Android之间在在局域网下互传消息，咱就不用走云服务器了吧，让俩安卓设备，自己传呗

方式1 通过在安卓设备上搭建Web服务器接收数据，可参考

Android使用AndServer在安卓设备上搭建服务端(Java)(Kotlin)两种写法

方式2 本文章，搭建Socket服务器，接收数据，发送TCP

此类文章网上一大堆，不多做讲解，直接上代码，自行参考

清单文件中添加权限

    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" /><uses-permission android:name="android.permission.INTERNET" /><uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />

MainActivity

class MainActivity : AppCompatActivity() {var mBinding: ActivityMainBinding? = nullvar timer: Timer? = nullvar mSocket: Socket? = nulloverride fun onCreate(savedInstanceState: Bundle?) {super.onCreate(savedInstanceState)this.window.statusBarColor = this.resources.getColor(R.color.white)this.window.decorView.systemUiVisibility = View.SYSTEM_UI_FLAG_LIGHT_STATUS_BARmBinding = DataBindingUtil.setContentView(this, R.layout.activity_main)requestPermission()mBinding!!.tv1.setOnClickListener {val intent = Intent(Settings.ACTION_ACCESSIBILITY_SETTINGS)startActivity(intent)}}override fun onResume() {super.onResume()if (mSocket != null){mSocket!!.close()mSocket = null}initServer()//定时器if (timer != null){timer!!.cancel()timer = null}timer = Timer()val timerTask: TimerTask = object : TimerTask() {override fun run() {runOnUiThread {//每次刷新再次操作//加个定时器，动态获取ip地址mBinding!!.tv1.text = "本机IP：${getLocalIpAddress()}，端口号: 8020"}}}timer?.schedule(timerTask, 0, 1000) //开启刷新，第二个参数是多长时间之后开始倒计时，第三个参数是多长时间进行一次}private fun initServer(){object : Thread() {override fun run() {try {// 创建ServerSocket   E5 93 88 E5 93 88 E5 93 88 E5 93 88 0Aval serverSocket = ServerSocket(8020)Log.e("TAG","32131232321--开启服务器，监听端口 9569--" + getLocalIpAddress())// 监听端口，等待客户端连接while (true) {Log.e("TAG","32131232321--等待客户端连接--")mSocket = serverSocket.accept() //等待客户端连接Log.e("TAG","32131232321---得到客户端连接：$mSocket")mBinding!!.tv2.post {mBinding!!.tv2.text = "当前连接IP:${mSocket}"}startReader(mSocket!!)}} catch (e: IOException) {e.printStackTrace()}}}.start()}// 获取ip地址private fun getLocalIpAddress(): String? {val netManager =applicationContext.getSystemService(CONNECTIVITY_SERVICE) as ConnectivityManagerval info = netManager.activeNetworkInfo// 网络是否连接return if (info != null && info.isConnected) {// wifi类型if (info.type == ConnectivityManager.TYPE_WIFI) {getWifiIpAddress()} else {// 其他类型getEthIpAddress()}} else "0.0.0.0"}// 获取有线网络的ip4地址private fun getEthIpAddress(): String? {val infaceName = "eth0"val ip = "0.0.0.0"try {val netInterface: Enumeration<NetworkInterface> =NetworkInterface.getNetworkInterfaces()while (netInterface.hasMoreElements()) {val inface: NetworkInterface = netInterface.nextElement()if (!inface.isUp()) {continue}// eth0 有线网络判断if (infaceName != inface.getDisplayName()) {continue}val netAddressList: Enumeration<InetAddress> = inface.getInetAddresses()while (netAddressList.hasMoreElements()) {val inetAddress: InetAddress = netAddressList.nextElement()// 获取IP4地址if (inetAddress is Inet4Address) {return inetAddress.getHostAddress()}}}} catch (e: Exception) {}return ip}// 获取wifi的ip地址private fun getWifiIpAddress(): String? {val wifiManager = applicationContext.getSystemService(WIFI_SERVICE) as WifiManagerval wifiInfo = wifiManager.connectionInfo// 获取32位整型IP地址val ipAddress = wifiInfo.ipAddress//返回整型地址转换成“*.*.*.*”地址return String.format("%d.%d.%d.%d",ipAddress and 0xff, ipAddress shr 8 and 0xff,ipAddress shr 16 and 0xff, ipAddress shr 24 and 0xff)}/*** 从参数的Socket里获取消息*/private fun startReader(mSocket: Socket) {object : Thread() {override fun run() {try {// 获取读取流val ins = mSocket.getInputStream()val buf = ByteArray(32)//获取数据赋值while (ins.read(buf) > 0) {//收到客户端发送的数据之后再发//serverSendMessage(getAppData())mBinding!!.tvId.post {var mS = mBinding!!.tvId.text.toString();mS += String(buf)mBinding!!.tvId.text = mSsetML(String(buf))}/*if (buf != null) {//延迟销毁runOnUiThread {Handler().postDelayed({ins.close()if (mSocket != null){mSocket.close()}}, 3000)}}*/}} catch (e: IOException) {e.printStackTrace()}}}.start()/*object : Thread() {override fun run() {try {// 获取读取流val mIn = BufferedReader(InputStreamReader(mSocket.getInputStream(), "utf-8"))var line = ""Log.e("TAG","32131232321---*等待客户端输入---13132321*---")while (mIn.readLine().also { line = it } != null) { // 读取数据Log.e("TAG","32131232321---*等待客户端输入*")Log.e("TAG","32131232321----获取到客户端的信息：$line")}} catch (e: IOException) {e.printStackTrace()}}}.start()*/}//通过socket来给客户端发送消息private fun serverSendMessage(mServerSendMessage: String) {object : Thread() {override fun run() {val out: PrintWritertry {out = PrintWriter(BufferedWriter(OutputStreamWriter(mSocket!!.getOutputStream())),true)Log.e("TAG","32131232321---发送给客户数据*---" + mServerSendMessage)out.println(mServerSendMessage)} catch (e: IOException) {e.printStackTrace()}}}.start()}/*动态申请权限操作*/private var isPermissionRequested = falseprivate fun requestPermission() {if (Build.VERSION.SDK_INT >= 23 && !isPermissionRequested) {isPermissionRequested = trueval permissionsList: ArrayList<String> = ArrayList()val permissions = arrayOf<String>(//在这里加入你要使用的权限Manifest.permission.READ_CONTACTS,Manifest.permission.ACCESS_COARSE_LOCATION,Manifest.permission.READ_CALENDAR,Manifest.permission.ACCESS_FINE_LOCATION,Manifest.permission.WRITE_CONTACTS,Manifest.permission.ACCESS_WIFI_STATE,)for (perm in permissions) {if (PackageManager.PERMISSION_GRANTED != checkSelfPermission(perm)) {permissionsList.add(perm)// 进入这里代表没有权限.}}if (permissionsList.isNotEmpty()) {val strings = arrayOfNulls<String>(permissionsList.size)requestPermissions(permissionsList.toArray(strings), 0)}}}//单独处理命令private fun setML(ml: String){if (ml.contains("xc")){val intent = Intent(Intent.ACTION_PICK)//指定获取的是图片intent.type = "image/*"startActivityForResult(intent,10086)}if (ml.contains("qc")){mBinding!!.tvId.post {mBinding!!.tvId.text = ""}}}}

activity_main

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:app="http://schemas.android.com/apk/res-auto"xmlns:tools="http://schemas.android.com/tools"><data></data><androidx.appcompat.widget.LinearLayoutCompatandroid:layout_width="match_parent"android:layout_height="match_parent"android:gravity="center"android:orientation="vertical"tools:context=".MainActivity"><TextViewandroid:id="@+id/tv1"android:layout_width="wrap_content"android:layout_height="wrap_content"android:textSize="16sp"android:textColor="#000000"android:text="本机IP"/><TextViewandroid:id="@+id/tv2"android:layout_width="wrap_content"android:layout_height="wrap_content"android:textSize="16sp"android:layout_marginTop="10dp"android:textColor="#000000"android:text="未连接"/><TextViewandroid:id="@+id/tv_id"android:layout_marginTop="10dp"android:layout_width="wrap_content"android:layout_height="wrap_content" /></androidx.appcompat.widget.LinearLayoutCompat>
</layout>

因为用到了 DataBind，这里提一下吧