如何在android中使用SQlite存储和检索特定用户的数据
[英]How to store and retrieve data for a particular user using SQlite in android
问题描述
我想保存用户凭据（名称），然后在该名称上我想为该特定用户保存一些数据。 我正在使用SQlite并且我已成功保存数据但我无法为特定用户制作它现在它正在为所有用户显示。 我的特定用户名目前保存在共享首选项中。 请告诉我适当的解决方案。
DB助手：
public class DBHelper extends SQLiteOpenHelper {
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_NAME = "NOTES";
public static final String USER_COLUMN_ID = "idu";
public static final String TABLE_USER_NAME = "name";
public static final String CREATE_TABLE_USER =
"CREATE TABLE " + TABLE_USER_NAME + "("
+ USER_COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT"
+ ")";
public DBHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(Notes.CREATE_TABLE_NOTE);
db.execSQL(CREATE_TABLE_USER);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
db.execSQL("DROP TABLE IF EXISTS " + TABLE_USER_NAME);
onCreate(db);
}
public long insertNote(String note) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(Notes.COLUMN_NOTE, note);
long id = db.insert(TABLE_NAME, null, values);
db.close();
return id;
}
public Notes getNote(long id) {
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.query(TABLE_NAME,
new String[]{Notes.NOTE_COLUMN_ID, Notes.COLUMN_NOTE},
Notes.NOTE_COLUMN_ID + "=?",
new String[]{String.valueOf(id)}, null, null, null, null);
if (cursor != null)
cursor.moveToFirst();
Notes notes = new Notes(
cursor.getInt(cursor.getColumnIndex(Notes.NOTE_COLUMN_ID)),
cursor.getString(cursor.getColumnIndex(Notes.COLUMN_NOTE)));
cursor.close();
return notes;
}
public List<Notes> getAllNotes() {
List<Notes> notes = new ArrayList<>();
String selectQuery = "SELECT * FROM " + TABLE_NAME + " ORDER BY " +
Notes.NOTE_COLUMN_ID + " DESC";
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
if (cursor.moveToFirst()) {
do {
Notes note = new Notes();
note.setId(cursor.getInt(cursor.getColumnIndex(Notes.NOTE_COLUMN_ID)));
note.setNote(cursor.getString(cursor.getColumnIndex(Notes.COLUMN_NOTE)));
notes.add(note);
} while (cursor.moveToNext());
}
db.close();
return notes;
}
public int getNotesCount() {
String countQuery = "SELECT * FROM " + TABLE_NAME;
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(countQuery, null);
int count = cursor.getCount();
cursor.close();
return count;
}
}
笔记：
public class Notes {
public static final String NOTE_COLUMN_ID = "id";
public static final String COLUMN_NOTE = "note";
public static final String TABLE_NAME = "notes";
private int id;
private String note;
public static final String CREATE_TABLE_NOTE =
"CREATE TABLE " + TABLE_NAME + "("
+ NOTE_COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT,"
+ COLUMN_NOTE + " TEXT"
+ ")";
public Notes() {
}
public Notes(int id, String note) {
this.id = id;
this.note = note;
}
public int getId() {
return id;
}
public String getNote() {
return note;
}
public void setNote(String note) {
this.note = note;
}
public void setId(int id) {
this.id = id;
}
}
分段
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_notes, container, false);
recyclerView = view.findViewById(R.id.recycler_view);
noNotesView = view.findViewById(R.id.empty_notes_view);
logout = view.findViewById(R.id.button_logout);
GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
.requestEmail()
.build();
mGoogleSignInClient = GoogleSignIn.getClient(getActivity(), gso);
GoogleSignInAccount acct = GoogleSignIn.getLastSignedInAccount(getActivity());
mUser = acct.getDisplayName().trim();
LoggedInSharedPreference.setGoogleUserId(getActivity(), mUser);
db = new DBHelper(getActivity());
user = db.insertUser(mUser);
notesList.addAll(db.getNotesByUser(user));
FloatingActionButton fab = (FloatingActionButton) view.findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
showNoteDialog(false, null, -1);
}
});
mAdapter = new NotesAdapter(getActivity(), notesList);
RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(getContext());
recyclerView.setLayoutManager(mLayoutManager);
recyclerView.setItemAnimator(new DefaultItemAnimator());
recyclerView.setAdapter(mAdapter);
toggleEmptyNotes();
recyclerView.addOnItemTouchListener(new NotesItemListener(getActivity(),
recyclerView, new NotesItemListener.ClickListener() {
@Override
public void onClick(View view, final int position) {
}
@Override
public void onLongClick(View view, int position) {
showActionsDialog(position);
}
}));
return view;
}
private void createNote(String note, long user) {
long id = db.insertNote(note, user);
Notes n = db.getNote(id);
if (n != null) {
notesList.add(0, n);
mAdapter.notifyDataSetChanged();
toggleEmptyNotes();
}
}
private void updateNote(String note, int position) {
Notes n = notesList.get(position);
n.setNote(note);
db.updateNote(n);
notesList.set(position, n);
mAdapter.notifyItemChanged(position);
toggleEmptyNotes();
}
private void deleteNote(int position) {
db.deleteNote(notesList.get(position));
notesList.remove(position);
mAdapter.notifyItemRemoved(position);
toggleEmptyNotes();
}
private void showActionsDialog(final int position) {
CharSequence charSequences[] = new CharSequence[]{"Edit", "Delete"};
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
builder.setTitle("Select");
builder.setItems(charSequences, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
if (which == 0) {
showNoteDialog(true, notesList.get(position), position);
} else {
deleteNote(position);
}
}
});
builder.show();
}
private void showNoteDialog(final boolean shouldUpdate, final Notes notes, final int position) {
LayoutInflater layoutInflaterAndroid = LayoutInflater.from(getContext());
View view = layoutInflaterAndroid.inflate(R.layout.note_dialog, null);
AlertDialog.Builder alertDialogBuilderUserInput = new AlertDialog.Builder(getActivity());
alertDialogBuilderUserInput.setView(view);
final EditText inputNote = view.findViewById(R.id.notes);
TextView dialogTitle = view.findViewById(R.id.dialog_title);
dialogTitle.setText(!shouldUpdate ? getString(R.string.new_note) : getString(R.string.edit_note));
if (shouldUpdate && notes != null) {
inputNote.setText(notes.getNote());
}
alertDialogBuilderUserInput
.setCancelable(false)
.setPositiveButton(shouldUpdate ? "update" : "save", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialogBox, int id) {
}
})
.setNegativeButton("cancel",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialogBox, int id) {
dialogBox.cancel();
}
});
final AlertDialog alertDialog = alertDialogBuilderUserInput.create();
alertDialog.show();
alertDialog.getButton(AlertDialog.BUTTON_POSITIVE).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (TextUtils.isEmpty(inputNote.getText().toString())) {
Toast.makeText(getActivity(), "Add Note", Toast.LENGTH_SHORT).show();
return;
} else {
alertDialog.dismiss();
}
if (shouldUpdate && notes != null) {
updateNote(inputNote.getText().toString(), position);
} else {
createNote(inputNote.getText().toString(), user);
}
}
});
}
}
1 个解决方案
解决方案1
0 已采纳 2019-06-19 20:56:30
您似乎需要Note（子）和它的用户（父）之间的关系。 假设一个Note只有一个用户（谁拥有该笔记）。 然后，您可以在存储Notes的表中添加一列。
由于User表具有使用INTEGER PRIMARY KEY定义的id列，因此该列是关系的理想候选者（它是索引的，也是唯一的（隐式））。 它将是一个整数值（在java中可能很长）。
为了保持一致，你需要为列名定义一个常量，所以添加： -
public static final String NOTE_COLUMN_USERMAP = "usermap";
然后，您可以定义更改CREATE_TABLE_NOTE常量以包含
+ NOTE_COLUMN_USERMAP + " INTEGER "; //<<<<<<<<<comma if needed after INTEGER
或者，如果您可能想要引入FOREIGN KEY约束并使用
+ NOTE_COLUMN_USERMAP + "INTEGER REFERENCES " + DBHelper.TABLE_USER_NAME + "(" + USER_COLUMN_ID + ") ON DELETE CASCADE ON UPDATE CASCADE "; //<<<<<<<<<comma if needed after 2nd CASCADE
- 有关外键的更多信息，请参阅SQLite外键支持
您将对Notes类/对象进行免费更改，以存储类中拥有用户的用户ID（地图/关系）（最好是长），并为id的id添加一个getter和setter。用户。 您还应该有一个构造函数，其中包含从数据库中检索Note时要使用的用户ID。
然后，您需要更改DBHelper的方法以满足额外的列。 例如
insertNote方法可能变成： -
public long insertNote(String note, long userMap) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(Notes.COLUMN_NOTE, note);
values.put(Notes.NOTE_COLUMN_USERMAP,userMap);
long id = db.insert(TABLE_NAME, null, values);
db.close();
return id;
}
getNotes方法可能变为： -
public Notes getNote(long id) {
Notes notes;
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.query(TABLE_NAME,
new String[]{Notes.NOTE_COLUMN_ID, Notes.COLUMN_NOTE,Notes.NOTE_COLUMN_USERMAP},
Notes.NOTE_COLUMN_ID + "=?",
new String[]{String.valueOf(id)}, null, null, null, null);
if (cursor.moveToFirst()) {
notes = new Notes(
cursor.getInt(cursor.getColumnIndex(Notes.NOTE_COLUMN_ID)),
cursor.getString(cursor.getColumnIndex(Notes.COLUMN_NOTE)),
cursor.getLong(cursor.getColumnIndex(Notes.NOTE_COLUMN_USERMAP))
);
}
cursor.close();
return notes;
}
- 请注意，上面假设构造函数具有用户映射的值作为最后一个。
- 注意检查Cursor的null是没用的，从SQliteDatabase方法返回时它永远不会为null。 因此，上面使用moveToFirst方法的结果来确定行是否存在。
- 注意，如果找不到Note，上面的内容将返回null（而不是失败）。
但我无法为特定用户制作它现在它正在为所有用户显示
在上面之后，您可以编写一个包含基于usermap列的WHERE子句的查询。
例如getNotesByUser可能是： -
public List<Notes> getNotesByUser(long usermap) {
List<Notes> notes = new ArrayList<>();
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.query(TABLE_NAME,
new String[]{Notes.NOTE_COLUMN_ID, Notes.COLUMN_NOTE,Notes.NOTE_COLUMN_USERMAP},
Notes.NOTE_COLUMN_USERMAP + "=?",
new String[]{String.valueOf(usermap)}, null, null, null, null);
while(cursor.moveToNext()) {
notes.add(new Notes(cursor.getInt(cursor.getColumnIndex(Notes.NOTE_COLUMN_ID)),
cursor.getString(cursor.getColumnIndex(Notes.COLUMN_NOTE)),
cursor.getLong(cursor.getColumnIndex(Notes.NOTE_COLUMN_USERMAP)))
);
}
cursor.close();
return notes;
}
- 注意更简单的while循环，即当无法进行移动时（即，在最后一行之后）， moveToNext方法返回false，因此不需要moveToFirst，因为它将为第一行执行此操作。
注意以上是原则上的代码。 它尚未经过测试，也未被运行，因此可能包含一些错误。 它已作为指南提供。
工作实例
以下是基于您的代码和上述答案的基本工作示例。 此外，还在名称表中添加了一个用于名称的附加列。
该应用程序添加了两个用户（Fred和Mary），然后为每个用户添加了2个备注。 然后它会提取所有音符，然后是Fred的所有音符，然后是Mary。 然后将3组提取的输出输出到日志。
导致 ：-
对于所有用户的所有笔记： -
06-20 12:29:22.901 2401-2401/seso56674777notes D/LOGNOTEALL: Note isMy Second Note ID is 4 Owned by User who's ID is 2 06-20 12:29:22.901 2401-2401/seso56674777notes D/LOGNOTEALL: Note isMy Second Note ID is 3 Owned by User who's ID is 1 06-20 12:29:22.901 2401-2401/seso56674777notes D/LOGNOTEALL: Note isMy First Note ID is 2 Owned by User who's ID is 2 06-20 12:29:22.901 2401-2401/seso56674777notes D/LOGNOTEALL: Note isMy First Note ID is 1 Owned by User who's ID is 1
对于Fred（用户ID为1）： -
06-20 12:29:22.901 2401-2401/seso56674777notes D/LOGNOTEFRED: Note isMy First Note ID is 1 Owned by User who's ID is 1 06-20 12:29:22.901 2401-2401/seso56674777notes D/LOGNOTEFRED: Note isMy Second Note ID is 3 Owned by User who's ID is 1
对于玛丽（用户的身份证号码是2）： -
06-20 12:29:22.901 2401-2401/seso56674777notes D/LOGNOTEMARY: Note isMy First Note ID is 2 Owned by User who's ID is 2 06-20 12:29:22.901 2401-2401/seso56674777notes D/LOGNOTEMARY: Note isMy Second Note ID is 4 Owned by User who's ID is 2
编码
Notes.java
public class Notes {
public static final String TABLE_NAME = "notes";
public static final String NOTE_COLUMN_ID = BaseColumns._ID;
public static final String COLUMN_NOTE = "note";
public static final String NOTE_COLUMN_USERMAP = "usermap";
public static final String CREATE_TABLE_NOTE = "CREATE TABLE IF NOT EXISTS " + TABLE_NAME + "(" +
NOTE_COLUMN_ID + " INTEGER PRIMARY KEY, " +
COLUMN_NOTE + " TEXT, " +
NOTE_COLUMN_USERMAP + " INTEGER " +
"REFERENCES " + DBHelper.TABLE_USER_NAME + "(" + DBHelper.USER_COLUMN_ID + ") " +
"ON DELETE CASCADE ON UPDATE CASCADE" +
")";
public Notes(int id, String note, long usermap) {
this.id = id;
this.note = note;
this.usermap = usermap;
}
public Notes() {}
private int id;
private String note;
private long usermap;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getNote() {
return note;
}
public void setNote(String note) {
this.note = note;
}
public long getUsermap() {
return usermap;
}
public void setUsermap(long usermap) {
this.usermap = usermap;
}
}
DBHelper.java
public class DBHelper extends SQLiteOpenHelper {
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_NAME = "NOTES";
public static final String USER_COLUMN_ID = "idu";
public static final String TABLE_USER_NAME = "name";
public static final String USER_COLUMN_NAME = TABLE_USER_NAME;
public static final String CREATE_TABLE_USER =
"CREATE TABLE " + TABLE_USER_NAME + "("
+ USER_COLUMN_ID + " INTEGER PRIMARY KEY,"
+ USER_COLUMN_NAME + " TEXT UNIQUE "
+ ")";
public DBHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(Notes.CREATE_TABLE_NOTE);
db.execSQL(CREATE_TABLE_USER);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + Notes.TABLE_NAME);
db.execSQL("DROP TABLE IF EXISTS " + TABLE_USER_NAME);
onCreate(db);
}
@Override
public void onConfigure(SQLiteDatabase db) {
super.onConfigure(db);
db.setForeignKeyConstraintsEnabled(true);
}
public long insertUser(String username) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues cv = new ContentValues();
cv.put(USER_COLUMN_NAME,username);
return db.insert(TABLE_USER_NAME,null,cv);
}
public long insertNote(String note, long usermap) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(Notes.COLUMN_NOTE, note);
values.put(Notes.NOTE_COLUMN_USERMAP,usermap);
long id = db.insert(Notes.TABLE_NAME, null, values);
db.close();
return id;
}
public Notes getNote(long id) {
Notes notes = null;
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.query(Notes.TABLE_NAME,
new String[]{Notes.NOTE_COLUMN_ID, Notes.COLUMN_NOTE, Notes.NOTE_COLUMN_USERMAP},
Notes.NOTE_COLUMN_ID + "=?",
new String[]{String.valueOf(id)},
null, null, null, null
);
if (cursor.moveToFirst()) {
notes = new Notes(
cursor.getInt(cursor.getColumnIndex(Notes.NOTE_COLUMN_ID)),
cursor.getString(cursor.getColumnIndex(Notes.COLUMN_NOTE)),
cursor.getLong(cursor.getColumnIndex(Notes.NOTE_COLUMN_USERMAP))
);
}
cursor.close();
return notes;
}
public List<Notes> getAllNotes() {
List<Notes> notes = new ArrayList<>();
String selectQuery = "SELECT * FROM " + Notes.TABLE_NAME + " ORDER BY " +
Notes.NOTE_COLUMN_ID + " DESC";
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
while (cursor.moveToNext()) {
Notes note = new Notes();
note.setId(cursor.getInt(cursor.getColumnIndex(Notes.NOTE_COLUMN_ID)));
note.setNote(cursor.getString(cursor.getColumnIndex(Notes.COLUMN_NOTE)));
note.setUsermap(cursor.getLong(cursor.getColumnIndex(Notes.NOTE_COLUMN_USERMAP)));
notes.add(note);
}
db.close();
return notes;
}
public List<Notes> getNotesByUser(long usermap) {
List<Notes> notes = new ArrayList<>();
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.query(Notes.TABLE_NAME,
new String[]{Notes.NOTE_COLUMN_ID, Notes.COLUMN_NOTE,Notes.NOTE_COLUMN_USERMAP},
Notes.NOTE_COLUMN_USERMAP + "=?",
new String[]{String.valueOf(usermap)}, null, null, null, null);
while(cursor.moveToNext()) {
notes.add(new Notes(cursor.getInt(cursor.getColumnIndex(Notes.NOTE_COLUMN_ID)),
cursor.getString(cursor.getColumnIndex(Notes.COLUMN_NOTE)),
cursor.getLong(cursor.getColumnIndex(Notes.NOTE_COLUMN_USERMAP)))
);
}
cursor.close();
return notes;
}
public int getNotesCount() {
String countQuery = "SELECT * FROM " + Notes.TABLE_NAME;
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(countQuery, null);
int count = cursor.getCount();
cursor.close();
return count;
}
}
- 注意覆盖onConfigure方法的附加项，这将打开ForeignKey支持（否则将忽略外键定义）。
- 注意AUTOINCREMENT已被删除，没有必要并且有开销。
- 请注意，为名称表添加了name列，并且它具有unqiue约束。
MainActivity.java
这将所有这些结合在一起
public class MainActivity extends AppCompatActivity {
DBHelper mDBHlpr;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mDBHlpr = new DBHelper(this);
long user1 = mDBHlpr.insertUser("Fred");
long user2 = mDBHlpr.insertUser("Mary");
Notes n1 = new Notes(-1,"My First Note",-1);
Notes n2 = new Notes(-1,"My Second Note",-1);
if (mDBHlpr.getNotesCount() < 1) {
mDBHlpr.insertNote(n1.getNote(), user1);
mDBHlpr.insertNote(n1.getNote(), user2);
mDBHlpr.insertNote(n2.getNote(), user1);
mDBHlpr.insertNote(n2.getNote(), user2);
}
List<Notes> allusers = mDBHlpr.getAllNotes();
List<Notes> fredsnotes = mDBHlpr.getNotesByUser(user1);
List<Notes> marysnotes = mDBHlpr.getNotesByUser(user2);
for (Notes n: allusers) {
logNote("ALL",n);
}
for (Notes n: fredsnotes) {
logNote("FRED",n);
}
for (Notes n: marysnotes) {
logNote("MARY",n);
}
}
private void logNote(String type, Notes n) {
Log.d("LOGNOTE" + type,"Note is" + n.getNote() + "\n\t ID is " + String.valueOf(n.getId()) + "\n\t" + "Owned by User who's ID is " + String.valueOf(n.getUsermap()));
}
}
- 请注意，上述内容仅适用于运行一次。 如果随后运行Fred和Mary的id都将为-1，因为由于名称重复而不会添加行，因此将不会提取到fredsnotes和marynotes中的注释。
Android：如何在sharedpreferences中存储和检索Hashmap数据？
[英]Android:how to store and retrieve Hashmap data in sharedpreferences?
声明:本站的技术帖子网页，遵循CC BY-SA 4.0协议，如果您需要转载，请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.