Android 2.3 Platform Highlights 日本語版 超訳

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The Android 2.3 platform introduces many new and exciting features for users and developers. This document provides a glimpse at some of the new features and technologies in Android 2.3. For detailed information about the new developer APIs, see the Android 2.3 version notes.
新しいAPIの詳細につきましては、「Android 2.3 version notes」を参照下さい。



The user interface is refined in many ways across the system, making it easier to learn, faster to use, and more power-efficient. A simplified visual theme of colors against black brings vividness and contrast to the notification bar, menus, and other parts of the UI. Changes in menus and settings make it easier for the user to navigate and control the features of the system and device.

より直感的なテキストの入力ですっげー捗る(Android Keyboardのみ)

The Android soft keyboard is redesigned and optimized for faster text input and editing. The keys themselves are reshaped and repositioned for improved targeting, making them easier to see and press accurately, even at high speeds. The keyboard also displays the current character and dictionary suggestions in a larger, more vivid style that is easier to read.
The keyboard adds the capability to correct entered words from suggestions in the dictionary. As the user selects a word already entered, the keyboard displays suggestions that the user can choose from, to replace the selection. The user can also switch to voice input mode to replace the selection. Smart suggestions let the user accept a suggestion and then return to correct it later, if needed, from the original set of suggestions.
New multitouch key-chording lets the user quickly enter numbers and symbols by pressing Shift+<letter> and ?123+<symbol>, without needing to manually switch input modes. From certain keys, users can also access a popup menu of accented characters, numbers, and symbols by holding the key and sliding to select a character.


When entering text or viewing a web page, the user can quickly select a word by press-hold, then copy to the clipboard and paste. Pressing on a word enters a free-selection mode — the user can adjust the selection area as needed by dragging a set of bounding arrows to new positions, then copy the bounded area by pressing anywhere in the selection area. For text entry, the user can slide-press to enter a cursor mode, then reposition the cursor easily and accurately by dragging the cursor arrow. With both the selection and cursor modes, no use of a trackball is needed.



The Android system takes a more active role in managing apps that are keeping the device awake for too long or that are consuming CPU while running in the background. By managing such apps — closing them if appropriate — the system helps ensure best possible performance and maximum battery life.
The system also gives the user more visibility over the power being consumed by system components and running apps. The Application settings provides an accurate overview of how the battery is being used, with details of the usage and relative power consumed by each component or application.


A shortcut to the Manage Applications control now appears in the Options Menu in the Home screen and Launcher, making it much easier to check and manage application activity. Once the user enters Manage Applications, a new Running tab displays a list of active applications and the storage and memory being used by each. The user can read further details about each application and if necessary stop an application or report feedback to its developer.

New ways of communicating, organizing

An updated set of standard applications lets the user take new approaches to managing information and relationships.

Internet calling
The user can make voice calls over the internet to other users who have SIP accounts. The user can add an internet calling number (a SIP address) to any Contact and can initiate a call from Quick Contact or Dialer. To use internet calling, the user must create an account at the SIP provider of their choice — SIP accounts are not provided as part of the internet calling feature. Additionally, support for the platform's SIP and internet calling features on specific devices is determined by their manufacturers and associated carriers.

Near-field communications
An NFC Reader application lets the user read and interact with near-field communication (NFC) tags. For example, the user can “touch” or “swipe” an NFC tag that might be embedded in a poster, sticker, or advertisement, then act on the data read from the tag. A typical use would be to read a tag at a restaurant, store, or event and then rate or register by jumping to a web site whose URL is included in the tag data. NFC communication relies on wireless technology in the device hardware, so support for the platform's NFC features on specific devices is determined by their manufacturers.

Downloads management
The Downloads application gives the user easy access to any file downloaded from the browser, email, or another application. Downloads is built on an completely new download manager facility in the system that any other applications can use, to more easily manage and store their downloads.


The application now lets the user access multiple cameras on the device, including a front-facing camera, if available.


Android 2.3 delivers a variety of features and APIs that let developers bring new types of applications to the Android platform.


Android 2.3 includes a variety of improvements across the system that make common operations faster and more efficient for all applications. Of particular interest to game developers are:

  • Concurrent garbage collector — The Dalivik VM introduces a new, concurrent garbage collector that minimizes application pauses, helping to ensure smoother animation and increased responsiveness in games and similar applications.
コンカレントGC----DalvikVMにコンカレントGCが採用されたよ!GCによる停止時間の低減、スムーズなアニメの支援、レスポンスの向上ができてゲームやそれ系アプリはいい感じになります。(mark and sweepから置き換わったんすかね?)

  • Faster event distribution — The plaform now handles touch and keyboard events faster and more efficiently, minimizing CPU utilization during event distribution. The changes improve responsiveness for all applications, but especially benefit games that use touch events in combination with 3D graphics or other CPU-intensive operations.

  • Updated video drivers — The platform uses updated third-party video drivers that improve the efficiency of OpenGL ES operations, for faster overall 3D graphics performance.
ビデオドライバのアップデート---OpenGL ESの3D処理系が早くなりました。サードパーティのいい感じのビデオドライバを使ってます。

Native input and sensor events
Applications that use native code can now receive and process input and sensor events directly in their native code, which dramatically improves efficiency and responsiveness.
Native libraries exposed by the platform let applications handle the same types of input events as those available through the framework. Applications can receive events from all supported sensor types and can enable/disable specific sensors and manage event delivery rate and queueing.
Gyroscope and other new sensors, for improved 3D motion processing(3Dのモーション処理を改善するためのジャイロスコープと新しいセンサー)
Android 2.3 adds API support for several new sensor types, including gyroscope, rotation vector, linear acceleration, gravity, and barometer sensors. Applications can use the new sensors in combination with any other sensors available on the device, to track three-dimensional device motion and orientation change with high precision and accuracy. For example, a game application could use readings from a gyroscope and accelerometer on the device to recognize complex user gestures and motions, such as tilt, spin, thrust, and slice.
Open API for native audio
The platform provides a software implementation of Khronos OpenSL ES, a standard API that gives applications access to powerful audio controls and effects from native code. Applications can use the API to manage audio devices and control audio input, output, and processing directly from native code
プラットフォームはKhrnos OpenSL ESのソフトウェア実装を提供する!(Khrnos OpenSL ESは組み込み用途を想定したクロスプラットフォーム対応のサウンドAPIだそうです)

Native graphics management
The platform provides an interface to its Khronos EGL library, which lets applications manage graphics contexts and create and manage OpenGL ES textures and surfaces from native code.
プラットフォームはKhronos EGLライブラリのインタフェースを提供するなり!これによってネイティブコード側で画像管理や生成、OpenGL ESのテクスチャやサーフェイスの管理ができるようになりました!

Native access to Activity lifecycle, window management
Native applications can declare a new type of Activity class, NativeActivity whose lifecycle callbacks are implemented directly in native code. The NativeActivity and its underlying native code run in the system just as do other Activities — they run in the application's system process and execute on the application's main UI thread, and they receive the same lifecycle callbacks as do other Activities.
The platform also exposes native APIs for managing windows, including the ability to lock/unlock the pixel buffer to draw directly into it. Through the API, applications can obtain a native window object associated with a framework Surface object and interact with it directly in native code.
Native access to assets, storage
Applications can now access a native Asset Manager API to retrieve application assets directly from native code without needing to go through JNI. If the assets are compressed, the platform does streaming decompression as the application reads the asset data. There is no longer a limit on the size of compressed .apk assets that can be read.
Additionally, applications can access a native Storage Manager API to work directly with OBB files downloaded and managed by the system. Note that although platform support for OBB is available in Android 2.3, development tools for creating and managing OBB files will not be available until early 2011.

(StrageManagerはどうも暗号化したファイルを操作するAPIっぽいです。OBBはOpaque Binary Blobsの略です。新しいフォーマットなのかー?)

Robust native development environment
The Android NDK (r5 or higher) provides a complete set of tools, toolchains, and libraries for developing applications that use the rich native environment offered by the Android 2.3 platform. For more information or to download the NDK, please see the Android NDK page.
AndroidNDK(r5以上)はAndroid2.3によって提供されるリッチなネイティブ環境を使ったアプリケーションを作るための完全なツール、ツールチェイン、ライブラリのセットをどーんと提供します。詳細な情報やらNDKのダウンロードはAndroid NDKへどうぞ。


Internet telephony(インターネット通話!)
Developers can now add SIP-based internet telephony features to their applications. Android 2.3 includes a full SIP protocol stack and integrated call management services that let applications easily set up outgoing and incoming voice calls, without having to manage sessions, transport-level communication, or audio record or playback directly.
Support for the platform's SIP and internet calling features on specific devices is determined by their manufacturers and associated carriers.


Near Field Communications (NFC)
The platform's support for Near Field Communications (NFC) lets developers get started creating a whole new class of applications for Android. Developers can create new applications that offer proximity-based information and services to users, organizations, merchants, and advertisers.
Using the NFC API, applications can respond to NFC tags “discovered” as the user “touches” an NFC-enabled device to elements embedded in stickers, smart posters, and even other devices. When a tag of interest is collected, applications can respond to the tag, read messages from it, and then store the messages, prompting the user as needed.
NFC communication relies on wireless technology in the device hardware, so support for the platform's NFC features on specific devices is determined by their manufacturers.
NFCはもう開発者が全く新しいAndroidアプリを作れるようにしちゃいます。開発者はFelica的なタッチしたりする系の情報やサービスをユーザや組織や商人や広告主に提供するアプリを作れます。NFC APIを使うと、ステッカーやポスターや他の端末にタッチする事で発見した埋め込まれたNFCタグに対して何やかや操作ができます。ユーザにプロンプトを出す必要があるけれども、アプリはタグに対してデータを読んだり、保存させたりできます。ただ、NFCはデバイスの無線技術に依存していますんで、使えるかどうかは端末ベンダーや携帯キャリアに依存すっからそこんとこ重ね重ねよろしく。


Mixable audio effects(オーディオエフェクトをミキシング)
A new audio effects API lets developers easily create rich audio environments by adding equalization, bass boost, headphone virtualization (widened soundstage), and reverb to audio tracks and sounds. Developers can mix multiple audio effects in a local track or apply effects globally, across multiple tracks.
Support for new media formats(新しいメディアフォーマットに対応)
The platform now offers built-in support for the VP8 open video compression format and the WebM open container format. The platform also adds support for AAC encoding and AMR wideband encoding (in software), so that applications can capture higher quality audio than narrowband.
プラットフォームはVP8 open video compression formatとWebM open container formatをサポートしました。その他ACCやAMR wideband(ソフトウェア実装)もサポートしました。これによって回線細くてもいい感じで音鳴らす事ができまっせ。
Access to multiple cameras(複数のカメラにアクセス)
The Camera API now lets developers access any cameras that are available on a device, including a front-facing camera. Applications can query the platform for the number of cameras on the device and their types and characteristics, then open the camera needed. For example, a video chat application might want to access a front-facing camera that offers lower-resolution, while a photo application might prefer a back-facing camera that offers higher-resolution.
Camera APIによってフロントカメラなどなどデバイスで使えるいくつかのカメラにアクセスできるようになります。アプリケーションからデバイスにのっている色々なタイプの複数のカメラについてプラットフォームに問い合わせる事ができます。そんで必要なカメラをオープンしましょう。例えばビデオチャットアプリなら低解像度のフロントカメラにアクセスしたいでしょう、写真アプリなら高解像度の背面カメラをつか


Media Framework

  • New media framework fully replaces OpenCore, maintaining all previous codec/container support for encoding and decoding.

  • Integrated support for the VP8 open video compression format and the WebM open container format

  • Adds AAC encoding and AMR wideband encoding
    対応音声コーデックにACCとAMR widebandが追加されました。

Linux Kernel

  • Upgraded to 2.6.35


  • SIP stack, configurable by device manufacturer

  • Support for Near Field Communications (NFC), configurable by device manufacturer

  • Updated BlueZ stack

Dalvik runtime

  • Dalvik VM:
    • Concurrent garbage collector (target sub-3ms pauses)
    • コンカレントGCになりました。
    • Adds further JIT (code-generation) optimizations
    • より最適化されたJIT
    • Improved code verification
    • 改善されたコードの検証をした?
    • StrictMode debugging, for identifying performance and memory issues

  • Core libraries:
    • Expanded I18N support (full worldwide encodings, more locales)
    • 拡張I18Nをサポート(国際化対応)
    • Faster Formatter and number formatting. For example, float formatting is 2.5x faster.
    • フォーマッタが超早くなった。floatをフォーマットすんのが2.5倍早くなった?
    • HTTP responses are gzipped by default. XML and JSON API response sizes may be reduced by 60% or more.
    • HTTPのレスポンンスをデフォルトでgzipでもらうようにして、XMLとかJSONのレスポンスサイズが60%縮んだっぽい。(Accept-Encodingにデフォルトでgzipつけるようにしたって事?)
    • New collections and utilities APIs
    • 新しいCollectionとかUtil系のAPIを追加
    • Improved network APIs
    • ネットワーク系APIを改善
    • Improved file read and write controls
    • ファイルI/O系を改善
    • Updated JDBC
    • JDBCを更新した。(DBに接続するあれ)
  • Updates from upstream projects:
    • OpenSSL 1.0.0a
    • BouncyCastle 1.45
    • ICU 4.4
    • zlib 1.2.5
For more information about the new developer APIs, see the Android 2.3 version notes and the API Differences Report.
開発者向けのAPIについてのより詳細な情報はAndroid 2.3 version notesとかAPI Differences Reportを見てね

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