Persistence using ormlite in Android (1) -- HelloOrmLite

 

Android has built-in sqlite, but the common development language java is object-oriented, while the database is relational, every conversion between the two is very troublesome (I am not familiar with the SQL language ). Java Web development has a lot of orm frameworks, but it is troublesome to directly use them on Android. I tried to find the Android orm framework. To tell the truth, there are several more.

The implementation considerations are: androrm Official Website: http://androrm.the-pixelpla.net/to put it bluntly, I have no idea about this. I have two packages in total. One is the dependency package: Apache Commons-Lang (2.6) and the other is the main package: androrm. jar cannot be used no matter how it is downloaded...

Then we considered db4o.

Official Website: http://www.db4o.com/

According to the official website, Android is supported, but I think the package is a little large, but the speed is a little slow.

 

The last thing we see is ormlite.

Official Website: http://ormlite.com/

A total of two packages: one is the ormlite-core-4.24.jar, the other is the ormlite-android-4.24.jar

Download to: http://ormlite.com/releases/ from the following URL

Follow the Convention below to create a Hello world Android project: HelloOrmLite

Add Folder: libs, copy the two required packages to it. Add reference

Create a model: Hello. java

Package cn. sdx. model;

 

Import com. j256.ormlite. field. DatabaseField;

 

Public class Hello {

@ DatabaseField (generatedId = true)

Int id;

@ DatabaseField

String word;

 

Public Hello (){

}

 

@ Override

Public String toString (){

StringBuilder sb = new StringBuilder ();

Sb. append ("id ="). append (id );

Sb. append (", word ="). append (word );

Return sb. toString ();

}

 

}

@ DatabaseField: Declares the id as the database field, and generatedId = true declares that the id is auto-incrementing.

Then rewrite toString ()

 

Add another DataHelper. java

 

Package cn. sdx. utils;

 

Import java. SQL. SQLException;

 

Import android. content. Context;

Import android. database. sqlite. SQLiteDatabase;

Import android. util. Log;

 

 

Import cn. sdx. model. Hello;

 

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;

 

Public class DataHelper extends OrmLiteSqliteOpenHelper {

 

Private static final String DATABASE_NAME = "HelloOrmlite. db ";

Private static final int DATABASE_VERSION = 1;

Private Dao <Hello, Integer> helloDao = null;

 

Public DataHelper (Context context ){

Super (context, DATABASE_NAME, null, DATABASE_VERSION );

}

 

@ Override

Public void onCreate (SQLiteDatabase db, ConnectionSource connectionSource ){

Try {

TableUtils. createTable (connectionSource, Hello. class );

} Catch (SQLException e ){

Log. e (DataHelper. class. getName (), "failed to create database", e );

E. printStackTrace ();

}

}

 

@ Override

Public void onUpgrade (SQLiteDatabase db, ConnectionSource connectionSource, int arg2,

Int arg3 ){

Try {

TableUtils. dropTable (connectionSource, Hello. class, true );

OnCreate (db, connectionSource );

} Catch (SQLException e ){

Log. e (DataHelper. class. getName (), "failed to update database", e );

E. printStackTrace ();

}

}

 

@ Override

Public void close (){

Super. close ();

HelloDao = null;

}

 

Public Dao <Hello, Integer> getHelloDataDao () throws SQLException {

If (helloDao = null ){

HelloDao = getDao (Hello. class );

}

Return helloDao;

}

}

 

Add a TextView to the layout File

Add database operations in HelloOrmliteActivity. java

 

The Code is as follows:

 

Package cn. sdx;

 

Import java. SQL. SQLException;

Import java. util. List;

 

Import com. j256.ormlite. android. apptools. OrmLiteBaseActivity;

Import com. j256.ormlite. dao. Dao;

 

Import android. OS. Bundle;

Import android. widget. TextView;

Import cn. sdx. model. Hello;

Import cn. sdx. utils. DataHelper;

 

Public class HelloOrmliteActivity extends OrmLiteBaseActivity <DataHelper> {

/** Called when the activity is first created .*/

@ Override

Public void onCreate (Bundle savedInstanceState ){

Super. onCreate (savedInstanceState );

SetContentView (R. layout. main );

TextView TV = (TextView) this. findViewById (R. id. output );

Try {

Dao <Hello, Integer> helloDao = getHelper (). getHelloDataDao ();

// Add data

For (int I = 0; I <2; I ++ ){

Hello hello = new Hello ("Hello" + I );

HelloDao. create (hello );

}

TV. setText (TV. getText () + "\ n" + "added data ");

// Query the added data

List <Hello> hellos = helloDao. queryForAll ();

For (Hello h: hellos ){

TV. setText (TV. getText () + "\ n" + h. toString ());

}

// Delete the first data entry

HelloDao. delete (hellos. get (0 ));

TV. setText (TV. getText () + "\ n" + "data deletion completed ");

// Re-query data

Hellos = helloDao. queryForAll ();

For (Hello h: hellos ){

TV. setText (TV. getText () + "\ n" + h. toString ());

}

// Modify data

Hello h1 = hellos. get (0 );

H1.setWord ("this is modified data ");

TV. setText (TV. getText () + "\ n" + "data modified ");

HelloDao. update (h1 );

// Re-query data

Hellos = helloDao. queryForAll ();

For (Hello h: hellos ){

TV. setText (TV. getText () + "\ n" + h. toString ());

}

 

} Catch (SQLException e ){

// TODO Auto-generated catch block

E. printStackTrace ();

}

 

}

}

The above implementation of database operations related to addition, deletion, and modification, the following is the effect:

OrmLite is very powerful, and the declaration of Model classes is very important. Foreign key constraints, non-empty checks, and other issues have relative solutions.

 

Author: Huang yunkun