在android项目里使用自带的SQLite数据库
好久没写博客了，因为项目需要，最近在研究android，使用android默认的访问sqlite的方法，访问的是：data/data/你的项目package/database/数据库名称下的数据库，假如要在项目中打包db文件，该怎么弄呢？
在网上看到一个老外的方法：
publicclass DataBaseHelper extends SQLiteOpenHelper{
//The
Android's default system path of your application database.
private static String DB_PATH =
"/data/data/你的项目package/databases/";
private static String DB_NAME = "数据库名称";
private SQLiteDatabase
myDataBase;
private final Context myContext;
public DataBaseHelper(Context context)
{
super(context, DB_NAME, null, 1);
this.myContext =
context;
}
public void createDataBase() throws IOException{
boolean dbExist =
checkDataBase();
if(dbExist){
//do
nothing - database already exist
}else{
//By
calling this method and empty database will be created into the default system
path
//of your application so we are gonna be able to
overwrite that database with our database.
this.getReadableDatabase();
try {
copyDataBase();
} catch (IOException e) {
throw new Error("Error copying
database");
}
}
}
private boolean
checkDataBase(){
SQLiteDatabase checkDB = null;
try{
String myPath = DB_PATH +
DB_NAME;
checkDB = SQLiteDatabase.openDatabase(myPath, null,
SQLiteDatabase.OPEN_READONLY);
}catch(SQLiteException e){
//database
does't exist yet.
}
if(checkDB != null){
checkDB.close();
}
return checkDB != null ? true : false;
}
private void copyDataBase() throws IOException{
//Open your
local db as the input stream
InputStream myInput =
myContext.getAssets().open(DB_NAME);
// Path to
the just created empty db
String outFileName = DB_PATH +
DB_NAME;
//Open the empty db as the output stream
OutputStream myOutput = new
FileOutputStream(outFileName);
//transfer
bytes from the inputfile to the outputfile
byte[] buffer = new byte[1024];
int length;
while ((length =
myInput.read(buffer))>0){
myOutput.write(buffer, 0,
length);
}
//Close the streams
myOutput.flush();
myOutput.close();
myInput.close();
}
public void openDataBase() throws SQLException{
//Open the
database
String myPath =
DB_PATH + DB_NAME;
myDataBase = SQLiteDatabase.openDatabase(myPath, null,
SQLiteDatabase.OPEN_READONLY);
}
@Override
public synchronized void close() {
if(myDataBase != null)
myDataBase.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db)
{
}
@Override
public
void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
// Add your
public helper methods to access and get content from the
database.
// You could return cursors by doing "return
myDataBase.query(....)" so it'd be easy
// to you
to create adapters for your views.
}
下面就可以使用 该 类实现数据库的操作了
myDbHelper = new DataBaseHelper(null);
myDbHelper = new DataBaseHelper(this);
try
{
myDbHelper.createDataBase();
} catch (IOException ioe) {
throw new Error("Unable to create
database");
}
try
{
myDbHelper.openDataBase();
}catch(SQLException sqle){
throw sqle;
}
实例化该类之后 就能在 data/data/your_project_package/database/
文件夹下面看到你的sqlite数据库文件了。
