import com.google.samples.apps.iosched.provider.ScheduleContract.Tags; //导入依赖的package包/类
/** Adds the tags filter query parameter to the given builder. */
private void addTagsFilter(SelectionBuilder builder, String tagsFilter) {
    // Note: for context, remember that session queries are done on a join of sessions
    // and the sessions_tags relationship table, and are GROUP'ed BY the session ID.
    String[] requiredTags = tagsFilter.split(",");
    if (requiredTags.length == 0) {
        // filtering by 0 tags -- no-op
        return;
    } else if (requiredTags.length == 1) {
        // filtering by only one tag, so a simple WHERE clause suffices
        builder.where(Tags.TAG_ID + "=?", requiredTags[0]);
    } else {
        // Filtering by multiple tags, so we must add a WHERE clause with an IN operator,
        // and add a HAVING statement to exclude groups that fall short of the number
        // of required tags. For example, if requiredTags is { "X", "Y", "Z" }, and a certain
        // session only has tags "X" and "Y", it will be excluded by the HAVING statement.
        String questionMarkTuple = makeQuestionMarkTuple(requiredTags.length);
        builder.where(Tags.TAG_ID + " IN " + questionMarkTuple, requiredTags);
        builder.having("COUNT(" + Qualified.SESSIONS_SESSION_ID + ") >= " + requiredTags.length);
    }
}
 

import com.google.samples.apps.iosched.provider.ScheduleContract.Tags; //导入依赖的package包/类
/**
 * Adds the {@code tagsFilter} query parameter to the given {@code builder}. This query
 * parameter is used by the {@link com.google.samples.apps.iosched.explore.ExploreSessionsActivity}
 * when the user makes a selection containing multiple filters.
 */
private void addTagsFilter(SelectionBuilder builder, String tagsFilter, String numCategories) {
    // Note: for context, remember that session queries are done on a join of sessions
    // and the sessions_tags relationship table, and are GROUP'ed BY the session ID.
    String[] requiredTags = tagsFilter.split(",");
    if (requiredTags.length == 0) {
        // filtering by 0 tags -- no-op
        return;
    } else if (requiredTags.length == 1) {
        // filtering by only one tag, so a simple WHERE clause suffices
        builder.where(Tags.TAG_ID + "=?", requiredTags[0]);
    } else {
        // Filtering by multiple tags, so we must add a WHERE clause with an IN operator,
        // and add a HAVING statement to exclude groups that fall short of the number
        // of required tags. For example, if requiredTags is { "X", "Y", "Z" }, and a certain
        // session only has tags "X" and "Y", it will be excluded by the HAVING statement.
        int categories = 1;
        if (numCategories != null && TextUtils.isDigitsOnly(numCategories)) {
            try {
                categories = Integer.parseInt(numCategories);
                LOGD(TAG, "Categories being used " + categories);
            } catch (Exception ex) {
                LOGE(TAG, "exception parsing categories ", ex);
            }
        }
        String questionMarkTuple = makeQuestionMarkTuple(requiredTags.length);
        builder.where(Tags.TAG_ID + " IN " + questionMarkTuple, requiredTags);
        builder.having(
                "COUNT(" + Qualified.SESSIONS_SESSION_ID + ") >= " + categories);
    }
}
 

import com.google.samples.apps.iosched.provider.ScheduleContract.Tags; //导入依赖的package包/类
@Override
public Cursor performQuery(@NonNull CursorModelLoader<TagMetadata> loader,
        @NonNull CancellationSignal cancellationSignal) {
    return ContentResolverCompat.query(loader.getContext().getContentResolver(),
            Tags.CONTENT_URI, TagMetadata.TAGS_PROJECTION, null, null, null,
            cancellationSignal);
}
 

import com.google.samples.apps.iosched.provider.ScheduleContract.Tags; //导入依赖的package包/类
/**
 * Adds the {@code tagsFilter} query parameter to the given {@code builder}. This query
 * parameter is used when the user makes a selection containing multiple filters.
 */
private void addTagsFilter(SelectionBuilder builder, String tagsFilter, String numCategories) {
    // Note: for context, remember that session queries are done on a join of sessions
    // and the sessions_tags relationship table, and are GROUP'ed BY the session ID.
    String[] requiredTags = tagsFilter.split(",");
    if (requiredTags.length == 0) {
        // filtering by 0 tags -- no-op
        return;
    } else if (requiredTags.length == 1) {
        // filtering by only one tag, so a simple WHERE clause suffices
        builder.where(Tags.TAG_ID + "=?", requiredTags[0]);
    } else {
        // Filtering by multiple tags, so we must add a WHERE clause with an IN operator,
        // and add a HAVING statement to exclude groups that fall short of the number
        // of required tags. For example, if requiredTags is { "X", "Y", "Z" }, and a certain
        // session only has tags "X" and "Y", it will be excluded by the HAVING statement.
        int categories = 1;
        if (numCategories != null && TextUtils.isDigitsOnly(numCategories)) {
            try {
                categories = Integer.parseInt(numCategories);
                LOGD(TAG, "Categories being used " + categories);
            } catch (Exception ex) {
                LOGE(TAG, "exception parsing categories ", ex);
            }
        }
        String questionMarkTuple = makeQuestionMarkTuple(requiredTags.length);
        builder.where(Tags.TAG_ID + " IN " + questionMarkTuple, requiredTags);
        builder.having(
                "COUNT(" + Qualified.SESSIONS_SESSION_ID + ") >= " + categories);
    }
}
 

import com.google.samples.apps.iosched.provider.ScheduleContract.Tags; //导入依赖的package包/类
@Override
public Uri getObserverUri(@NonNull CursorModelLoader<TagMetadata> loader) {
    return Tags.CONTENT_URI;
}