BaseColumns以及自定义Column

android provider 包下自带的BaseColumn

/*
 * Copyright (C) 2006 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 android.provider;

public interface BaseColumns
{
    /**
     * The unique ID for a row.
     * <P>Type: INTEGER (long)</P>
     */
    public static final String _ID = "_id";

    /**
     * The count of rows in a directory.
     * <P>Type: INTEGER</P>
     */
    public static final String _COUNT = "_count";
}

基于basecolumn自定义自己表的Column

public static final class PhoneLabelColumns implements BaseColumns {
        //必要的部分  ---begin-----
        public static final String TABLE = "phone_label";

        public static final String COUNT = "count";
        public static final String NUMBER = "number";
        public static final String LABEL = "label";
        //必要的部分  ----end-----

        private static final String[] PROJECTION = {
                _ID, // 0
                NUMBER, // 1
                LABEL, // 2
                COUNT, // 3
        };

        public static int COLUMN_NUMBER = 1;
        public static final int COLUMN_LABEL = 2;
        public static final int COLUMN_COUNT = 3;
    }