src/com/android/documentsui/DirectoryLoader.java

/*
 * Copyright (C) 2013 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.documentsui;

import static com.android.documentsui.DirectoryFragment.TYPE_NORMAL;
import static com.android.documentsui.DirectoryFragment.TYPE_RECENT_OPEN;
import static com.android.documentsui.DirectoryFragment.TYPE_SEARCH;

import android.content.ContentResolver;
import android.content.Context;
import android.database.Cursor;
import android.net.Uri;
import android.os.CancellationSignal;

import com.android.documentsui.model.Document;
import com.android.internal.util.Predicate;
import com.google.android.collect.Lists;

import libcore.io.IoUtils;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

public class DirectoryLoader extends UriDerivativeLoader<List<Document>> {

    private final int mType;
    private Predicate<Document> mFilter;
    private Comparator<Document> mSortOrder;

    public DirectoryLoader(Context context, Uri uri, int type, Predicate<Document> filter,
            Comparator<Document> sortOrder) {
        super(context, uri);
        mType = type;
        mFilter = filter;
        mSortOrder = sortOrder;
    }

    @Override
    public List<Document> loadInBackground(Uri uri, CancellationSignal signal) {
        final ArrayList<Document> result = Lists.newArrayList();

        // TODO: send selection and sorting hints to backend
        final ContentResolver resolver = getContext().getContentResolver();
        final Cursor cursor = resolver.query(uri, null, null, null, null, signal);
        try {
            while (cursor != null && cursor.moveToNext()) {
                final Document doc;
                switch (mType) {
                    case TYPE_NORMAL:
                    case TYPE_SEARCH:
                        doc = Document.fromDirectoryCursor(uri, cursor);
                        break;
                    case TYPE_RECENT_OPEN:
                        doc = Document.fromRecentOpenCursor(resolver, cursor);
                        break;
                    default:
                        throw new IllegalArgumentException("Unknown type");
                }

                if (mFilter == null || mFilter.apply(doc)) {
                    result.add(doc);
                }
            }
        } finally {
            IoUtils.closeQuietly(cursor);
        }

        if (mSortOrder != null) {
            Collections.sort(result, mSortOrder);
        }

        return result;
    }
}