我是android中的数据库新手。我想知道如何从我的数据库中获取行ID，例如NAME。我现在使用了下面的一些reasearch，我坚持在显示部分。
public class DestinateurTable {
public String TABLE_NAME="destinateur";
public String ROW_ID="rowid";
public String NAME="name";
public String AGENCE="agence";
public String EMAIL="email";
}
public class Destinataire {
public String rowid,name,agence,email;
}
**My DBHelper.class**
public class DBHelper {
private final String DATABASE_PATH = "/data/data/.../databases/";
private final String DATABASE_NAME = "...sqlite";
private final static int DATABASE_VERSION = 1;
private Context context;
private SQLiteDatabase database = null;
OpenHelper openHelper=null;
StringBuilder query =null;
Cursor cursor=null;
DestinateurTable destinataireTable = new DestinateurTable();
public static DBHelper dbHelper = null;
private DBHelper(Context context) {
this.context = context;
openHelper = new OpenHelper(this.context);
this.database = openHelper.getWritableDatabase();
try {
createDataBase();
openDataBase();
} catch (IOException e) {
e.printStackTrace();
}
}
public static DBHelper getInstance(Context context)
{
if(dbHelper == null)
dbHelper = new DBHelper(context);
return dbHelper;
}
public void openDataBase() throws SQLException{
//Open the database
String myPath = DATABASE_PATH + DATABASE_NAME;
database = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
}
/**
* Creates a empty database on the system and rewrites it with your own database.
* */
public void createDataBase() throws IOException
{
openHelper.getReadableDatabase();
if(getDBAlreadyCopiedToDeviceOnceFlag(context) == false){
try {
copyDataBase();
setDBAlreadyCopiedToDeviceOnceFlag(context);
} catch (IOException e) {
e.printStackTrace();
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
*/
@SuppressWarnings("unused")
private boolean checkDataBase(){
SQLiteDatabase checkDB = null;
try{
String myPath = DATABASE_PATH + DATABASE_NAME;
checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
}catch(SQLiteException e){
//database does't exist yet.
}
if(checkDB != null){
checkDB.close();
}
return checkDB != null ? true : false;
}
/**
* Copies your database from your local assets-folder to the just created empty database in the
* system folder, from where it can be accessed and handled.
* This is done by transfering bytestream.
* */
private void copyDataBase() throws IOException{
//Open your local db as the input stream
InputStream myInput = context.getAssets().open(DATABASE_NAME);
// Path to the just created empty db
String outFileName = DATABASE_PATH + DATABASE_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();
}
private class OpenHelper extends SQLiteOpenHelper
{
@SuppressWarnings("unused")
SQLiteStatement insertStmt;
public OpenHelper(Context context)
{
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@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 setDBAlreadyCopiedToDeviceOnceFlag(Context ctx)
{
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(ctx);
SharedPreferences.Editor editor = prefs.edit();
editor.putBoolean("isDBAlreadyCopiedToDeviceOnce", true);
editor.commit();
}
public boolean getDBAlreadyCopiedToDeviceOnceFlag(Context ctx)
{
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(ctx);
boolean isDBAlreadyCopiedToDeviceOnce = prefs.getBoolean("isDBAlreadyCopiedToDeviceOnce", false);
return isDBAlreadyCopiedToDeviceOnce;
}
////////////////////////////
//// Write your methods here
////////////////////////////
public ArrayList<Destinataire> getDestinataireList()
{
ArrayList<Destinataire> items=new ArrayList<Destinataire>();
try
{
query = new StringBuilder();
query.append("select * from "+destinataireTable.TABLE_NAME);
cursor=this.database.rawQuery(query.toString(),null);
if (cursor.moveToFirst())
{
do
{
Destinataire d=new Destinataire();
d.rowid=cursor.getString(cursor.getColumnIndex(destinataireTable.ROW_ID));
d.name=cursor.getString(cursor.getColumnIndex(destinataireTable.NAME));
d.agence=cursor.getString(cursor.getColumnIndex(destinataireTable.AGENCE));
d.email=cursor.getString(cursor.getColumnIndex(destinataireTable.EMAIL));
items.add(d);
}
while (cursor.moveToNext());
}
if (cursor != null && !cursor.isClosed())
{
cursor.close();
}
}
catch(SQLiteException e){
e.printStackTrace();
return null;
}
return items;
}
//--here
public boolean addDestinataire(Destinataire d){
this.database.beginTransaction();
try{
ContentValues contentValues=new ContentValues();
contentValues.put(destinataireTable.ROW_ID, d.rowid);
contentValues.put(destinataireTable.NAME, d.name);
contentValues.put(destinataireTable.AGENCE, d.agence);
contentValues.put(destinataireTable.EMAIL, d.email);
this.database.insert(destinataireTable.TABLE_NAME,null,contentValues);
this.database.setTransactionSuccessful();
} catch(Exception e){
e.printStackTrace();
return false;
} finally{
this.database.endTransaction();
}
return true;
}
public boolean deleteDestinataire(String id){
try {
String query="delete from " + destinataireTable.TABLE_NAME+" where "+destinataireTable.ROW_ID+"='"+id+"'";
this.database.execSQL(query);
}
catch(SQLiteException e){
e.printStackTrace();
return false;
}
return true;
}
}
答案 0 :(得分：0)
您的整个数据库操作似乎没问题。你提到现在要显示数据。 最常见的方法是使用ListView，它连接到Adapter，你可以直接使用Cursor的适配器，但你已经把它作为List，所以你可以使用ArrayAdapter
要将其用作简单测试，您就可以开始了解它是如何工作的。创建一个extends ListActivity的新活动，然后在其上编写以下代码：
public class MyListActivity extends ListActivity{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ArrayList<Destinataire> items = getDestinataireList();
ArrayAdapter<Destinataire> adapter = new ArrayAdapter<Destinataire>(this, android.R.layout.simple_list_item_1 , android.R.id.text1, items)
setListAdapter(adapter);
}
}
还在Destinataire类中包含此行：
@Override
public String toString() {
return name + " " + agence + " " + email;
}
这是一个非常基本的示例，并未进行优化（例如，您应该使用后台线程从数据库加载数据），但它应显示一个列表，其中数据库中的每个项目都显示name agence email。< / p>
快乐的编码！
修改
这一行：
new ArrayAdapter<Destinataire>(this, android.R.layout.simple_list_item_1 , android.R.id.text1, items)
...有一些重要的部分，所以让我解释一下：