ContentProvider of four components

  First of all, let's understand what is ContentProvider, Simply speaking , occasionally android When the application needs to share internal data with other data , At this time ContentProvider With some kind of Uri Provide data to the outside world in the form of , Allow other applications to access or modify data , At this time, other applications will use ContentResolver according to Uri To access the data specified by the operation . in other words ContentProvider The function of is to expose the data available for operation .

// Let's define a ContentProvider Subclasses of , This class does not access the underlying data , Only for understanding

public class MyContentProvider extends ContentProvider{
	// stay ContetnProvider Called after creation 
		public boolean onCreate() {
			// TODO Auto-generated method stub
			return false;
		}
		// Returns the current uri Of MIME type , If it's time to URI The corresponding data may include multiple records 
		// that MIME Type string   That is to say vnd.android.dir/ start 
//		 If it's time to URI The corresponding data has only one record   The MIME Type string   That is to say vnd.android.cursor.item/ start 
		public String getType(Uri uri) {
			// TODO Auto-generated method stub
			return null;
		}
	// The following methods can be built according to the development needs , For example, you can add and delete 


	// according to Uri Insert Values Corresponding data 
	public Uri insert(Uri uri, ContentValues values) {
		// TODO Auto-generated method stub
		return null;
	}
	// according to Uri Delete selection Appoint   All records matched by the condition of 
		public int delete(Uri uri, String selection, String[] selectionArgs) {
			// TODO Auto-generated method stub
			return 0;
		}

	// according to uri modify selection All records matching the specified conditions 
		public int update(Uri uri, ContentValues values, String selection,
				String[] selectionArgs) {
			// TODO Auto-generated method stub
			return 0;
		}
	// according to uri Query out selection All records matching the specified conditions , And you can specify which columns to query   In what way (order) Sort 
	public Cursor query(Uri uri, String[] projection, String selection,
			String[] selectionArgs, String sortOrder) {
		// TODO Auto-generated method stub
		return null;
	}

	

}

// stay ContentProvider Before being called by other programs , Need to be in manifest This... Is configured in the file ContentProvider

// stay application Internal configuration

<provider 
            android:name=".MyContentProvider"
            android:authorities="org.crazyit.provider.firstprovider"
            android:exported="true" />

// Now let's continue to create a class for another application , To simulate how to access ContentProvider Of Uri Corresponding data

public class FirstResolver extends Activity{

	// Define a ContentResolver object 
	ContentResolver cr;
	// Converts a string to Uri
	Uri uri=Uri.parse("content://org.crazyit.provider.firstprovider/");
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		// TODO Auto-generated method stub
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		// Get one ContentResolver object 
		cr=getContentResolver();
		
	}
	// Monitoring methods 
	public void query(View source)
	{
		// call ContentResolver Of query() Method 
		// What is actually returned is this Uri Corresponding ContentProvider Of query The return value of 
		Cursor c=cr.query(uri, null, "query_where", null, null);
		Toast.makeText(this, " long-range ContentProvider Back to Cursor by ："+c, Toast.LENGTH_SHORT).show();
	}
	public void insert(View Source)
	{
		ContentValues va=new ContentValues();
		va.put("name", "hahaha");
		// call ContentResolver Of insert() Method 
		// What is actually returned is this Uri Corresponding ContentProvider Of insert() The return value of 
		Uri newUri=cr.insert(uri, va);
		Toast.makeText(this, " long-range ContentProvider Newly inserted record Uri by ："+newUri, Toast.LENGTH_SHORT).show();	
	}
	public void update(View source)
	{
		ContentValues va=new ContentValues();
		va.put("name", "hahaha");
		// call ContentResolver Of update() Method 
		// What is actually returned is this Uri Corresponding ContentProvider Of update() The return value of 
		int count=cr.update(uri, va, "update_where", null);
		Toast.makeText(this, " long-range ContentProvider The number of updated records is ："+count, Toast.LENGTH_SHORT).show();
	}
	public void delete(View source)
	{
		// call ContentResolver Of delete() Method 
		// What is actually returned is this Uri Corresponding ContentProvider Of delete() The return value of 
		int count=cr.delete(uri, "delete_where", null);
		Toast.makeText(this, " long-range ContentProvider The number of records deleted is ："+count, Toast.LENGTH_SHORT).show();
	}
}

 Android Itself provides a lot of ContentProvider, For example, contact information , System multimedia , Developers can also use ContentResolver To call the system ContentProvider Provided query(),insert(),update(), and delete() Other methods .

// Create a project , Yes Android Operate the address book provided by the system

public class MainActivity extends Activity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		ContentResolver cr = getContentResolver();
		Cursor c = cr.query(Contacts.CONTENT_URI, new String[] { Contacts._ID,
				Contacts.DISPLAY_NAME }, null, null, null);
		if (c != null) {
			while (c.moveToNext()) {
				int id = c.getInt(c.getColumnIndex("_id"));
				Log.i("info", "_id:" + id);
				Log.i("info",
						"name:" + c.getString(c.getColumnIndex("display_name")));
				Cursor c1 = cr.query(Phone.CONTENT_URI, new String[] {
						Phone.NUMBER, Phone.TYPE },
						Phone.CONTACT_ID + "=" + id, null, null);
				//  According to contact ID Find out the phone number of the contact 
				if (c1 != null) {
					while (c1.moveToNext()) {
						int type = c1.getInt(c1.getColumnIndex(Phone.TYPE));
						if (type == Phone.TYPE_HOME) {
							Log.i("info",
									" Home phone ："
											+ c1.getString(c1
													.getColumnIndex(Phone.NUMBER)));
						} else if (type == Phone.TYPE_MOBILE) {
							Log.i("info",
									" mobile phone ："
											+ c1.getString(c1
													.getColumnIndex(Phone.NUMBER)));
						}
					}
					c1.close();
				}
				//  According to the contact's ID Go and find out the email address of the contact 
				Cursor c2 = cr.query(Email.CONTENT_URI, new String[] {
						Email.DATA, Email.TYPE }, Email.CONTACT_ID + "=" + id,
						null, null);
				if (c2 != null) {
					while (c2.moveToNext()) {
						int type = c2.getInt(c2.getColumnIndex(Email.DATA));
						if (type == Email.TYPE_WORK) {
							Log.i("info",
									" Work 1 mailbox ："
											+ c2.getString(c2
													.getColumnIndex(Email.DATA)));
						}
					}
					c2.close();
				}
			} 
			c.close();
		}
	}

}

public class MainActivity extends Activity {


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ContentResolver cr =  getContentResolver();
        // To contact   Insert a row of data 
        ContentValues values = new ContentValues();
       Uri uri =  cr.insert(RawContacts.CONTENT_URI, values);
       Long raw_contact_id = ContentUris.parseId(uri);
       values.clear();
       // Insert person name 
       values.put(StructuredName.RAW_CONTACT_ID, raw_contact_id);
       values.put(StructuredName.DISPLAY_NAME, " Zhang Sansan ");
       values.put(StructuredName.MIMETYPE, StructuredName.CONTENT_ITEM_TYPE);
       uri = cr.insert(Data.CONTENT_URI, values);
       // Insert phone information 
       values.clear();
       values.put(Phone.RAW_CONTACT_ID,raw_contact_id);
       values.put(Phone.NUMBER,"13333333333");
       values.put(Phone.MIMETYPE, Phone.CONTENT_ITEM_TYPE);
       uri = cr.insert(Data.CONTENT_URI, values);

    }