Detailed description of Android SDK design goals

It is generally a collection of development tools used by software engineers to build application software for specific software packages, software frameworks, hardware platforms, operating systems, etc, this Android SDK Security helps reduce the possibility that malicious applications may damage devices.

As mentioned above, Android runs on the Linux kernel. Android applications are programmed in Java and run in a VM. It should be noted that this VM is not the JVM you think, but Dalvik Virtual Machine, which is an open source technology. Each Android Application runs in an instance of Dalvik VM. This instance resides in a process managed by the Linux kernel, as shown in:

 An Android application consists of one or more components:

Applications with visual UI are implemented by activities. When you select an application from the home screen or application initiator, an action is triggered. The service should be used for any application that requires a long period of time, such as a network monitor or an Update Check application. Content Providers can regard content providers as database servers.

The task of the content provider is to manage access to persistent data, such as the SQLite database. If the application is very simple, you may not need to create a content provider. If you want to build a large application or an application that needs to provide data for multiple activities or applications, you can use the content provider for data access.

The broadcast receiver Android Application can be used to process a data element or respond to an event, such as receiving a text message. Android applications are deployed to devices together with an AndroidManifest. xml file. AndroidManifest. xml contains necessary configuration information.

So that it can be properly installed on the device. It includes the required class name and the type of event that the application can process, and the license required to run the application. For example, if an application needs to access the network-for example, to download a file-the permission must be explicitly listed in the manifest file. Many applications may have enabled this specific license. This declarative Security helps reduce the possibility that malicious applications may damage devices.

The next section describes the development environment required to build an Android Application. The required Tools can be used to develop Android applications without the Eclipse and Android Developer Tools plug-ins. However, you need to be familiar with the Android SDK.

Android SDK is released as a ZIP file. You can decompress the file to a directory on the hard disk. Since there are multiple SDK updates, we recommend that you consciously organize the development environment so that you can easily switch between different SDK installations. The SDK includes: Java archive files, including all Android SDK classes required for building applications. The ention.html and docs directories provide local and online SDK documentation.

These documents are mainly in the form of JavaDocs to facilitate the navigation of a large number of packages in the SDK. The document also includes a link to the Advanced Development Guide and the Android community. The samples subdirectory contains the source code of various applications, including ApiDemo, which demonstrates many APIs. This sample application can be used as a good starting point for Android application development.

Contains all command line tools used to build Android applications. The most common and useful tool is the adb utility Android Debug Bridge ). This directory contains the driver required to connect the development environment to Android-supported devices such as G1 or Android Dev 1 to unlock the development mobile phone. Only Windows developers need these files.