Support Library官方教程(3)android studio中导入支援包

Support Library Setup

　　How you setup the Android Support Libraries in your development project depends on what features you want to use and what range of Android platform versions you want to support with your application.

　　This document guides you through downloading the Support Library package and adding libraries to your development environment.

Downloading the Support Libraries

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　　The Android Support Library package is provided as a supplemental download to the Android SDK and is available through the Android SDK Manager. Follow the instructions below to obtain the Support Library files.

　　To download the Support Library through the SDK Manager:

1. Start the Android SDK Manager.
2. In the SDK Manager window, scroll to the end of the Packages list, find theExtras folder and, if necessary, expand to show its contents.
3. Select the Android Support Library item.

   Note: If you're developing with Android Studio, select and install the Android Support Repository item instead.

4. Click the Install packages... button.

　　　　　　Figure 1. The Android SDK Manager with the Android Support Library selected.

　　After downloading, the tool installs the Support Library files to your existing Android SDK directory. The library files are located in the following subdirectory of your SDK: <sdk>/extras/android/support/ directory.

Choosing Support Libraries

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　　Before adding a Support Library to your application, decide what features you want to include and the lowest Android versions you want to support. For more information on the features provided by the different libraries, see Support Library Features.

Adding Support Libraries

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　　In order to use a Support Library, you must modify your application's project's classpath dependencies within your development environment. You must perform this procedure for each Support Library you want to use.

　　Some Support Libraries contain resources beyond compiled code classes, such as images or XML files. For example, the v7 appcompat and v7 gridlayout libraries include resources.

　保用支援包时要反它们导入项目中，而有些支援包有资源文件，也要把它们导入。如v7 appcompat和 v7 girdlayout就有资源文件

　　If you are not sure if a library contains resources, check the Support Library Features page. The following sections describe how to add a Support Library with or without resources to your application project.

Adding libraries without resources（无资源文件支援包的导入步骤）

　　To add a Support Library without resources to your application project:

1. Make sure you have downloaded the Android Support Repository using the SDK Manager.
2. Open the build.gradle file for your application.
3. Add the support library to the dependencies section. For example, to add the v4 support library, add the following lines:

    dependencies {
        ...
        compile "com.android.support:support-v4:18.0.+"
    }

Adding libraries with resources（有资源文件支援包的导入步骤）

　　To add a Support Library with resources (such as v7 appcompat for action bar) to your application project:

1. Make sure you have downloaded the Android Support Repository using the SDK Manager.
2. Open the build.gradle file for your application.
3. Add the support library feature project identifier to the dependencies section. For example, to include the appcompat project add compile "com.android.support:appcompat-v7:18.0.+" to the dependencies section, as shown in the following example:

    dependencies {
        ...
        compile "com.android.support:appcompat-v7:18.0.+"
    }

Using Support Library APIs

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　　Support Library classes that provide support for existing framework APIs typically have the same name as framework class but are located in the android.support class packages, or have a *Compat suffix.

　支援包中的类多在android.support中，或以 *Compat 为后缀

　　Caution: When using classes from the Support Library, be certain you import the class from the appropriate package. For example, when applying the ActionBar class:

• android.support.v7.app.ActionBar when using the Support Library.
• android.app.ActionBar when developing only for API level 11 or higher.

　　Note: After including the Support Library in your application project, we strongly recommend using the ProGuard tool to prepare your application APK for release. In addition to protecting your source code, the ProGuard tool also removes unused classes from any libraries you include in your application, which keeps the download size of your application as small as possible. For more information, see ProGuard.

　如果使用了支援包，通常要生成发布版的apk时，要用ProGuard优化，混淆，减少apk的体积。

　　Further guidance for using some Support Library features is provided in the Android developer training classes, guides and samples. For more information about the individual Support Library classes and methods, see the android.support packages in the API reference.

Manifest Declaration Changes

　　If you are increasing the backward compatibility of your existing application to an earlier version of the Android API with the Support Library, make sure to update your application's manifest. Specifically, you should update the android:minSdkVersion element of the <uses-sdk> tag in the manifest to the new, lower version number, as shown below:

<uses-sdk
      android:minSdkVersion="7"
      android:targetSdkVersion="17" />

　　The manifest setting tells Google Play that your application can be installed on devices with Android 2.1 (API level 7) and higher.

If you are using Gradle build files, the minSdkVersion setting in the build file overrides the manifest settings.

 apply plugin: 'com.android.application'

 android {
     ...

     defaultConfig {
         minSdkVersion 8
         ...
     }
     ...
 }

　　In this case, the build file setting tells Google Play that the default build variant of your application can be installed on devices with Android 2.2 (API level 8) and higher. For more information about build variants, see Build System Overview.

　　Note: If you are including the v4 support and v7 appcompat libraries in your application, you should specify a minimum SDK version of "7" (and not "4"). The highest support library level you include in your application determines the lowest API version in which it can operate.

Code Samples（示例的位置）

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　　Each Support Library includes code samples to help you get started using the support APIs. The code is included in the download from the SDK Manager and is placed inside the Android SDK installation directory, as listed below:

• 4v Samples: <sdk>/extras/android/support/samples/Support4Demos/
• 7v Samples: <sdk>/extras/android/support/samples/Support7Demos/
• 13v Samples: <sdk>/extras/android/support/samples/Support13Demos/
• App Navigation: <sdk>/extras/android/support/samples/SupportAppNavigation/

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