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[英]Using BufferedReader.readLine() in a while loop properly
[英]Kotlin BufferedReader.readLine() cause infinite loop
我在Kotlin中制作简单的Client-Server应用程序。 我遇到了BufferedReader.readLine()的问题。 我的服务器发送了几行文本,读取它们后,BufferedReader阻止了该程序,因此它不会继续运行。 看起来它仍在等待输入。 我不知道如何解决。 这是我的客户代码:
package Client
import java.io.BufferedReader
import java.io.IOException
import java.io.InputStreamReader
import java.io.PrintWriter
import java.net.Socket
class ConnectionHandler(client : Socket) {
private val reader : BufferedReader = BufferedReader(InputStreamReader(client.getInputStream()))
private val writer : PrintWriter = PrintWriter(client.getOutputStream(), true)
private var running : Boolean = false
fun handle() {
running = true
while (running) {
read()
write()
}
}
private fun write(){
var intput: String? = readLine()
if (intput != null) {
writer.println(intput)
if(intput.toLowerCase() == "exit")
running = false
}
}
private fun read(){
var output : String? = "Server:"
while (output != null) {
println(output)
output = reader.readLine()
}
}
}
这是我的服务器代码:
package Server
import java.io.BufferedReader
import java.io.InputStreamReader
import java.io.PrintWriter
import java.net.Socket
class ClientHandler(private val client : Socket) {
private val reader : BufferedReader = client.getInputStream().bufferedReader()
private val writer : PrintWriter = PrintWriter(client.getOutputStream(), true)
private var running : Boolean = false
fun handle(){
running = true
writer.println("Welcome to Server")
writer.println("Possible operations: + - / *")
writer.println("Example input 1 + 2 (notice the spaces between signs)")
writer.println("To Exit write EXIT")
while (running){
try {
val text = reader.readLine()
if (text.toLowerCase() == "exit"){
shutdown()
continue
}
val values = text.split(" ")
val result = Calculator().calculate(values[0].toInt(), values[2].toInt(), values[1])
writer.println(" = $result" )
}catch (ex: Exception){
writer.println("Something went wrong, need to exit")
shutdown()
}
}
}
private fun shutdown(){
running = false;
writer.println("exit")
client.close()
println("${client.inetAddress.hostAddress} closed connection")
}
}
客户端读取最后一行“ To Exit write EXIT”,然后等待,接受输入。
readLine()
将阻塞并等待输入,并且仅当套接字关闭时才返回null
。 您需要调整客户端/服务器通信协议,以便服务器在完成写入后发送一个特殊的标记,而客户端在接收到该标记时会退出read
功能中的循环。
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