1. 基础概念
计算机网络,网络通信的两个要素,IP地址(主机),端口Port(软件),通信协议(TCP/IP,三次握手四次挥手)
2. TCP实现聊天
客户端:
- 连接服务器Socket
- 发送消息
服务器:
- 建立服务的端口ServerSocket
- 等待用户的链接accept
- 接收用户的消息
示例:
创建Client类:
package com.netprogram;
import java.io.IOException;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;
//客户端
public class TcpClientDemo01 {
public static void main(String[] args) throws IOException {
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. 需要端口号
int port = 9999;
//3. 创建一个socket连接
socket = new Socket(serverIp,port);
//4. 发送消息
os = socket.getOutputStream();
os.write("欢迎连接".getBytes());
} catch (Exception e) {
e.printStackTrace();
} finally {
//关闭资源,用try{}catch{}按顺序关,JDK1.7之后有了try-with-resource处理机制简化代码
if (os != null){
os.close();
}
if (socket != null){
socket.close();
}
}
}
}
创建Server类:
package com.netprogram;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.ServerSocket;
import java.net.Socket;
//服务端
public class TcpServerDemo01 {
public static void main(String[] args) throws IOException {
ServerSocket serverSocket = null;
Socket socket = null;
InputStream is = null;
ByteArrayOutputStream baos = null;
try {
//1. 需要有一个地址
serverSocket = new ServerSocket(9999);
/*
//2. 等待客户端连接
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());
*/
while (true){ //这里可以循环监听
//2. 等待客户端连接
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){
baos.close();
}
if (is != null){
is.close();
}
if (socket != null){
socket.close();
}
if (serverSocket != null){
serverSocket.close();
}
}
}
}
结果:
关闭连接简化机制:
3. TCP文件上传实现
客户端:
package com.netprogram.demo02;
import java.io.*;
import java.net.Socket;
public class TcpClientDemo02 {
public static void main(String[] args) throws Exception {
//1. 创建一个socket连接
Socket socket = new Socket("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("IU.jpg"));
//4.写出文件
byte[] buffer = new byte[1024];
int len;
while ((len = fis.read(buffer))!=-1){
os.write(buffer,0,len);
}
//5. 通知服务器已经发送
socket.shutdownOutput();
//6.确定服务器接收完毕,才能够断开连接
InputStream ips = socket.getInputStream();
//String byte[]
ByteArrayOutputStream baos = new ByteArrayOutputStream();
byte[] buffer1 = new byte[2048];
int len1;
while ((len1 = ips.read(buffer1))!=-1){
baos.write(buffer1,0,len1);
}
System.out.println(baos.toString());
//7.关闭资源
baos.close();
ips.close();
fis.close();
os.close();
socket.close();
}
}
服务端:
package com.netprogram.demo02;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;
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(); //阻塞式监听
//3. 获取输入流
InputStream is = socket.getInputStream();
//4. 文件输出
FileOutputStream fos = new FileOutputStream("IUCopy.jpg");
byte[] buffer = new byte[1024];
int len;
while ((len = is.read(buffer))!=-1){
fos.write(buffer,0,len);
}
//5. 通知客户端接收完毕
OutputStream ops = socket.getOutputStream();
ops.write("接收完毕,允许断开".getBytes());
//6. 关闭资源
ops.close();
fos.close();
is.close();
socket.close();
serverSocket.close();
}
}
4. 初识Tomcat
服务端
- 自定义 S
- Tomcat服务器(Java后台开发) S
客户端:
- 自定义 C
- 浏览器 B
解压Tomcat包,打开bin目录中的starup.bat,启动完毕,浏览器输入localhost:8080即可进入网站
5. UDP
发短信:不用连接,需要知道对方的地址
没有真正的客户端、服务端概念
6. UDP消息发送
发送端:
package com.netprogram.demo03;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
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";
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:
package com.netprogram.demo03;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.util.Arrays;
//还是需要等待发送端的连接
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
System.out.println(packet.getAddress().getHostAddress());
System.out.println(new String(packet.getData()));
//关闭连接
socket.close();
}
}
7. UDP聊天实现
单方发送接收消息
发送消息:
package com.netprogram.demo04;
import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
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
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
String data = reader.readLine();
byte[] data1 = data.getBytes();
DatagramPacket packet = new DatagramPacket(data1,0, data1.length,new InetSocketAddress("localhost",6666));
socket.send(packet);
socket.close();
}
}
接收消息:
package com.netprogram.demo04;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
public class UdpReceiverDemo01 {
public static void main(String[] args) throws Exception{
DatagramSocket socket = new DatagramSocket(6666);
while (true) {
//准备接受包裹
byte[] container = new byte[1024];
DatagramPacket packet = new DatagramPacket(container, 0, container.length);
socket.receive(packet); //阻塞式接收包裹
byte[] data = packet.getData();
String data1 = new String(data,0, data.length);
System.out.println(data1);
System.out.println(data1.length());
if (data1.trim().equals("bye")){ //字符数组除了bye还有0值,转换成String都是空格,所以需要trim减掉多余部分
break; //退出循环,关闭连接
}
}
socket.close();
}
}
在线咨询
两个人都可以是接收方、发送方
示例:
创建TalkReceive类:
package com.netprogram.demo05;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
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() {
while (true) {
try {
//准备接受包裹
byte[] container = new byte[1024];
DatagramPacket packet = new DatagramPacket(container, 0, container.length);
socket.receive(packet); //阻塞式接收包裹
byte[] data = packet.getData();
String data1 = new String(data, 0, data.length);
System.out.println(msgFrom + ":" + data1);
if (data1.trim().equals("bye")) { //字符数组除了bye还有0值,转换成String都是空格,所以需要trim减掉多余部分
break; //退出循环,关闭连接
}
} catch (IOException e) {
e.printStackTrace();
}
}
socket.close();
}
}
创建TalkSend类:
package com.netprogram.demo05;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
import java.net.SocketException;
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);
} catch (SocketException e) {
e.printStackTrace();
}
reader = new BufferedReader(new InputStreamReader(System.in));
}
@Override
public void run() {
while (true) {
try {
String data = reader.readLine();
byte[] data1 = data.getBytes();
DatagramPacket packet = new DatagramPacket(data1,0, data1.length,new InetSocketAddress(this.toIp,this.toPort));
socket.send(packet);
if (data.equals("bye")){
break;
}
} catch (IOException e) {
e.printStackTrace();
}
}
socket.close();
}
}
创建TalkStudent类:
package com.netprogram.demo05;
public class TalkStudent {
public static void main(String[] args) {
//开启两个线程
new Thread(new TalkSend(6666,"Localhost",8888)).start();
new Thread(new TalkReceive(9999,"Teacher")).start();
}
}
创建TalkTeacher类:
package com.netprogram.demo05;
public class TalkTeacher {
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,"Student")).start();
}
}
学生端结果:
教师端结果:
(两边都输入bye可以结束程序)
8. URL下载网络资源
URL(uniform resourse locator):统一资源定位符,定位互联网上的某一个资源
DNS域名解析:将形如www.baidu.com的域名解析成IP地址
协议://IP地址:端口/项目名/资源
示例:
package com.netprogram.demo06;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.InetAddress;
import java.net.URL;
import java.net.URLConnection;
public class UrlDown {
public static void main(String[] args) throws Exception{
//1. 下载地址
URL url = new URL("http://localhost:8080/yue/important.txt");
//2. 连接到这个资源 HTTP
HttpURLConnection urlConnection = (HttpURLConnection)url.openConnection();
//3. 写文件
InputStream is = urlConnection.getInputStream();
FileOutputStream fos = new FileOutputStream("f:\\example.txt");
byte[] buffer = new byte[1024];
int len;
while ((len = is.read(buffer)) != -1){
fos.write(buffer,0,len); //写数据
}
//4. 关资源,断连接
fos.close();
is.close();
urlConnection.disconnect();
}
}
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