androidstudio中外部数据库的导入

来源：互联网发布：u盘ubuntu分区教程编辑：程序博客网时间：2024/06/05 19:40

由于工具的不同，在androidstudio中导入外部数据库也是有所不同，下面教大家怎么在as中导入db，注意往下看

1.切换project视图 src->main->新建assets

至于为什么，往下看:

2.创建DBMain继承自

                         SQLiteOpenHelper

public class DBMain extends SQLiteOpenHelper {    private static String DB_PATH= "data/data/com.safephone.lwp.importdatabase/databases/";    private static String DB_NAME = "ii";    private SQLiteDatabase dbObj;    private final Context context;    public DBMain(Context context) {        super(context,  DB_NAME , null, 3);        this. context  = context;    }    public void createDB() throws IOException {        this.getReadableDatabase();        try {            copyDB();        } catch (IOException e) {            throw new Error("Error copying database");        }    }    private boolean checkDB(){        SQLiteDatabase checkDB = null;        try{            String path = DB_PATH + DB_NAME;            checkDB = SQLiteDatabase.openDatabase(path, null, SQLiteDatabase.OPEN_READONLY);            if (checkDB!=null)            {                Cursor c= checkDB.rawQuery("SELECT * FROM bank", null);                Log.i("Cursor.......",c.getString(0));                c.moveToFirst();                String contents[]=new String[80];                int flag=0;                while(! c.isAfterLast())                {                    String temp="";                    String s2=c.getString(0);                    String s3=c.getString(1);                    String s4=c.getString(2);                    temp=temp+"\n Id:"+s2+"\tType:"+s3+"\tBal:"+s4;                    contents[flag]=temp;                    flag=flag+1;                    Log.i("DB values.........",temp);                    c.moveToNext();                }            }            else            {                return false;            }        }catch(SQLiteException e){            e.printStackTrace();        }        if(checkDB != null){            checkDB.close();        }        return checkDB != null ? true : false;    }    public void copyDB() throws IOException{        try {            InputStream ip =  context.getAssets().open(DB_NAME+".db");            Log.i("Input Stream....",ip+"");            String op=  DB_PATH  +  DB_NAME ;            OutputStream output = new FileOutputStream( op);            byte[] buffer = new byte[1024];            int length;            while ((length = ip.read(buffer))>0){                output.write(buffer, 0, length);                Log.i("Content.... ",length+"");            }            output.flush();            output.close();            ip.close();        }        catch (IOException e) {            Log.v("error", e.toString());        }    }    public void openDB() throws SQLException {        String myPath = DB_PATH + DB_NAME;        dbObj = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);        Log.i("open DB......",dbObj.toString());    }    @Override    public synchronized void close() {        if(dbObj != null)            dbObj.close();        super.close();    }    @Override    public void onCreate(SQLiteDatabase db) {    }    @Override    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {    }}
3.Mainactivity的oncreate方法中

protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    DBMain db;    db = new DBMain(this);    try {        db.createDB();    } catch (IOException ioe) {        throw new Error("Database not created....");    }    try {        db.openDB();    }catch(SQLException sqle){        throw sqle;    }    SQLiteDatabase db1;    db1=openOrCreateDatabase("ii",SQLiteDatabase.CREATE_IF_NECESSARY,null);    Cursor c= db1.rawQuery("SELECT * FROM bank",null);    c.moveToFirst();    String temp="";    while(! c.isAfterLast())    {        String s2=c.getString(0);        String s3=c.getString(1);        String s4=c.getString(2);        temp=temp+"\n Id:"+s2+"\tType:"+s3+"\tBal:"+s4;        c.moveToNext();    }}

ok,大功告成，觉得可以请点赞

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