上次博客带领大家学习了计算机网络编程的基础知识，本次博客带领大家学习计算机网络中的协议，如TCP协议、UDP协议等等。
TCP协议
客户端：
- 连接服务器 Socket
- 发送消息
//客户端
public class TcpClientDemo01 {
public static void main(String[] args) {
Socket socket = null;
OutputStream os = null;
try {
//1. 要知道服务器的地址
InetAddress serverIP = InetAddress.getByName("127.0.0.1");
int port=9999;
//2.创建一个socket连接
socket = new Socket(serverIP,port);
//3.发送消息 IO流
os = socket.getOutputStream();
os.write("你好，我是ld".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();
}
}
}
}
}
服务器
- 建立服务的端口 ServerSocket
- 等待用户的连接 accept
- 接收用的消息
//服务端
public class TcpserverDemo01 {
public static void main(String[] args) {
ServerSocket serverSocket = null;
Socket socket = null;
InputStream is = null;
ByteArrayOutputStream baos = null;
try {
//1.我得有一个地址
serverSocket=new ServerSocket(9999);
while (true){
//2. 等待客户端连接过来
socket = serverSocket.accept();
//3. 读取客户端的消息
is = socket.getInputStream();
//管道流
baos = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int len;
while((len = is.read(buffer))!=-1){
baos.write(buffer,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(is != null){
try {
is.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();
}
}
}
}
}
- 案例：文件的上传！
//客户端
public class TcpClientDemo02 {
public static void main(String[] args) throws Exception {
//1. 创建一个Socket连接。
Socket socket = new Socket(InetAddress.getByName("127.0.0.1"), 9000);
//2. 创建一个输出流
OutputStream os =socket.getOutputStream();
//3. 读取文件
FileInputStream fis = new FileInputStream(new File("boluo.jpg"));
//4. 写出文件
byte[] buffer = new byte[1024];
int len;
while ((len = fis.read(buffer))!=-1){
os.write(buffer,0,len);
}
socket.shutdownOutput();
//确定服务器接收完毕，才能够断开连接
InputStream inputStream = socket.getInputStream();
ByteArrayOutputStream baos = new ByteArrayOutputStream();
byte[] buffer2 = new byte[1024];
int len2;
while((len2=inputStream.read(buffer2))!=-1){
baos.write(buffer2,0,len2);
}
System.out.println(baos.toString());
//5.关闭资源
baos.close();
inputStream.close();
fis.close();
os.close();
socket.close();
}
}
//服务端
public class TcpserverDemo02 {
public static void main(String[] args) throws IOException {
//1. 创建服务
ServerSocket serverSocket = new ServerSocket(9000);
//2. 监听客户端的连接
Socket socket= serverSocket.accept(); //阻塞式监听，会一直等待客户端连接。
//3.获取输入流
InputStream is = socket.getInputStream();
//4. 文件输出
FileOutputStream fos = new FileOutputStream(new File("receive.jpg"));
byte[] buffer = new byte[1024];
int len;
while ((len = is.read(buffer))!= -1){
fos.write(buffer,0,len);
}
//通知客户端我接收完毕了
OutputStream os = socket.getOutputStream();
os.write("我接收完毕了，可以断开了".getBytes());
//关闭资源
os.close();
fos.close();
is.close();
socket.close();
serverSocket.close();
}
}
UDP协议
发送端和接收端不需要建立连接，但需要对方的地址！
- 发送端
//不需要连接服务器
public class UdpClientDemo01 {
public static void main(String[] args) throws Exception {
// 1. 建立一个Socket
DatagramSocket socket = new DatagramSocket();
// 2. 建个包
String msg = "你好啊，服务器！";
InetAddress localhost = InetAddress.getByName("localhost");
int port = 9090;
//数据，数据的长度起始，要发送给谁
DatagramPacket packet = new DatagramPacket(msg.getBytes(),0,msg.getBytes().length,localhost,port);
//3.发送包
socket.send(packet);
//4. 关闭流
socket.close();
}
}
- 接收端
public class UdpServerDemo01 {
public static void main(String[] args) throws Exception {
//开放端口
DatagramSocket socket = new DatagramSocket(9090);
//接收数据包
byte[] buffer = new byte[1024];
DatagramPacket packet = new DatagramPacket(buffer, 0, buffer.length);
socket.receive(packet);
System.out.println(packet.getAddress().getHostAddress());
System.out.println(new String(packet.getData(),0,packet.getLength()));
//关闭流
socket.close();
}
}
- 案例一：循环接收
public class UdpSenderDemo01 {
public static void main(String[] args) throws Exception {
DatagramSocket socket = new DatagramSocket(8888);
//准备数据：控制台读取System.in
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
while (true){
String data = reader.readLine();
byte[] datas = data.getBytes();
DatagramPacket packet = new DatagramPacket(datas,0,datas.length,new InetSocketAddress("localhost",6666));
socket.send(packet);
if(data.equals("bye")){
break;
}
}
socket.close();
}
}
public class UdpReceiveDemo01 {
public static void main(String[] args) throws Exception {
DatagramSocket socket = new DatagramSocket(6666);
//准备接收包裹
while(true){
byte[] container = new byte[1024];
DatagramPacket packet = new DatagramPacket(container,0,container.length);
socket.receive(packet);//阻塞式接收包裹
//断开连接 bye
byte[] data = packet.getData();
String receiveData =new String(data,0,data.length);
System.out.println(receiveData);
if(receiveData.equals("bye")){
break;
}
}
socket.close();
}
}
- 案例二：UDP多线程在线咨询
public class TalkSend implements Runnable{
DatagramSocket socket = null;
BufferedReader reader = null;
private int fromPort;
private String toIP;
private int toPort;
public TalkSend(int fromPort, String toIP, int toPort) {
this.fromPort = fromPort;
this.toIP = toIP;
this.toPort = toPort;
try {
socket = new DatagramSocket(fromPort);
reader = new BufferedReader(new InputStreamReader(System.in));
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
public void run() {
while (true){
try {
String data = reader.readLine();
byte[] datas = data.getBytes();
DatagramPacket packet = new DatagramPacket(datas,0,datas.length,new InetSocketAddress(this.toIP,this.toPort));
socket.send(packet);
if(data.equals("bye")){
break;
}
} catch (IOException e) {
e.printStackTrace();
}
}
socket.close();
}
}
public class TalkReceive implements Runnable {
DatagramSocket socket = null;
private int port;
private String msgFrom;
public TalkReceive(int port,String msgFrom) {
this.port = port;
this.msgFrom=msgFrom;
try {
socket = new DatagramSocket(port);
} catch (SocketException e) {
e.printStackTrace();
}
}
@Override
public void run() {
//准备接收包裹
while(true){
try {
byte[] container = new byte[1024];
DatagramPacket packet = new DatagramPacket(container,0,container.length);
socket.receive(packet);//阻塞式接收包裹
//断开连接 bye
byte[] data = packet.getData();
String receiveData =new String(data,0,data.length);
System.out.println(msgFrom+"："+receiveData);
if(receiveData.equals("bye")){
break;
}
} catch (IOException e) {
e.printStackTrace();
}
}
socket.close();
}
public class TalkStudent {
public static void main(String[] args) {
//开启两个线程
new Thread(new TalkSend(7777,"localhost",9999)).start();
new Thread(new TalkReceive(8888,"老师")).start();
}
}
public class TalkTeacher {
public static void main(String[] args) {
//开启两个线程
new Thread(new TalkSend(5555,"localhost",8888)).start();
new Thread(new TalkReceive(9999,"学生")).start();
}
}
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