//省略了引包 public?class?UDPServer?{ public?static?void?main(String[]?args)?throws?Exception?{ int?count=0; //?創(chuàng)建服務(wù)器端DatagramSocket，指定端口 DatagramSocket?socket=new?DatagramSocket(8800); //?創(chuàng)建數(shù)據(jù)報(bào)，用于接受客戶端發(fā)送的數(shù)據(jù)，客戶端發(fā)送的信息存儲(chǔ)在packet里 byte[]?data=new?byte[1024];//創(chuàng)建字節(jié)數(shù)組，指定接受的數(shù)據(jù)包的大小 DatagramPacket?packet=new?DatagramPacket(data,?data.length); System.out.println("Server?is?ready"); while(true) { //等待接受數(shù)據(jù) socket.receive(packet); //啟動(dòng)線程 UDPServerThread?udp=new?UDPServerThread(socket,packet); Thread?t=new?Thread(udp); t.start(); count++; System.out.println("歷史連接數(shù):"+count); } } } public?class?UDPServerThread?implements?Runnable?{ DatagramSocket?socket=null; DatagramPacket?packet=null; //構(gòu)造方法 public?UDPServerThread(DatagramSocket?socket,DatagramPacket?packet) { this.socket=socket; this.packet=packet; } @Override public?void?run(){ /* *?接受數(shù)據(jù) */ ??????? //?讀取數(shù)據(jù) String?info=new?String(packet.getData(),?0,?packet.getLength()); System.out.println("我是服務(wù)器，客戶端說(shuō)："+info); /* *?發(fā)送數(shù)據(jù) */ //定義客戶端地址和端口，以及要發(fā)送的信息 InetAddress?address=packet.getAddress(); int?port=packet.getPort(); byte[]?data2="歡迎您！".getBytes(); //創(chuàng)建數(shù)據(jù)報(bào) DatagramPacket?packet2=new?DatagramPacket(data2,?data2.length,?address,?port); //發(fā)送信息 try?{ socket.send(packet2); }?catch?(IOException?e)?{ //?TODO?Auto-generated?catch?block e.printStackTrace(); }finally{ ???socket.close(); } } } public?class?UDPClient?{ public?static?void?main(String[]?args)?throws?Exception??{ /* *?發(fā)送信息給服務(wù)器 */ DatagramPacket?packet=null; DatagramSocket?socket=null; //1.定義服務(wù)器地址，端口號(hào)，數(shù)據(jù) InetAddress?address=InetAddress.getByName("localhost"); int?port=8800; byte[]?data="用戶名:admin;密碼:123".getBytes(); //2.創(chuàng)建數(shù)據(jù)報(bào) packet=new?DatagramPacket(data,?data.length,address,port); //3.創(chuàng)建DatagramSocket對(duì)象 socket=new?DatagramSocket(); //4.向服務(wù)器發(fā)送數(shù)據(jù) socket.send(packet); /* *?接受服務(wù)器信息 */ //1.創(chuàng)建數(shù)據(jù)報(bào)，用于接受服務(wù)器端響應(yīng)的數(shù)據(jù) byte[]?data2=new?byte[1024]; DatagramPacket?packet2=new?DatagramPacket(data2,?data2.length); //2.接受數(shù)據(jù)并輸出 socket.receive(packet2); String?reply=new?String(data2,?0,?packet2.getLength()); System.out.println("我是客戶端,服務(wù)器返回信息是:"+reply); //3.關(guān)閉資源 socket.close(); } } //這樣的代碼有什么問(wèn)題嗎？運(yùn)行服務(wù)器端后，再運(yùn)行幾次客戶端就會(huì)報(bào)錯(cuò)異常信息是：Exception in thread "main" java.net.SocketException: socket closed