JAVA學習-網路程式設計
阿新 • • 發佈：2022-03-08
TCP實現聊天（Local）
服務端
package com.myTCP.chatDemo; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.io.InputStream; import java.net.ServerSocket; import java.net.Socket; public class ServerChat { public static void main(String[] args) { ServerSocket serverSocket = null; Socket socket = null; InputStream inputStream = null; ByteArrayOutputStream baos = null; try { //服務端需要一個地址 serverSocket = new ServerSocket(829); //服務端等待客戶端的連線 accept方法，就是等待客戶端連線 socket = serverSocket.accept(); //讀取客戶端訊息 inputStream = socket.getInputStream(); //管道流用於輸出 baos =new ByteArrayOutputStream(); byte[] bytes = new byte[1024]; int Len; while ((Len = inputStream.read(bytes)) != -1){ baos.write(bytes,0 ,Len); } System.out.println(baos.toString()); } catch (IOException e) { e.printStackTrace(); } finally { if (baos != null){ try { baos.close(); } catch (IOException e) { e.printStackTrace(); } } if (inputStream != null){ try { inputStream.close(); } catch (IOException e) { e.printStackTrace(); } } if (socket != null){ try { socket.close(); } catch (IOException e) { e.printStackTrace(); } } if (serverSocket != null){ try { serverSocket.close(); } catch (IOException e) { e.printStackTrace(); } } } } }
客戶端
package com.myTCP.chatDemo; import java.io.IOException; import java.io.OutputStream; import java.net.InetAddress; import java.net.Socket; import java.net.UnknownHostException; public class ClientChat { public static void main(String[] args) { Socket socket = null; OutputStream os = null; try { //獲得服務端IP InetAddress serverIP = InetAddress.getByName("127.0.0.1"); //填寫服務端IP和埠到客戶端 socket = new Socket(serverIP,829); //輸出流連到客戶端的輸出方法 os = socket.getOutputStream(); //輸出流輸出內容 os.write("hello,world!".getBytes()); } catch (Exception e) { e.printStackTrace(); } finally { if (os != null){ try { os.close(); } catch (IOException e) { e.printStackTrace(); } } if (socket != null){ try { socket.close(); } catch (IOException e) { e.printStackTrace(); } } } } }
TCP檔案上傳（Local）
UDP發簡訊（Local）
初級
傳送端
package com.myUDP.chatDemo01; import java.net.*; public class mySend { public static void main(String[] args) { DatagramSocket socket = null; try { socket = new DatagramSocket(); String msg ="hello,world"; InetAddress localhost = InetAddress.getByName("localhost"); int port = 829; DatagramPacket packet = new DatagramPacket(msg.getBytes(),0,msg.length(),localhost,port); socket.send(packet); } catch (Exception e) { e.printStackTrace(); } finally { } } }
接收端
package com.myUDP.chatDemo01;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.Socket;
import java.net.SocketException;
public class myReceive {
public static void main(String[] args) {
DatagramSocket socket = null;
DatagramPacket packet = null;
try {
socket = new DatagramSocket(829);//設定自己接收的埠
byte[] buffer = new byte[1024];//緩衝區
packet = new DatagramPacket(buffer,0,buffer.length);//接收資料包
socket.receive(packet);//阻塞式監聽
System.out.println(new String(packet.getData(),0,packet.getLength()));//輸出資料包接收到的內容
} catch (Exception e) {
e.printStackTrace();
} finally {
if (socket != null){
socket.close();
}
}
}
}
實現控制檯迴圈傳送
傳送端：
package com.myUDP.demo02;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.*;
public class Demo02 {
public static void main(String[] args) {
try {
DatagramSocket socket = new DatagramSocket(666) ;
while (true){
byte[] bytes = new byte[1024];
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
String sendBytes = reader.readLine();
bytes = sendBytes.getBytes();
InetAddress inetAddress = InetAddress.getLocalHost();
DatagramPacket packet = new DatagramPacket(bytes,0,bytes.length,inetAddress,888 );
socket.send(packet);
if (sendBytes.equals("bye")){
break;
}
}
socket.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
接收端
package com.myUDP.demo02;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
public class Demo02b {
public static void main(String[] args) {
try {
DatagramSocket socket = new DatagramSocket(888);
while (true){
byte[] buff = new byte[1024];
DatagramPacket packet = new DatagramPacket(buff,0,buff.length);
socket.receive(packet);
System.out.println(new String(buff,0, packet.getLength()));//注意，這裡必須是獲取packet的長度，byte[]的長度是1024！！
if (new String(buff,0, packet.getLength()).equals("bye")){
break;
}
}
socket.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
實現多執行緒互動式聊天
傳送訊息執行緒
package com.myUDP.demo04;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
public class SendMsg implements Runnable{
DatagramSocket socket;
BufferedReader reader;
private int toIP;
private int fromIP;
public SendMsg(int toIP, int fromIP) {
this.toIP = toIP;
this.fromIP = fromIP;
}
@Override
public void run() {
try {
socket = new DatagramSocket(fromIP) ;
reader = new BufferedReader(new InputStreamReader(System.in));
while (true){
byte[] bytes = new byte[1024];
String sendBytes = reader.readLine();
bytes = sendBytes.getBytes();
InetAddress inetAddress = InetAddress.getLocalHost();
DatagramPacket packet = new DatagramPacket(bytes,0,bytes.length,inetAddress,toIP );
socket.send(packet);
if (sendBytes.equals("bye")){
break;
}
}
socket.close();
System.exit(0);
} catch (Exception e) {
e.printStackTrace();
}
}
}
接收訊息執行緒
package com.myUDP.demo04;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
public class ReceiveMsg implements Runnable{
DatagramSocket socket;
private int recIP;
private String recName;
public ReceiveMsg(int recIP, String recName) {
this.recIP = recIP;
this.recName = recName;
}
@Override
public void run() {
try {
socket = new DatagramSocket(recIP);
while (true){
byte[] buff = new byte[1024];
DatagramPacket packet = new DatagramPacket(buff,0,buff.length);
socket.receive(packet);
System.out.println(recName+":"+new String(buff,0, packet.getLength()));//注意，這裡必須是獲取packet的長度，byte[]的長度是1024！！
if (new String(buff,0, packet.getLength()).equals("bye")){
break;
}
}
socket.close();
System.exit(0);
} catch (Exception e) {
e.printStackTrace();
}
}
}
客戶端啟動執行緒
package com.myUDP.demo04;
public class Student {
public static void main(String[] args) {
new Thread(new SendMsg(888,01)).start();
new Thread(new ReceiveMsg(666,"老師")).start();
}
}
////////////////////////////////
package com.myUDP.demo04;
public class Teacher {
public static void main(String[] args) {
new Thread(new SendMsg(666,02)).start();
new Thread(new ReceiveMsg(888,"學生")).start();
}
}
關於try-catch遇到的問題
注意一個問題！！！ try-catch 裡面new的物件一旦離開了try-catch就沒了，會出現空指標異常。
但如果是放在構造器裡面，相當於一出生就new了，是可以使用的！！！
例如，舉個例子，傳送執行緒：
package com.myUDP.demo03;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
public class SendMsg implements Runnable {
DatagramSocket socket = null;
DatagramPacket packet = null;
private int toPort;
private int formPort;
BufferedReader reader = null;
public SendMsg( int toPort, int formPort) {
this.toPort = toPort;
this.formPort = formPort;
try {
this.socket = new DatagramSocket(formPort);
this.reader = new BufferedReader(new InputStreamReader(System.in));
} catch (SocketException e) {
e.printStackTrace();
}
}
@Override
public void run() {
try {
while (true){
//String sendBytes = this.reader.readLine();
byte[] bytes = this.reader.readLine().getBytes(); //這裡不要定義1024，因為不清楚具體長度
this.packet = new DatagramPacket(bytes,0,bytes.length,InetAddress.getLocalHost(),toPort);
this.socket.send(packet);
String sendBytes = new String(bytes,0, bytes.length);
if (sendBytes.equals("bye")){
break;
}
socket.close();
}
} catch (Exception e) {
e.printStackTrace();
}
}
}