简易版react-native与node端udp通讯

最近做rn项目中做到通讯模块，需要app端与硬件进行通讯，正常的通讯用的都是websocket，但是当app端ip变化的时候，需要app进行广播告知硬件进行相应的改变，这个时候就需要用到upd广播。我们这里用到的是这个库：[react-native-udp](https://github.com/tradle/react-native-udp

)

1. 首先 引入库

npm install --save react-native-udp

2.和原生进行链接

react-native link react-native-udp
# OR, if you're using react-native older than 0.31:
rnpm link react-native-udp

3配置原生模块

• Register and load the Native Module in your Main application (import, getPackages)

import com.tradle.react.UdpSocketsModule;           // <--- import //

public class MainApplication extends Application implements ReactApplication {
    ...
    @Override
    protected List<ReactPackage> getPackages() {
        return Arrays.<ReactPackage>asList(
            new MainReactPackage(),
            new UdpSocketsModule()              // <- add here //
        );
    }
}

• package.json
  only if you want to write require('dgram') in your javascript

{
  "browser": {
    "dgram": "react-native-udp"
  }
}

3.rn部分

import dgram from 'react-native-udp';
import { udpPort } from '../config';

const toByteArray = obj => {
  var uint = new Uint8Array(obj.length);
  for (let i = 0, l = obj.length; i < l; i++) {
    uint[i] = obj.charCodeAt(i);
  }

  return new Uint8Array(uint);
}

export const sendUdpMessage = async (bCast, message) => {
  let socket = dgram.createSocket('udp4')
  const buf = toByteArray(JSON.stringify(message))
  socket.send(buf, 0, buf.length, udpPort, bCast, err => {
    if (err) {
      alert('error')
      socket && socket.close()
      // TODO: 错误处理
      return
    }
    socket && socket.close()
    alert('message was sent')
  })
}

4. 写一个简单的js 文件 node端进行测联调。

 var dgram = require("dgram");

var server = dgram.createSocket("udp4");

server.on("error", function (err) {
    console.log("server error:\n" + err.stack);
    server.close();
});

server.on("message", function (msg, rinfo) {
    console.log("server got: " + msg + " from " +
        rinfo.address + ":" + rinfo.port);
});

server.on("listening", function () {
    var address = server.address();
    console.log("server listening " +
        address.address + ":" + address.port);
});

server.bind(12347);