Android OrmLite and androidormlite

Android OrmLite and androidormlite

Recently, I am using the ormlite framework for database operations. Here is a simple demo to learn.

1. Download the jar package

Here ormlite-core-5.0.jar and ormlite-android-5.0.jar are used

Place the downloaded jar package in the libs folder of our project.

2. Create an object class Object

Each object class corresponds to a table, and a Student class is created under the bean directory in our project.

Package com. item. jiejie. lite. db; import com. j256.ormlite. field. databaseField; import com. j256.ormlite. table. databaseTable;/*** defines the object class Bean, which represents a table * class to be persisted to the database. Before the class name, add @ DatabaseTable, to generate the corresponding table class members, add @ DatabaseField to generate the fields in the previous table * Note: the constructor * Created by jiejie on must have no parameters in the class to be persisted. */@ DatabaseTable (tableName = "tb_hello") public class Hello {@ DatabaseField (generatedId = true) private int id; @ DatabaseField (columnName = "name") private String name; @ DatabaseField (columnName = "sex") private String sex; @ DatabaseField (columnName = "age") private int age;/** common parameter * generatedId = true primary key, automatically Generated id the field under this annotation must be an integer (int long) * id = true primary key * unique = true unique constraint default false * columnName = "name" Table field name, the default variable name * canBeNull = false is a non-empty constraint. The default value is true. It can be null. If it is set to false, it cannot be null * foreign = true foreign key reference, the field cannot be of the original type. An object should be defined as a foreign key reference. In the class of the foreign key object, there must be an ID field (ID, generatedId, generatedIdSequence) * foreignAutoRefersh = true when using a foreign key reference, because the foreign key reference of ormlite uses an object, if you add this field, it will be queried, the * foreign key object data will be queried back. Otherwise, the foreign key data will only have a value for the primary key of the object, the remaining values are null * defaultValue = "James" default * index = true index creation default * uniqueIndex = true unique index default is false * // empty constructor must be required yes, otherwise, the database fails to be created. public Hello () {} public Hello (String name, String sex, int age) {this. name = name; this. sex = sex; this. age = age;} public String getName () {return name;} public void setName (String name) {this. name = name;} public String getSex () {return sex;} public void setSex (String sex) {this. sex = sex;} public int getAge () {return age;} public void setAge (int age) {this. age = age ;}@ Override public String toString () {return "Hello {" + "name = '" + name +' \ ''+ ", sex = '"+ sex +' \'' + ", age =" + age + '}';}}

3. compile our data helper class

Package com. item. jiejie. lite. db; import android. content. context; import android. database. sqlite. SQLiteDatabase; import android. util. log; import com. j256.ormlite. android. apptools. ormLiteSqliteOpenHelper; import com. j256.ormlite. dao. dao; import com. j256.ormlite. support. connectionSource; import com. j256.ormlite. table. tableUtils; import java. SQL. SQLException;/*** write DAO class * Created by jiejie on. */public class DataHelper extends OrmLiteSqliteOpenHelper {private static final String TABLE_NAME = "Hellotext. db ";/*** no helloDao table corresponds to a */private Dao <Hello, Integer> helloDao = null;/** constructor */public DataHelper (Context context) {super (context, TABLE_NAME, null, 1) ;}// create a data Table @ Override public void onCreate (SQLiteDatabase sqLiteDatabase, ConnectionSource connectionSource) {try {TableUtils. createTable (connectionSource, Hello. class); Log. d ("jiejie", "database created successfully");} catch (SQLException e) {e. printStackTrace (); Log. d ("jiejie", "database updated successfully") ;}// database update @ Override public void onUpgrade (SQLiteDatabase sqLiteDatabase, ConnectionSource connectionSource, int I, int i1) {try {TableUtils. dropTable (connectionSource, Hello. class, true); onCreate (sqLiteDatabase, connectionSource);} catch (SQLException e) {e. printStackTrace () ;}}/*** obtain the Helper * 1 for a single instance. privatize constructors first * 2. provide external static method * 3. in the method, it is determined that if the method already exists, it will not be created. If it does not exist, then it will always have only one DataHelper object * 4. to ensure thread security, you need to provide another thread security keyword synchronized */private static DataHelper instance; public static synchronized DataHelper getHeper (Context context) {if (instance = null) {synchronized (DataHelper. class) {if (instance = null) {instance = new DataHelper (context) ;}}return instance;} public Dao <Hello, Integer> getHelloDao () throws SQLException {if (helloDao = null) {helloDao = getDao (Hello. class);} return helloDao;} public synchronized void clearData (Class <Hello> clase) {try {TableUtils. clearTable (connectionSource, clase);} catch (SQLException e) {e. printStackTrace () ;}/ *** release resource */@ Override public void close () {super. close (); helloDao = null ;}}

4. Write our Dao class for addition, deletion, modification, and query operations

Package com. item. jiejie. lite. db; import android. content. context; import com. j256.ormlite. dao. dao; import com. j256.ormlite. support. databaseConnection; import java. SQL. SQLException; import java. SQL. savepoint; import java. util. arrayList; import java. util. list;/*** defines the data access object and adds, deletes, modifies, and queries the specified table * Created by jiejie on. */public class HelloDao {private Dao <Hello, Integer> helloDao; private DataHelper dataHelper;/*** constructor to obtain Database Help class instances, get the corresponding Dao * @ param context */public HelloDao (Context context) {try {dataHelper = DataHelper. getHeper (context); helloDao = dataHelper. getHelloDao ();} catch (SQLException e) {e. printStackTrace () ;}}/*** add a record * @ param hello */public void add (Hello hello) {try {helloDao. create (hello);} catch (SQLException e) {e. printStackTrace () ;}}/*** insert a large amount of data * enable transaction * disable automatic commit * @ param hellos */public void addList (List <Hello> hellos) {try {DatabaseConnection conn = helloDao. startThreadConnection (); Savepoint savepoint = conn. setSavePoint (null); helloDao. setAutoCommit (conn, false); for (Hello hello: hellos) {helloDao. createOrUpdate (hello);} conn. commit (savepoint); helloDao. endThreadConnection (conn);} catch (SQLException e) {e. printStackTrace () ;}}/*** delete a record * @ param hello */public void delete (Hello hello) {try {helloDao. delete (hello);} catch (SQLException e) {e. printStackTrace () ;}}/*** update a record * @ param hello */public void update (Hello hello) {try {helloDao. update (hello);} catch (SQLException e) {e. printStackTrace () ;}}/*** query a record * @ param id * @ return */public Hello queryForId (int id) {Hello hello = null; try {hello = helloDao. queryForId (id);} catch (SQLException e) {e. printStackTrace ();} return hello;}/*** query all records * @ return */public List <Hello> queryForAll () {List <Hello> hellos = new ArrayList <> (); try {hellos = helloDao. queryForAll ();} catch (SQLException e) {e. printStackTrace () ;}return hellos ;}}

5. Test

During the test, when I simulate inserting 3 W pieces of data, I found that different simulators have different insertion times, and some 9 s have to be nearly 10 s,

Maybe I still have some problems when writing and inserting big data.

Private class TaskDb extends AsyncTask <Integer, Void, Long >{@ Override protected void onPreExecute () {super. onPreExecute () ;}@ Override protected Long doInBackground (Integer... params) {long start = System. currentTimeMillis (); List <Hello> hList = new ArrayList <Hello> (); for (int I = 0; I <10000; I ++) {Hello hello = new Hello ("Hello" + I, "nan", I); hList. add (hello);} helloDao. addList (hList); long endTime = System. currentTimeMillis (); return endTime-start;} @ Override protected void onPostExecute (Long aLong) {super. onPostExecute (aLong); Log. d ("jiejie", "data loaded successfully" + aLong); Toast. makeText (MainActivity. this, "when data is loaded successfully" + aLong, Toast. LENGTH_SHORT ). show ();}}