网络编程
感谢狂神说！！！（公众号以及B站）
网络编程
1.1、 概述
1.2 、网络通信的要素
1.3、 IP
public class TestInetAddress {
public static void main(String[] args) {
try {
//查询本机ip地址
InetAddress inetAddress1 = InetAddress.getByName("127.0.0.1");
System.out.println(inetAddress1);
InetAddress inetAddress3 = InetAddress.getByName("localhost");
System.out.println(inetAddress3);
InetAddress inetAddress4 = InetAddress.getLocalHost();
System.out.println(inetAddress4);
//查询网站ip地址
InetAddress inetAddress2 = InetAddress.getByName("www.baidu.com");
System.out.println(inetAddress2);
//常用方法
//System.out.println(inetAddress2.getAddress());
System.out.println(inetAddress2.getCanonicalHostName());//规范的ip
System.out.println(inetAddress2.getHostAddress());//ip
System.out.println(inetAddress2.getHostName());//域名或电脑的名字
} catch (UnknownHostException e) {
e.printStackTrace();
}
}
1.4、 端口
端口表示计算机上的一个程序的进程：
-
不同的进程有不同的端口号！用来区分软件！
-
被规定0-65535
-
端口分类
-
共有端口0~1023
- HTTP : 80
- HTTPS : 443
- FTP : 21
- Telent :23
-
程序注册端口：1024~49151，分配用户或者程序
- Tomcat : 8080
- MySQL :3306
- Oracle ：1521
-
动态，私有：49152~65535
-
netstat -ano #查看所有的端口 netstat -ano|findstr "5900" #查看指定的端口 tasklist|findstr "5204" #查看指定进程 -
public class TestScoketAddress { public static void main(String[] args) { InetSocketAddress inetSocketAddress = new InetSocketAddress("127.0.0.1", 8080); InetSocketAddress inetSocketAddress2 = new InetSocketAddress("localhost", 8080); System.out.println(inetSocketAddress); System.out.println(inetSocketAddress2); System.out.println(inetSocketAddress.getAddress()); System.out.println(inetSocketAddress.getHostName());//地址 System.out.println(inetSocketAddress.getPort());//端口 } }
-
1.5、通信协议
协议：约定，就好比我们的普通话
网络通信协议：速率，传输码率，代码结构，传输控制。。。。
TCP/IP协议簇
重要：
- TCP:用户传输协议
- UDP：用户数据报协议
出名的协议：
- TCP：
- IP：网络互联协议
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TCP udp 对比
TCP ：打电话
-
连接，稳定
-
三次握手，四次挥手
三次握手： 最少需要三次，保证稳定连接！ A：你愁啥？ B：瞅你咋地？ A：干一场！ 四次挥手： A：我要走了 B：你真的要走了吗？ B：你真的真的要走了吗？ A：我真的要走了！ -
客户端，服务端
-
传输完成，释放连接，效率低
UDP：发短信
- 不连接，不稳定
- 客户端，服务端：没有明确的界限
- 不管有没有准备好
- 导弹
- DDOS : 洪水攻击！（饱和攻击）
1.6、TCP
客户端：
-
连接服务器Socket
-
发送消息
-
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，端口号 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".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：
-
建立服务器的端口ServerSocket
-
等待用户的链接 accept
-
接收用户的消息
-
public class TcpServiceDemo01 { 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(); } } } } }
文件上传
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 outputStream = socket.getOutputStream();
//3、读取文件
FileInputStream fis = new FileInputStream(new File("JJ.png"));
//4、写出文件
byte[] buffer = new byte[1024];
int len;
while ((len=fis.read(buffer))!=-1){
outputStream.write(buffer,0,len);
}
//通知服务器，我已经结束了
socket.shutdownOutput();//我已经传输完了
//确定服务器接收完毕，才能断开连接
InputStream inputStream = socket.getInputStream();
//String byte[]
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
fis.close();
outputStream.close();
socket.close();
}
}
服务器
public class TcpServerDemo02 {
public static void main(String[] args) throws Exception {
//1、创建服务
ServerSocket serverSocket = new ServerSocket(9000);
//2、监听客户端的连接
Socket socket = serverSocket.accept();
//3、获取输入流
InputStream is = socket.getInputStream();
//4、文件输出
FileOutputStream fos = new FileOutputStream(new File("lin.png"));
byte[] buffer = new byte[1024];
int len;
while ((len=is.read(buffer))!=-1){
fos.write(buffer,0,len);
}
//通知客户端我已经接收完毕了
OutputStream os = socket.getOutputStream();
os.write("接收完毕！".getBytes());
//5、关闭资源
fos.close();
is.close();
socket.close();
serverSocket.close();
}
}
1.7、UDP
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(8080);
//2、建个包
String msg = "你好";
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(), port);
//3、发送包
socket.send(packet);
//4、关闭流
socket.close();
}
}
接收端
//还是要等待客户端的链接，但是没有真正意义上的服务器
public class UdpServerDemo02 {
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);//阻塞接收
System.out.println(packet.getAddress().getHostAddress());
System.out.println(new String(packet.getData(),0,packet.getLength()));
//关闭连接
socket.close();
}
}
在线聊天
public class TalkSend implements Runnable{
DatagramSocket socket = null;
BufferedReader reader = null;
private int fromPort;//哪来的ip
private String toIP;//要发送到的ip
private int toPort;//要发送到的端口
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){ //持续输出
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 (Exception 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 (Exception e) {
e.printStackTrace();
}
}
@Override
public void run() {
while (true) {
try {
//准备接收包裹
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
byte[] data = packet.getData();
String receiveData = new String(data, 0, data.length);
System.out.println(msgFrom + ":" + receiveData);
if (receiveData.equals("bye")) {
break;
}
} catch (Exception e) {
e.printStackTrace();
}
}
socket.close();
}
}
测试
public class TalkStudent {
public static void main(String[] args) {
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) {
new Thread(new TalkSend(5555,"localhost",8888)).start();
new Thread(new TalkReceive(9999,"学生")).start();
}
}
1.8、URL
浙公网安备 33010602011771号