An Overview of Android Content Providers
An Android content provider provides you with access to sharable data structures commonly called databases.The basic procedure is as follows:
1. Get permission to open the database.
2. Query the data.
3. Access the data.
Data can be in Android internal memory or in external memory such as an SD card, or even on an external server that is remote to the Android device itself.
SQLite:open source DBMS.
The "Lite" or "Light" part delineates that this is a "lightweight" version of the DBMS.
SQLite is a part of Android.
Contacts Database Contact Providers
the Contacts database interfaces that work with Android 1.x phones are different than the ones that work on the Android 2.x phones.
CONTENT_URI: points to the data location.
Defining Security Permissions
We need to get permissions to use certain areas of the OS so that Android can implement a robust level of security within its OS infrastructure.
(1)Contact DataBase
AndroidManifest.xml
<uses-permission android:name="android.permission.READ_CONTACTS"></uses-permission> <uses-permission android:name="android.permission.WRITE_CONTACTS"></uses-permission>
\layout\contacts.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical">
<Button
android:tag="query"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="click to query contacts db"/>
<Button
android:tag="add"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="click to add contacts db"/>
<Button
android:tag="update"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="click to update contacts db"/>
<Button
android:tag="delete"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="click to delete contacts db"/>
</LinearLayout>
public class Contacts extends Activity implements OnClickListener {
private View rootView;
private Uri queryUri;
private Uri addUri;
private Uri updateUri;
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
rootView=LayoutInflater.from(this).inflate(R.layout.contacts, null);
this.setContentView(rootView);
Button btnQuery=(Button)rootView.findViewWithTag("query");
btnQuery.setOnClickListener(this);
Button btnAdd=(Button)rootView.findViewWithTag("add");
btnAdd.setOnClickListener(this);
Button btnUpdate=(Button)rootView.findViewWithTag("update");
btnUpdate.setOnClickListener(this);
Button btnDelete=(Button)rootView.findViewWithTag("delete");
btnDelete.setOnClickListener(this);
}
public void onClick(View v) {
// TODO Auto-generated method stub
String tag=(String)v.getTag();
if("query".equals(tag)){
this.queryContacts();
}else if("add".equals(tag)){
this.addContacts("test1", "123123");
}else if("update".equals(tag)){
this.updateContacts("111111");
}else if("delete".equals(tag)){
}
}
private void queryContacts(){
String[] cols=new String[]{People.NAME,People.NUMBER};
queryUri=People.CONTENT_URI;
Cursor cursor=managedQuery(queryUri,cols,null,null,null);
if(cursor.moveToFirst()){
String name=null;
String number=null;
do{
name=cursor.getString(cursor.getColumnIndex(People.NAME));
number=cursor.getString(cursor.getColumnIndex(People.NUMBER));
Toast.makeText(this, name+" "+number, Toast.LENGTH_SHORT).show();
}while(cursor.moveToNext());
}
}
private void addContacts(String newName,String newNumber){
ContentValues myContent=new ContentValues();
myContent.put(People.NAME, newName);
addUri=this.getContentResolver().insert(People.CONTENT_URI, myContent);
Uri contentUri=Uri.withAppendedPath(addUri, People.Phones.CONTENT_DIRECTORY);
myContent.clear();
myContent.put(People.Phones.TYPE, People.TYPE_MOBILE);
myContent.put(People.NUMBER, newNumber);
updateUri=this.getContentResolver().insert(contentUri, myContent);
Toast.makeText(this, "New Contact:"+newName+" "+newNumber, Toast.LENGTH_LONG).show();
}
private void updateContacts(String newNumber){
if(updateUri==null){
Toast.makeText(this, "You need to create a new contact to update!",Toast.LENGTH_LONG).show();
}else{
ContentValues number=new ContentValues();
number.put(People.Phones.TYPE, People.TYPE_MOBILE);
number.put(People.NUMBER, newNumber);
this.getContentResolver().update(updateUri, number, null, null);
Toast.makeText(this, "Updated phone number to: " + newNumber,Toast.LENGTH_SHORT).show();
}
}
private void deleteContacts(){
if(updateUri==null){
Toast.makeText(this, "You need to create a new contact to delete!", Toast.LENGTH_LONG).show();
}else{
this.getContentResolver().delete(addUri, null, null);
Toast.makeText(this, "Deleted contact at: " + addUri.toString(),Toast.LENGTH_SHORT).show();
addUri=null;
updateUri=null;
}
}
}