引用外部数据库（sqlite)

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public class DbManager {
    private static final String DB_NAME = "data1.db";//文件名，自己修改
    private static final String PACKAGE_NAME = "com.example.aaaaaa.test";//包名，自己修改
    private static final String DB_PATH = "/data" + Environment.getDataDirectory().getAbsolutePath() + "/" + PACKAGE_NAME+ "/databases";   //存放路径( /data/data/com.*.*(package name)/database)
    private SQLiteDatabase db;
    private Context context;
    DbManager(Context context) {
        this.context = context;
    }
    //对外提供的打开数据库接口
    public void openDataBase() {
        this.db = this.openDataBase(DB_PATH + "/" + DB_NAME);
    }
    //获取打开后的数据库
    public SQLiteDatabase getDb() {
        return this.db;
    }
    // 本地打开数据方法
    private SQLiteDatabase openDataBase(String filePath) {
        try {
            File myDataPath = new File(DB_PATH);
            if (!myDataPath.exists()) {
                myDataPath.mkdirs();// 假设没有这个文件夹,则创建
            }
            if (!(new File(filePath).exists())) {// 推断数据库文件是否存在，若不存在则运行导入，存在则直接打开数据库
                InputStream is = context.getResources().openRawResource(R.raw.data1);
                FileOutputStream fos = new FileOutputStream(filePath);
                int BUFFER_SIZE = 400000;
                byte[] buffer = new byte[BUFFER_SIZE];
                int readCount;
                while((readCount = is.read(buffer))>0){
                    fos.write(buffer,0,readCount);
                }
                fos.close();
                is.close();
            }
            //打开数据库
            SQLiteDatabase db = SQLiteDatabase.openOrCreateDatabase(filePath,null);
            return db;
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }
    //关闭数据库
    public  void closeDataBase() {
        if(this.db!=null)db.close();
    }
}

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<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

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DbManager manager = new DbManager(MainActivity.this);
manager.openDataBase();