blocks|key|231115|text|它与Android的库依赖管理有关。有关详细信息，请参阅http://tools.android.com/recent/dealingwithdependenciesinandroidprojects|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|231116|entityMap|0|LINK|mutability|MUTABLE|url|http://tools.android.com/recent/dealingwithdependenciesinandroidprojects^0|S|20|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

It has to do with library dependency management of Android. for details see <a href="http://tools.android.com/recent/dealingwithdependenciesinandroidprojects" rel="nofollow">http://tools.android.com/recent/dealingwithdependenciesinandroidprojects</a>

blocks|key|2885662|text|如何将外部jar依赖项添加到Android项目的构建路径(内部或外部)对实际构建过程(更具体地说是在编译和索引步骤)没有影响，它所做的只是告诉构建过程在编译和索引步骤在哪里查找所需的jar。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2885663|Java+Build+Path+-+Libraries窗口中显示的Android+Dependencies元素只是ADT插件用于管理/分组jar依赖项的另一个抽象层。您的外部jar文件(在本例中为android-support-v4.jar)在该窗口中出现的位置(在Android+Dependencies内部或外部)没有区别。|offset|length|style|CODE|2885664|自从r17以来，依赖项管理已经有了很大的改进，建议使用libs/+directory来存储所有的jar依赖项(请参考你的内部方式)，这被认为是一种自动化的方法(因为ADT插件现在变得更智能了)，请参阅Revisions+for+ADT+17.0.0|2885665|2885666|新构建功能|blockquote|2885667|2885668|2885669|2885670|添加了自动设置JAR依赖项的功能。/libs文件夹中的所有.jar文件都会添加到构建配置中(类似于Ant构建系统的工作方式)。此外，库项目所需的.jar文件也会自动添加到依赖于这些库项目的项目中。(更多信息)|unordered-list-item|2885671|2885672|但是，如果您愿意，您仍然可以使用旧方法(参考您的外部方法)，这被认为是手动方法(因为ADT+plugin以前是愚蠢的)，请参阅Recent+Changes‎+for+r17+Release|2885673|2885674|重要提示:如果您仍然手动引用jar库，而不是将它们放在libs/下，请注意以下事项：|2885675|2885676|2885677|2885678|如果项目是库项目，则这些jar库不会自动对应用程序项目可见。您真的应该将这些文件移动到libs/|2885679|2885680|2885681|如果项目是应用程序，则可以执行此操作，但必须确保将jar文件标记为已导出。|2885682|2885683|以一种将库包含在"Android+Dependencies“组中的方式导入库有什么好处吗？|2885684|自动化as手动从依赖管理的角度来看，在计算机科学界，自动化总是被认为比手动更少出错。|2885685|entityMap|0|LINK|mutability|MUTABLE|url|http://developer.android.com/sdk/eclipse-adt.html|1|http://tools.android.com/recent/dealingwithdependenciesinandroidprojects^0|0|0|R|X|K|3P|K|0|2S|O|0|0|0|0|0|0|0|0|0|1R|V|1|0|0|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|1N|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|1O|8|@$D|1P|E|1Q|F|G]|$D|1R|E|1S|F|G]|$D|1T|E|1U|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|1V|8|@]|9|@$D|1W|E|1X|1|1Y]]|A|$]]|$1|J|3|-4|5|6|7|1Z|8|@]|9|@]|A|$]]|$1|K|3|L|5|M|7|20|8|@]|9|@]|A|$]]|$1|N|3|-4|5|6|7|21|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|22|8|@]|9|@]|A|$]]|$1|P|3|-4|5|6|7|23|8|@]|9|@]|A|$]]|$1|Q|3|R|5|S|7|24|8|@]|9|@]|A|$]]|$1|T|3|-4|5|6|7|25|8|@]|9|@]|A|$]]|$1|U|3|V|5|6|7|26|8|@]|9|@$D|27|E|28|1|29]]|A|$]]|$1|W|3|-4|5|6|7|2A|8|@]|9|@]|A|$]]|$1|X|3|Y|5|M|7|2B|8|@]|9|@]|A|$]]|$1|Z|3|-4|5|6|7|2C|8|@]|9|@]|A|$]]|$1|10|3|-4|5|6|7|2D|8|@]|9|@]|A|$]]|$1|11|3|-4|5|6|7|2E|8|@]|9|@]|A|$]]|$1|12|3|13|5|S|7|2F|8|@]|9|@]|A|$]]|$1|14|3|-4|5|6|7|2G|8|@]|9|@]|A|$]]|$1|15|3|-4|5|6|7|2H|8|@]|9|@]|A|$]]|$1|16|3|17|5|S|7|2I|8|@]|9|@]|A|$]]|$1|18|3|-4|5|6|7|2J|8|@]|9|@]|A|$]]|$1|19|3|1A|5|6|7|2K|8|@]|9|@]|A|$]]|$1|1B|3|1C|5|6|7|2L|8|@]|9|@]|A|$]]|$1|1D|3|-4|5|6|7|2M|8|@]|9|@]|A|$]]]|1E|$1F|$5|1G|1H|1I|A|$1J|1K]]|1L|$5|1G|1H|1I|A|$1J|1M]]]]

How do you add external jar dependencies into your Android project's build path (internally or externally) make no difference on the actual build process (more specifically at compile and dex step), all it does is to tell build process where to looking for the required jars at compile and dex step.
The <code>Android Dependencies</code> element shown in <code>Java Build Path - Libraries</code> window is just another abstract layer that ADT plugin used for managing/grouping jar dependencies. where your external jar files (in your case android-support-v4.jar) appears (inside or outside <code>Android Dependencies</code>) in that window makes no difference.
Since r17, dependencies management has been much improved, and it is recommended to use libs/ directory store all jar dependencies (refer to you internal way), which is considered as a automation approach (as ADT plugin becomes more smarter now), see <a href="http://developer.android.com/sdk/eclipse-adt.html" rel="noreferrer">Revisions for ADT 17.0.0</a>:
<blockquote>
New build features
<ul>
<li>Added feature to automatically setup JAR dependencies. Any .jar files in the /libs folder are added to the build configuration (similar to how the Ant build system works). Also, .jar files needed by library projects are also automatically added to projects that depend on those library projects. (more info)</li>
</ul>
</blockquote>
However, you can still use the old way (refer to you external way) if you prefer, which is considered as a manual approach (as ADT plugin was stupid before), see <a href="http://tools.android.com/recent/dealingwithdependenciesinandroidprojects" rel="noreferrer">Recent Changes‎ for r17 Release</a>:
<blockquote>
Important: If you are still referencing jar libraries manually instead of putting them under libs/ be aware of the following:
<ul>
<li>If the project is a Library project, these jar libraries will not be automatically visible to application projects. You should really move these to libs/
</li>
<li>If the project is an application, this can work but you must make sure to mark the jar files as exported.
</li>
</ul>
</blockquote>
<h3>Is there an advantage to importing a library in a way that it is included in the &quot;Android Dependencies&quot; group?</h3>
Automation vs. Manual from dependency management perspective, automation is always considered as more errorless than manual in the world of computer science.

blocks|key|229625|text|第一，show+show，‘我不敢相信他们没有测试这个’，把外部jar放在libs目录的缺点是你不能为它们设置javadoc位置，因为选项显示为'None+(不可修改)‘。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|229626|因此，我仍然在构建属性中使用导出选项|229627|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

The number one, show stopping, 'I can't believe they didn't test this', disadvantage of putting external jars in the libs directory is that you can't set the javadocs location for them, as the option shows as 'None (non modifiable)'.

Hence I still use Export option in build properties

blocks|key|228829|text|从Eclipse+FAQ|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|228830|228831|内部资源驻留在工作台的某个项目中，因此由工作台管理；与其他资源一样，这些资源也可以由工作台进行版本管理。外部资源不是工作台的一部分，只能通过引用使用。例如，JRE通常是外部的并且非常大，并且不需要将其与VCM系统相关联。|blockquote|228832|228833|228834|因此，非常简单，如果您希望能够将JAR作为项目的一部分进行管理，并将其公开给SCM等，则将其视为内部资源，否则，将其视为外部资源。它不会对最终产生的APK产生任何影响，这只是一个日食的事情。|228835|如果希望避免每次要使用库时都创建副本，请将其视为外部资源。但是，我建议您研究一下maven和android+maven+plugin，maven有一点学习曲线(特别是如果您习惯于“制作”或"ant“风格的构建脚本)，但这是非常值得的。|228836|entityMap|0|LINK|mutability|MUTABLE|url|http://help.eclipse.org/helios/index.jsp?topic=/org.eclipse.jdt.doc.user/reference/ref-jdt-faq.htm|1|http://maven.apache.org/|2|http://code.google.com/p/maven-android-plugin/^0|1|B|0|0|0|0|0|0|0|14|5|1|1A|K|2|0^^$0|@$1|2|3|4|5|6|7|Z|8|@]|9|@$A|10|B|11|1|12]]|C|$]]|$1|D|3|-4|5|6|7|13|8|@]|9|@]|C|$]]|$1|E|3|F|5|G|7|14|8|@]|9|@]|C|$]]|$1|H|3|-4|5|6|7|15|8|@]|9|@]|C|$]]|$1|I|3|-4|5|6|7|16|8|@]|9|@]|C|$]]|$1|J|3|K|5|6|7|17|8|@]|9|@]|C|$]]|$1|L|3|M|5|6|7|18|8|@]|9|@$A|19|B|1A|1|1B]|$A|1C|B|1D|1|1E]]|C|$]]|$1|N|3|-4|5|6|7|1F|8|@]|9|@]|C|$]]]|O|$P|$5|Q|R|S|C|$T|U]]|V|$5|Q|R|S|C|$T|W]]|X|$5|Q|R|S|C|$T|Y]]]]

From the <a href="http://help.eclipse.org/helios/index.jsp?topic=/org.eclipse.jdt.doc.user/reference/ref-jdt-faq.htm" rel="nofollow">Eclipse FAQ</a>

<blockquote>
 An internal resource resides in some project in the workbench and is therefore managed by the workbench; like other resources, these resources can be version managed by the workbench. An external resource is not part of the workbench and can be used only by reference. For example, a JRE is often external and very large, and there is no need to associate it with a VCM system.
</blockquote>

So, quite simply, if you want to be able to manage a JAR as part as the project, exposing it to SCM and such, then treat it as a internal resource otherwise, treat it as a external resource. It will not make any difference in the APK produced in the end, its simply a eclipse thing.

If you want to avoid creating a copy each time you want to use your library, treat it as a external resource. But, can I suggest you look into <a href="http://maven.apache.org/" rel="nofollow">maven</a> and the <a href="http://code.google.com/p/maven-android-plugin/" rel="nofollow">android maven plugin</a>, maven has a bit of a learning curve (especially if you are used to "make" or "ant" style build scripts), but it is very much worth the effort.

Post ADT 17, non-Android libraries need to be included either in the "libs" folders of the project or exported via the "Order and Export" tab in the build path. What's the difference (if any) between importing a library externally:

<img src="https://i.stack.imgur.com/Fe6IR.png" alt="External1">

<img src="https://i.stack.imgur.com/AvfQ7.png" alt="External2">

And internally:

<img src="https://i.stack.imgur.com/RfhqI.png" alt="Internal2">

<img src="https://i.stack.imgur.com/dW08p.png" alt="Internal1">

Is there an advantage to importing a library in a way that it is included in the "Android Dependencies" group?

Benefits in Android to importing a library internally vs externally

Android

Java

在ADT 17之后，非Android库需要包含在项目的"libs“文件夹中，或者通过构建路径中的"Order and Export”选项卡导出。在外部导入库有什么区别(如果有的话)​​​​和内部的​​​​以一种将库包含在"Android Dependencies“组中的方式导入库有什么好处吗？

问Android内部导入库与外部导入库的优势
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