Introduction to the Android ormlite framework

1. ormlite framework
1. Download the core package coreand android libraries from http://ormlite.com/releases/and then add two jarpackages to the project.
2. Stored data object entity
Public class Entity {
@ DatabaseField (generatedId = true) // The auto-increment primary key.
Int id;
@ DatabaseField // declare string as a database Field
String string;
Public Entity (){
// There must be a non-argument constructor in ormlite
}
...
}
Ormlite is used to configure the persistence parameters of the class through annotation. The common parameters are as follows:
1. Table Name: if not specified, the table name is the class name.
@ DatabaseTable (tableName = "dataTableName ")
2. Field: There are many properties that can be configured.
@ DatabaseField
(1) primary key:
@ DatabaseField (id = true)
(2) column name: If this parameter is not specified, it is the same as the variable name.
@ DatabaseField (columnName = "columnName ")
(3) Data Type: Generally, you do not need to specify the data type, which can be obtained according to the java class.
@ DatabaseField (dataType = DataType. INTEGER)
(4) default value:
@ DatabaseField (defaultValue = "0 ")
(5) Length: generally used for String type
@ DatabaseField (width = 13)
(6) can it be blank? The default value is True.
@ DatabaseField (canBeNull = false)
3. The data DataHelper class is required to create and manage the database. The DataHelper class inherits OrmLiteSqliteOpenHelper. The onCreate, onUpgrade, and close methods are implemented in overwriting.
@ Override
Public void onCreate (SQLiteDatabase db, ConnectionSource connectionSource ){
Try {
Log. e (DataHelper. class. getName (), "Start database creation ");
TableUtils. createTable (connectionSource, Entity. class );
Log. e (DataHelper. class. getName (), "database created successfully ");
} Catch (SQLException e ){
Log. e (DataHelper. class. getName (), "failed to create database", e );
}
}
@ Override
Public void onUpgrade (SQLiteDatabase db, ConnectionSource connectionSource, int arg2, int arg3 ){
Try {
TableUtils. dropTable (connectionSource, Entity. class, true );
OnCreate (db, connectionSource );
Log. e (DataHelper. class. getName (), "database updated ");
} Catch (SQLException e ){
Log. e (DataHelper. class. getName (), "failed to update database", e );
}
}
@ Override
Public void close (){
Super. close ();
}
4. The corresponding data Dao class is required, that is, the data access interface.
Public class EntityDao {
Public List findData (Dao Entitydao, int id) throws SQLException {
HashMap EntityMap = new HashMap ();
UserguideMap. put ("id", id );
List EntityLists = entityDao. queryForFieldValues (EntityMap );
Return EntityLists = null? Null: EntityLists;
}
Public void addEntity (Dao entityDao, String string) throws SQLException {
Entity = new Entity (string );
EntityDao. create (Entity );
}
}
5. Call
Ormlite can be used in two ways. One is to inherit the corresponding OrmLiteBaseActivity. but like xxxx Activity itself must inherit BaseActivity, so you must use another method: Add a method to activity to get helper, and add a method to onDestroy to close helper in time.
Private DataHelper dataHelper = null;
Private DataHelper getHelper (){
If (dataHelper = null ){
DataHelper = OpenHelperManager. getHelper (this, DataHelper. class );
}
Return dataHelper;
}
@ Override
Protected void onDestroy (){
// TODO Auto-generated method stub
Super. onDestroy ();
If (dataHelper! = Null ){
OpenHelperManager. releaseHelper ();
DataHelper = null;
}
}
The database operation implementation code is as follows:
EntityDao dao = new EntityDao ();
Try {
Dao dataDao = getHelper (). getDataDao ();
// Query operation call
List simpledataList = dao. findData (dataDao, 1 );
// Add operation call
Dao. addEntity (dataDao, "demotest ");
} Catch (SQLException e ){
E. printStackTrace ();