Room 公开了哪些 SQLite 方法？
Which SQLite methods are exposed by Room?
我正在开发一个高度依赖 database 的应用程序。因此，为此，我决定使用 Room。但在开始之前，我几乎没有什么顾虑，我试图找到但没有成功。
- 我可以更改房间中的页面和缓存大小吗？
NGQP有房间吗？- 可以
Vaccum吗？
- 我可以查询已经创建的 SQLite 数据库吗？也就是说我的sd卡上已经有数据库了，我可以直接用room吗？
- 我可以在房间里使用 Pragmas 吗？
回复 2 - NGQP 是否有空间？
我相信 NGQP 基本上依赖于 SQLIte 版本，如果您使用的 SQLite 版本有它，它应该可以工作，即 3.8.0 所以 API21+ 但是
Some device manufacturers include different versions of SQLite on
their devices.android.database.sqlite
This may also be of interest - The Next-Generation Query Planner
Re 4 - 我可以查询已经创建的 SQLite 数据库吗？即我的sd卡上已经有数据库了，我可以直接用room吗？
这可能很有趣
当然没有理由不能在 Room 之外打开数据库，例如有一个 SQLiteOpenHelper 的子class。但是我想 房间警察 :) 可以想出很多你不应该这样做的理由。
回复 1、3 和 5
我相信您可以覆盖扩展 RoomDatabase class 的 class 的 init 方法，这是数据库打开前的安全位置RoomDatabase 子class.
例如:-
@Database(entities = Todo.class, version = 1, exportSchema = false)
public abstract class TodoDatabase extends RoomDatabase {
public abstract TodoDAO todoDAO();
@Override
public void init(DatabaseConfiguration dbconfig) {
Log.d("ROOM_INIT","Room init invoked - Databse name is " + dbconfig.name);
String dbpath = (dbconfig.context).getDatabasePath(dbconfig.name).getPath();
if (ifDBExists(dbpath)) {
SQLiteDatabase db = SQLiteDatabase.openDatabase(dbpath, null,Context.MODE_PRIVATE);
actionCustomConfiguration(db);
db.close();
}
super.init(dbconfig);
}
private boolean ifDBExists(String dbpath) {
File db = new File(dbpath);
if(db.exists()) return true;
File dir = new File(db.getParent());
if (!dir.exists()) {
dir.mkdirs();
}
return false;
}
private void actionCustomConfiguration(SQLiteDatabase db) {
Log.d("ROOM_CUSTCONFIG","Custom Configuration invoked.");
db.execSQL("VACUUM");
logDatabaseInfo(db);
}
private static void logDatabaseInfo(SQLiteDatabase db) {
// Issue PRAGMA database_list commnand
Cursor dblcsr = db.rawQuery(PRAGMA_STATEMENT + PRAGMA_DATABASELIST,null);
// Write databases to the log
while (dblcsr.moveToNext()) {
Log.d(CSU_TAG,"DatabaseList Row " + Integer.toString(dblcsr.getPosition() + 1) +
" Name=" + dblcsr.getString(dblcsr.getColumnIndex(PRAGMA_DBLIST_NAME_COL)) +
" File=" + dblcsr.getString(dblcsr.getColumnIndex(PRAGMA_DBLIST_FILE_COL))
);
}
dblcsr.close();
// Issue PRAGMA user_version to get the version and write to the log
//Note! to set user_version use execSQL not rawQuery
Cursor uvcsr = db.rawQuery(PRAGMA_STATEMENT + PRAGMA_USERVERSION,null);
while (uvcsr.moveToNext()) {
Log.d(CSU_TAG,"Database Version = " +
Integer.toString(uvcsr.getInt(uvcsr.getColumnIndex(PRAGMA_USERVERSION))));
}
uvcsr.close();
// Select all table entry rows from sqlite_master
Cursor tlcsr = db.rawQuery("SELECT * FROM " +
SQLITE_MASTER + " WHERE " +
SM_TABLE_TYPE_COLUMN + "='" + SM_TYPE_TABLE + "'"
,null);
// For each table write table information to the log
// (inner loop gets column info per table)
while (tlcsr.moveToNext()) {
String current_table = tlcsr.getString(tlcsr.getColumnIndex(SM_TABLENAME_COLUMN));
Log.d(CSU_TAG,
"Table Name = " + current_table +
" Created Using = " + tlcsr.getString(tlcsr.getColumnIndex(SM_SQL_COLUMN)),
null
);
// Issue PRAGMA tabel_info for the current table
Cursor ticsr = db.rawQuery(PRAGMA_STATEMENT + PRAGMA_TABLEINFO +
"(" + current_table + ")",
null
);
// Write column info (see headings below) to the log
while (ticsr.moveToNext()) {
Log.d(CSU_TAG,"Table = " +
current_table +
" ColumnName = " +
ticsr.getString(ticsr.getColumnIndex(PRAGMA_TABLEINFO_NAME_COl)) +
" ColumnType = " +
ticsr.getString(ticsr.getColumnIndex(PRAGMA_TABLEINFO_TYPE_COL)) +
" Default Value = " +
ticsr.getString(ticsr.getColumnIndex(PRAGMA_TABLEINFO_DEFAULTVALUE_COL)) +
" PRIMARY KEY SEQUENCE = " + Integer.toString(
ticsr.getInt(ticsr.getColumnIndex(PRAGMA_TABLEINFO_PRIMARYKEY_COL))
)
);
}
ticsr.close();
}
tlcsr.close();
}
}
上面的示例输出：-
12-18 02:21:33.157 1607-1607/mjt.roomtodo D/ROOM_INIT: Room init invoked - Databse name is tododb
12-18 02:21:33.157 1607-1607/mjt.roomtodo D/ROOM_CUSTCONFIG: Custom Configuration invoked.
12-18 02:21:33.165 1607-1607/mjt.roomtodo D/SQLITE_CSU: DatabaseList Row 1 Name=main File=/data/data/mjt.roomtodo/databases/tododb
12-18 02:21:33.165 1607-1607/mjt.roomtodo D/SQLITE_CSU: Database Version = 1
12-18 02:21:33.169 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table Name = android_metadata Created Using = CREATE TABLE android_metadata (locale TEXT)
12-18 02:21:33.169 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table = android_metadata ColumnName = locale ColumnType = TEXT Default Value = null PRIMARY KEY SEQUENCE = 0
12-18 02:21:33.169 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table Name = room_master_table Created Using = CREATE TABLE room_master_table (id INTEGER PRIMARY KEY,identity_hash TEXT)
12-18 02:21:33.169 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table = room_master_table ColumnName = id ColumnType = INTEGER Default Value = null PRIMARY KEY SEQUENCE = 1
12-18 02:21:33.169 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table = room_master_table ColumnName = identity_hash ColumnType = TEXT Default Value = null PRIMARY KEY SEQUENCE = 0
12-18 02:21:33.169 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table Name = Todo Created Using = CREATE TABLE `Todo` (`_id` INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, `description` TEXT, `starts` INTEGER NOT NULL, `finishes` INTEGER NOT NULL, `status_flags` INTEGER NOT NULL, `repeat_code` INTEGER NOT NULL, `repeat_multiplier` INTEGER NOT NULL, `added_count` INTEGER NOT NULL)
12-18 02:21:33.169 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table = Todo ColumnName = _id ColumnType = INTEGER Default Value = null PRIMARY KEY SEQUENCE = 1
12-18 02:21:33.169 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table = Todo ColumnName = description ColumnType = TEXT Default Value = null PRIMARY KEY SEQUENCE = 0
12-18 02:21:33.169 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table = Todo ColumnName = starts ColumnType = INTEGER Default Value = null PRIMARY KEY SEQUENCE = 0
12-18 02:21:33.169 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table = Todo ColumnName = finishes ColumnType = INTEGER Default Value = null PRIMARY KEY SEQUENCE = 0
12-18 02:21:33.169 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table = Todo ColumnName = status_flags ColumnType = INTEGER Default Value = null PRIMARY KEY SEQUENCE = 0
12-18 02:21:33.173 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table = Todo ColumnName = repeat_code ColumnType = INTEGER Default Value = null PRIMARY KEY SEQUENCE = 0
12-18 02:21:33.173 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table = Todo ColumnName = repeat_multiplier ColumnType = INTEGER Default Value = null PRIMARY KEY SEQUENCE = 0
12-18 02:21:33.173 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table = Todo ColumnName = added_count ColumnType = INTEGER Default Value = null PRIMARY KEY SEQUENCE = 0
12-18 02:21:33.173 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table Name = sqlite_sequence Created Using = CREATE TABLE sqlite_sequence(name,seq)
12-18 02:21:33.173 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table = sqlite_sequence ColumnName = name ColumnType = Default Value = null PRIMARY KEY SEQUENCE = 0
12-18 02:21:33.173 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table = sqlite_sequence ColumnName = seq ColumnType = Default Value = null PRIMARY KEY SEQUENCE = 0
我正在开发一个高度依赖 database 的应用程序。因此，为此，我决定使用 Room。但在开始之前，我几乎没有什么顾虑，我试图找到但没有成功。
- 我可以更改房间中的页面和缓存大小吗？
NGQP有房间吗？- 可以
Vaccum吗？ - 我可以查询已经创建的 SQLite 数据库吗？也就是说我的sd卡上已经有数据库了，我可以直接用room吗？
- 我可以在房间里使用 Pragmas 吗？
回复 2 - NGQP 是否有空间？
我相信 NGQP 基本上依赖于 SQLIte 版本，如果您使用的 SQLite 版本有它，它应该可以工作，即 3.8.0 所以 API21+ 但是
Some device manufacturers include different versions of SQLite on their devices.android.database.sqlite
This may also be of interest - The Next-Generation Query Planner
Re 4 - 我可以查询已经创建的 SQLite 数据库吗？即我的sd卡上已经有数据库了，我可以直接用room吗？
这可能很有趣
当然没有理由不能在 Room 之外打开数据库，例如有一个 SQLiteOpenHelper 的子class。但是我想 房间警察 :) 可以想出很多你不应该这样做的理由。
回复 1、3 和 5
我相信您可以覆盖扩展 RoomDatabase class 的 class 的 init 方法，这是数据库打开前的安全位置RoomDatabase 子class.
例如:-
@Database(entities = Todo.class, version = 1, exportSchema = false)
public abstract class TodoDatabase extends RoomDatabase {
public abstract TodoDAO todoDAO();
@Override
public void init(DatabaseConfiguration dbconfig) {
Log.d("ROOM_INIT","Room init invoked - Databse name is " + dbconfig.name);
String dbpath = (dbconfig.context).getDatabasePath(dbconfig.name).getPath();
if (ifDBExists(dbpath)) {
SQLiteDatabase db = SQLiteDatabase.openDatabase(dbpath, null,Context.MODE_PRIVATE);
actionCustomConfiguration(db);
db.close();
}
super.init(dbconfig);
}
private boolean ifDBExists(String dbpath) {
File db = new File(dbpath);
if(db.exists()) return true;
File dir = new File(db.getParent());
if (!dir.exists()) {
dir.mkdirs();
}
return false;
}
private void actionCustomConfiguration(SQLiteDatabase db) {
Log.d("ROOM_CUSTCONFIG","Custom Configuration invoked.");
db.execSQL("VACUUM");
logDatabaseInfo(db);
}
private static void logDatabaseInfo(SQLiteDatabase db) {
// Issue PRAGMA database_list commnand
Cursor dblcsr = db.rawQuery(PRAGMA_STATEMENT + PRAGMA_DATABASELIST,null);
// Write databases to the log
while (dblcsr.moveToNext()) {
Log.d(CSU_TAG,"DatabaseList Row " + Integer.toString(dblcsr.getPosition() + 1) +
" Name=" + dblcsr.getString(dblcsr.getColumnIndex(PRAGMA_DBLIST_NAME_COL)) +
" File=" + dblcsr.getString(dblcsr.getColumnIndex(PRAGMA_DBLIST_FILE_COL))
);
}
dblcsr.close();
// Issue PRAGMA user_version to get the version and write to the log
//Note! to set user_version use execSQL not rawQuery
Cursor uvcsr = db.rawQuery(PRAGMA_STATEMENT + PRAGMA_USERVERSION,null);
while (uvcsr.moveToNext()) {
Log.d(CSU_TAG,"Database Version = " +
Integer.toString(uvcsr.getInt(uvcsr.getColumnIndex(PRAGMA_USERVERSION))));
}
uvcsr.close();
// Select all table entry rows from sqlite_master
Cursor tlcsr = db.rawQuery("SELECT * FROM " +
SQLITE_MASTER + " WHERE " +
SM_TABLE_TYPE_COLUMN + "='" + SM_TYPE_TABLE + "'"
,null);
// For each table write table information to the log
// (inner loop gets column info per table)
while (tlcsr.moveToNext()) {
String current_table = tlcsr.getString(tlcsr.getColumnIndex(SM_TABLENAME_COLUMN));
Log.d(CSU_TAG,
"Table Name = " + current_table +
" Created Using = " + tlcsr.getString(tlcsr.getColumnIndex(SM_SQL_COLUMN)),
null
);
// Issue PRAGMA tabel_info for the current table
Cursor ticsr = db.rawQuery(PRAGMA_STATEMENT + PRAGMA_TABLEINFO +
"(" + current_table + ")",
null
);
// Write column info (see headings below) to the log
while (ticsr.moveToNext()) {
Log.d(CSU_TAG,"Table = " +
current_table +
" ColumnName = " +
ticsr.getString(ticsr.getColumnIndex(PRAGMA_TABLEINFO_NAME_COl)) +
" ColumnType = " +
ticsr.getString(ticsr.getColumnIndex(PRAGMA_TABLEINFO_TYPE_COL)) +
" Default Value = " +
ticsr.getString(ticsr.getColumnIndex(PRAGMA_TABLEINFO_DEFAULTVALUE_COL)) +
" PRIMARY KEY SEQUENCE = " + Integer.toString(
ticsr.getInt(ticsr.getColumnIndex(PRAGMA_TABLEINFO_PRIMARYKEY_COL))
)
);
}
ticsr.close();
}
tlcsr.close();
}
}
上面的示例输出：-
12-18 02:21:33.157 1607-1607/mjt.roomtodo D/ROOM_INIT: Room init invoked - Databse name is tododb
12-18 02:21:33.157 1607-1607/mjt.roomtodo D/ROOM_CUSTCONFIG: Custom Configuration invoked.
12-18 02:21:33.165 1607-1607/mjt.roomtodo D/SQLITE_CSU: DatabaseList Row 1 Name=main File=/data/data/mjt.roomtodo/databases/tododb
12-18 02:21:33.165 1607-1607/mjt.roomtodo D/SQLITE_CSU: Database Version = 1
12-18 02:21:33.169 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table Name = android_metadata Created Using = CREATE TABLE android_metadata (locale TEXT)
12-18 02:21:33.169 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table = android_metadata ColumnName = locale ColumnType = TEXT Default Value = null PRIMARY KEY SEQUENCE = 0
12-18 02:21:33.169 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table Name = room_master_table Created Using = CREATE TABLE room_master_table (id INTEGER PRIMARY KEY,identity_hash TEXT)
12-18 02:21:33.169 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table = room_master_table ColumnName = id ColumnType = INTEGER Default Value = null PRIMARY KEY SEQUENCE = 1
12-18 02:21:33.169 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table = room_master_table ColumnName = identity_hash ColumnType = TEXT Default Value = null PRIMARY KEY SEQUENCE = 0
12-18 02:21:33.169 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table Name = Todo Created Using = CREATE TABLE `Todo` (`_id` INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, `description` TEXT, `starts` INTEGER NOT NULL, `finishes` INTEGER NOT NULL, `status_flags` INTEGER NOT NULL, `repeat_code` INTEGER NOT NULL, `repeat_multiplier` INTEGER NOT NULL, `added_count` INTEGER NOT NULL)
12-18 02:21:33.169 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table = Todo ColumnName = _id ColumnType = INTEGER Default Value = null PRIMARY KEY SEQUENCE = 1
12-18 02:21:33.169 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table = Todo ColumnName = description ColumnType = TEXT Default Value = null PRIMARY KEY SEQUENCE = 0
12-18 02:21:33.169 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table = Todo ColumnName = starts ColumnType = INTEGER Default Value = null PRIMARY KEY SEQUENCE = 0
12-18 02:21:33.169 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table = Todo ColumnName = finishes ColumnType = INTEGER Default Value = null PRIMARY KEY SEQUENCE = 0
12-18 02:21:33.169 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table = Todo ColumnName = status_flags ColumnType = INTEGER Default Value = null PRIMARY KEY SEQUENCE = 0
12-18 02:21:33.173 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table = Todo ColumnName = repeat_code ColumnType = INTEGER Default Value = null PRIMARY KEY SEQUENCE = 0
12-18 02:21:33.173 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table = Todo ColumnName = repeat_multiplier ColumnType = INTEGER Default Value = null PRIMARY KEY SEQUENCE = 0
12-18 02:21:33.173 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table = Todo ColumnName = added_count ColumnType = INTEGER Default Value = null PRIMARY KEY SEQUENCE = 0
12-18 02:21:33.173 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table Name = sqlite_sequence Created Using = CREATE TABLE sqlite_sequence(name,seq)
12-18 02:21:33.173 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table = sqlite_sequence ColumnName = name ColumnType = Default Value = null PRIMARY KEY SEQUENCE = 0
12-18 02:21:33.173 1607-1607/mjt.roomtodo D/SQLITE_CSU: Table = sqlite_sequence ColumnName = seq ColumnType = Default Value = null PRIMARY KEY SEQUENCE = 0