Android如何导入已有的外部数据库

数据库类：

importjava.io.File;importjava.io.FileNotFoundException;importjava.io.FileOutputStream;importjava.io.IOException;importjava.io.InputStream;importandroid.content.Context;importandroid.database.sqlite.SQLiteDatabase;importandroid.os.Environment;importandroid.util.Log;publicclassDBManager {    privatefinalintBUFFER_SIZE =400000;    publicstaticfinalString DB_NAME ="countries.db";//保存的数据库文件名    publicstaticfinalString PACKAGE_NAME ="com.android.ImportDatabase";    publicstaticfinalString DB_PATH ="/data"            + Environment.getDataDirectory().getAbsolutePath() +"/"            + PACKAGE_NAME; //在手机里存放数据库的位置     privateSQLiteDatabase database;    privateContext context;     DBManager(Context context) {        this.context = context;}     Public void openDatabase() {        this.database =this.openDatabase(DB_PATH +"/"+ DB_NAME);    }     privateSQLiteDatabase openDatabase(String dbfile) {        try{            if(!(newFile(dbfile).exists())) {　　//判断数据库文件是否存在，若不存在则执行导入，否则直接打开数据库                InputStream is =this.context.getResources().openRawResource(                        R.raw.countries);//欲导入的数据库                FileOutputStream fos =newFileOutputStream(dbfile);                byte[] buffer =new byte[is.available()];                intcount =0;                while((count = is.read(buffer)) >0) {                    fos.write(buffer,0, count);                }                fos.close();                is.close();            } SQLiteDatabase db = SQLiteDatabase.openOrCreateDatabase(dbfile,                    null);            returndb;        }catch(FileNotFoundException e) {            Log.e("Database","File not found");            e.printStackTrace();        }catch(IOException e) {            Log.e("Database","IO exception");            e.printStackTrace();        }        returnnull;    }Public void closeDatabase() {        this.database.close();}

在主窗体上进行调用：

Public class RootView extends Activity {     publicDBManager dbHelper;   @Override    Public void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);        setContentView(R.layout.main);         dbHelper =newDBManager(this);        dbHelper.openDatabase();        dbHelper.closeDatabase();     }

此时在DDMS中可以查看到，外部数据库已经成功导入

在需要使用数据库的类里

Public class TaxiActivity extends Activity {     privateS QLiteDatabase database;        ArrayList CITY;@Override    publicvoidonCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);        setContentView(R.layout.main);                 database = SQLiteDatabase.openOrCreateDatabase(DBManager.DB_PATH +"/"+ DBManager.DB_NAME,null); CITY = getCity(); // do something with CITY         database.close();}privateArrayList getCity() {                 Cursor cur = database.rawQuery("SELECT city.id_city, city.name FROM taxi, city WHERE city.id_city = taxi.id_city GROUP BY city.id_city",null);                 if(cur !=null) {            intNUM_CITY = cur.getCount();            ArrayList taxicity =newArrayList(NUM_CITY);            if(cur.moveToFirst()) {                do{                    String name = cur.getString(cur.getColumnIndex("name"));                    intid = cur.getInt(cur.getColumnIndex("id_city"));                    CityClass city =newCityClass("",0);                    System.out.println(name); //额外添加一句，把select到的信息输出到Logcat                    city.city_name = name;                    city.city_id = id;                    taxicity.add(city);                }while(cur.moveToNext());            }            returntaxicity;        }else{            returnnull;        }    }}

更多相关文章

随机推荐