安卓 英文 外文 文献翻译 android api级别.doc

Android API Levels As you develop your application on Android, it s useful to understand the plat s general approach to API change management. It s also important to understand the API Level identifier and the role it plays in ensuring your application s compatibility with devices on which it may be installed. The sections below provide ination about API Level and how it affects your applications. For ination about how to use the “Filter by API Level“ control available in the API reference documentation, see Filtering the documentation at the end of this document. What is API Level? API Level is an integer value that uniquely identifies the framework API revision offered by a version of the Android plat. The Android plat provides a framework API that applications can use to interact with the underlying Android system. The framework API consists of:  A core set of packages and classes  A set of XML elements and attributes for declaring a manifest file  A set of XML elements and attributes for declaring and accessing resources  A set of Intents  A set of permissions that applications can request, as well as permission enforcements included in the system Each successive version of the Android plat can include updates to the Android application framework API that it delivers. Updates to the framework API are designed so that the new API remains compatible with earlier versions of the API. That is, most changes in the API are additive and introduce new or replacement functionality. As parts of the API are upgraded, the older replaced parts are deprecated but are not removed, so that existing applications can still use them. In a very small number of cases, parts of the API may be modified or removed, although typically such changes are only needed to ensure API robustness and application or system security. All other API parts from earlier revisions are carried forward without modification. The framework API that an Android plat delivers is specified using an integer identifier called “API Level“. Each Android plat version supports exactly one API Level, although support is implicit for all earlier API Levels (down to API Level 1). The initial release of the Android plat provided API Level 1 and subsequent releases have incremented the API Level. The following table specifies the API Level supported by each version of the Android plat.Plat Version API Level Android 3.0 11 Android 2.3.3 10 Android 2.3 9 Android 2.2 8 Android 2.1 7 Android 2.0.1 6 Android 2.0 5 Android 1.6 4 Android 1.5 3 Android 1.1 2 Android 1.0 1 Uses of API Level in Android The API Level identifier serves a key role in ensuring the best possible experience for users and application developers:  It lets the Android plat describe the maximum framework API revision that it supports  It lets applications describe the framework API revision that they require  It lets the system negotiate the installation of applic