Android TCP客户端尝试连接到服务器

Question

我正在尝试创建一个 TCP 客户端来尝试连接到服务器。如果无法访问服务器，则必须在固定时间后重试。如果连接丢失，则应尝试重新连接。连接后，它应该能够从服务器读取数据（ASCII 字符串）。这段代码没有按预期工作[应用程序在没有服务器的情况下崩溃]。 我该如何解决？ （注意：服务器非常不可靠，不能期望优雅地断开连接）

package com.thinkalvb.sensorstorm

import android.util.Log
import java.io.BufferedReader
import java.io.IOException
import java.io.InputStreamReader
import java.net.Socket
import java.net.SocketException
private const val TAG = "Storm_Commander"

class Commander : Runnable {
    private lateinit var mTcpSocket: Socket

    override fun run() {
        val serverAddress = MainActivity.serverAddress
        val serverPort = MainActivity.portNumber
        while(!Thread.currentThread().isInterrupted) {
            try {
                Log.d(TAG,"Waiting for Server")
                mTcpSocket = Socket(serverAddress, serverPort)
                mTcpSocket.soTimeout = 5000
                mTcpSocket.keepAlive = true
                val receiveBuffer = BufferedReader(InputStreamReader(mTcpSocket.getInputStream(), "UTF-8"))
                Log.d(TAG,"Connected to Server")

                while (true) {
                    val command = receiveBuffer.readLine()
                    if (command != null) {
                        Log.d(TAG, command)
                    }
                }
            } catch (e: SocketException) {
                Log.e(TAG, "Socket Error:", e)
            } catch (e: IOException) {
                Log.e(TAG, "IO Error:", e)
            } finally {
                mTcpSocket.close()
                Log.d(TAG,"Client socket closed")
            }
        }
    }
}

整个项目在 Github https://github.com/ThinkalVB/SensorStorm

错误：

2021-03-25 21:05:44.201 1865-1865/com.thinkalvb.sensorstorm D/Storm_Location: Location Service created
2021-03-25 21:05:44.204 1865-1865/com.thinkalvb.sensorstorm D/Storm_Acceleration: Acceleration Sensor created
2021-03-25 21:05:44.204 1865-1865/com.thinkalvb.sensorstorm D/Storm_Orientation: Orientation Sensor created
2021-03-25 21:05:44.290 1865-1865/com.thinkalvb.sensorstorm D/Storm_Camera: Camera Service created
2021-03-25 21:05:44.290 1865-1865/com.thinkalvb.sensorstorm D/Storm_Temperature: Temperature Sensor created
2021-03-25 21:05:44.292 1865-1865/com.thinkalvb.sensorstorm D/Storm_MainActivity: Main Activity created
2021-03-25 21:05:48.986 1865-1865/com.thinkalvb.sensorstorm D/Storm_MainActivity: Service starting
2021-03-25 21:05:48.987 1865-1957/com.thinkalvb.sensorstorm D/Storm_Commander: Waiting for Server
2021-03-25 21:07:56.396 1865-1957/com.thinkalvb.sensorstorm E/Storm_Commander: Socket Error:
    java.net.ConnectException: failed to connect to /10.0.2.2 (port 1357) from /:: (port 37528): connect failed: ETIMEDOUT (Connection timed out)
        at libcore.io.IoBridge.connect(IoBridge.java:137)
        at java.net.PlainSocketImpl.socketConnect(PlainSocketImpl.java:137)
        at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:390)
        at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:230)
        at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:212)
        at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:436)
        at java.net.Socket.connect(Socket.java:621)
        at java.net.Socket.connect(Socket.java:570)
        at java.net.Socket.<init>(Socket.java:450)
        at java.net.Socket.<init>(Socket.java:250)
        at com.thinkalvb.sensorstorm.Commander.run(Commander.kt:20)
        at java.lang.Thread.run(Thread.java:764)
     Caused by: android.system.ErrnoException: connect failed: ETIMEDOUT (Connection timed out)
        at libcore.io.Linux.connect(Native Method)
        at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:118)
        at libcore.io.IoBridge.connectErrno(IoBridge.java:151)
        at libcore.io.IoBridge.connect(IoBridge.java:129)
        at java.net.PlainSocketImpl.socketConnect(PlainSocketImpl.java:137) 
        at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:390) 
        at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:230) 
        at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:212) 
        at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:436) 
        at java.net.Socket.connect(Socket.java:621) 
        at java.net.Socket.connect(Socket.java:570) 
        at java.net.Socket.<init>(Socket.java:450) 
        at java.net.Socket.<init>(Socket.java:250) 
        at com.thinkalvb.sensorstorm.Commander.run(Commander.kt:20) 
        at java.lang.Thread.run(Thread.java:764) 
2021-03-25 21:07:56.405 1865-1865/com.thinkalvb.sensorstorm D/Storm_MainActivity: Service stopping

Answer 1

为那些寻找一些代码的人提供临时解决方案。

while(!Thread.currentThread().isInterrupted) {
    try {
        Log.d(TAG, "Waiting for Server")
        mTcpSocket = Socket()
        mTcpSocket.connect(serverSocketAddress, 10000)
        mTcpSocket.keepAlive = true
        mTcpSocket.soTimeout = 15000

        if(mTcpSocket.isConnected){
            mTCPBufferIncoming = BufferedReader(InputStreamReader(mTcpSocket.getInputStream(), "UTF-8"))
            Log.d(TAG, "Connected to Server")
            processCommands()
        }
        mTcpSocket.close()
    } catch (e: SocketException) {
        Log.e(TAG, "Socket Error:", e)
    } catch (e: IOException) {
        Log.e(TAG, "IO Error:", e)
    } catch (e: Exception) {
        Log.e(TAG, "Exception:", e)
    }
}

private fun processCommands()
{
    var command: String
    while (mTCPBufferIncoming.readLine().also { command = it } != null) {
        Log.d(TAG, command)
    }
}