsumerIrService删除
在system/core/rootdir/init.rc中on boot节点中增加如下代码：
setprop config.disable_consumerir true

3. LockSettingsService
在SystemServer.java中屏蔽LOCK_SETTINGS_SERVICE_CLASS的启动
/* by liuderu
traceBeginAndSlog(“StartLockSettingsService”);
try {
mSystemServiceManager.startService(LOCK_SETTINGS_SERVICE_CLASS);
lockSettings = ILockSettings.Stub.asInterface(
ServiceManager.getService(“lock_settings”));
} catch (Throwable e) {
reportWtf(“starting LockSettingsService service”, e);
}
traceEnd(); */

屏蔽bootPhase对lockSetting的检查：
/* by liuderu
traceBeginAndSlog(“StartBootPhaseLockSettingsReady”);
mSystemServiceManager.startBootPhase(SystemService.PHASE_LOCK_SETTINGS_READY);
traceEnd();
*/

4. MmsServiceBroker
删除SystemServer中
/* by liuderu
traceBeginAndSlog(“StartMmsService”);
mmsService = mSystemServiceManager.startService(MmsServiceBroker.class);
traceEnd();
*/

第二个地方
/*by liuderu
traceBeginAndSlog(“MakeMmsServiceReady”);
try {
if (mmsServiceF != null) mmsServiceF.systemRunning();
} catch (Throwable e) {
reportWtf(“Notifying MmsService running”, e);
}
traceEnd();
*/

5. TextServicesManagerService
禁止拼写检查服务
public boolean isSpellCheckerEnabled() {
//default from true to false, by liuderu
return getBoolean(Settings.Secure.SPELL_CHECKER_ENABLED, false);
}

6. AccountManagerService裁剪
SystemServer.java去掉相关代码
/* by liuderu traceBeginAndSlog(“StartAccountManagerService”);
mSystemServiceManager.startService(ACCOUNT_SERVICE_CLASS);
traceEnd();*/

ContentService.java
private SyncManager getSyncManager() {
if (SystemProperties.getBoolean(“config.disable_network”, false)) {
return null;
}

return null;

/*by liuderu
synchronized(mSyncManagerLock) {
try {
// Try to create the SyncManager, return null if it fails (e.g. the disk is full).
if (mSyncManager == null) mSyncManager = new SyncManager(mContext, mFactoryTest);
} catch (SQLiteException e) {
Log.e(TAG, “Can’t create SyncManager”, e);
}
return mSyncManager;
} */
}

DefaultPermissionGrantPolicy.java
第一部分：
/*by liuderu
// Calendar provider
PackageParser.Package calendarProviderPackage = getDefaultProviderAuthorityPackageLPr(
CalendarContract.AUTHORITY, userId);
if (calendarProviderPackage != null) {
grantRuntimePermissionsLPw(calendarProviderPackage, CONTACTS_PERMISSIONS, userId);
grantRuntimePermissionsLPw(calendarProviderPackage, CALENDAR_PERMISSIONS,
true, userId);
grantRuntimePermissionsLPw(calendarProviderPackage, STORAGE_PERMISSIONS, userId);
}

// Calendar provider sync adapters

List<PackageParser.Package> calendarSyncAdapters = getHeadlessSyncAdapterPackagesLPr(
calendarSyncAdapterPackages, userId);
final int calendarSyncAdapterCount = calendarSyncAdapters.size();
for (int i = 0; i < calendarSyncAdapterCount; i++) {
PackageParser.Package calendarSyncAdapter = calendarSyncAdapters.get(i);
if (doesPackageSupportRuntimePermissions(calendarSyncAdapter)) {
grantRuntimePermissionsLPw(calendarSyncAdapter, CALENDAR_PERMISSIONS, userId);
}
}

// Contacts
Intent contactsIntent = new Intent(Intent.ACTION_MAIN);
contactsIntent.addCategory(Intent.CATEGORY_APP_CONTACTS);
PackageParser.Package contactsPackage = getDefaultSystemHandlerActivityPackageLPr(
contactsIntent, userId);
if (contactsPackage != null
&& doesPackageSupportRuntimePermissions(contactsPackage)) {
grantRuntimePermissionsLPw(contactsPackage, CONTACTS_PERMISSIONS, userId);
grantRuntimePermissionsLPw(contactsPackage, PHONE_PERMISSIONS, userId);
}

// Contacts provider sync adapters
List<PackageParser.Package> contactsSyncAdapters = getHeadlessSyncAdapterPackagesLPr(
contactsSyncAdapterPackages, userId);
final int contactsSyncAdapterCount = contactsSyncAdapters.size();
for (int i = 0; i < contactsSyncAdapterCount; i++) {
PackageParser.Package contactsSyncAdapter = contactsSyncAdapters.get(i);
if (doesPackageSupportRuntimePermissions(contactsSyncAdapter)) {
grantRuntimePermissionsLPw(contactsSyncAdapter, CONTACTS_PERMISSIONS, userId);
}
}

// Contacts provider
PackageParser.Package contactsProviderPackage = getDefaultProviderAuthorityPackageLPr(
ContactsContract.AUTHORITY, userId);
if (contactsProviderPackage != null) {
grantRuntimePermissionsLPw(contactsProviderPackage, CONTACTS_PERMISSIONS,
true, userId);
grantRuntimePermissionsLPw(contactsProviderPackage, PHONE_PERMISSIONS,
true, userId);
grantRuntimePermissionsLPw(contactsProviderPackage, STORAGE_PERMISSIONS, userId);
}*/

第二部分：
/* by liuderu
String[] contactsSyncAdapterPackages = (syncAdapterPackagesProvider != null) ?
syncAdapterPackagesProvider.getPackages(ContactsContract.AUTHORITY, userId) : null;
String[] calendarSyncAdapterPackages = (syncAdapterPackagesProvider != null) ?
syncAdapterPackagesProvider.getPackages(CalendarContract.AUTHORITY, userId) : null;*/

UsageStatsService.java

void reportContentProviderUsage(String authority, String providerPkgName, int userId) {
/*by liuderu
// Get sync adapters for the authority
String[] packages = ContentResolver.getSyncAdapterPackagesForAuthorityAsUser(
authority, userId);
for (String packageName: packages) {
// Only force the sync adapters to active if the provider is not in the same package and
// the sync adapter is a system package.
try {
PackageInfo pi = mPackageManager.getPackageInfoAsUser(
packageName, PackageManager.MATCH_SYSTEM_ONLY, userId);
if (pi == null || pi.applicationInfo == null) {
continue;
}
if (!packageName.equals(providerPkgName)) {
setAppIdleAsync(packageName, false, userId);
}
} catch (NameNotFoundException e) {
// Shouldn’t happen
}
}
*/
}

ContactsProvider2.java
case BACKGROUND_TASK_UPDATE_ACCOUNTS: {
/*by liuderu
Context context = getContext();
if (!mAccountUpdateListenerRegistered) {
AccountManager.get(context).addOnAccountsUpdatedListener(this, null, false);
mAccountUpdateListenerRegistered = true;
}

// Update the accounts for both the contacts and profile DBs.
Account[] accounts = AccountManager.get(context).getAccounts();
switchToContactMode();
boolean accountsChanged = updateAccountsInBackground(accounts);
switchToProfileMode();
accountsChanged |= updateAccountsInBackground(accounts);

switchToContactMode();

updateContactsAccountCount(accounts);
updateDirectoriesInBackground(accountsChanged);*/
break;
}

7. PrintManagerService
在SystemServer中删除相关代码
/*
if (mPackageManager.hasSystemFeature(PackageManager.FEATURE_PRINTING)) {
traceBeginAndSlog(“StartPrintManager”);
mSystemServiceManager.startService(PRINT_MANAGER_SERVICE_CLASS);
traceEnd();
}
*/

8. CoverageService
在SystemServer中删除相关代码
/*by liuderu
if (!disableNonCoreServices && CoverageService.ENABLED) {
traceBeginAndSlog(“AddCoverageService”);
ServiceManager.addService(CoverageService.COVERAGE_SERVICE, new CoverageService());
traceEnd();
}
*/

9. DiskStatsService
在SystemServer中删除相关代码
/*by liuderu
traceBeginAndSlog(“StartDiskStatsService”);
try {
ServiceManager.addService(“diskstats”, new DiskStatsService(context));
} catch (Throwable e) {
reportWtf(“starting DiskStats Service”, e);
}
traceEnd();
*/