Use of the lightweight database SQLite

This article does not involve a number of conceptual things, please forgive us a lot

This is the simple frame of Android SQLite.

Using SQLite is about 3 steps

The first step: Create your own Sqliteopenhelper class

Step two: Create a DAO layer in the database with the operations of the database

Step three: Use the DAO layer operation in activity (multi-threaded form, prevent card interface)

First step: Create Sqliteopenhelper

/** * @author Skyfin * @time 2015/6/4 */public class MyDatabase extends Sqliteopenhelper {/** * database name */public final Stati C String db_name = "Classaateinfo";/** * The version number of the database */public final static int version = 1;/** * @param The default constructed function */public Mydat Abase (context context, String name, cursorfactory factory,int version) {Super (context, name, Factory, version);//TODO automatically Into the constructor stub}public MyDatabase (context context, String name, cursorfactory factory,int version, Databaseerrorhandler ErrorHandler) {Super (context, name, Factory, version, ErrorHandler);//todo}/** * @param in order to not pass in the database name and version information each time */public Mydat Abase (Context context) {This (context, db_name, NULL, VERSION);} /** * @param in order to update the database name and version information */public MyDatabase (context context, int version) {This (context, db_name, NULL, version);} /* * (non-Javadoc) * * @see * android.database.sqlite.sqliteopenhelper#oncreate (Android.database.sqlite *). Sqlitedatabase) * Created database primary key ID name and phone */@Overridepublic void OnCreate (Sqlitedatabase db) {//TODO CREATE DATABASE to databaseMake String sql = "CREATE TABLE IF not EXISTS student" + "(" + "ID int primary key autoincrement," + "name varchar ()," + "phone int) ";d b.execsql (SQL);} /* (non-Javadoc) * @see android.database.sqlite.sqliteopenhelper#onupgrade (android.database.sqlite.SQLiteDatabase, int , int) * * Change Database version operation */@Overridepublic void Onupgrade (sqlitedatabase db, int oldversion, int newversion) {//TODO Change Database Edition This operation//string sql = "Updete student";//db.execsql (sql);} @Overridepublic void OnOpen (Sqlitedatabase db) {//TODO Open Database Super.onopen (db);}}

Step two: Create Studentdao to encapsulate related operations

public class Studentdao {MyDatabase MyDatabase = Null;public Studentdao (context context) {MyDatabase = new MyDatabase (cont EXT);} Public Studentdao (context context, int version) {myDatabase = new MyDatabase (context, version);} /** * * @param implement data insertion */public void InsertData (Student stu) {/* * method one used (?) The placeholder for the overloaded execsql (String sql, object[] bindargs) method *///try {//LOG.I ("Skyfin", "Insert Datebase" + stu.id);//String sql = "INSERT into student (Id,name,phone) VALUES (?,?,?)";  /Sqlitedatabase db = Mydatabase.getwritabledatabase ();//Db.execsql (SQL, new object[] {stu.id, stu.name, stu.phone});// Db.close ();//} catch (Exception e) {//E.printstacktrace ();///Todo:handle exception//}/* * Method two uses contentvalues word Gencun The form */sqlitedatabase db = Mydatabase.getwritabledatabase (); Contentvalues values = new Contentvalues () values.put ("id", stu.id), Values.put ("name", Stu.name); Values.put ("Phone", Stu.phone); Long rowid = Db.insert ("student", null, values);//Returns the line number of the newly added record, regardless of the primary key ID Db.close ();} Test public void Insert () {log.i ("Skyfin", "Test");} public void Seleteall () {/* * * Method one query form */try {log.i ("Skyfin", "select Datebase"); String sql = "SELECT * from student"; Sqlitedatabase db = Mydatabase.getwritabledatabase (); Produces a new cursor, cursor class forward and backward cursor cursor = db.rawquery (sql,null); while (Cursor.movetonext ()) {int id = cursor.getint (cursor.getcolumnindex ("id")); String name = cursor.getstring (Cursor.getcolumnindex ("name")); int phone = Cursor.getint (Cursor.getcolumnindex ("Phone")); Log print output log.i ("Skyfin", "query-->" + "ID:" +id+ "Name:" +name+ "Phone:" +phone ");} Db.close (); } catch (Exception e) {//TODO auto-generated catch block E.printstacktrace ();} /* * Method two query form *///try {//sqlitedatabase db = Mydatabase.getwritabledatabase ();//cursor Cursor = db.query ("Student" ,//new string[] {"id", "name", "Phone"}, null,//null, NULL, NULL, NULL, NULL);////while (Cursor.movetonext ()) {//log.i ("s Kyfin "," cursor ");//int id = cursor.getint (cursor.getcolumnindex (" id "));//string name = Cursor.getstring (Cursor.getcolumnindex ("name")),//int phone = Cursor.getint (Cursor.getcolumnindex ("Phone")),////log print output//log.i (" Skyfin "," query--> "+" ID: "+ ID +" Name: "+ name//+" Phone: "+ Phone";////}//cursor.close ();//db.close ();/} catch (Exception e) {////TODO auto-generated catch block//e.printstacktrace ();/}} public void Update () {try {sqlitedatabase db = Mydatabase.getwritabledatabase ();//contentvalues is a key-value form, similar to the map Contentvalues values = new Contentvalues () values.put ("id", 1020),//key is the field name, value is Values.put ("name", "Doubi"); Values.put ("Phone", 1234); The//update function is followed by a conditional db.update ("student", Values, "Id=?", New string[]{"123"}); Db.close ();} catch (Exception e) {//TODO auto-generated catch block E.printstacktrace ();}} public void Delete () {Sqlitedatabase db = Mydatabase.getwritabledatabase ();//and update similar to Db.delete ("student", "ID<?", New string[]{"$"});d B.close ();}}

Finally used in the activity

public class Mainactivity extends Activity implements Onclicklistener {public Studentdao Studentdao = Null;public EditText edit_id= null;public EditText edit_name= null;public EditText edit_phone= null;public button ok_btn = Null;public button    SHOW_BTN = null;public Button update_btn = null;        @Override protected void OnCreate (Bundle savedinstancestate) {super.oncreate (savedinstancestate);        Setcontentview (R.layout.activity_main);        Studentdao = new Studentdao (Getapplicationcontext ());        edit_id = (EditText) Findviewbyid (r.id.id);        Edit_name = (EditText) Findviewbyid (r.id.name);        Edit_phone = (EditText) Findviewbyid (r.id.phonenum);        OK_BTN = (Button) Findviewbyid (R.id.ok);        SHOW_BTN = (Button) Findviewbyid (r.id.show);        UPDATE_BTN = (Button) Findviewbyid (r.id.update);        Ok_btn.setonclicklistener (this);        Show_btn.setonclicklistener (this);    Update_btn.setonclicklistener (this); } @Override Public Boolean OncreateoPtionsmenu (Menu menu) {//Inflate the menu; This adds items to the action bar if it is present.        Getmenuinflater (). Inflate (R.menu.main, menu);    return true; } @Override public boolean onoptionsitemselected (MenuItem Item) {//Handle Action Bar item clicks here.  The action bar would//automatically handle clicks on the Home/up button, so long/As you specify a parent        Activity in Androidmanifest.xml.        int id = item.getitemid ();        if (id = = r.id.action_settings) {return true;    } return super.onoptionsitemselected (item); } @Overridepublic void OnClick (View v) {//TODO auto-generated method stub switch (V.getid ()) {Case R.id.ok:toast.maketext (  Getapplicationcontext (), "clicked on the Confirmation button", Toast.length_short). Show (); LOG.I ("Skyfin", "insert into Datebase"), final Student Student = new Student (); Student.setid (Integer.parseint (edit_ Id.gettext (). ToString ()); Student.setname (Edit_name.gettext (). ToString ()); Student.setphone (Integer.parsEint (Edit_phone.gettext (). toString ()));    LOG.I ("Skyfin", student.tostring ()); New Thread (New Runnable () {@Overridepublic void run () {log.i ("Skyfin", "Insert Thread is running"); Studentdao.insertdata (student);}}). Start (); Break;case r.id.show:new Thread (New Runnable () {@Overridepublic void run () {log.i ("Skyfin", "Select Thread is RU Nning "); Studentdao.seleteall ();}). Start (); Break;case r.id.update:new Thread (New Runnable () {@Overridepublic void run () {log.i ("Skyfin", "Update thread is Running "); Studentdao.update ();//studentdao.delete ();}). Start (); break;default:break;}}}

Dome

Use of the lightweight database SQLite