phonegap Overview

PhoneGap 和 Cordova的关系阐述

是PhoneGap贡献给Apache后的开源项目，是从PhoneGap中抽出的核心代码，是驱动PhoneGap的核心引擎。你可以把他想象成类似于Webkit和Google Chrome的关系。

Apache Cordova is an open-source mobile development framework. It allows you to use standard web technologies such as HTML5, CSS3, and JavaScript for cross-platform development, avoiding each mobile platforms' native development language. Applications execute within wrappers targeted to each platform, and rely on standards-compliant API bindings to access each device's sensors, data, and network status.

Apache Cordova graduated in October 2012 as a top level project within the Apache Software Foundation (ASF). Through the ASF, future Cordova development will ensure open stewardship of the project. It will always remain free and open source under the Apache License, Version 2.0. Visit cordova.apache.org for more information.

Use Apache Cordova if you are:

• a mobile developer and want to extend an application across more than one platform, without having to re-implement it with each platform's language and tool set.

• a web developer and want to deploy a web app that's packaged for distribution in various app store portals.

• a mobile developer interested in mixing native application components with a WebView (browser window) that can access device-level APIs, or if you want to develop a plugin interface between native and WebView components.

Basic Components

Apache Cordova applications rely on a common config.xml file that provides information about the app and specifies parameters affecting how it works, such as whether it responds to orientation shifts. This file adheres to the W3C's Packaged Web App, or widget, specification.

The application itself is implemented as a web page, named index.html by default, that references whatever CSS, JavaScript, images, media files, or other resources are necessary for it to run. The app executes as a WebView within the native application wrapper, which you distribute to app stores.

The Cordova-enabled WebView may provide the application with its entire user interface. On some platforms, it can also be a component within a larger, hybrid application that mixes the WebView with native application components. (See Embedding WebViews for details.)

A plugin interface is available for Cordova and native components to communicate with each other. This enables you to invoke native code from JavaScript. As of version 3.0, plugins provide bindings to standard device APIs. Third-party plugins provide additional bindings to features not necessarily available on all platforms. You can find these third-party plugins in the plugin registry and use them in your application. You can also develop your own plugins, as described in the Plugin Development Guide. Plugins may be necessary, for example, to communicate between Cordova and custom native components.

Development Paths

As of version 3.0, you can use two basic workflows to create a mobile app. While you can often use either workflow to accomplish the same task, they each offer advantages:

• Cross-platform workflow: Use this workflow if you want your app to run on as many different mobile operating systems as possible, with little need for platform-specific development. This workflow centers around the cordova utility, otherwise known as the Cordova CLI, that was introduced with Cordova 3.0. The CLI is a high-level tool that allows you to build projects for many platforms at once, abstracting away much of the functionality of lower-level shell scripts. The CLI copies a common set of web assets into subdirectories for each mobile platform, makes any necessary configuration changes for each, runs build scripts to generate application binaries. The CLI also provides a common interface to apply plugins to your app. For more details on the CLI, see The Command-Line Interface. Unless you have a need for the platform-centered workflow, the cross-platform workflow is recommended.

• Platform-centered workflow: Use this workflow if you want to focus on building an app for a single platform and need to be able to modify it at a lower level. You need to use this approach, for example, if you want your app to mix custom native components with web-based Cordova components, as discussed in Embedding WebViews. As a rule of thumb, use this workflow if you need to modify the project within the SDK. This workflow relies on a set of lower-level shell scripts that are tailored for each supported platform, and a separate Plugman utility that allows you to apply plugins. While you can use this workflow to build cross-platform apps, it is generally more difficult because the lack of a higher-level tool means separate build cycles and plugin modifications for each platform. Still, this workflow allows you greater access to development options provided by each SDK, and is essential for complex hybrid apps. See the various Platform Guides for details on each platform's available shell utilities.

When first starting out, it may be easiest to use the cross-platform workflow to create an app, as described in The Command-line Interface. You then have the option to switch to a platform-centered workflow if you need the greater control the SDK provides. Lower-level shell utilities are available at cordova.apache.org in a separate distribution than the CLI. For projects initially generated by the CLI, these shell tools are also available in the project's various platforms/*/cordova directories.

NOTE: Once you switch from the CLI-based workflow to one centered around the platform-specific SDKs and shell tools, you can't go back. The CLI maintains a common set of cross-platform source code, which on each build it uses to write over platform-specific source code. To preserve any modifications you make to the platform-specific assets, you need to switch to the platform-centered shell tools, which ignore the cross-platform source code, and instead relies on the platform-specific source code.

Installing Cordova

The installation of Cordova will differ depending on the workflow above you choose:

• Cross-platform workflow: see The Command-Line Interface.

• Platform-centered workflow: see the Platform Guides.

After installing Cordova, it is recommended that you review the Platform Guides for the mobile platforms that you will be developing for. It is also recommended that you also review the Privacy Guide, Security Guide, and Next Steps. For configuring Cordova, see The config.xml File. For accessing native function on a device from JavaScript, refer to the Plugin APIs. And refer to the other included guides as necessary.