#react-native学习笔记 ##1.问题描述 ###1. 无法链接到服务器

com.facebook.react.devsupport.DebugServerException: Could not connect to development server.

URL: http://localhost:8081/index.android.bundle?platform=android&dev=true&hot=false
                                                                
Try the following to fix the issue:
• Ensure that the packager server is running
• Ensure that your device/emulator is connected to your machine and has USB debugging enabled - run 'adb devices' to see a list of connected devices
• If you're on a physical device connected to the same machine, run 'adb reverse tcp:8081 tcp:8081' to forward requests from your device
• If your device is on the same Wi-Fi network, set 'Debug server host & port for device' in 'Dev settings' to your machine's IP address and the port of the local dev server - e.g. 10.0.1.1:8081
at com.facebook.react.devsupport.DevServerHelper$1.onFailure(DevServerHelper.java:203)
at com.squareup.okhttp.Call$AsyncCall.execute(Call.java:175)
at com.squareup.okhttp.internal.NamedRunnable.run(NamedRunnable.java:33)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
at java.lang.Thread.run(Thread.java:841)

• 解决方案
  设置DEV Settings 将DEBUGGING内容设置成为当前IP+端口号,eg:18.18.19.163:8081
  如果上述方法还不生效则可能是packager server未开启, * npm start 多数情况下在执行react-native run-android的时候packager server会自动开启

###2.无法运行

jax$  react-native run-android
Starting JS server...
Building and installing the app on the device (cd android && ./gradlew installDebug...

Could not install the app on the device, read the error above for details.
Make sure you have an Android emulator running or a device connected and have
set up your Android development environment:
https://facebook.github.io/react-native/docs/android-setup.html

jax$ adb devices
List of devices attached
192.168.56.101:5555	device

• 解决方案
  you might check the permissions on android/gradlew
  they should be 755 not 644
  run chmod 755 android/gradlew inside your app root folder
  then run react-native run-android and it should work again.

###3.Application example has not been registered.

 Application example has not been registered. This is either due to a require() error during initialization or failure to call AppRegistry.registerComponent.

• 解决方案

1. Killing all node processes solved this one for me.
2. 检查是否在index.android.js或index.ios.js中出错
3. 是否在android工程或这ios工程中修改出错,部分情况下可以查看git diff,之前出现过一个在android工程中修改的时候

public class MainActivity extends ReactActivity {

    /**
     - Returns the name of the main component registered from JavaScript.
     - This is used to schedule rendering of the component.
     */
    @Override
    protected String getMainComponentName() {
        return "Gank";//不小心将这个地方这个改了,改成了 return "example";但是我的项目是Gank
    }
}

###4.[iOS 0.29.0]TypeError: Network request failed

TypeError: Network request failed
    at XMLHttpRequest.xhr.onerror (http://localhost:8081/index.ios.bundle?platform=ios&dev=true&minify=false:24437:8)
    at XMLHttpRequest.dispatchEvent (http://localhost:8081/index.ios.bundle?platform=ios&dev=true&minify=false:9960:15)
    at XMLHttpRequest.setReadyState (http://localhost:8081/index.ios.bundle?platform=ios&dev=true&minify=false:25890:6)
    at XMLHttpRequest.__didCompleteResponse (http://localhost:8081/index.ios.bundle?platform=ios&dev=true&minify=false:25748:6)
    at http://localhost:8081/index.ios.bundle?platform=ios&dev=true&minify=false:25823:52
    at RCTDeviceEventEmitter.emit (http://localhost:8081/index.ios.bundle?platform=ios&dev=true&minify=false:9191:23)
    at MessageQueue.__callFunction (http://localhost:8081/index.ios.bundle?platform=ios&dev=true&minify=false:7279:23)
    at http://localhost:8081/index.ios.bundle?platform=ios&dev=true&minify=false:7183:8
    at guard (http://localhost:8081/index.ios.bundle?platform=ios&dev=true&minify=false:7131:1)
    at MessageQueue.callFunctionReturnFlushedQueue (http://localhost:8081/index.ios.bundle?platform=ios&dev=true&minify=false:7182:1)

@(IOS)[模拟器, https,http]

• 解决方案

1. 修改Info.plist 中的`NSAppTransportSecurity NSAllowsArbitraryLoads ` 部分内容
2. iOS Simulator -> Reset Contents and Settings... -> Reset
3. 重新运行react-native run-ios