Android CalDAV Demo

可以使用Android中提供的SyncAdapter框架来实现CalDAV同步，以下是一个简单的CalDAV Demo：

1. 创建SyncAdapter

public class CalDavSyncAdapter extends AbstractThreadedSyncAdapter {
    private final AccountManager mAccountManager;

    public CalDavSyncAdapter(Context context, boolean autoInitialize) {
        super(context, autoInitialize);
        mAccountManager = AccountManager.get(context);
    }

    @Override
    public void onPerformSync(Account account, Bundle extras, String authority, ContentProviderClient provider, SyncResult syncResult) {
        //TODO: 实现CalDAV同步逻辑
    }
}

2. 在AndroidManifest.xml中注册SyncAdapter

<service android:name=".CalDavSyncAdapter"
         android:exported="true"
         android:process=":sync">
    <intent-filter>
        <action android:name="android.content.SyncAdapter" />
    </intent-filter>
    <meta-data android:name="android.content.SyncAdapter"
               android:resource="@xml/syncadapter" />
</service>

3. 在res/xml目录下创建syncadapter.xml文件，指定SyncAdapter的属性

<sync-adapter xmlns:android="http://schemas.android.com/apk/res/android"
              android:accountType="com.example.caldav"
              android:userVisible="true"
              android:supportsUploading="true"
              android:allowParallelSyncs="false"
              android:isAlwaysSyncable="true" />

4. 在MainActivity中创建账户并启动同步

public class MainActivity extends AppCompatActivity {
    private Account mAccount;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mAccount = new Account("username", "com.example.caldav");
        AccountManager accountManager = AccountManager.get(this);
        accountManager.addAccountExplicitly(mAccount, null, null);

        ContentResolver.setIsSyncable(mAccount, "com.android.calendar", 1);
        ContentResolver.setSyncAutomatically(mAccount, "com.android.calendar", true);
        ContentResolver.addPeriodicSync(mAccount, "com.android.calendar", new Bundle(), 60);
    }
}

5. 实现CalDAV同步逻辑

private void syncCalendars(Account account) {
    CalDavAccount calDavAccount = getCalDavAccount(account);

    List<CalDavCalendar> remoteCalendars = getRemoteCalendars(calDavAccount);
    List<CalDavCalendar> localCalendars = getLocalCalendars(account);

    for (CalDavCalendar remoteCalendar : remoteCalendars) {
        if (!localCalendars.contains(remoteCalendar)) {
            createLocalCalendar(account, remoteCalendar);
        } else {
            updateLocalCalendar(account, remoteCalendar);
        }
    }

    for (CalDavCalendar localCalendar : localCalendars) {
        if (!remoteCalendars.contains(localCalendar)) {
            deleteLocalCalendar(account, localCalendar);
        }
    }
}

private CalDavAccount getCalDavAccount(Account account) {
    String username = account.name;
    String password = AccountManager.get(this).getPassword(account);

    //TODO: 创建CalDavAccount对象
}

private List<CalDavCalendar> getRemoteCalendars(CalDavAccount calDavAccount) {
    //TODO: 获取远程CalDAV服务器上的日历列表
}

private List<CalDavCalendar> getLocalCalendars(Account account) {
    List<CalDavCalendar> localCalendars = new ArrayList<>();

    Cursor cursor = getContentResolver().query(Calendars.CONTENT_URI, null,
            Calendars.ACCOUNT_NAME + " = ? AND " + Calendars.ACCOUNT_TYPE + " = ?",
            new String[]{account.name, account.type}, null);

    while (cursor.moveToNext()) {
        String name = cursor.getString(cursor.getColumnIndex(Calendars.NAME));
        String displayName = cursor.getString(cursor.getColumnIndex(Calendars.CALENDAR_DISPLAY_NAME));
        String description = cursor.getString(cursor.getColumnIndex(Calendars.CALENDAR_DESCRIPTION));
        String timeZone = cursor.getString(cursor.getColumnIndex(Calendars.CALENDAR_TIME_ZONE));
        int color = cursor.getInt(cursor.getColumnIndex(Calendars.CALENDAR_COLOR));
        int accessLevel = cursor.getInt(cursor.getColumnIndex(Calendars.CALENDAR_ACCESS_LEVEL));
        boolean syncEvents = cursor.getInt(cursor.getColumnIndex(Calendars.SYNC_EVENTS)) == 1;

        //TODO: 创建CalDavCalendar对象并添加到localCalendars列表中
    }

    cursor.close();

    return localCalendars;
}

private void createLocalCalendar(Account account, CalDavCalendar remoteCalendar) {
    ContentValues values = new ContentValues();
    values.put(Calendars.ACCOUNT_NAME, account.name);
    values.put(Calendars.ACCOUNT_TYPE, account.type);
    values.put(Calendars.NAME, remoteCalendar.getName());
    values.put(Calendars.CALENDAR_DISPLAY_NAME, remoteCalendar.getDisplayName());
    values.put(Calendars.CALENDAR_DESCRIPTION, remoteCalendar.getDescription());
    values.put(Calendars.CALENDAR_TIME_ZONE, remoteCalendar.getTimeZone());
    values.put(Calendars.CALENDAR_COLOR, remoteCalendar.getColor());
    values.put(Calendars.CALENDAR_ACCESS_LEVEL, remoteCalendar.getAccessLevel());
    values.put(Calendars.SYNC_EVENTS, 1);

    getContentResolver().insert(Calendars.CONTENT_URI, values);
}

private void updateLocalCalendar(Account account, CalDavCalendar remoteCalendar) {
    ContentValues values = new ContentValues();
    values.put(Calendars.NAME, remoteCalendar.getName());
    values.put(Calendars.CALENDAR_DISPLAY_NAME, remoteCalendar.getDisplayName());
    values.put(Calendars.CALENDAR_DESCRIPTION, remoteCalendar.getDescription());
    values.put(Calendars.CALENDAR_TIME_ZONE, remoteCalendar.getTimeZone());
    values.put(Calendars.CALENDAR_COLOR, remoteCalendar.getColor());
    values.put(Calendars.CALENDAR_ACCESS_LEVEL, remoteCalendar.getAccessLevel());

    getContentResolver().update(Calendars.CONTENT_URI, values,
            Calendars.ACCOUNT_NAME + " = ? AND " + Calendars.ACCOUNT_TYPE + " = ?" +
                    " AND " + Calendars.NAME + " = ?",
            new String[]{account.name, account.type, remoteCalendar.getName()});
}

private void deleteLocalCalendar(Account account, CalDavCalendar localCalendar) {
    getContentResolver().delete(Calendars.CONTENT_URI,
            Calendars.ACCOUNT_NAME + " = ? AND " + Calendars.ACCOUNT_TYPE + " = ?" +
                    " AND " + Calendars.NAME + " = ?",
            new String[]{account.name, account.type, localCalendar.getName()});
}