Java网络编程快速入门【狂神篇】
1、网络编程的目的
无线电台。。。。传播交流信息、数据交换、通信
想要达到这个效果需要什么：
- 如何准确的定位网络上的一台主机 ip地址 端口，定位到这个计算机上的某个资源
- 找到了这个主机，如何传输数据
Javaweb： 网页编程 B/s
网络编程：TCP/IP C/S
2、网络通信的要素
如何实现网络的通信？
通信双方地址：
-
IP
-
端口号
-
192.168.16.124：:5900
-
规则：网络通信的协议
TCP/IP
小结：
- 网络编程中有两个主要的问题
- 如何准确的定位到网络上的一台或多台主机
- 找到主机之后如何进行通信
- 网络编程中有两个主要的问题
- 网络编程中高端要素
- IP和端口号 IP
- 网络通信协议 udp tcp
- 万物皆对象
3、ip
ip地址：inteAddress 查看本地cmd ipconfig
- 唯一定位一台网络上计算机
- 127.0.0.1：本机localhost
- ip地址的分类
- ipv4/Ipv6
- ipv4 127.0.0.1 4个字节组成。 0~255 42亿个
- ipv6 fe80::60f8:dddd:6bea:17a7%5 ，128位。8个无符号整数！
- ipv4/Ipv6
try {
InetAddress localHost = InetAddress.getLocalHost();
System.out.println(localHost);
InetAddress[] inetAddress1 = InetAddress.getAllByName("127.0.0.1");
System.out.println(inetAddress1);
System.out.println(InetAddress.getByName("localhost"));
} catch (UnknownHostException e) {
e.printStackTrace();
}
}
4、端口
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
public static void main(String[] args) {
InetSocketAddress inetSocketAddress = new InetSocketAddress("127.0.0.1", 8080);
InetSocketAddress localhost = new InetSocketAddress("localhost", 8080);
System.out.println(inetSocketAddress);
System.out.println(localhost);
}
}
5、通信协议
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：实际上是一组协议
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
6、TCP
6.1、模拟客户端发送消息，服务端接收消息
import java.io.IOException;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.Socket;
import java.nio.charset.StandardCharsets;
/**
* @author ajun
* Date 2021/6/29
* @version 1.0
* 模拟客户端发送消息
*/
public class TCPClient {
public static void main(String[] args) throws IOException {
//socket连接
Socket socket = null;
//输出流
OutputStream os = null;
try{
//服务器地址
InetAddress host = InetAddress.getByName("127.0.0.1");
//服务器端口
int port = 9999;
//创建socket连接
socket = new Socket(host, port);
//获取输出流
os = socket.getOutputStream();
//发送消息
os.write("Hi，Ajun!".getBytes(StandardCharsets.UTF_8));
}finally {
//关闭输出流
if(os!=null){
os.close();
}
//关闭连接
if(socket!=null){
socket.close();
}
}
}
}
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.ServerSocket;
import java.net.Socket;
/**
* @author ajun
* Date 2021/6/29
* @version 1.0
* 模拟服务端接收消息
*/
public class TCPService {
public static void main(String[] args) {
//服务
ServerSocket serverSocket = null;
//连接
Socket socket = null;
//输入流
InputStream is = null;
//管道流
ByteArrayOutputStream baos = null;
try {
while (true) {
//创建服务
serverSocket = new ServerSocket(9999);
//等待客户端连接
socket = serverSocket.accept();//阻塞式监听，会一直等待客户端连接
//获取输入流
is = socket.getInputStream();
//建立管道流，接收消息
baos = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int len;
//读取消息
//int read(byte[] b)：读取若干字节并填充到byte[]数组，返回读取的字节数
while ((len = is.read(buffer)) != -1) {
//把 buffer 中的数据从 0 到 len，写入 baos
baos.write(buffer, 0, len);
}
System.out.println("收到!" + baos.toString());
}
}catch (IOException e){
}finally {
try{
//关闭管道流
if (baos != null) {
baos.close();
}
//关闭输入流
if (is != null) {
is.close();
}
//关闭连接
if (socket != null) {
socket.close();
}
//关闭服务
if (serverSocket != null) {
serverSocket.close();
}
}catch (IOException e){
}
}
}
}
6.2、文件上传
package com.ajun;
import java.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;
/**
* @author ajun
* Date 2021/6/29
* @version 1.0
* 模拟文件上传客户端
*/
public class TCPFileUploadClient {
public static void main(String[] args) throws Exception {
//创建连接
Socket socket = new Socket(InetAddress.getByName("127.0.0.1"), 9900);
//获取输出流
OutputStream outputStream = socket.getOutputStream();
//读取文件
FileInputStream inputStream = new FileInputStream("IMG_20200809_090035.jpg");
//写入文件
byte[] buffer = new byte[1024];
int len;
while((len=inputStream.read(buffer))!=-1){
outputStream.write(buffer,0,len);
}
//上传完毕：关闭连接
socket.shutdownOutput();
//确定服务端接收完毕，然后再关闭连接
InputStream inputStream1 = socket.getInputStream();//接收服务端反馈信息
ByteArrayOutputStream os2 = new ByteArrayOutputStream();//把接收到的信息输出
byte[] buffer2 = new byte[1024];
int len2;
while ((len2 = inputStream1.read(buffer2))!=-1){
os2.write(buffer2,0,len2);
}
System.out.println(os2.toString());
//read是阻塞的，执行完之后，后面的代码才可以执行
//关闭
inputStream1.close();
os2.close();
inputStream.close();
outputStream.close();
socket.close();
}
}
package com.ajun;
import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.nio.charset.StandardCharsets;
/**
* @author ajun
* Date 2021/6/29
* @version 1.0
* 模拟文件接收服务端
*/
@SuppressWarnings({"all"})
public class TCPFileUploadService {
public static void main(String[] args) throws IOException {
//创建服务
ServerSocket serverSocket = new ServerSocket(9900);
//监听连接
Socket socket = serverSocket.accept();
//获取输入流
InputStream inputStream = socket.getInputStream();
//文件输出
FileOutputStream fos = new FileOutputStream("service.jpg");
byte[] buffer = new byte[1024];
int len;
while((len = inputStream.read(buffer))!=-1){
fos.write(buffer,0,len);
}
//通知客户端接收完毕
OutputStream os = socket.getOutputStream();
os.write("接收完毕".getBytes(StandardCharsets.UTF_8));
//write是阻塞的，执行完之后，后面的代码才可以执行
//关闭
os.close();
fos.close();
inputStream.close();
socket.close();
serverSocket.close();
}
}
7、UDP
不需要连接，有地址和端口即可
7.1、发送消息
package com.ajun;
import java.io.IOException;
import java.net.*;
/**
* @author ajun
* Date 2021/6/30
* @version 1.0
* 客户端发送消息
*/
public class UDPClient {
public static void main(String[] args) throws IOException {
DatagramSocket socket = null;
try{
//建立socket
socket = new DatagramSocket();
//建立要发送的数据包
String msg = "Hello world!";
byte[] buffer = msg.getBytes();
InetAddress host = InetAddress.getByName("localhost");
int port = 9999;
DatagramPacket packet = new DatagramPacket(buffer,0,buffer.length,host,port);
//发送
socket.send(packet);
}finally {
//关闭连接
socket.close();
}
}
}
package com.ajun;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
/**
* @author ajun
* Date 2021/6/30
* @version 1.0
* 服务端接收消息
*/
public class UDPService {
public static void main(String[] args) throws IOException {
DatagramSocket socket = null;
try{
//开放端口
socket = new DatagramSocket(9999);
//准备接收数据的容器
byte[] buffer = new byte[1024];
DatagramPacket packet = new DatagramPacket(buffer, 0, buffer.length);
//接收
socket.receive(packet);
System.out.println("接收到的数据："+new String(packet.getData(),0,packet.getLength()));
}finally {
//关闭
socket.close();
}
}
}
7.2、循环发送
键盘自定义输入
循环发送
package com.ajun;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
/**
* @author ajun
* Date 2021/6/30
* @version 1.0
* 发送
*/
public class UDPSender {
public static void main(String[] args) throws IOException {
DatagramSocket socket = null;
BufferedReader reader = null;
try{
//建立连接
socket = new DatagramSocket(9000);//本机端口
//准备数据：控制台输入
reader = new BufferedReader(new InputStreamReader(System.in));
System.out.println("请输入要发送的消息...[注：bye 为退出]");
//循环发送
while (true){
String data = reader.readLine();
byte[] datas = data.getBytes();
InetAddress host = InetAddress.getByName("localhost");
int port = 8000;//接收方端口
DatagramPacket packet = new DatagramPacket(datas, 0, datas.length, host, port);
//发送
socket.send(packet);
if(data.equals("bye")){
break;
}
}
}finally {
//关闭
reader.close();
socket.close();
}
}
}
package com.ajun.com.ajun;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
/**
* @author ajun
* Date 2021/6/30
* @version 1.0
* 接收
*/
public class UDPService {
public static void main(String[] args) throws IOException {
DatagramSocket socket = null;
try{
//开启服务，监听连接
socket = new DatagramSocket(8000);
//循环接收
while (true){
//准备接收
byte[] buffer = new byte[1024];
DatagramPacket packet = new DatagramPacket(buffer, 0, buffer.length);
//接收
socket.receive(packet);//阻塞式
byte[] serviceData = packet.getData();
String sd = new String(serviceData, 0, packet.getLength());
System.out.println(sd);
if(sd.equals("bye")){
break;
}
}
}finally {
//关闭
socket.close();
}
}
}
7.3、聊天
只有双方都输入 bye 时，进程才会结束
一方输入 bye 时，只有这一方断开，另一方还在连接中
- 发送器
package com.ajun;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.*;
/**
* @author ajun
* Date 2021/6/30
* @version 1.0
* 发送消息
*/
public class TalkSend implements Runnable {
private DatagramSocket socket = null;//连接
private BufferedReader reader = null;//输入流
private int fromPort;//发送方端口
private int toPort;//接收方端口
private String toHost;//接收主机
private InetAddress host;
//构造器
public TalkSend(int fromPort, int toPort, String toHost) {
this.fromPort = fromPort;
this.toPort = toPort;
this.toHost = toHost;
try {
host = InetAddress.getByName(toHost);
} catch (UnknownHostException e) {
e.printStackTrace();
}
}
@Override
public void run() {
try {
//建立连接
socket = new DatagramSocket(fromPort);//本机端口
//准备数据：控制台输入
reader = new BufferedReader(new InputStreamReader(System.in));
//System.out.println("我是 " + Thread.currentThread().getName());
System.out.println("发送消息...[注：bye 为退出]");
while (true) {
String data = reader.readLine();
byte[] datas = data.getBytes();
DatagramPacket packet = new DatagramPacket(datas, 0, datas.length, host, toPort);
//发送
socket.send(packet);
if (data.equals("bye")) {
break;
}
}
} catch (IOException e) {
e.printStackTrace();
}finally {
//关闭
if(reader!=null){
try {
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if(socket!=null){
socket.close();
}
}
}
}
- 接收器
package com.ajun;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
/**
* @author ajun
* Date 2021/6/30
* @version 1.0
* 接收消息
*/
public class TalkReceive implements Runnable {
private DatagramSocket socket = null;
private int receivePort;//接收端口
private String sender;//发送方
public TalkReceive(int receivePort, String sender) {
this.receivePort = receivePort;
this.sender = sender;
}
@Override
public void run() {
try {
//开启服务，监听连接
socket = new DatagramSocket(receivePort);
while (true) {
//准备接收
byte[] buffer = new byte[1024];
DatagramPacket packet = new DatagramPacket(buffer, 0, buffer.length);
//接收
socket.receive(packet);//阻塞式
byte[] serviceData = packet.getData();
String sd = new String(serviceData, 0, packet.getLength());
System.out.println("[" + sender + "] " + sd);
if (sd.equals("bye")) {
break;
}
}
} catch (IOException e) {
}finally {
//关闭
if (socket != null) {
socket.close();
}
}
}
}
- 聊天一方
package com.ajun;
/**
* @author ajun
* Date 2021/6/30
* @version 1.0
* 聊天一方：小王
*/
public class Person1 {
public static void main(String[] args) {
//小王：发送端口9600，接收端口9700
//小花：发送端口9800，接收端口9900
TalkSend send = new TalkSend(9600, 9900, "localhost");//小王给小花发送消息
TalkReceive receive = new TalkReceive(9700,"小花");//小王接收小花消息
new Thread(send).start();
new Thread(receive).start();
}
}
- 聊天另一方
package com.ajun;
/**
* @author ajun
* Date 2021/6/30
* @version 1.0
* 聊天另一方：小花
*/
public class Person2 {
public static void main(String[] args) {
//小王：发送端口9600，接收端口9700
//小花：发送端口9800，接收端口9900
TalkSend send = new TalkSend(9800, 9700, "localhost");//小花给小王发送消息
TalkReceive receive = new TalkReceive(9900,"小王");//小花接收小王的消息
new Thread(send).start();
new Thread(receive).start();
}
}
8、URL
URL（Uniform Resource Locator,统一资源定位器）
-
URL由三部分组成：资源类型、存放资源的主机域名、资源文件名。
-
也可认为由4部分组成：协议、主机、端口、路径
-
URL的一般语法格式为：
-
(带方括号[]的为可选项)：
-
protocol / hostname[:port] / path / [;parameters][?query]#fragment