有一件重要的事情需要检查，到目前为止还没有人提到: 检查你的本地防火墙，确保它是关闭的。

请看我的回答: https://stackoverflow.com/a/41400708/1459275

当你的服务器运行(react-native start)时，将JS文件捆绑到你的apk中下载到你的应用程序的assets目录:

curl "http://localhost:8081/index.android.bundle?platform=android" -o "android/app/src/main/assets/index.android.bundle"

在下一个版本(0.12)中，我们将修复react-native bundle命令，以与预期的android项目一起工作。

从项目目录中运行

react-native start

输出如下:

$ react-native start
 ┌────────────────────────────────────────────────────────────────────────────┐ 
 │  Running packager on port 8081.                                            │ 
 │                                                                            │ 
 │  Keep this packager running while developing on any JS projects. Feel      │ 
 │  free to close this tab and run your own packager instance if you          │ 
 │  prefer.                                                                   │ 
 │                                                                            │ 
 │  https://github.com/facebook/react-native                                  │ 
 │                                                                            │ 
 └────────────────────────────────────────────────────────────────────────────┘ 
Looking for JS files in
   /home/user/AwesomeProject 


React packager ready.

[11:30:10 PM] <START> Building Dependency Graph
[11:30:10 PM] <START> Crawling File System
[11:30:16 PM] <END>   Crawling File System (5869ms)
[11:30:16 PM] <START> Building in-memory fs for JavaScript
[11:30:17 PM] <END>   Building in-memory fs for JavaScript (852ms)
[11:30:17 PM] <START> Building in-memory fs for Assets
[11:30:17 PM] <END>   Building in-memory fs for Assets (838ms)
[11:30:17 PM] <START> Building Haste Map
[11:30:18 PM] <START> Building (deprecated) Asset Map
[11:30:18 PM] <END>   Building (deprecated) Asset Map (220ms)
[11:30:18 PM] <END>   Building Haste Map (759ms)
[11:30:18 PM] <END>   Building Dependency Graph (8319ms)

删除你手机上的App !我尝试了几个步骤，但最终还是成功了。

If you tried to run your app before but failed, delete it from your android device. Run $ react-native run-android Open the React Rage Shake Menu from within your app on your android device, go to Dev Settings and then to Debug server host & port for device. There enter your server IP (IP of your computer) and host 8081, e.g. 192.168.50.35:8081. On a mac you can find the IP of your computer at System Preferences -> Network -> Advanced... -> TCP/IP -> IPv4 Address. Open the Rage Shake Menu again and click Reload JS.

此错误可以通过以下步骤轻松解决:

    //run the command at /android sdk / platforms-tool folder
        adb reverse tcp:8081 tcp:8081

    //now come to root folder of your app
    1. npm start
    2. create 'assets' folder inside rootApp/android/app/src/main/
    3. curl "http://localhost:8081/index.android.bundle?platform=android" -o "android/app/src/main/assets/index.android.bundle"
    4. make sure anyone physical or virtual device attached is running.
    5. react-native run-android

在android上的应用程序中，我打开菜单(Genymotion中的命令+ M) -> Dev Settings ->设备的调试服务器主机和端口

设置为:localhost:8081

这对我很管用。