Android：如何创建自己的光标类？
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我在Android中使用Sqlite，并且要从数据库中获取值，请使用以下方法：
Cursor cursor = sqliteDatabase.rawQuery(\"select title,category from table\", null);
int columnIndexTitle = cursor.getColumnIndex(\"title\");
iny columnIndexCategory = cursor.getColumnIndex(\"category\");
cursor.moveToFirst();
while (cursor.moveToNext()) {
String title = cursor.getString(columnIndexTitle);
String category = cursor.getString(columnIndexCategory);
}
cursor.close();
getColumnIndex()
getString()
String title = cursor.getString(\"title\");
sqliteDatabase.rawQuery
没有找到相关结果
已邀请:
5 个回复
闯舱酮
夏瓤跋棘
与一起使用的最佳方法。在我的情况下，我需要向Cursor提供一个额外的属性，以携带更多的信息，所以我的用例与问题的内容并不完全相同。发表我的发现，希望对您有所帮助。 对我来说，最棘手的部分是SQLiteDatabase查询方法返回一个Cursor，我需要将自定义子类传递给Cursor。 我在Android API中找到了解决方案：使用CursorWrapper类。似乎正是为此目的而设计的。 班级：public class MyCustomCursor extends CursorWrapper { public MyCustomCursor(Cursor cursor) { super(cursor); } private int myAddedAttribute; public int getMyAddedAttribute() { return myAddedAttribute; } public void setMyAddedAttribute(int myAddedAttribute) { this.myAddedAttribute = myAddedAttribute; } }public MyCustomCursor getCursor(...) { SQLiteDatabase DB = ...; Cursor rawCursor = DB.query(...); MyCustomCursor myCursor = new MyCustomCursor(rawCursor); myCursor.setMyAddedAttribute(...); return myCursor; }蜂佬渺
class MartinCursor { private Cursor cursor; MartinCursor(Cursor cursor) { this.cursor = cursor; } String getString(String column) { .... } }class MartinCursorHelper { static String getString(Cursor cursor, String column) { .... } }补蹲农界维
bot，还有适用于的方法在数据库上运行查询并在第一行的第一列中返回值的实用程序方法。 就像是貉骂
public class ExtendedCursor extends AbstractCursor { /** The cursor to wrap. */ private final Cursor mCursor; /** The name of the additional column. */ private final String mColumnName; /** The value to be assigned to the additional column. */ private final Object mValue; /** * Creates a new cursor which extends the given cursor by adding a column with a constant value. * * @param cursor the cursor to extend * @param columnName the name of the additional column * @param value the value to be assigned to the additional column */ public ExtendedCursor(Cursor cursor, String columnName, Object value) { mCursor = cursor; mColumnName = columnName; mValue = value; } @Override public int getCount() { return mCursor.getCount(); } @Override public String[] getColumnNames() { String[] columnNames = mCursor.getColumnNames(); int length = columnNames.length; String[] extendedColumnNames = new String[length + 1]; System.arraycopy(columnNames, 0, extendedColumnNames, 0, length); extendedColumnNames[length] = mColumnName; return extendedColumnNames; }