ServerSoket/Socket聊天簡單實現V3(多線程，多個客戶端對一個服務器，客戶端可接收可發送，服務器可接收可發送【發送後需等到再次接收到消息才能再次發送】)

知識點：每當服務器端接收到一個客戶端連接，就會另起一個新的線程進行處理，這樣就不會因爲某個客戶端處理的阻塞，而導致其他客戶端得不到處理。
待優化：新建線程比較耗費資源，考慮使用線程池做初步優化，減少因頻繁創建線程帶來的開銷
源碼如下：分服務器Server/客戶端Client/工具類Util三個類。
package communication;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.ServerSocket;
import java.net.Socket;

/**

• @author Dylaniou

• 需要先啓動服務器
  */
  public class Server {
  static ServerSocket serverSocket = null;
  static int port = 18000;
  static Socket socket = null;
  static int clientID = 0;
  public static void main(String[] args){
  try {
  serverSocket = new ServerSocket(port);
  } catch (IOException e) {
  Util.printlnfo(“IO異常，服務器啓動失敗”);
  e.printStackTrace();
  }
  Util.printlnfo(“服務器啓動成功，等待客戶端連接”);
  while(true){
  try {
  socket = serverSocket.accept();
  } catch (IOException e) {
  Util.printlnfo(“IO異常，等待客戶端連接失敗”);
  e.printStackTrace();
  }
  ++clientID;
  Util.printlnfo(“收到客戶端連接” );

   	new Thread(new ServerDeal(socket,clientID)).start();
   	/*DataOutputStream dos = null;
   	BufferedReader br = null;
   	BufferedReader br2 = null;
   	BufferedWriter bw = null;
   	
   	try {
   		dos = new DataOutputStream(socket.getOutputStream());
   		dos.writeInt(clientID);//告知客戶端，服務器爲其分配的ID
   		dos.flush();
   		Util.printlnfo("發送爲客戶端分配的ID:"+ clientID + ",準備接收客戶端消息" );
   		br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
   		br2 = new BufferedReader(new InputStreamReader(System.in));
   		bw = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
   		String line = null;
   		while((line = br.readLine())!=null){
   			Util.printlnfo("客戶端" + clientID + ":" + line+ "，服務器請回答~");
   			line = br2.readLine();
   			bw.write(line);
   			bw.newLine();
   			bw.flush();
   			Util.printlnfo("服務器：" + line+ "，客戶端請回答~");
   			line = null;
   		}
   	} catch (IOException e) {
   		Util.printlnfo("讀寫時出現IO異常");
   		e.printStackTrace();
   	}finally {
   		try {
   			if(dos!=null) dos.close();
   			if(br2!=null) br2.close();
   			if(br2!=null) bw.close();
   			if(br2!=null) br.close();
   		} catch (IOException e) {
   			Util.printlnfo("關閉時出現IO異常");
   			e.printStackTrace();
   		}
   	}*/
   }
  

  }
  }

class ServerDeal extends Thread{
Socket socket;
int clientID;
ServerDeal(Socket socket,int clientID){
this.socket = socket;
this.clientID = clientID;
}
public void run(){
DataOutputStream dos = null;
BufferedReader br = null;
BufferedReader br2 = null;
BufferedWriter bw = null;

	try {
		dos = new DataOutputStream(socket.getOutputStream());
		dos.writeInt(clientID);//告知客戶端，服務器爲其分配的ID
		dos.flush();
		Util.printlnfo("發送爲客戶端分配的ID:"+ clientID + ",準備接收客戶端消息" );
		br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
		br2 = new BufferedReader(new InputStreamReader(System.in));
		bw = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
		String line = null;
		while((line = br.readLine())!=null){
			Util.printlnfo("客戶端" + clientID + ":" + line+ "，服務器請回答~");
			line = br2.readLine();
			bw.write(line);
			bw.newLine();
			bw.flush();
			Util.printlnfo("服務器：" + line+ "，客戶端請回答~");
			line = null;
		}
	} catch (IOException e) {
		Util.printlnfo("讀寫時出現IO異常");
		e.printStackTrace();
	}finally {
		try {
			if(dos!=null) dos.close();
			if(br2!=null) br2.close();
			if(br2!=null) bw.close();
			if(br2!=null) br.close();
		} catch (IOException e) {
			Util.printlnfo("關閉時出現IO異常");
			e.printStackTrace();
		}
	}
}

}

package communication;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.DataInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.Socket;
import java.net.UnknownHostException;

/**

• @author Dylaniou

• 需要先啓動服務器
  */
  public class Client {
  static Socket socket = null;
  static int port = 18000;
  static int clientID = 0;
  public static void main(String[] args) {
  try {
  socket = new Socket(“localhost”,port);
  } catch (UnknownHostException e) {
  Util.printlnfo(“客戶端與服務器建立socket連接失敗：無法識別的主機”);
  e.printStackTrace();
  } catch (IOException e) {
  Util.printlnfo(“客戶端與服務器建立socket連接失敗：IO異常”);
  e.printStackTrace();
  }
  Util.printlnfo(“客戶端與服務器成功建立socket連接，準備接收服務器爲其分配的ID”);

   DataInputStream dis = null;
   BufferedReader br = null;
   BufferedReader br2 = null;
   BufferedWriter bw = null;
   
   try {
   	//獲取服務器分配的ID
   	dis = new DataInputStream(socket.getInputStream());
   	clientID = dis.readInt();
   	Util.printlnfo("成功接收到服務器爲其分配的ID:" + clientID + "，準備發送消息");
   	//發送命令行消息給服務器
   	//將命令行字節輸入流轉換爲字符輸入流，利用緩衝字符輸入流讀取命令行消息
   	br = new BufferedReader(new InputStreamReader(System.in));
   	//將socket字節輸出流轉換爲字符輸出流，利用緩衝字符輸出流輸出命令行消息
   	bw = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
   	br2 = new BufferedReader(new InputStreamReader(socket.getInputStream()));
   	String line =null;
   	while((line = br.readLine())!=null){
   		Util.printlnfo( "客戶端" + clientID + ":" + line+"，服務器請回答~");
   		bw.write(line);
   		bw.newLine();//用於終止輸出，不然命令行輸入再多內容也無法發送出去
   		bw.flush();
   		Util.printlnfo("服務器：" + br2.readLine() + "，客戶端"+ clientID + "請回答~");
   		line = null;
   	}
   } catch (IOException e) {
   	Util.printlnfo("讀寫時出現IO異常");
   	e.printStackTrace();
   }finally {
   	try {
   		if(dis!=null) dis.close();
   		if(br2!=null) br2.close();
   		if(br2!=null) bw.close();
   		if(br2!=null) br.close();
   	} catch (IOException e) {
   		Util.printlnfo("關閉時出現IO異常");
   		e.printStackTrace();
   	}
   }
  

  }
  }

package communication;

import java.text.SimpleDateFormat;
import java.util.Date;

public class Util {
public static String getCurrentTime(){
Date date=new Date();
//這個方法也是需要導包的
//注意第二個mm要大寫,不然月份會有錯誤
SimpleDateFormat sdf=new SimpleDateFormat(“yyy-MM-dd hh:mm:ss:SSS”);
return sdf.format(date);
}
public static void printlnfo(String info){
System.out.println(getCurrentTime()+":"+info);
}
}