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我有三個spinners。第三個旋轉器依賴於第二個旋轉器，第二個旋轉器依賴於第一個旋轉器。微調器中的字段正在由外部sqlite數據庫填充。 現在的問題是，如果我有一個巨大的數據庫說成千上萬的記錄，我必須爲所有千條記錄寫條件，這樣當我點擊第一個微調器的第一個位置時，結果值應該顯示在第二個微調器上，所以在第三個微調。用外部Sqlite數據庫填充微調器
A
回答
2
//這是我的主要活動類
public class MainActivity extends Activity implements OnItemSelectedListener{
private CarHelper dbcarhelper=null;
private Cursor ourCursor = null,cur=null,vercur=null;
private CarAdapter car_adapter = null;
public Spinner spinner,spinner2,spinner3,spinner4;
public String a;
@Override
protected void onCreate(Bundle savedInstanceState)
{
try
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
spinner = (Spinner)findViewById(R.id.spinner1);
spinner2=(Spinner)findViewById(R.id.spinner2);
spinner3= (Spinner)findViewById(R.id.spinner3);
dbcarhelper = new CarHelper(this);
dbcarhelper.createDatabase();
dbcarhelper.openDataBase();
ourCursor = dbcarhelper.getCursor();
startManagingCursor(ourCursor);
car_adapter = new CarAdapter(ourCursor);
spinner.setAdapter(car_adapter);
spinner.setOnItemSelectedListener(this);
startManagingCursor(cur);
spinner2.setOnItemSelectedListener(this);
startManagingCursor(vercur);
}
catch(Exception e)
{
Log.e("ERROR","ERROR IN CODE:" + e.toString());
e.printStackTrace();
}
}
class CarAdapter extends CursorAdapter
{
CarAdapter(Cursor c) {
super(MainActivity.this, c);
}
@Override
public void bindView(View row, Context ctxt, Cursor c) {
CarHolder holder= (CarHolder)row.getTag();
holder.populateFrom(c,dbcarhelper);
}
@Override
public View newView(Context ctxt, Cursor c, ViewGroup parent) {
// TODO Auto-generated method stub
LayoutInflater inflater = getLayoutInflater();
View row = inflater.inflate(R.layout.row, parent, false);
CarHolder holder= new CarHolder(row);
row.setTag(holder);
return (row);
}
}
static class CarHolder {
private TextView make = null, model= null, ver=null;
CarHolder (View row)
{
make = (TextView)row.findViewById(R.id.carText);
model = (TextView)row.findViewById(R.id.carText);
ver = (TextView)row.findViewById(R.id.carText);
}
void populateFrom(Cursor c,CarHelper r)
{
make.setText(r.getName(c));
model.setText(r.getName(c));
ver.setText(r.getName(c));
}
}
public void onItemSelected(AdapterView<?> parent, View arg1,int position,long arg3)
{
int id = parent.getId();
switch(id)
{
case R.id.spinner1:
int b = spinner.getSelectedItemPosition();
b++;
a = Integer.toString(b);
if(a!=null)
{
dbcarhelper.m_pop(a);
}
CarHelper ch = new CarHelper(getApplicationContext());
List<String> lables = ch.getAllLabels();
//ch.getAllLabels(str);
ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(this,
android.R.layout.simple_spinner_item, lables);
dataAdapter
.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner2.setAdapter(dataAdapter);
break;
case R.id.spinner2:
int i = spinner.getSelectedItemPosition();
i++;
a = Integer.toString(i);
if(a!=null)
{
dbcarhelper.v_pop(a);
}
CarHelper c = new CarHelper(getApplicationContext());
List<String> lable = c.getAllLabel();
ArrayAdapter<String> dAdapter = new ArrayAdapter<String>(this,
android.R.layout.simple_spinner_item, lable);
dAdapter
.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner3.setAdapter(dAdapter);
break;
}
}
@Override
public void onNothingSelected(AdapterView<?> arg0) {
// TODO Auto-generated method stub
}
1
//這是我的助手類
public class CarHelper extends SQLiteOpenHelper{
private static final String DATABASE_PATH= "//data//data//com.example.dropdown//databases//";
private static final String DATABASE_NAME= "car_Database.sqlite";
private static final int SCHEMA_VERSION =1;
public static final String COLUMN_ID = "_id";
public static final String TABLE_NAME = "Make";
public static final String COLUMN_TITLE = "car_make";
public static final String TABLE_MODEL = "Model";
public static final String COLUMN_MODEL = "car_model";
public static final String TABLE_VER = "Version";
public static final String COLUMN_VER = "car_ver";
public SQLiteDatabase dbsqlite,db1;
private final Context myContext;
public CarHelper(Context context) {
super(context, DATABASE_NAME, null, SCHEMA_VERSION);
this.myContext = context;
// TODO Auto-generated constructor stub
}
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
}
public void createDatabase()
{
createDB();
}
private void createDB()
{
boolean dbExist = DBExists();
if(!dbExist)
{
this.getReadableDatabase();
copyDBFromResource();
}
}
private boolean DBExists()
{
SQLiteDatabase db = null;
try
{
String databasePath = DATABASE_PATH + DATABASE_NAME;
db = SQLiteDatabase.openDatabase(databasePath,null, SQLiteDatabase.OPEN_READWRITE);
db.setLocale(Locale.getDefault());
db.setLockingEnabled(true);
db.setVersion(1);
}
catch(SQLiteException e)
{
Log.e("AqlHelper","database not found");
}
if(db!=null)
{
db.close();
}
return db!=null ? true : false;
}
private void copyDBFromResource()
{
InputStream ip = null;
OutputStream op = null;
String dbFilePath = DATABASE_PATH + DATABASE_NAME;
try
{
ip= myContext.getAssets().open(DATABASE_NAME);
op = new FileOutputStream(dbFilePath);
byte[] buffer = new byte[1024];
int length;
while((length = ip.read(buffer))>0)
{
op.write(buffer, 0, length);
}
op.flush();
op.close();
ip.close();
}
catch(IOException e)
{
throw new Error("Problemcopying database from Resource");
}
}
public void openDataBase() throws SQLException
{
String myPath = DATABASE_PATH + DATABASE_NAME;
dbsqlite = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
}
@Override
public synchronized void close()
{
if(dbsqlite != null)
{
dbsqlite.close();
}
super.close();
}
public Cursor getCursor()
{
SQLiteQueryBuilder queryBuilder = new SQLiteQueryBuilder();
queryBuilder.setTables(TABLE_NAME);
String[] asColumnsToReturn = new String[] {COLUMN_ID,COLUMN_TITLE};
Cursor mCursor = queryBuilder.query(dbsqlite, asColumnsToReturn, null, null, null, null, "car_make ASC");
return mCursor;
}
public void m_pop(String st){
String a = st;
dbsqlite.execSQL("delete from temp");
dbsqlite.execSQL("insert into temp(name) select car_model from Model where make_id="+a);
}
public List<String> getAllLabels(){
List<String> labels = new ArrayList<String>();
String selectQuery = "select name from temp";
dbsqlite = this.getReadableDatabase();
Cursor cursor = dbsqlite.rawQuery(selectQuery, null);
if (cursor.moveToFirst()) {
do {
labels.add(cursor.getString(cursor.getColumnIndex("name")));
} while (cursor.moveToNext());
}
cursor.close();
dbsqlite.close();
return labels;
}
public void v_pop(String st){
String a = st;
dbsqlite.execSQL("delete from temp");
dbsqlite.execSQL("insert into temp(name) select car_ver from Version where _id="+a);
}
public List<String> getAllLabel(){
List<String> label = new ArrayList<String>();
String selectQuery = "select name from temp";
dbsqlite = this.getReadableDatabase();
Cursor cursor = dbsqlite.rawQuery(selectQuery, null);
if (cursor.moveToFirst()) {
do {
label.add(cursor.getString(cursor.getColumnIndex("name")));
} while (cursor.moveToNext());
}
cursor.close();
dbsqlite.close();
return label;
}
public String getName(Cursor c){
return (c.getString(1));
}
}