Scala聊天應用程序阻塞問題

Question

我正在Scala中編寫聊天應用程序，問題與客戶端有關，客戶端在將數據發送到回顯服務器之前從StdIn（哪些塊）讀取數據，因此如果連接了多個客戶端那麼在StdIn完成讀取之前，他們不會從服務器接收數據。我在想，本地IO，即從標準輸入和讀取讀取/寫入插座應是在單獨的線程，但我不能想辦法做到這一點，下面是客戶端單碼：

import java.net._ 
import scala.io._ 
import java.io._ 
import java.security._ 

object Client { 

    var msgAcc = "" 

    def main(args: Array[String]): Unit = { 
    val conn = new ClientConnection(InetAddress.getByName(args(0)), args(1).toInt) 
    val server = conn.connect() 
    println("Enter a username") 
    val user = new User(StdIn.readLine()) 
    println("Welcome to the chat " + user.username) 
    sys.addShutdownHook(this.shutdown(conn, server)) 
    while (true) { 
    val txMsg = StdIn.readLine()//should handle with another thread? 
    if (txMsg != null) { 
     conn.sendMsg(server, user, txMsg) 
     val rxMsg = conn.getMsg(server) 
     val parser = new JsonParser(rxMsg) 
     val formattedMsg = parser.formatMsg(parser.toJson()) 
     println(formattedMsg) 
     msgAcc = msgAcc + formattedMsg + "\n" 
     } 
    } 
    } 

    def shutdown(conn: ClientConnection, server: Socket): Unit = { 
    conn.close(server) 
    val fileWriter = new BufferedWriter(new FileWriter(new File("history.txt"), true)) 
    fileWriter.write(msgAcc) 
    fileWriter.close() 
    println("Leaving chat, thanks for using") 
    } 

} 

下面

是ClientConnection類：

import javax.net.ssl.SSLSocket 
import javax.net.ssl.SSLSocketFactory 
import javax.net.SocketFactory 
import java.net.Socket 
import java.net.InetAddress 
import java.net.InetSocketAddress 
import java.security._ 
import java.io._ 
import scala.io._ 
import java.util.GregorianCalendar 
import java.util.Calendar 
import java.util.Date 
import com.sun.net.ssl.internal.ssl.Provider 
import scala.util.parsing.json._ 

class ClientConnection(host: InetAddress, port: Int) { 

    def connect(): Socket = { 
    Security.addProvider(new Provider()) 
    val sslFactory = SSLSocketFactory.getDefault() 
    val sslSocket = sslFactory.createSocket(host, port).asInstanceOf[SSLSocket] 
    sslSocket 
    } 

    def getMsg(server: Socket): String = new BufferedSource(server.getInputStream()).getLines().next() 

    def sendMsg(server: Socket, user: User, msg: String): Unit = { 
    val out = new PrintStream(server.getOutputStream()) 
    out.println(this.toMinifiedJson(user.username, msg)) 
    out.flush() 
    } 

    private def toMinifiedJson(user: String, msg: String): String = { 
    s"""{"time":"${this.getTime()}","username":"$user","msg":"$msg"}""" 
    } 

    private def getTime(): String = { 
    val cal = Calendar.getInstance() 
    cal.setTime(new Date()) 
    "(" + cal.get(Calendar.HOUR_OF_DAY) + ":" + cal.get(Calendar.MINUTE) + ":" + cal.get(Calendar.SECOND) + ")" 
    } 

    def close(server: Socket): Unit = server.close() 
} 

這是使用一個線程從標準輸入到讀出的客戶機單：

import java.net._ 
import scala.io._ 
import java.io._ 
import java.security._ 
import java.util.NoSuchElementException 

object Client { 

    var msgAcc = "" 

    def main(args: Array[String]): Unit = { 
    val conn = new ClientConnection(InetAddress.getByName(args(0)), args(1).toInt) 
    val server = conn.connect() 
    println("Enter a username") 
    val user = new User(StdIn.readLine()) 
    println("Welcome to the chat " + user.username) 
    sys.addShutdownHook(this.shutdown(conn, server)) 
    new Thread(conn).start() 
    while (true) { 
    val tx = conn.tx 
    if (tx != null) { 
     conn.sendMsg(server, user, tx) 
     val rxMsg = conn.getMsg(server) 
     val parser = new JsonParser(rxMsg) 
     val formattedMsg = parser.formatMsg(parser.toJson()) 
     println(formattedMsg) 
     msgAcc = msgAcc + formattedMsg + "\n" 
     } 
    } 
    } 

    def shutdown(conn: ClientConnection, server: Socket): Unit = { 
    conn.close(server) 
    val fileWriter = new BufferedWriter(new FileWriter(new File("history.txt"), true)) 
    fileWriter.write(msgAcc) 
    fileWriter.close() 

這是可運行延伸的ClientConnection類：

import javax.net.ssl.SSLSocket 
import javax.net.ssl.SSLSocketFactory 
import javax.net.SocketFactory 
import java.net.Socket 
import java.net.InetAddress 
import java.net.InetSocketAddress 
import java.security._ 
import java.io._ 
import scala.io._ 
import java.util.GregorianCalendar 
import java.util.Calendar 
import java.util.Date 
import com.sun.net.ssl.internal.ssl.Provider 
import scala.util.parsing.json._ 

class ClientConnection(host: InetAddress, port: Int) extends Runnable { 

    var tx: String = null 

    override def run(): Unit = { 
    tx = StdIn.readLine() 
    } 

    def connect(): Socket = { 
    Security.addProvider(new Provider()) 
    val sslFactory = SSLSocketFactory.getDefault() 
    val sslSocket = sslFactory.createSocket(host, port).asInstanceOf[SSLSocket] 
    sslSocket 
    } 

    def getMsg(server: Socket): String = new BufferedSource(server.getInputStream()).getLines().next() 

    def sendMsg(server: Socket, user: User, msg: String): Unit = { 
    val out = new PrintStream(server.getOutputStream()) 
    out.println(this.toMinifiedJson(user.username, msg)) 
    out.flush() 
    } 

    private def toMinifiedJson(user: String, msg: String): String = { 
    s"""{"time":"${this.getTime()}","username":"$user","msg":"$msg"}""" 
    } 

    private def getTime(): String = { 
    val cal = Calendar.getInstance() 
    cal.setTime(new Date()) 
    "(" + cal.get(Calendar.HOUR_OF_DAY) + ":" + cal.get(Calendar.MINUTE) + ":" + cal.get(Calendar.SECOND) + ")" 
    } 

    def close(server: Socket): Unit = server.close() 
} 

Answer 1

所以，你已經成功地移動輸入到Runnable的閱讀，所以它會在另一個Thread運行，但現在當我們看在你的主線程的邏輯，我們可以看到，它總是會發該消息如果不是null。有幾個問題是：

• 你不是在run方法循環，​​所以你只會收到一個消息，然後你run方法終止 - 你想在一個包裝這個while(true)或​​讓你不斷更新它。
• 只有在向服務器發送消息之後，您仍然在打印出來自服務器的消息。你應該解耦，這樣發送消息到服務器完全在另一個線程上完成。

東西沿着這一線路可能會解決這個問題：

//This is your new run method in your Runnable 
override def run(): Unit = { 
    while(true) { 
     tx = StdIn.readLine() 
     conn.sendMsg(server, user, tx) //Note you'll need to pass those references in somehow 
    } 
}` 

然後，在你的主線程，只是處理得到的消息，並打印出來：

new Thread(conn).start() 
while (true) { 
    //note the lack of sending messages in here 
    val rxMsg = conn.getMsg(server) 
    val parser = new JsonParser(rxMsg) 
    val formattedMsg = parser.formatMsg(parser.toJson()) 
    println(formattedMsg) 
    msgAcc = msgAcc + formattedMsg + "\n" 
} 

這樣，這兩種行爲在不同的線程上。