AN4430 datasheet(11/42 Pages) STMICROELECTRONICS

11 / 42 page

DocID025722 Rev 1

11/42

AN4430

Android Application Overview

user ID to the application which needs to share data like a file, or by requesting permission

to access device data such as camera’s data, SMS data, and so on. Data request is done

via an Android component that handles the sharing of the data as a service or a content

provider. The permissions are granted at the installation time by the android permission

system. Permission can be automatically granted, rejected or asked to the user. By this way

the android system implements the principle of least privilege.

1.3.2

Application components

Android applications are written using application components. Application Android strategy

is to be able to share application resources among all application installed on an Android

device. In this way application can publish its resources so they can be used by other

applications. Android system allows to automatically instantiate the Java object owner of the

desired component. This approach implies in a first hand that application simply request to

Android system to start the desired component within the application that contain it, and in

the second hand Android applications don’t have an single entry point but rather get

components that the system can instantiate on demand.

Android components can be categorized in 4 main families:

•

Activities

•

Services

•

Broadcast receivers

•

Content providers

The 3 last families are shortly described in this application note as they are note deeply

used to demonstrate the NFC implementation use case.

Those components are asynchronously activated by messages called intents. On intent,

Android system finds the right component to respond to it and instantiates it if necessary by

a request from a content resolver method call.

1.3.3

Intents and Intent filters

Intent overview

Intent is a messaging object used to request an action from a component to other one and

then to facilitate communication between components. Intents are used on Android System

to:

•

Start an activity

•

Start a service

•

Deliver a broadcast

Structure of intent implicitly defines the two intent types:

•

Explicit intent: specifies the component to start by name. Typically use to start a

component from the same application as the component caller.

•

Implicit intent: declares a general action to perform without giving a component to start.

Caller doesn’t know the name of the capable component. Android system is then in

charge to find the appropriate component able to answer the caller request. Android

system looks for intent listed in the component’s intent filters declares in the manifest

file. If several components are identified, Android System displays a selectable list to

let the final user to decide which component to use.

AN4430 Datasheet(PDF) 11 Page - STMicroelectronics

AN4430 Datasheet(HTML) 11 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42

Datasheet Download

Link URL