网络通信的要素
目录
- 网络通信的要素
- 1. IP地址
- 2. Java中的InetAddress包
- 3. 端口
- 4. 通信协议
- 5. TCP
- 1. 客户端
- 2. 服务器
- 3. 文件上传
- 6. Tomcat
- 7. UDP
- 1. UDP实现发送消息
- 2. 咨询
- 3. 在线咨询
- 8. URL
1. IP地址
InetAddress
-
唯一定位一台网络上的计算机
-
127.0.0.1：本机 localhost
-
IP地址的分类
-
IPV4/IPV 6
-
IPV4：127.0.0.1 4个字节组成，0-255，42亿个；30亿都在北美，亚洲4亿
-
IPV6：128位。8个无符号整数（十六进制，abcde）
2001:0bb2:aaaa:0015:0000:0000:1aaa:1312
-
-
公网（互联网）-私网（局域网）
-
192.168.XX.XX 专门给组织内部使用的
-
ABCD类地址
-
-
域名：解决记忆IP问题
2. Java中的InetAddress包
package com.wang.lesson01;
import java.net.InetAddress;
import java.net.UnknownHostException;
/**
* @author wang
* @creatTime 2020/8/7
*/
//测试IP
public class Test01 {
public static void main(String[] args) {
//快捷键 clt+alt+t
try {
//查询本机地址
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()); //规范的名字
System.out.println(inetAddress2.getHostAddress()); //ip
System.out.println(inetAddress2.getHostName()); //域名，或者本机的名字
} catch (UnknownHostException e) {
e.printStackTrace();
}
}
}
3. 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！
-
被规定为0~65535
-
TCP，UDP：单个协议下，端口号不能冲突
-
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，分配给用户或者程序
- Tomcat：8080
- MySQL：3306
- Orale：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 "8696" #查看指定端口的进程 Ctrl + Shift + Esc #打开任务管理器package com.wang.lesson01; import java.net.InetSocketAddress; /** * @author wang * @creatTime 2020/8/7 */ public class TestIntSocketAddress { public static void main(String[] args) { InetSocketAddress inetSocketAddress = new InetSocketAddress("127.0.0.1", 8080); System.out.println(inetSocketAddress.toString()); InetSocketAddress inetSocketAddress2 = new InetSocketAddress("localhost", 8080); System.out.println(inetSocketAddress2.toString()); System.out.println(inetSocketAddress.getAddress()); System.out.println(inetSocketAddress.getHostName()); //地址 System.out.println(inetSocketAddress.getPort()); //端口 } } -
4. 通信协议
协议：约定
网络通信协议：速率，传输码率，代码结构，传输控制
问题：复杂
解决方法：大事化小---->分层
TCP/IP协议簇：实际上是一种协议
重要
- TCP：用户传输协议
- UDP：用户数据报协议
出名的协议
- TCP
- IP：网络互连协议
TCP UDP对比
TCP：打电话
- 连接，稳定
- 三次握手，四次挥手
- 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，都可以发给你
- 类比：导弹
- DDOS：饱和攻击
5. TCP
1. 客户端
- 连接服务器Socket
- 发送消息
package com.wang.lesson02;
import java.io.IOException;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.Socket;
/**
* @author wang
* @creatTime 2020/8/7
*/
//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");
//2. 端口号
int port = 9999;
//3. 创建一个socket连接
socket = new Socket(serverIP, port);
//4. 发送消息IO流
os = socket.getOutputStream();
os.write("这是一行字".getBytes());
} catch (Exception e) {
e.printStackTrace();
} finally {
if (socket != null){
try {
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (os != null){
try {
os.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
2. 服务器
- 建立服务端的端口
- 等待用户的连接accept()，返回客户的socket
- 接收用户的消息
package com.wang.lesson02;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.ServerSocket;
import java.net.Socket;
/**
* @author wang
* @creatTime 2020/8/7
*/
//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);
//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 {
//关闭资源
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();
}
}
}
}
}
3. 文件上传
服务器端
package com.wang.lesson02;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.nio.file.Files;
import java.nio.file.NoSuchFileException;
import java.nio.file.Paths;
/**
* @author wang
* @creatTime 2020/8/7
*/
public class TCPServerDemo02 {
public static void main(String[] args) throws Exception{
//1.创建服务
ServerSocket serverSocket = new ServerSocket(9999);
//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，由于同名的文件存在时会抛出异常，因此先删除同名文件
try{
Files.delete(Paths.get("pic_receive.jpg"));
Files.copy(is, Paths.get("pic_receive.jpg"));
} catch (NoSuchFileException e) {
//如果同名文件不存在，则在NoSuchFileException中直接复制
Files.copy(is, Paths.get("pic_receive.jpg"));
}
//通知客户端我接收完毕了
OutputStream os = socket.getOutputStream();
os.write("我接收完毕了，你可以断开了".getBytes());
is.close();
socket.close();
serverSocket.close();
}
}
客户端
package com.wang.lesson02;
import java.io.ByteArrayOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.Socket;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
/**
* @author wang
* @creatTime 2020/8/7
*/
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("localhost"), 9999);
//2. 创建一个输出流
OutputStream os = socket.getOutputStream();
//文件流 Files用copy写到输入输出流，用readAllXXX读进来
//3. 读取文件
Path filePath = Paths.get("pic.jpg");
//4. 写出文件
Files.copy(filePath, os);
//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();
ByteArrayOutputStream baos = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int len;
while ((len = inputStream.read(buffer)) != -1){
baos.write(buffer,0,len);
}
System.out.println(baos.toString());
//5.关闭资源
baos.close();
inputStream.close();
os.close();
socket.close();
}
}
6. Tomcat
服务端
- 自定义 S
- Tomcat S：Java后台开发
客户端
- 自定义 C
- 浏览器 B
7. UDP
发短信：不用连接，需要知道对方的地址！
1. UDP实现发送消息
package com.wang.lesson03;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
/**
* @author wang
* @creatTime 2020/8/10
*/
//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 = "Hello, Server!";
//发送给谁
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();
}
}
UDP实现接收消息
package com.wang.lesson03;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
/**
* @author wang
* @creatTime 2020/8/10
*/
//还要等待客户端的连接
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); //阻塞接收
//关闭连接
socket.close();
//public String(byte[] bytes,int index,int length) 把字节数组的一部分转成字符串
System.out.println(new String(packet.getData(), 0, packet.getData().length));
}
}
2. 咨询
循环发送消息
package com.wang.chat;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
/**
* @author wang
* @creatTime 2020/8/10
*/
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[] dataBytes = data.getBytes();
DatagramPacket packet = new DatagramPacket(dataBytes, 0, dataBytes.length, new InetSocketAddress("localhost", 6666));
socket.send(packet);
if (data.equals("bye"))
break;
}
socket.close();
}
}
循环接收消息
package com.wang.chat;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
/**
* @author wang
* @creatTime 2020/8/10
*/
public class UDPReceiveDemo01 {
public static void main(String[] args) throws Exception {
DatagramSocket socket = new DatagramSocket(6666);
while (true) {
//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
//当接收到"bye"，断开连接
byte[] data = packet.getData();
String receiveData = new String(data, 0, data.length);
System.out.println(receiveData);
if (receiveData.equals("bye"))
break;
}
socket.close();
}
}
3. 在线咨询
两个人都可以是发送方，也都可以是接收方：使用多线程
循环发送消息
package com.wang.chat;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
/**
* @author wang
* @creatTime 2020/8/10
*/
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() {
//准备数据：控制台读取System.in
while (true) {
try {
String data = reader.readLine();
byte[] dataBytes = data.getBytes();
DatagramPacket packet = new DatagramPacket(dataBytes, 0, dataBytes.length, new InetSocketAddress(this.toIP, this.toPort));
socket.send(packet);
if (data.equals("bye"))
break;
} catch (IOException e) {
e.printStackTrace();
}
}
socket.close();
}
}
循环接收消息
package com.wang.chat;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
/**
* @author wang
* @creatTime 2020/8/10
*/
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() {
try {
while (true) {
//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
//当接收到"bye"，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 (IOException e) {
e.printStackTrace();
}
socket.close();
}
}
老师端
package com.wang.chat;
/**
* @author wang
* @creatTime 2020/8/10
*/
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();
}
}
学生端
package com.wang.chat;
/**
* @author wang
* @creatTime 2020/8/10
*/
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();
}
}
8. URL
统一资源定位符：定位互联网上的某一个资源
DNS域名解析：www.baidu.com ===> XXX.XX.XX.X
组成：
协议://ip地址:端口/项目名/资源
可以少但是不能多
package com.wang.lesson04;
import java.net.MalformedURLException;
import java.net.URL;
/**
* @author wang
* @creatTime 2020/8/10
*/
public class URLDemo01 {
public static void main(String[] args) throws MalformedURLException {
URL url = new URL("http://localhost:8080/helloworld/index.jsp?username=wang&password=123");
System.out.println(url.getProtocol()); //协议
System.out.println(url.getHost()); //主机ip
System.out.println(url.getPort()); //端口
System.out.println(url.getPath()); //文件
System.out.println(url.getFile()); //全路径
System.out.println(url.getQuery()); //参数
}
}
利用URL下载文件
package com.wang.lesson04;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.nio.file.Files;
import java.nio.file.NoSuchFileException;
import java.nio.file.Path;
import java.nio.file.Paths;
/**
* @author wang
* @creatTime 2020/8/10
*/
public class URLDown {
public static void main(String[] args) throws Exception {
//1.下载地址
URL url = new URL("https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1597050462137&di=e81d42b6c04eeff13b8011bdcdb7b5e7&imgtype=0&src=http%3A%2F%2Ft8.baidu.com%2Fit%2Fu%3D1484500186%2C1503043093%26fm%3D79%26app%3D86%26f%3DJPEG%3Fw%3D1280%26h%3D853");
//2.连接到这个资源 用Http
HttpURLConnection urlConnection = (HttpURLConnection)url.openConnection();
InputStream inputStream = urlConnection.getInputStream();
//利用Path和Files简化文件的IO
String filePath = "download_pic.jpg";
Path path = Paths.get(filePath);
//考虑到可能存在同名文件，先删除同名文件，再copy
try {
Files.delete(path);
Files.copy(inputStream, path);
} catch (NoSuchFileException e) {
//不存在同名文件，会抛出NoSuchFileException，此时直接copy
Files.copy(inputStream, path);
}
inputStream.close();
}
}