本流程图基于MTK平台 Android 7.0，本流程只作为沟通学习使用

工作中遇到一个问题，手机登陆Google账户并同步账户里面的contacts后，本地保存的联系人数据被无缘无故的删除了，甚是奇怪，通过对比前后的数据库我们发现，同步后直接把我们的本地账户给删除了，所以导致属于这个账户的所有联系人都不见了，那么无缘无故为什么会删除本地账户呢？我们先抛出问题，等我们看完整个流程再回来看看真是什么。前提，我们的手机是被客制化过，不是android原生系统。

整体流程图

android 账号同步实现拉活_android 账号同步实现拉活

部分流程说明

我们重点看看updateAccountsInBackground这个方法

后台更新账户，判断账户是否合法，不合法就删除合法就保存

private boolean updateAccountsInBackground(Account[] systemAccounts) {
        if (!haveAccountsChanged(systemAccounts)) { //判断当前账户是否有改变
            return false;
        }
.....
        Log.i(TAG, "Accounts changed");

        invalidateFastScrollingIndexCache();

        final ContactsDatabaseHelper dbHelper = mDbHelper.get();
        final SQLiteDatabase db = dbHelper.getWritableDatabase();
.....
        try {
            // First, remove stale rows from raw_contacts, groups, and related tables.

            // All accounts that are used in raw_contacts and/or groups.
            final Set<AccountWithDataSet> knownAccountsWithDataSets
                    = dbHelper.getAllAccountsWithDataSets();

            // Find the accounts that have been removed.
            final List<AccountWithDataSet> accountsWithDataSetsToDelete = Lists.newArrayList();
            for (AccountWithDataSet knownAccountWithDataSet : knownAccountsWithDataSets) {
                if (knownAccountWithDataSet.isLocalAccount()

                        || !canDeleteAccount(knownAccountWithDataSet)

                        || knownAccountWithDataSet.inSystemAccounts(systemAccounts, mSkipRemoval)) {
                    continue;
                }
                accountsWithDataSetsToDelete.add(knownAccountWithDataSet);//保存需要删除的账户，后面如果这个list不为空就删除里面账户的相关信息
            }

            if (!accountsWithDataSetsToDelete.isEmpty()) {
                for (AccountWithDataSet accountWithDataSet : accountsWithDataSetsToDelete) {
.....做一些数据库删除操作，把这个账户相关的数据都删除
              }
            }

            // Second, remove stale rows from Tables.SETTINGS and Tables.DIRECTORIES
            removeStaleAccountRows(
                    Tables.SETTINGS, Settings.ACCOUNT_NAME, Settings.ACCOUNT_TYPE, systemAccounts);
            removeStaleAccountRows(Tables.DIRECTORIES, Directory.ACCOUNT_NAME,
                    Directory.ACCOUNT_TYPE, systemAccounts);
.....一些删除操作
            /// @}

            // Third, remaining tasks that must be done in a transaction.
            // TODO: Should sync state take data set into consideration?
            dbHelper.getSyncState().onAccountsChanged(db, systemAccounts);
            saveAccounts(systemAccounts);//保存新加的账户

            db.setTransactionSuccessful();
        } finally {
.....
        mAccountWritability.clear();

        updateContactsAccountCount(systemAccounts);
        updateProviderStatus();
        return true;
    }

haveAccountsChanged

查看账户是否有变更

@VisibleForTesting
    boolean haveAccountsChanged(Account[] currentSystemAccounts) {
        final ContactsDatabaseHelper dbHelper = mDbHelper.get();
        final Set<Account> knownAccountSet;
        try {
            knownAccountSet =
                    stringToAccounts(dbHelper.getProperty(DbProperties.KNOWN_ACCOUNTS, ""));
        } catch (IllegalArgumentException e) {
            // Failed to get the last known accounts for an unknown reason.  Let's just
            // treat as if accounts have changed.
            return true;
        }
        final Set<Account> currentAccounts = Sets.newHashSet(currentSystemAccounts);
        return !knownAccountSet.equals(currentAccounts);
    }

isLocalAccount

通过账户类型判断当前账户是否是本地账户

public static final String ACCOUNT_TYPE_LOCAL_PHONE = "Local Phone Account";
    private static final String ACCOUNT_TYPE_SIM = "SIM Account";
    private static final String ACCOUNT_TYPE_USIM = "USIM Account";
    private static final String ACCOUNT_TYPE_RUIM = "RUIM Account";
    private static final String ACCOUNT_TYPE_CSIM = "CSIM Account";
    private static final String LOCAL_ACCOUNT_TYPES = "('" +
            ACCOUNT_TYPE_LOCAL_PHONE + "' , '" +
            ACCOUNT_TYPE_SIM + "' , '" +
            ACCOUNT_TYPE_USIM + "' , '" +
            ACCOUNT_TYPE_RUIM + "' , '" +
            ACCOUNT_TYPE_CSIM + "')";
    /**
     * Check if the account is local account
     */
    public static boolean isLocalAccount(String accountType, String accountName) {
        return (accountType == null && accountName == null)
                || (accountType != null && LOCAL_ACCOUNT_TYPES.contains(accountType));
    }

inSystemAccounts

判断当前账户是不是系统合法账户

public boolean inSystemAccounts(Account[] systemAccounts, boolean skip) {
        // Note we don't want to create a new Account object from this instance, as it may contain
        // null account name/type, which Account wouldn't accept.  So we need to compare field by
        // field.

        for (Account systemAccount : systemAccounts) {
            if (Objects.equal(systemAccount.name, getAccountName())//通过获取账户名和账户类型来判断
                    && Objects.equal(systemAccount.type, getAccountType())) {
                return true;
            }
        }
        return false;
    }

saveAccounts

将合法账户保存下来并更新一些值

@VisibleForTesting
    void saveAccounts(Account[] systemAccounts) {
        final ContactsDatabaseHelper dbHelper = mDbHelper.get();
        dbHelper.setProperty(
                DbProperties.KNOWN_ACCOUNTS, accountsToString(Sets.newHashSet(systemAccounts)));
    }

问题解决

回顾我们的问题，我们是发现登陆账户同步联系人后，本地账户被删除了，然而我们本地账户是被客制化了的，根据上面的流程我们可以知道，添加账户后会检查已存在的账户和加入的账户是否是本地账户，并检查账户是否合法，那么我们就有怀疑点了，是否是我们的本地账户类型不合法呢？所以我们就有了解决办法。
1.把我们预置的本地账户类型改成代码中本地账户合法的类型
2.把我们预置的本地账户类型添加到LOCAL_ACCOUNT_TYPES 中，让其成为一个合法的本地账户类型