我正在制作一个Android应用程序，并希望将数据发送到SQLite数据库。我应该如何编码？
这是我创建表格的方式
public class DBHelper extends SQLiteOpenHelper {
private final static String DATABASE_NAME = "UserInfo.db";
public DBHelper(Context context) {
super(context, DATABASE_NAME, null, 1);
}
@Override
public void onCreate(SQLiteDatabase sqLiteDatabase) {
String CREATE_TABLE =
"CREATE TABLE " + UserProfile.Users.TABLE_NAME + " (" +
UserProfile.Users._ID + " INTEGER PRIMARY KEY," +
UserProfile.Users.COLUMN_USERNAME + " TEXT," +
UserProfile.Users.COLUMN_DOB + " TEXT," +
UserProfile.Users.COLUMN_GENDER + " TEXT," +
UserProfile.Users.COLUMN_PASSWORD + " TEXT )";
sqLiteDatabase.execSQL(CREATE_TABLE);
}
这是此代码中的onUpgrade方法
@Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
}
这是我将addInfo方法添加到此类的方法
public long addInfo(String username, String password){
SQLiteDatabase sqLiteDatabase = getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(UserProfile.Users.COLUMN_USERNAME, username);
contentValues.put(UserProfile.Users.COLUMN_PASSWORD, password);
long rowId = sqLiteDatabase.insert(UserProfile.Users.TABLE_NAME, null, contentValues);
return rowId;
}
public int updateInfo(String userId, String userName, String password, String dob, String gender){
SQLiteDatabase sqLiteDatabase = getWritableDatabase();
ContentValues values = new ContentValues();
values.put(UserProfile.Users.COLUMN_USERNAME, userName);
values.put(UserProfile.Users.COLUMN_PASSWORD, password);
values.put(UserProfile.Users.COLUMN_GENDER, gender);
values.put(UserProfile.Users.COLUMN_DOB, dob);
String selection = UserProfile.Users._ID + " = ?";
String args[] = {userId};
int count = sqLiteDatabase.update(UserProfile.Users.TABLE_NAME, values, selection, args);
return count;
}
下面是readAllInfo的数组列表
public ArrayList readAllInfo(){
SQLiteDatabase sqLiteDatabase = getReadableDatabase();
String[] projection = {
UserProfile.Users._ID,
UserProfile.Users.COLUMN_USERNAME,
UserProfile.Users.COLUMN_DOB,
UserProfile.Users.COLUMN_GENDER,
UserProfile.Users.COLUMN_PASSWORD
};
下面用于排序的代码
String sortOrder = UserProfile.Users._ID + " DESC";
Cursor cursor = sqLiteDatabase.query(
UserProfile.Users.TABLE_NAME,
projection,
null,
null,
null,
null,
sortOrder
);
ArrayList<User> list = new ArrayList<>();
if (cursor.getCount() > 0){
while(cursor.moveToNext()){
User newUser = new User();
int id = cursor.getInt(cursor.getColumnIndexOrThrow(UserProfile.Users._ID));
String user = cursor.getString(cursor.getColumnIndexOrThrow(UserProfile.Users.COLUMN_USERNAME));
String date = cursor.getString(cursor.getColumnIndexOrThrow(UserProfile.Users.COLUMN_DOB));
String gen = cursor.getString(cursor.getColumnIndexOrThrow(UserProfile.Users.COLUMN_GENDER));
String pass = cursor.getString(cursor.getColumnIndexOrThrow(UserProfile.Users.COLUMN_PASSWORD));
newUser.setUserId(id+"");
newUser.setUserName(user);
newUser.setDateOfBirth(date);
newUser.setGender(gen);
newUser.setPassword(pass);
list.add(newUser);
}
}
return list;
}
我用于readAllInfo方法的数组列表是这个
public ArrayList readAllInfo(String userId, String userName){
String selection;
String[] args = {""};
if(userId == null){
selection = UserProfile.Users.COLUMN_USERNAME + " LIKE ?";
args[0] = userName;
}
else
{
selection = UserProfile.Users._ID + " = ?";
args[0] = userId;
}
SQLiteDatabase sqLiteDatabase = getReadableDatabase();
String[] projection = {
UserProfile.Users._ID,
UserProfile.Users.COLUMN_USERNAME,
UserProfile.Users.COLUMN_DOB,
UserProfile.Users.COLUMN_GENDER,
UserProfile.Users.COLUMN_PASSWORD
};
String sortOrder = UserProfile.Users._ID + " DESC";
Cursor cursor = sqLiteDatabase.query(
UserProfile.Users.TABLE_NAME,
projection,
selection,
args,
null,
null,
sortOrder
);
ArrayList<User> list = new ArrayList<>();
if (cursor.getCount() > 0){
while(cursor.moveToNext()){
User newUser = new User();
int id = cursor.getInt(cursor.getColumnIndexOrThrow(UserProfile.Users._ID));
String user = cursor.getString(cursor.getColumnIndexOrThrow(UserProfile.Users.COLUMN_USERNAME));
String date = cursor.getString(cursor.getColumnIndexOrThrow(UserProfile.Users.COLUMN_DOB));
String gen = cursor.getString(cursor.getColumnIndexOrThrow(UserProfile.Users.COLUMN_GENDER));
String pass = cursor.getString(cursor.getColumnIndexOrThrow(UserProfile.Users.COLUMN_PASSWORD));
newUser.setUserId(id+"");
newUser.setUserName(user);
newUser.setDateOfBirth(date);
newUser.setGender(gen);
newUser.setPassword(pass);
list.add(newUser);
}
}
return list;
}
public int deleteInfo(String username){
SQLiteDatabase sqLiteDatabase = getReadableDatabase();
String selection = UserProfile.Users._ID + " = ?";
String[] args = {username};
int deletedRows = sqLiteDatabase.delete(UserProfile.Users.TABLE_NAME, selection, args);
return deletedRows;
}
}
答案 0 :(得分：2)
运行您的代码，它可以正常工作，因为这样的问题是您使用什么来确定它不起作用。
作为示例，在您的活动中使用您的代码以及以下内容：-
public class MainActivity extends AppCompatActivity {
DBHelper mDBHelper;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mDBHelper = new DBHelper(this);
mDBHelper.addInfo("UserFred","passwordforfred");
mDBHelper.addInfo("UserMary","passwordformary");
mDBHelper.updateInfo("1","UserWasFred","fred","2019-01-01","x");
mDBHelper.updateInfo("2","UserEasMary","Mary","2019-02-01","Y");
ArrayList<User> allusers = mDBHelper.readAllInfo();
for (User u: allusers) {
Log.d("USERINFO1","User is " + u.getUserName() + " DOB is " + u.getDateOfBirth());
}
ArrayList<User> auser = mDBHelper.readAllInfo("1","UserWasFred");
for (User u: auser) {
Log.d("USERINFO2","User is " + u.getUserName() + " DOB is " + u.getDateOfBirth());
}
mDBHelper.addInfo("UselessUser","useless");
allusers = mDBHelper.readAllInfo();
for (User u: allusers) {
Log.d("USERINFO3","User is " + u.getUserName() + " DOB is " + u.getDateOfBirth());
}
mDBHelper.deleteInfo("Uselessuser");
allusers = mDBHelper.readAllInfo();
for (User u: allusers) {
Log.d("USERINFO4","User is " + u.getUserName() + " DOB is " + u.getDateOfBirth());
}
mDBHelper.deleteInfo("3"); //<<<<<<<<<<< Works but userId passed
allusers = mDBHelper.readAllInfo();
for (User u: allusers) {
Log.d("USERINFO5","User is " + u.getUserName() + " DOB is " + u.getDateOfBirth());
}
}
}
日志的输出显示上述所有操作均符合预期：-
06-04 08:04:53.874 D/USERINFO1: User is UserEasMary DOB is 2019-02-01 06-04 08:04:53.874 D/USERINFO1: User is UserWasFred DOB is 2019-01-01 06-04 08:04:53.875 D/USERINFO2: User is UserWasFred DOB is 2019-01-01 06-04 08:04:53.880 D/USERINFO3: User is UselessUser DOB is null 06-04 08:04:53.880 D/USERINFO3: User is UserEasMary DOB is 2019-02-01 06-04 08:04:53.880 D/USERINFO3: User is UserWasFred DOB is 2019-01-01 06-04 08:04:53.880 D/USERINFO4: User is UselessUser DOB is null 06-04 08:04:53.880 D/USERINFO4: User is UserEasMary DOB is 2019-02-01 06-04 08:04:53.880 D/USERINFO4: User is UserWasFred DOB is 2019-01-01 06-04 08:04:53.887 D/USERINFO5: User is UserEasMary DOB is 2019-02-01 06-04 08:04:53.887 D/USERINFO5: User is UserWasFred DOB is 2019-01-01