我目前正在开发一个包含SQLite数据库的Android应用程序..我正在尝试使用Android 2.1的模拟器，它工作正常..但它不适用于比Android 2.1更新的版本....
在我的应用程序中，我在SQLite管理器上创建了一个外部SQLite数据库，然后我将此数据库复制到
应用程序首次启动时，“/ data / data /”+ getPackageName（）+“/ databases / MyDB”。
从资产文件夹复制数据库的代码：
try{
try {
String destPath = "/data/data/" + getPackageName() + "/databases/MyDB";
File f = new File(destPath);
if (!f.exists()) {
CopyDB( getBaseContext().getAssets().open("mydb"),
new FileOutputStream(destPath));
}
} catch (FileNotFoundException e) {
e.printStackTrace();
copyDB功能：
public void CopyDB(InputStream inputStream, OutputStream outputStream)
throws IOException {
//---copy 1K bytes at a time---
byte[] buffer = new byte[1024];
int length;
while ((length = inputStream.read(buffer)) > 0) {
outputStream.write(buffer, 0, length);
}
outputStream.flush();
inputStream.close();
outputStream.close();
}
DBAdapter类：
public class DBAdapter {
public static final String KEY_ROWID = "_id";
public static final String KEY_NAME = "username";
public static final String KEY_PASSWORD = "password";
private static final String DATABASE_NAME = "MyDB";
private static final String DATABASE_TABLE = "users";
private static final int DATABASE_VERSION = 3;
private final Context context;
private DatabaseHelper DBHelper;
private SQLiteDatabase db;
public DBAdapter(Context ctx)
{
this.context = ctx;
DBHelper = new DatabaseHelper(context);
}
private static class DatabaseHelper extends SQLiteOpenHelper
{
DatabaseHelper(Context context)
{
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db)
{
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
{
}
}
//---opens the database---
public DBAdapter open() throws SQLException
{
db = DBHelper.getWritableDatabase();
return this;
}
//---closes the database---
public void close()
{
DBHelper.close();
}
//---retrieves all the users---
public Cursor getAllusers()
{
return db.query(DATABASE_TABLE, new String[] {KEY_ROWID, KEY_NAME,
KEY_PASSWORD}, null, null, null, null, null);
}
//---retrieves a particular user---
public User getuser(String username) throws SQLException
{
Cursor mCursor =
db.query(true, DATABASE_TABLE, new String[] {KEY_ROWID,
KEY_NAME, KEY_PASSWORD}, KEY_NAME + "=" + "'"+username+ "'", null,
null, null, null, null);
if(mCursor.moveToFirst())
{
mCursor.moveToFirst();
User u=new User(Integer.valueOf(mCursor.getString(0)),mCursor.getString(1),mCursor.getString(2));
return u;
}else
return null;
}
public List<Device> getNotupdatedDevices() {
List<Device> Devices = new ArrayList<Device>();
SQLiteDatabase db = DBHelper.getWritableDatabase();
Cursor myCursor =
db.query("Devices", new String[] {"_DeviceID","current_state","current_level","current_CD_Channel" }, "updated=?", new String[] {"false"}, null, null, null);
if (myCursor.moveToFirst()) {
do {
Device d = new Device(Integer.valueOf(myCursor.getString(0)), myCursor.getString(1),Integer.valueOf(myCursor.getString(2)), Float.valueOf(myCursor.getString(3)));
Devices.add(d);
} while (myCursor.moveToNext());
return Devices;
}
return null;
}
public Device getDevice(String DeviceType,String RoomType,int floor) throws SQLException
{
Cursor mCursor =
db.query("Rooms", new String[] {"_RoomID" }, "RoomType=? AND floor=?", new String[] {RoomType, floor+""}, null, null, null);
if(mCursor.moveToFirst())
{
mCursor.moveToFirst();
int id=Integer.valueOf(mCursor.getString(0));
Cursor myCursor =
db.query("Devices", new String[] {"current_state","current_level","current_CD_Channel" }, "DeviceType=? AND RoomID=?", new String[] {DeviceType, id+""}, null, null, null);
if(myCursor.moveToFirst())
{
myCursor.moveToFirst();
Device d=new Device(DeviceType,floor,RoomType,myCursor.getString(0), Integer.valueOf(myCursor.getString(1)),Float.valueOf(myCursor.getString(2)));
return d;
}else
return null;
}else
return null;
}
public void updateDevice(int floor, String RoomType, String DeviceType, String current_state,int current_level,float current_CD_Channel ) {
SQLiteDatabase db = DBHelper.getWritableDatabase();
Cursor mCursor =
db.query("Rooms", new String[] {"_RoomID" }, "RoomType=? AND floor=?", new String[] {RoomType, floor+""}, null, null, null);
mCursor.moveToFirst();
int id=Integer.valueOf(mCursor.getString(0));
ContentValues values = new ContentValues();
values.put("current_state", current_state);
values.put("current_level", current_level);
values.put("current_CD_Channel", current_CD_Channel);
values.put("updated", "false");
db.update("Devices", values, "RoomID= ? AND DeviceType=?",new String[] { String.valueOf(id),DeviceType });
db.close();
}
public void SyncDevice(int id, String current_state,int current_level,float current_CD_Channel ) {
SQLiteDatabase db = DBHelper.getWritableDatabase();
ContentValues values = new ContentValues();
values.put("current_state", current_state);
values.put("current_level", current_level);
values.put("current_CD_Channel", current_CD_Channel);
values.put("updated", "true");
// updating row
db.update("Devices", values, "_DeviceID= ?", new String[] { String.valueOf(id) });
db.close();
}
}
在冰淇淋三明治模拟器上运行应用程序时的logcat消息：
06-26 22:59:29.418: E/AndroidRuntime(6230): FATAL EXCEPTION: main
06-26 22:59:29.418: E/AndroidRuntime(6230): android.database.sqlite.SQLiteException: no such table: users: , while compiling: SELECT DISTINCT _id, username, password FROM users WHERE username='aya'
06-26 22:59:29.418: E/AndroidRuntime(6230): at android.database.sqlite.SQLiteCompiledSql.native_compile(Native Method)
06-26 22:59:29.418: E/AndroidRuntime(6230): at android.database.sqlite.SQLiteCompiledSql.<init>(SQLiteCompiledSql.java:68)
06-26 22:59:29.418: E/AndroidRuntime(6230): at android.database.sqlite.SQLiteProgram.compileSql(SQLiteProgram.java:143)
06-26 22:59:29.418: E/AndroidRuntime(6230): at android.database.sqlite.SQLiteProgram.compileAndbindAllArgs(SQLiteProgram.java:361)
06-26 22:59:29.418: E/AndroidRuntime(6230): at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:127)
06-26 22:59:29.418: E/AndroidRuntime(6230): at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:94)
06-26 22:59:29.418: E/AndroidRuntime(6230): at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:53)
06-26 22:59:29.418: E/AndroidRuntime(6230): at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:47)
06-26 22:59:29.418: E/AndroidRuntime(6230): at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1564)
06-26 22:59:29.418: E/AndroidRuntime(6230): at android.database.sqlite.SQLiteDatabase.queryWithFactory(SQLiteDatabase.java:1449)
06-26 22:59:29.418: E/AndroidRuntime(6230): at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1405)
06-26 22:59:29.418: E/AndroidRuntime(6230): at cse.HomeAutomation.DBAdapter.getuser(DBAdapter.java:79)
06-26 22:59:29.418: E/AndroidRuntime(6230): at cse.HomeAutomation.Login$1.onClick(Login.java:53)
06-26 22:59:29.418: E/AndroidRuntime(6230): at android.view.View.performClick(View.java:3511)
06-26 22:59:29.418: E/AndroidRuntime(6230): at android.view.View$PerformClick.run(View.java:14105)
06-26 22:59:29.418: E/AndroidRuntime(6230): at android.os.Handler.handleCallback(Handler.java:605)
06-26 22:59:29.418: E/AndroidRuntime(6230): at android.os.Handler.dispatchMessage(Handler.java:92)
06-26 22:59:29.418: E/AndroidRuntime(6230): at android.os.Looper.loop(Looper.java:137)
06-26 22:59:29.418: E/AndroidRuntime(6230): at android.app.ActivityThread.main(ActivityThread.java:4424)
06-26 22:59:29.418: E/AndroidRuntime(6230): at java.lang.reflect.Method.invokeNative(Native Method)
06-26 22:59:29.418: E/AndroidRuntime(6230): at java.lang.reflect.Method.invoke(Method.java:511)
06-26 22:59:29.418: E/AndroidRuntime(6230): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
06-26 22:59:29.418: E/AndroidRuntime(6230): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
06-26 22:59:29.418: E/AndroidRuntime(6230): at dalvik.system.NativeStart.main(Native Method)
我搜索了很多但没找到解决这个问题的方法...... 非常感谢你:)
答案 0 :(得分：0)
您尚未创建表格
@Override
public void onCreate(SQLiteDatabase db)
{
}
应该是
http://www.vogella.com/articles/AndroidSQLite/article.html
// Database creation sql statement
private static final String DATABASE_CREATE = "create table "
+ TABLE_COMMENTS + "(" + COLUMN_ID
+ " integer primary key autoincrement, " + COLUMN_COMMENT
+ " text not null);";
public MySQLiteHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase database) {
database.execSQL(DATABASE_CREATE);//<--------------------
}
答案 1 :(得分：0)
您有一个复制数据库的功能，但是您没有显示您从哪里调用，这会影响结果。我通常在我的db helper类的构造函数中调用这样的东西（它也包含在那里）。
修改
完整示例
public class DBAdapter {
// DB info
public static final String MAIN_DATABASE_NAME = "Bowers";
public static final int MAIN_DATABASE_VERSION = 1;
public static String MAIN_DB_PATH = "/data/data/cdc.workshopapps.BowersMfgHelper/databases/";
// static strings removed for brevity
// database control variables
private DatabaseHelper mDbHelper;
private static SQLiteDatabase mDb;
private static Context mCtx;
private static class DatabaseHelper extends SQLiteOpenHelper {
DatabaseHelper(Context context, String dbname, int dbversion) {
super(context, dbname, null, dbversion);
if (checkDataBase(dbname)) {
openDataBase(dbname);
} else {
try {
this.getReadableDatabase();
copyDataBase(dbname);
this.close();
openDataBase(dbname);
} catch (IOException e) {
throw new Error("Error copying database");
}
Toast.makeText(context,
"Initial " + dbname + " database has been created",
Toast.LENGTH_LONG).show();
}
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}
public DBAdapter(Context ctx) {
DBAdapter.mCtx = ctx;
}
public DBAdapter open(String dbname, int dbversion) throws SQLException {
mDbHelper = new DatabaseHelper(mCtx, dbname, dbversion);
mDb = mDbHelper.getWritableDatabase();
return this;
}
public void close() {
mDbHelper.close();
}
private static void copyDataBase(String dbname) throws IOException {
InputStream myInput = mCtx.getAssets().open(dbname);
String outFileName = MAIN_DB_PATH + dbname;
OutputStream myOutput = new FileOutputStream(outFileName);
byte[] buffer = new byte[1024];
int length;
while ((length = myInput.read(buffer)) > 0) {
myOutput.write(buffer, 0, length);
}
myOutput.flush();
myOutput.close();
myInput.close();
}
private static boolean checkDataBase(String dbname) {
SQLiteDatabase checkDB = null;
boolean exist = false;
try {
String db = MAIN_DB_PATH + dbname;
checkDB = SQLiteDatabase.openDatabase(db, null,
SQLiteDatabase.OPEN_READONLY);
} catch (SQLiteException e) {
Log.v("db log", "database does't exist");
}
if (checkDB != null) {
exist = true;
checkDB.close();
}
return exist;
}
private static void openDataBase(String dbname) throws SQLException {
String dbPath = MAIN_DB_PATH + dbname;
mDb = SQLiteDatabase.openDatabase(dbPath, null,
SQLiteDatabase.OPEN_READWRITE);
}
// insert, update, delete and cursor methods follow, removed for brevity
}
我已经将它用于Android 3.2 ......