在Java中创建异步多线程聊天应用程序
先决条件： Java中的数据报
在本文中，我们将学习如何使用Java中的数据报在Java中创建异步消息传递应用程序。在这种情况下，异步意味着服务器和客户端都可以独立地相互发送文本，而无需等待对方的任何类型的响应。我们将使用多线程的概念在DatagramPackets的帮助下实现进程之间的发送和接收文本消息。数据报是在应用程序之间传递的信息包。一旦数据报被发布到它的预定目标，它是独立的，不能保证它会到达，甚至不能保证某个应用程序会在那里接收它。 Java在UDP（用户数据报协议）协议之上实现数据报。
下面是上述方法的实现。
UnsyncChatServer.java
import java.net.*;
import java.io.*;
import java.util.*;
public class UnSyncChatServer {
public static void main(String args[])
throws IOException, InterruptedException
{
// Create DatagramSocket and get ip
DatagramSocket ss = new DatagramSocket(1234);
InetAddress ip = InetAddress.getLocalHost();
System.out.println("Running UnSyncChatServer.java");
System.out.println("Server is Up....");
// Create a sender thread
// with a nested runnable class definition
Thread ssend;
ssend = new Thread(new Runnable() {
@Override
public void run()
{
try {
Scanner sc = new Scanner(System.in);
while (true) {
synchronized (this)
{
byte[] sd = new byte[1000];
// scan new message to send
sd = sc.nextLine().getBytes();
DatagramPacket sp
= new DatagramPacket(
sd,
sd.length,
ip,
5334);
// send the new packet
ss.send(sp);
String msg = new String(sd);
System.out.println("Server says: "
+ msg);
// exit condition
if ((msg).equals("bye")) {
System.out.println("Server"
+ " exiting... ");
break;
}
System.out.println("Waiting for"
+ " client response... ");
}
}
}
catch (Exception e) {
System.out.println("Exception occured");
}
}
});
Thread sreceive;
sreceive = new Thread(new Runnable() {
@Override
public void run()
{
try {
while (true) {
synchronized (this)
{
byte[] rd = new byte[1000];
// Receive new message
DatagramPacket sp1
= new DatagramPacket(
rd,
rd.length);
ss.receive(sp1);
// Convert byte data to string
String msg
= (new String(rd)).trim();
System.out.println("Client ("
+ sp1.getPort()
+ "):"
+ " "
+ msg);
// Exit condition
if (msg.equals("bye")) {
System.out.println("Client"
+ " connection closed.");
break;
}
}
}
}
catch (Exception e) {
System.out.println("Exception occured");
}
}
});
ssend.start();
sreceive.start();
ssend.join();
sreceive.join();
}
}UnsyncChatClient.java
import java.io.*;
import java.net.*;
import java.util.Scanner;
public class UnSyncChatClient {
public static void main(String args[])
throws IOException, InterruptedException
{
// create DatagramSocket and get ip
DatagramSocket cs
= new DatagramSocket(5334);
InetAddress ip
= InetAddress.getLocalHost();
System.out.println("Running UnSyncChatClient.java");
System.out.println("Client is Up....");
// create a sender thread with a nested
// runnable class definition
Thread csend;
csend = new Thread(new Runnable() {
@Override
public void run()
{
try {
Scanner sc = new Scanner(System.in);
while (true) {
synchronized (this)
{
byte[] sd = new byte[1000];
// scan new message to send
sd = sc.nextLine().getBytes();
// create datagram packet
// for new message
DatagramPacket sp
= new DatagramPacket(
sd,
sd.length,
ip,
1234);
// send the new packet
cs.send(sp);
String msg = new String(sd);
System.out.println("Client says: "
+ msg);
// exit condition
if (msg.equals("bye")) {
System.out.println("client "
+ "exiting... ");
break;
}
System.out.println("Waiting for "
+ "server response...");
}
}
}
catch (IOException e) {
System.out.println("Exception occured");
}
}
});
// create a receiver thread with a nested
// runnable class definition
Thread creceive;
creceive = new Thread(new Runnable() {
@Override
public void run()
{
try {
while (true) {
synchronized (this)
{
byte[] rd = new byte[1000];
// receive new message
DatagramPacket sp1
= new DatagramPacket(
rd,
rd.length);
cs.receive(sp1);
// convert byte data to string
String msg = (new String(rd)).trim();
System.out.println("Server: " + msg);
// exit condition
if (msg.equals("bye")) {
System.out.println("Server"
+ " Stopped....");
break;
}
}
}
}
catch (IOException e) {
System.out.println("Exception occured");
}
}
});
csend.start();
creceive.start();
csend.join();
creceive.join();
}
}输出：窗口 1 (Java)
Running UnSyncChatServer.java
Server is Up....
Client (5334): hey
hi
Server says: hi
Waiting for client response...
ssup?
Server says: ssup?
Waiting for client response...
Client (5334): good
Client (5334): u?
good as well
Server says: good as well
Waiting for client response...
Client (5334): bye
Client connection closed.
bye
Server says: bye
Server exiting...
输出：窗口 2 (Java)
Running UnSyncChatClient.java
Client is Up....
hey
Client says: hey
Waiting for server response...
Server: hi
Server: ssup?
good
Client says: good
Waiting for server response...
u?
Client says: u?
Waiting for server response...
Server: good as well
bye
Client says: bye
client exiting...
Server: bye
Server Stopped...
笔记：
- 使用离线 IDE 运行此程序，因为在线 IDE 可能会超时。
- 先运行程序 1，再运行程序 2。