[英]Getting a 'Connection refused: connect' error because parseInt in Java Socket after passing data to the server from client?
我试图从客户端向服务器传递一个Integer因此在 Server 类中，我可以使用该整数作为斐波那契函数的参数。 问题是程序运行得非常好，并且在添加以下几行之前连接已经很好：
String transformedData = data.toString();
int transformedInt = Integer.parseInt(transformedData);
int result = fibonacci(transformedInt);
因此，当我将任何字符串从客户端传递到服务器时，我不知道为什么会出现错误（如下）
java.net.ConnectException: Connection refused: connect
at java.base/sun.nio.ch.Net.connect0(Native Method)
at java.base/sun.nio.ch.Net.connect(Net.java:503)
at java.base/sun.nio.ch.Net.connect(Net.java:492)
at java.base/sun.nio.ch.NioSocketImpl.connect(NioSocketImpl.java:588)
at java.base/java.net.SocksSocketImpl.connect(SocksSocketImpl.java:333)
at java.base/java.net.Socket.connect(Socket.java:648)
at java.base/java.net.Socket.connect(Socket.java:597)
at java.base/java.net.Socket.<init>(Socket.java:520)
at java.base/java.net.Socket.<init>(Socket.java:294)
at ajHomeWork1/cop2805.Client.main(Client.java:14)
另外，我是 Java 套接字编程的新手，所以我真的不知道将字节数据转换为 Integer 的操作是否是该程序的正确方法
服务器类：
public class Server {
static int fibonacci(int numb) // Recursive Fibonacci
{
if (numb <= 1)
return numb;
return fibonacci(numb-1) + fibonacci(numb-2);
}
public static void main(String[] args) {
ServerSocket server = null;
boolean shutdown = false;
try {
server = new ServerSocket(1238);
System.out.println("Port bound. Accepting Conncetions");
} catch (IOException e) {
e.printStackTrace();
System.exit(-1);
}
while(!shutdown) {
Socket client = null;
InputStream input = null;
OutputStream output = null;
try {
client = server.accept();
input = client.getInputStream();
output = client.getOutputStream();
int n = input.read();
byte[] data = new byte[n];
String transformedData = data.toString();
int transformedInt = Integer.parseInt(transformedData);
int result = fibonacci(transformedInt);
input.read(data);
String clientInput = new String(data, StandardCharsets.UTF_8);
clientInput.replace("\n", "");
System.out.println("Client said " + clientInput);
String response = "Your input was [" + clientInput + "]" + " Fibonacci result of " + transformedInt + " is : " + result;
output.write(response.length());
output.write(response.getBytes());
client.close();
if(clientInput.equalsIgnoreCase("shutdown")) {
System.out.println("Shutting down....");
shutdown = true;
}
}
catch (IOException e) {
e.printStackTrace();
continue;
}
}
}
}
这是客户端类：
public class Client {
public static void main(String[] args) {
System.out.print("Input an int : ");
BufferedReader userInput = new BufferedReader(new InputStreamReader(System.in));
try {
String userString = userInput.readLine();
Socket connection = new Socket("127.0.0.1",1238);
InputStream input = connection.getInputStream();
OutputStream output = connection.getOutputStream();
output.write(userString.length());
output.write(userString.getBytes());
int n = input.read();
byte[] data = new byte[n];
input.read(data);
String serverResponse = new String(data, StandardCharsets.UTF_8);
System.out.println("Server said: " + serverResponse);
if(!connection.isClosed())
connection.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
客户端和服务器处理数据的方式存在几个逻辑错误。 但是在建立连接后对数据的错误处理不会导致“连接被拒绝”错误。 该错误意味着客户端中的new Socket("127.0.0.1",1238)语句在交换任何数据之前失败。 这意味着客户端根本无法连接到服务器，要么是因为：
一旦您解决了该问题并可以正确建立连接，请尝试更类似于以下有关数据交换的操作：
服务器类：
public class Server {
static int fibonacci(int numb) // Recursive Fibonacci
{
if (numb <= 1)
return numb;
return fibonacci(numb-1) + fibonacci(numb-2);
}
public static void main(String[] args) {
ServerSocket server = null;
boolean shutdown = false;
try {
server = new ServerSocket(1238);
System.out.println("Port bound. Accepting Conncetions");
} catch (IOException e) {
e.printStackTrace();
System.exit(-1);
}
while (!shutdown) {
try {
Socket client = server.accept();
DataInputStream input = new DataInputStream(new BufferedInputStream(client.getInputStream()));
DataOutputStream output = new DataOutputStream(new BufferedOutputStream(client.getOutputStream()));
int n = input.readInt();
byte[] data = new byte[n];
input.readFully(data);
String clientInput = new String(data, StandardCharsets.UTF_8);
clientInput.replace("\n", "");
System.out.println("Client said " + clientInput);
String response;
if (clientInput.equalsIgnoreCase("shutdown"))
{
System.out.println("Shutting down....");
response = "Shutting down";
shutdown = true;
}
else
{
int transformedInt = Integer.parseInt(clientInput);
int result = fibonacci(transformedInt);
response = "Your input was [" + clientInput + "] Fibonacci result of " + Integer.toString(transformedInt) + " is : " + Integer.toString(result);
}
data = response.getBytes(StandardCharsets.UTF_8);
output.writeInt(data.length());
output.write(data, 0, data.length());
output.flush();
client.close();
}
catch (IOException e) {
e.printStackTrace();
}
}
}
}
客户端类：
public class Client {
public static void main(String[] args) {
System.out.print("Input an int : ");
BufferedReader userInput = new BufferedReader(new InputStreamReader(System.in));
try {
String userString = userInput.readLine();
Socket connection = new Socket("127.0.0.1", 1238);
DataInputStream input = new DataInputStream(new BufferedInputStream(connection.getInputStream()));
DataOutputStream output = new DataOutputStream(new BufferedOutputStream(connection.getOutputStream()));
bytes[] data = userString.getBytes(StandardCharsets.UTF_8);
output.writeInt(data.length());
output.write(data, 0, data.length());
output.flush();
int n = input.readInt();
data = new byte[n];
input.readFully(data);
String serverResponse = new String(data, StandardCharsets.UTF_8);
System.out.println("Server said: " + serverResponse);
connection.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
java.net.ConnectException：连接被拒绝：client / server tcp socket中的connect ,, error
[英]java.net.ConnectException: Connection refused: connect ,,error in client /server tcp socket
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