服務器與客戶端互發信息 Test2.java ~~~ package chat.a2; import java.net.*; import java.io.*; public class Test2 { //構造函數 public Test2(){ try { //new一個端口 ServerSocket ss=new ServerSocket(9999); System.out.println("服務器正在監聽.."); Socket s=ss.accept();//接收服務器傳過來的信息 InputStreamReader isr=new InputStreamReader(s.getInputStream()); BufferedReader br = new BufferedReader(isr); PrintWriter pw =new PrintWriter(s.getOutputStream(),true); InputStreamReader isr2=new InputStreamReader(System.in);//輸入信息 BufferedReader br2 = new BufferedReader(isr2); while(true){ String xinxi = br.readLine(); System.out.println("客戶端說："+xinxi); System.out.println("我說"); String fasong = br2.readLine(); pw.println(fasong); } } catch (Exception e) { // TODO: handle exception } } public static void main(String[] args) { Test2 t=new Test2(); } } ~~~ Test3.java ~~~ package chat.a2; import java.net.*; import java.io.*; public class Test3 { public static void main(String[] args) { Test3 t=new Test3(); } public Test3(){ try { Socket s=new Socket("127.0.0.1",9999); PrintWriter pw =new PrintWriter(s.getOutputStream(),true); InputStreamReader isr=new InputStreamReader(System.in); BufferedReader br = new BufferedReader(isr); InputStreamReader isr2=new InputStreamReader(s.getInputStream()); BufferedReader br2 = new BufferedReader(isr2); while(true){ System.out.println("我發言："); String fasong = br.readLine(); pw.println(fasong); String jieshou = br2.readLine(); System.out.println("服務器說："+jieshou); } } catch (Exception e) { // TODO: handle exception } } } ~~~ 先啟動服務器Test2.java，再啟動客戶端Test3.java 服務器控制臺：  客戶端控制臺：