在android中常用存储数据的基本就三种，sqlite,SharedPreferences,文件存储，其中针对于对象存储，使用sqlite比较多，因为可以对其进行增删改查。本文主要讲解SQLiteOpenHelper的封装使用，代码引用自https://github.com/iMeiji/Toutiao

具体使用

主要方法包括创建数据库和数据库的升级。

构造函数：包含三个参数，context，name,factory,version

onCreate：主要创建了三张表单

getDatabase：这里其实可以获取两个数据库，分别是getWritableDatabase与getReadableDatabase，这两者的区别不是特别大，都具有对数据库的读写 权限。

getWritableDatabase取得的实例是以读写的方式打开数据库，如果打开的数据库磁盘满了，此时只能读不能写，此时调用了getWritableDatabase的实例，那么将会发生错误（异常）

getReadableDatabase取得的实例是先调用getWritableDatabase以读写的方式打开数据库，如果数据库的磁盘满了，此时返回打开失败，继而用getReadableDatabase的实例以只读的方式去打开数据库

onUpgrade：主要用于数据库的升级，这里面

public class DatabaseHelper extends SQLiteOpenHelper { private static final String DB_NAME = "Toutiao"; private static final int DB_VERSION = 5; private static final String CLEAR_TABLE_DATA = "delete from "; private static final String DROP_TABLE = "drop table if exists "; private static DatabaseHelper instance = null; private static SQLiteDatabase db = null; private DatabaseHelper(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) { super(context, name, factory, version); } private static synchronized DatabaseHelper getInstance() { if (instance == null) { instance = new DatabaseHelper(InitApp.AppContext, DB_NAME, null, DB_VERSION); } return instance; } public static synchronized SQLiteDatabase getDatabase() { if (db == null) { db = getInstance().getWritableDatabase(); } return db; } public static synchronized void closeDatabase() { if (db != null) { db.close(); } } @Override public void onCreate(SQLiteDatabase db) { db.execSQL(NewsChannelTable.CREATE_TABLE); db.execSQL(MediaChannelTable.CREATE_TABLE); db.execSQL(SearchHistoryTable.CREATE_TABLE); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { switch (oldVersion) { case 1: db.execSQL(MediaChannelTable.CREATE_TABLE); break; case 2: db.execSQL(CLEAR_TABLE_DATA + NewsChannelTable.TABLENAME);//删除表中的数据 break; case 3: ContentValues values = new ContentValues(); values.put(NewsChannelTable.ID, ""); values.put(NewsChannelTable.NAME, "推荐"); values.put(NewsChannelTable.IS_ENABLE, 0); values.put(NewsChannelTable.POSITION, 46); db.insert(NewsChannelTable.TABLENAME, null, values);//新建表 break; case 4: db.execSQL(SearchHistoryTable.CREATE_TABLE); break; } }}

表操作的封装

addInitData添加初始化数据

add插入到表中

query查询特定数据

public class NewsChannelDao { private SQLiteDatabase db; public NewsChannelDao() { this.db = DatabaseHelper.getDatabase(); } public void addInitData() { String categoryId[] = InitApp.AppContext.getResources().getStringArray(R.array.mobile_news_id); String categoryName[] = InitApp.AppContext.getResources().getStringArray(R.array.mobile_news_name); for (int i = 0; i < 8; i++) { add(categoryId[i], categoryName[i], Constant.NEWS_CHANNEL_ENABLE, i); } for (int i = 8; i < categoryId.length; i++) { add(categoryId[i], categoryName[i], Constant.NEWS_CHANNEL_DISABLE, i); } } public boolean add(String channelId, String channelName, int isEnable, int position) { ContentValues values = new ContentValues(); values.put(NewsChannelTable.ID, channelId); values.put(NewsChannelTable.NAME, channelName); values.put(NewsChannelTable.IS_ENABLE, isEnable); values.put(NewsChannelTable.POSITION, position); long result = db.insert(NewsChannelTable.TABLENAME, null, values); return result != -1; } public List<NewsChannelBean> query(int isEnable) { Cursor cursor = db.query(NewsChannelTable.TABLENAME, null, NewsChannelTable.IS_ENABLE + "=?", new String[]{isEnable + ""}, null, null, null); List<NewsChannelBean> list = new ArrayList<>(); while (cursor.moveToNext()) { NewsChannelBean bean = new NewsChannelBean(); bean.setChannelId(cursor.getString(NewsChannelTable.ID_ID)); bean.setChannelName(cursor.getString(NewsChannelTable.ID_NAME)); bean.setIsEnable(cursor.getInt(NewsChannelTable.ID_ISENABLE)); bean.setPosition(cursor.getInt(NewsChannelTable.ID_POSITION)); list.add(bean); } cursor.close(); return list; } public List<NewsChannelBean> queryAll() { Cursor cursor = db.query(NewsChannelTable.TABLENAME, null, null, null, null, null, null); List<NewsChannelBean> list = new ArrayList<>(); while (cursor.moveToNext()) { NewsChannelBean bean = new NewsChannelBean(); bean.setChannelId(cursor.getString(NewsChannelTable.ID_ID)); bean.setChannelName(cursor.getString(NewsChannelTable.ID_NAME)); bean.setIsEnable(cursor.getInt(NewsChannelTable.ID_ISENABLE)); bean.setPosition(cursor.getInt(NewsChannelTable.ID_POSITION)); list.add(bean); } cursor.close(); return list; } public void updateAll(List<NewsChannelBean> list) { } public boolean removeAll() { int result = db.delete(NewsChannelTable.TABLENAME, null, null); return result != -1; }}

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。