Java Can';在Android Studio VD上查看SQLite数据库
我是Android studio的新手,但多年来一直在Netbeans上编写Java代码。我一直在尝试如何将SQLite链接到Android Studio。我设法让DatabaseHelper代码正常工作,但我现在仍在做什么?数据库已在SQLitebrowser上创建。以下是databasehelper类:Java Can';在Android Studio VD上查看SQLite数据库,java,android,sqlite,android-studio,Java,Android,Sqlite,Android Studio,我是Android studio的新手,但多年来一直在Netbeans上编写Java代码。我一直在尝试如何将SQLite链接到Android Studio。我设法让DatabaseHelper代码正常工作,但我现在仍在做什么?数据库已在SQLitebrowser上创建。以下是databasehelper类: public class DataBaseHelper extends SQLiteOpenHelper { String DB_PATH = null; private static
public class DataBaseHelper extends SQLiteOpenHelper {
String DB_PATH = null;
private static String DB_NAME = "Restaurant";
private SQLiteDatabase myDataBase;
private final Context myContext;
/**
* Constructor
* Takes and keeps a reference of the passed context in order to access to the application assets and resources.
*/
public DataBaseHelper(Context context) {
super(context, DB_NAME, null, 1);
this.myContext = context;
this.DB_PATH = "/data/data/" + context.getPackageName() + "/" + "databases";
}
/**
* Creates an empty database on the system and rewrites it with my database.
* */
public void createDataBase() throws IOException{
boolean dbExist = checkDataBase();
if(dbExist){
}else{
//By calling this method and empty database will be created into the default system path
//of the 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");
}
}
}
/**
* Check if the database already exist to avoid re-copying the file each time you open the application.
* @return true if it exists, false if it doesn't
*/
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;
}
/*
* Copies my database from the local assets-folder to the just created empty database in the
* system folder, from where it can be accessed and handled by java
*/
private void copyDataBase() throws IOException{
//Open the 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);
}
//Closes them
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) {
if (newVersion>oldVersion){
try{
copyDataBase();
} catch
(IOException e){
e.printStackTrace();
}
}
}
}
我现在要做什么才能在列表中查看此文件?是否要获取.db文件?或者别的什么?我正在制作一个应用程序来显示SQLite数据库中的餐厅菜单,所以我想让.db文件以列表格式显示,这意味着您无法生成.db文件?或者你找不到.db文件我已经创建了.db文件,它位于assets文件夹中,但我无法在程序中显示它?如何从我放在程序中的.db文件中提取信息并在应用程序屏幕上显示这些信息有一些数据库方法,您必须实现这些方法才能获取和显示数据。