Department of Famous Door Android (9)

Introduced

Using SQLite in Android, ContentProvider

Database Support (SQLite)-The Android development platform provides an API for manipulating SQLite databases

Content provider (ContentProvider)-when data needs to be shared between applications, you can use ContentProvider to define URIs in a program so that other applications can access the specified data through this URI

1, SQLite's Demo

Databasehelper.java

Package com.webabcd.SQLite;

Import Android.content.Context;
Import Android.database.sqlite.SQLiteDatabase;
Import Android.database.sqlite.SQLiteOpenHelper;
Import Android.database.sqlite.SQLiteDatabase.CursorFactory;

Helper Classes for database operations
public class Databasehelper extends Sqliteopenhelper {

Databasehelper (context context, String name, cursorfactory cursorfactory, int version) {
Super (context, name, cursorfactory, version);
}

@Override
public void OnCreate (Sqlitedatabase db) {
TODO operations on a database after the database is created
}

@Override
public void Onupgrade (sqlitedatabase db, int oldversion, int newversion) {
TODO Change the operation of the database version
}

@Override
public void OnOpen (Sqlitedatabase db) {
Super.onopen (DB);

TODO first executes each time the database is successfully opened
}
}

Main.java

Package com.webabcd.SQLite;

Import Java.util.Random;

Import android.app.Activity;
Import android.content.ContentValues;
Import Android.database.Cursor;
Import android.database.SQLException;
Import Android.database.sqlite.SQLiteDatabase;
Import Android.os.Bundle;
Import Android.view.View;
Import Android.widget.Button;
Import Android.widget.TextView;

public class Main extends activity {

Private Databasehelper DBHelper;

private static final String database_name= "db.db";
private static final int database_version=1;
private static final String table_name= "employee";

TextView txtmsg;

/** called the activity is a. */
@Override
public void OnCreate (Bundle savedinstancestate) {
Super.oncreate (savedinstancestate);
Setcontentview (R.layout.main);

Dbhelper=new Databasehelper (this, database_name, NULL,
Database_version);

Txtmsg= (TextView) This.findviewbyid (r.id.txtmsg);

Button btn1= (button) This.findviewbyid (R.ID.BTN1);
Btn1.settext ("CREATE TABLE");
Btn1.setonclicklistener (New Button.onclicklistener () {
public void OnClick (View v) {
CreateTable ();
}
});

Button btn2= (button) This.findviewbyid (R.ID.BTN2);
Btn2.settext ("Insert 3 Records");
Btn2.setonclicklistener (New Button.onclicklistener () {
public void OnClick (View v) {
InsertItem ();
}
});

Button btn3= (button) This.findviewbyid (R.ID.BTN3);
Btn3.settext ("Delete all Records");
Btn3.setonclicklistener (New Button.onclicklistener () {
public void OnClick (View v) {
DeleteItem ();
}
});

Button btn4= (button) This.findviewbyid (R.ID.BTN4);
Btn4.settext ("Update specified data");
Btn4.setonclicklistener (New Button.onclicklistener () {
public void OnClick (View v) {
UpdateItem ();
}
});

Button btn5= (button) This.findviewbyid (R.ID.BTN5);
Btn5.settext ("Show All Data");
Btn5.setonclicklistener (New Button.onclicklistener () {
public void OnClick (View v) {
Showitems ();
}
});

Button btn6= (button) This.findviewbyid (R.ID.BTN6);
Btn6.settext ("delete table");
Btn6.setonclicklistener (New Button.onclicklistener () {
public void OnClick (View v) {
Droptable ();
}
});
}

Creating data Tables
private void CreateTable () {
Sqlitedatabase db=dbhelper.getwritabledatabase ();
String sql= "CREATE TABLE IF not EXISTS" + table_name
+ "(ID integer PRIMARY KEY, Name VARCHAR, age INTEGER);";
try {
Db.execsql (SQL);
Txtmsg.append ("data table successfully created \ n");
catch (SQLException ex) {
Txtmsg.append ("Data table creation error \ n" + ex.tostring () + "\ n");
}
}

Inserting data
private void InsertItem () {
Sqlitedatabase db=dbhelper.getwritabledatabase ();

try {
Random random=new Random ();
for (int i=0 i < 3; i++) {
String sql= "INSERT INTO" + table_name
+ "(name, age) VALUES (' name ' + string.valueof (i))
+ "'," + random.nextint () + ")";
Execsql ()-Executes the specified SQL
Db.execsql (SQL);
}
Txtmsg.append ("successfully insert 3 data \ n");
catch (SQLException ex) {
Txtmsg.append ("Insert data failed \ n" + ex.tostring () + "\ n");
}
}

Delete data
private void DeleteItem () {
try {
Sqlitedatabase db=dbhelper.getwritabledatabase ();
Db.delete (TABLE_NAME, "ID < 999999", NULL);
Txtmsg.append ("successfully delete data \ n");
catch (SQLException e) {
Txtmsg.append ("delete data failed \ n");
}
}

Update data
private void UpdateItem () {
Sqlitedatabase db=dbhelper.getwritabledatabase ();

try {
Contentvalues values=new contentvalues ();
Values.put ("Name", "batch updated names");

Db.update (table_name, values, "ID&LT;?", New string[] {"3"});
Txtmsg.append ("Successfully update data \ n");
catch (SQLException e) {
Txtmsg.append ("Update data failed \ n");
}
}

Querying data
private void Showitems () {
Sqlitedatabase db=dbhelper.getreadabledatabase ();

try {
String[] column={"id", "name", "Age"};
Cursor cursor=db.query (table_name, column, NULL, NULL, NULL,
NULL, NULL);
Integer Num=cursor.getcount ();
Txtmsg.append ("Total" + integer.tostring (num) + "record \ n");
Cursor.movetofirst ();

while (Cursor.getposition ()!= Cursor.getcount ()) {
Txtmsg.append (Integer.tostring (Cursor.getposition ()) + ","
+ string.valueof (cursor.getstring (0)) + ","
+ cursor.getstring (1) + ","
+ string.valueof (cursor.getstring (2)) + "\ n");
Cursor.movetonext ();
}
catch (SQLException ex) {
Txtmsg.append ("read data failed \ n" + ex.tostring () + "\ n");
}
}

Delete data table
private void droptable () {
Sqlitedatabase db=dbhelper.getwritabledatabase ();
String sql= "DROP TABLE IF EXISTS" + table_name;
try {
Db.execsql (SQL);
Txtmsg.append ("Data table deletion succeeded \ n");
catch (SQLException ex) {
Txtmsg.append ("Data table deletion error \ n" + ex.tostring () + "\ n");
}
}
}