建立V7包库（Library）项目以供其他项目引

1. Chapter: 使用support-v7 ActionBar前的那些坑
2. 1. 1. 建立V7包库（Library）项目以供其他项目引用
   2. 2. v7库项目themes_base.xml相关文件报错问题
   3. 3. 关于引用Theme.AppCompat theme的报错问题

以前3.0以前的版本要使用ActionBar，必须使用国外大牛写的ActionBarSherlock这个开源项目。2013年的Google I/O大会之后，Google官方在android-support-v7包中添加了ActionBar，开始让2.1以后的版本支持ActionBar，从此以后曾经最火的Android开源项目ActionBarSherlock可以退出历史舞台了。

要是用v7包中ActionBar也很简单，但有一个需要注意的地方。有些人可能刚开始仅仅是把android-support-v7-appcompat.jar导入项目中，但是在设置Activity的theme时会报错，提示找不到"@style/Theme.AppCompat"。这是由于我们要把v7和资源文件一起导入才行，仅仅导入V7包是不够的。

Eclipse下具体使用步骤为（摘自Android官网）：

Create a library project based on the support library code:

1. Make sure you have downloaded the Android Support Library using the SDK Manager.
2. Create a library project and ensure the required JAR files are included in the project‘s build path:
   1. Select File > Import.
   2. Select Existing Android Code Into Workspace and click Next.
   3. Browse to the SDK installation directory and then to the Support Library folder. For example, if you are adding theappcompat project, browse to /extras/android/support/v7/appcompat/.
   4. Click Finish to import the project. For the v7 appcompat project, you should now see a new project titled android-support-v7-appcompat.
   5. In the new library project, expand the libs/ folder, right-click each .jar file and select Build Path > Add to Build Path. For example, when creating the the v7 appcompat project, add both the android-support-v4.jar andandroid-support-v7-appcompat.jar files to the build path.
   6. Right-click the project and select Build Path > Configure Build Path.
   7. In the Order and Export tab, check the .jar files you just added to the build path, so they are available to projects that depend on this library project. For example, the appcompat project requires you to export both the android-support-v4.jar and android-support-v7-appcompat.jar files.
   8. Uncheck Android Dependencies.
   9. Click OK to complete the changes.

You now have a library project for your selected Support Library that you can use with one or more application projects.

Add the library to your application project:

1. In the Project Explorer, right-click your project and select Properties.
2. In the Library pane, click Add.
3. Select the library project and click OK. For example, the appcompat project should be listed as android-support-v7-appcompat.
4. In the properties window, click OK.

Once your project is set up with the support library, here‘s how to add the action bar:

1. Create your activity by extending ActionBarActivity.
2. Use (or extend) one of the Theme.AppCompat themes for your activity. For example:

Now your activity includes the action bar when running on Android 2.1 (API level 7) or higher.

On API level 11 or higher

The action bar is included in all activities that use the Theme.Holo theme (or one of its descendants), which is the default theme when either the targetSdkVersion or minSdkVersion attribute is set to "11" or higher. If you don‘t want the action bar for an activity, set the activity theme to Theme.Holo.NoActionBar.

简单地说，就是：

1. 先升级SDK的Support Library；
2. 以SDK目录下/extras/android/support/v7/appcompat/为基础新建一个项目；
3. 将这个项目libs下的v4、v7包Build Path；
4. Configure Build Path。

基于5.0的V7包库项目

然后这个项目就可以被其它项目引用了。

2) v7库项目themes_base.xml相关文件报错问题

如果你用最新的SDK，可能新建的v7库项目会有这样的错误：

错误信息大概类似：

error: Error retrieving parent for item: No resource found that matches the given name ‘android:TextAppearance.Material‘.
error: Error retrieving parent for item: No resource found that matches the given name ‘android:Widget.Material.*‘
error: Error: No resource found that matches the given name: attr ‘android:actionModeShareDrawable‘.

解决办法很简单：

The only thing you have to do is to open the project.properties file of the android-support-v7-appcompat and change the target from target=android-19 to target=android-21. Afterwards just do a Project --> Clean... so that the changes take effect.

就是把编译环境改成SDK 21就行了。两种方法，打开project.properties，将target=android-7（或者其它）改成target=android-21；你也可以右键项目名，点击Android，修改Project Build Target为Google APIs 21。

然后clean一下，项目报错就会消失。

3) 关于引用Theme.AppCompat theme的报错问题

当 v7 库项目搭建好了，并且别的项目也引用了，你觉得应该没什么错误，但是运行报错了，大概报这样的错：

You need to use a Theme.AppCompat theme (or descendant) with this activity.

这错误很明显，也很简单，原来继承自ActionBarActivity的类必须指定固定的集中Theme风格，而这些Theme风格是需要导入V7中的appcompat LIB库工程，编译后再引用才能引用使用。

打开你项目的AndroidManifest.xml，找到android:theme="@style/xxx"，改成v7包里提供的方案就行了。比如：

更多色彩方案可以自己在Application Tab页去Browse。

stackoverflow 上有更详尽的讨论：http://stackoverflow.com/questions/21814825/you-need-to-use-a-theme-appcompat-theme-or-descendant-with-this-activity