概述

該資料庫工具類依賴了Room的相關包，使用很方便，現整理歸檔如下。使用時可以直接當做工具類使用。

引入依賴

implementation 'android.arch.persistence:db:1.0.0'
implementation 'android.arch.persistence:db-framework:1.0.0'

建立SupportDbManager

package com.example.a002034.myapplication.db;


import android.arch.persistence.db.SupportSQLiteDatabase;
import android.arch.persistence.db.SupportSQLiteOpenHelper;
import android.support.annotation.NonNull;

import java.util.concurrent.atomic.AtomicInteger;

/**
 * DbManager.
 *
 * @author xuzhuyun
 */
public class SupportDbManager {
    private SupportSQLiteOpenHelper mOpenHelper;
    private SupportSQLiteDatabase mDb;
    private AtomicInteger mOpenCounter;

    public SupportDbManager(@NonNull SupportSQLiteOpenHelper openHelper) {
        this.mOpenHelper = openHelper;
        this.mOpenCounter = new AtomicInteger();
    }

    public void destroy() {
        this.mOpenHelper.close();
        this.mOpenHelper = null;
        this.mDb = null;
        this.mOpenCounter.set(0);
        this.mOpenCounter = null;
    }

    public synchronized SupportSQLiteDatabase openDb() {
        if (this.mOpenCounter.incrementAndGet() == 1) {
            this.mDb = this.mOpenHelper.getWritableDatabase();
        }

        return this.mDb;
    }

    public synchronized void closeDb() {
        if (this.mOpenCounter.decrementAndGet() == 0) {
            this.mOpenHelper.close();
        }

    }
}
 

建立DbHelper

package com.example.a002034.myapplication.db;

/**
 * .
 *
 * @author
 */

import android.arch.persistence.db.SupportSQLiteDatabase;
import android.arch.persistence.db.SupportSQLiteOpenHelper;
import android.arch.persistence.db.framework.FrameworkSQLiteOpenHelperFactory;
import android.util.Log;

import com.example.a002034.myapplication.Configs;
import com.example.a002034.myapplication.RootApp;

/**
 * SQLiteOpenHelper.
 *
 * @author xuzhuyun
 */
public class DbHelper {
    private static final String TAG = "DbHelper";

    private SupportSQLiteOpenHelper mOpenHelper;

    public DbHelper() {
        SupportSQLiteOpenHelper.Configuration configuration = SupportSQLiteOpenHelper.Configuration.builder(RootApp.getInstance())
                .name(Configs.DB_NAME)
                .callback(new DbCallback(Configs.DB_VERSION))
                .build();
        SupportSQLiteOpenHelper.Factory factory = new FrameworkSQLiteOpenHelperFactory();
        mOpenHelper = factory.create(configuration);
    }

    public SupportSQLiteOpenHelper getOpenHelper() {
        return mOpenHelper;
    }

    class DbCallback extends SupportSQLiteOpenHelper.Callback {

        DbCallback(int version) {
            super(version);
        }

        @Override
        public void onCreate(SupportSQLiteDatabase db) {
            Log.i(TAG, "[db] 建立資料庫");
//            db.execSQL(Cabinet.CREATE_TABLE);
//            db.execSQL(Cell.CREATE_TABLE);
//            db.execSQL(Parcel.CREATE_TABLE);
        }

        @Override
        public void onUpgrade(SupportSQLiteDatabase db, int oldVersion, int newVersion) {
            Log.i(TAG,
                    "[db] 升級資料庫，db = [" + db.getPath() + "], oldVersion = [" + oldVersion + "], currentVersion = [" + newVersion + "]");
        }
    }
}
 

以上RootApp是我們自定義的Application類，目的是獲取Context物件，這裡自己獲取就好.我的RootApp程式碼是:

package com.example.a002034.myapplication;

import android.app.Application;

/**
 * Application.
 *
 * @author xuzhuyun
 */
public class RootApp extends Application {

    private static final String TAG = "RootApp";
    private static RootApp mContext;

    @Override
    public void onCreate() {
        super.onCreate();
        mContext = this;
        //初始化資料庫
        Configs.getInstance().init();
    }

    public static RootApp getInstance() {
        if (mContext == null) {
            mContext = new RootApp();
        }
        return mContext;
    }

}
 

記得在Application類中初始化資料庫。

建立用到的配置類Configs

package com.example.a002034.myapplication;
import com.example.a002034.myapplication.db.DbHelper;
import com.example.a002034.myapplication.db.SupportDbManager;

/**
 * 全域性配置類.
 *
 * @author xuzhuyun
 */
public class Configs {
    /**
     * 資料庫名稱.
     */
    public static final String DB_NAME = "test.db";
    /**
     * 資料庫版本號.
     */
    public static final int DB_VERSION = 1;

    private SupportDbManager mDbManager;

    private Configs() {
    }

    public void init() {
        initPersistent();
    }

    public SupportDbManager getDbManager() {
        if (mDbManager == null) {
            throw new IllegalStateException("must invoke method init() first");
        }
        return mDbManager;
    }

    private void initPersistent() {
        DbHelper smartDbHelper = new DbHelper();
        mDbManager = new SupportDbManager(smartDbHelper.getOpenHelper());
    }

    private static class SingletonHolder {
        private static final Configs INSTANCE = new Configs();
    }

    public static Configs getInstance() {
        return SingletonHolder.INSTANCE;
    }
}

呼叫

獲取SupportDbManager物件和SupportSQLiteDatabase物件

 SupportDbManager dbManager = Configs.getInstance().getDbManager();
 SupportSQLiteDatabase db = dbManager.openDb();

Demo下載