封装篇——DataBase 数据库整理（greenDao示例）

今天心情烦躁，一直在想着怎么起本篇博文的开头…
之前有在做一个即时通讯的功能，既然是即时通讯吧，那么就需要存储数据在本地咯，所以就有了关于数据库使用的一个简单封装，今天抽空整理了一下思路，故而有了本文。

本文将从 数据库基础接口抽离，greenDao知识，greenDao的个性化基类封装和一个简单示例 为序向各位读者说明一下作者的思路以及实践。

数据库操作基础接口

数据库操作无非就是 增、删、改、查、事务，好接下来就可以细化了（可能不全，欢迎建议与指正）。

• 插入 INSERT
  
  • 单条数据
  • 多条数据事务插入
    
• 删除 DELETE
  
  • 请直接看图（打字累了，什么时候能实现意念打字构图 ???）…
  • 漏了一个 删除所有表：dropDatabase()
    
• 改 UPDATE
  
  • …
    
• 查询 SELECT
  
  • 查询所有
  • 根据 id 查询
  • sql 语句查询
    
• 事务 Transaction
  
  • 事务 runInTx(Runnable runnable)

interface IDatabase

public interface IDatabase {

    boolean insert(M m);

    boolean delete(M m);

    boolean deleteByKey(K key);

    boolean deleteList(List mList);

    boolean deleteByKeyInTx(K... key);

    boolean deleteAll();

    boolean insertOrReplace(@NonNull M m);

    boolean update(M m);

    boolean updateInTx(M... m);

    boolean updateList(List mList);

    M selectByPrimaryKey(K key);

    List loadAll();

    boolean refresh(M m);
    /**
     * 清理缓存
     */
    void clearDaoSession();

    /**
     * Delete all tables and content from our database
     */
    boolean dropDatabase();

    /**
     * 事务
     */
    void runInTx(Runnable runnable);

    /**
     * 添加集合
     *
     * @param mList
     */
    boolean insertList(List mList);

    /**
     * 添加集合
     *
     * @param mList
     */
    boolean insertOrReplaceList(List mList);

    /**
     * 自定义查询
     *
     * @return
     */
    QueryBuilder getQueryBuilder();

    /**
     * @param where
     * @param selectionArg
     * @return
     */
    List queryRaw(String where, String... selectionArg);
}

greenDao知识：

特性

- 知识点

- 数据库类型有只读、读写两种
- AsyncSession（API : https://github.com/greenrobot/greenDAO）

- 使用技巧：

greenDao个性化基类

这边需要针对于 greenDao 的一些个性化的动作做相应的封装。这边分为 “库操作” 与 “独有动作”两类

• 个性化 库操作

  • 忘记一个：关闭数据库连接

  

• 独有动作封装

  

calss AbstractDatabaseManager

public abstract class AbstractDatabaseManager<M, K> implements IDatabase<M, K> {
    private static final String DEFAULT_DATABASE_NAME = "wenld.db";
    /**
     * The Android Activity reference for access to DatabaseManager.
     */
    private static DaoMaster.DevOpenHelper mHelper;
    protected static DaoSession daoSession;
    /**
     * 初始化OpenHelper
     * @param context
     */
    public static void initOpenHelper(@NonNull Context context) {
        mHelper = getOpenHelper(context, DEFAULT_DATABASE_NAME);
        openWritableDb();
    }
    /**
     * 初始化OpenHelper     *
     * @param context
     * @param dataBaseName
     */
    public static void initOpenHelper(@NonNull Context context, @NonNull String dataBaseName) {
        mHelper = getOpenHelper(context, dataBaseName);
        openWritableDb();
    }
    /**     * Query for readable DB     */
    protected static void openReadableDb() throws SQLiteException {
        daoSession = new DaoMaster(getReadableDatabase()).newSession();
    }
    /**     * Query for writable DB     */
    protected static void openWritableDb() throws SQLiteException {
        daoSession = new DaoMaster(getWritableDatabase()).newSession();
    }

    private static SQLiteDatabase getWritableDatabase() {
        return mHelper.getWritableDatabase();
    }

    private static SQLiteDatabase getReadableDatabase() {
        return mHelper.getReadableDatabase();
    }

    /**     * 在applicaiton中初始化DatabaseHelper     */
    private static DaoMaster.DevOpenHelper getOpenHelper(@NonNull Context context, @Nullable String dataBaseName) {
        closeDbConnections();
        return new DaoMaster.DevOpenHelper(context, dataBaseName, null);
    }

    /**
     * 只关闭helper就好,看源码就知道helper关闭的时候会关闭数据库
     */
    public static void closeDbConnections() {
        if (mHelper != null) {
            mHelper.close();
            mHelper = null;
        }
        if (daoSession != null) {
            daoSession.clear();
            daoSession = null;
        }
    }

    @Override
    public void clearDaoSession() {
        if (daoSession != null) {
            daoSession.clear();
            daoSession = null;
        }
    }

    @Override
    public boolean dropDatabase() {
        try {
            openWritableDb();
            // DaoMaster.dropAllTables(database, true); // drops all tables
            // mHelper.onCreate(database); // creates the tables
//          daoSession.deleteAll(BankCardBean.class); // clear all elements
            // from
            // a table
        } catch (Exception e) {
            return false;
        }
        return true;
    }

    @Override
    public boolean insert(@NonNull M m) {
        try {
            if (m == null)
                return false;
            openWritableDb();
            getAbstractDao().insert(m);
        } catch (SQLiteException e) {
            return false;
        }
        return true;
    }

    @Override
    public boolean insertOrReplace(@NonNull M m) {
        try {
            if (m == null)
                return false;
            openWritableDb();
            getAbstractDao().insertOrReplace(m);
        } catch (SQLiteException e) {
            return false;
        }
        return true;
    }

    @Override
    public boolean delete(@NonNull M m) {
        try {
            if (m == null)
                return false;
            openWritableDb();
            getAbstractDao().delete(m);
        } catch (SQLiteException e) {
            return false;
        }
        return true;
    }

    @Override
    public boolean deleteByKey(K key) {
        try {
            if (StringUtils.isEmpty(key.toString()))
                return false;
            openWritableDb();
            getAbstractDao().deleteByKey(key);
        } catch (SQLiteException e) {
            return false;
        }
        return true;
    }

    @Override
    public boolean deleteByKeyInTx(K... key) {
        try {
            openWritableDb();
            getAbstractDao().deleteByKeyInTx(key);
        } catch (SQLiteException e) {
            return false;
        }
        return true;
    }

    @Override
    public boolean deleteList(List mList) {
        try {
            if (mList == null || mList.size() == 0)
                return false;
            openWritableDb();
            getAbstractDao().deleteInTx(mList);
        } catch (SQLiteException e) {
            return false;
        }
        return true;
    }

    @Override
    public boolean deleteAll() {
        try {
            openWritableDb();
            getAbstractDao().deleteAll();
        } catch (SQLiteException e) {
            return false;
        }
        return true;
    }

    @Override
    public boolean update(@NonNull M m) {
        try {
            if (m == null)
                return false;
            openWritableDb();
            getAbstractDao().update(m);
        } catch (SQLiteException e) {
            return false;
        }
        return true;
    }

    @Override
    public boolean updateInTx(M... m) {
        try {
            if (m == null)
                return false;
            openWritableDb();
            getAbstractDao().updateInTx(m);
        } catch (SQLiteException e) {
            return false;
        }
        return true;
    }

    @Override
    public boolean updateList(List mList) {
        try {
            if (mList == null || mList.size() == 0)
                return false;
            openWritableDb();
            getAbstractDao().updateInTx(mList);
        } catch (SQLiteException e) {
            return false;
        }
        return true;
    }

    @Override
    public M selectByPrimaryKey(@NonNull K key) {
        try {
            openReadableDb();
            return getAbstractDao().load(key);
        } catch (SQLiteException e) {
            return null;
        }
    }

    @Override
    public List loadAll() {
        openReadableDb();
        return getAbstractDao().loadAll();
    }

    @Override
    public boolean refresh(@NonNull M m) {
        try {
            if (m == null)
                return false;
            openWritableDb();
            getAbstractDao().refresh(m);
        } catch (SQLiteException e) {
            return false;
        }
        return true;
    }

    @Override
    public void runInTx(Runnable runnable) {
        try {
            openWritableDb();
            daoSession.runInTx(runnable);
        } catch (SQLiteException e) {
        }
    }

    @Override
    public boolean insertList(@NonNull List list) {
        try {
            if (list == null || list.size() == 0)
                return false;
            openWritableDb();
            getAbstractDao().insertInTx(list);
        } catch (SQLiteException e) {
            return false;
        }
        return true;
    }

    /**
     * @param list
     * @return
     */
    @Override
    public boolean insertOrReplaceList(@NonNull List list) {
        try {
            if (list == null || list.size() == 0)
                return false;
            openWritableDb();
            getAbstractDao().insertOrReplaceInTx(list);
        } catch (SQLiteException e) {
            return false;
        }
        return true;
    }

    @Override
    public QueryBuilder getQueryBuilder() {
        openReadableDb();
        return getAbstractDao().queryBuilder();
    }

    /**
     * @param where
     * @param selectionArg
     * @return
     */
    @Override
    public List queryRaw(String where, String... selectionArg) {
        openReadableDb();
        return getAbstractDao().queryRaw(where, selectionArg);
    }

    public Query queryRawCreate(String where, Object... selectionArg) {
        openReadableDb();
        return getAbstractDao().queryRawCreate(where, selectionArg);
    }

    public Query queryRawCreateListArgs(String where, Collection