[英]Bind Exception when trying to send UDP packet
我正在制作一個點對點聊天應用程序,為此我編寫了以下代碼用於與一個人聊天。 此代碼適用於 localhost(127.0.0.1) 但不適用於任何特定的 ip 地址 (192.168.43.118) 並引發 bindexception。 請幫忙。
import java.sql.*;
import java.io.*;
import java.net.*;
import java.util.Scanner;
public class communicate {
public static void main(String args[]) throws Exception {
communicate ob = new communicate();
String ip = "192.168.43.118";
ob.text(ip);
}
public void text(String friend_ip) throws Exception{
System.out.println("Press 'Exit' to exit the chat");
int send_port = 40002;
int receive_port = 40002;
//InetAddress inetaddr = InetAddress.getByName(friend_ip);
byte[] ipAddr = new byte[] { (byte)192, (byte)168, (byte)43, (byte)118 };
System.out.println(ipAddr.length);
InetAddress inetaddr = InetAddress.getByAddress(ipAddr);
System.out.println("B");
DatagramSocket serverSocket = new DatagramSocket(receive_port, inetaddr);
System.out.println("YO");
Runnable send = new SendMsg(send_port, friend_ip, serverSocket);
Runnable receive = new GetMsg(friend_ip, receive_port, serverSocket);
Thread t1 = new Thread(send);
Thread t2 = new Thread(receive);
t1.start();
t2.start();
}
class SendMsg implements Runnable {
private DatagramSocket senderSocket;
private int send_port;
private String sendto_ip;
SendMsg(int port, String friend_ip, DatagramSocket ds)throws Exception {
senderSocket = new DatagramSocket(64432);
send_port = port;
sendto_ip = friend_ip;
}
public void run(){
try {
while(true) {
String sendString;
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
sendString = br.readLine();
byte[] sendData = sendString.getBytes();
byte[] ipAddr = new byte[] { (byte)192, (byte)168, (byte)43, (byte)118 };
InetAddress inetAddress = InetAddress.getByAddress(ipAddr);
DatagramPacket sendPacket = new DatagramPacket (sendData, sendData.length, inetAddress, send_port);
senderSocket.send(sendPacket);
System.out.println("Message Sent");
}
}
catch(Exception e) {
System.out.println("Exc at Sender\n" + e);
}
finally {
if(senderSocket != null) senderSocket.close();
}
}
}
class GetMsg implements Runnable{
private DatagramSocket serverSocket;
private String friend_ip;
private int receive_port;
GetMsg(String ip, int port, DatagramSocket ds) throws Exception{
friend_ip = ip;
receive_port = port;
serverSocket = ds;
}
public void run(){
try {
while(true) {
byte[] receiveData = new byte[10000];
DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
serverSocket.receive(receivePacket);
String message = new String (receivePacket.getData(), 0, receivePacket.getLength());
System.out.println(friend_ip + ": " + message);
}
}
catch(Exception e) {
System.out.println("Exc at Rec\n" + e);
}
finally {
if(serverSocket != null) serverSocket.close();
}
}
}
}
當我在終端上運行它時,顯示以下輸出
Press 'Exit' to exit the chat
4
B
Exception in thread "main" java.net.BindException: Cannot assign requested address (Bind failed)
at java.base/java.net.PlainDatagramSocketImpl.bind0(Native Method)
at java.base/java.net.AbstractPlainDatagramSocketImpl.bind(AbstractPlainDatagramSocketImpl.java:131)
at java.base/java.net.DatagramSocket.bind(DatagramSocket.java:394)
at java.base/java.net.DatagramSocket.<init>(DatagramSocket.java:244)
at java.base/java.net.DatagramSocket.<init>(DatagramSocket.java:301)
at communicate.text(communicate.java:21)
at communicate.main(communicate.java:10)
由於未打印“YO”,因此錯誤似乎出現在我嘗試創建 DatagramSocket 的文本方法中。 我哪里錯了?
如果要讀取,請不要綁定遠程地址。 只需創建一個本地 UDP 套接字(它將是一個服務器套接字),然后讀取/寫入其緩沖區。 您只能綁定到本地網絡接口,並且必須在此之前進行初始化。 因此,您無法綁定到未使用的 Wifi 或未插入的以太網適配器。
如果要在不同線程上測試同一個 java 程序中的發送者和接收者,則必須使用兩個不同的套接字。
提示:使用InetAddress.getByName(IPv4)
進行字符串 IP 輸入,您不需要字節數組。
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