1.计算机网络概念
JavaWeb : 网页编程 B/S架构
网络编程: TCP/IP C/S架构
TCP/IP模型:
应用层---传输层--网络层--数据链路层
网络编程中的要素
IP 和 端口号
网络通信
2.IP
ip地址:InetAddress
1.唯一定位一台网络上计算机
2.127.0.0.1: 本机localhost
3.ip地址的分类
IPV4/IPv6
package cn.bloghut.lesson01;
import java.net.InetAddress;
import java.net.UnknownHostException;
public class TestInetAddress {
public static void main(String[] args) throws Exception {
//查询本机的ip地址
InetAddress localhost = InetAddress.getByName("localhost");
System.out.println(localhost);
InetAddress localHost = InetAddress.getLocalHost();
System.out.println(localHost);
System.out.println("=================");
//查询网站ip地址
InetAddress name = InetAddress.getByName("www.baidu.com");
System.out.println(name);
System.out.println("=================");
//常用方法
//System.out.println(name.getAddress());
System.out.println(name.getHostAddress());//获取主机ip地址
System.out.println(name.getHostName());// 获取域名
System.out.println(name.getCanonicalHostName());//获取规范的主机ip地址
}
}
3.端口(计算机一个进程)
TCP ,UDP: 每个都有 0-65535 * 2 ,单个协议下,端口号不能冲突
下列是百度端口号
HTTP : 80
HTTPS :443
FTP : 21
Telet : 23
package cn.bloghut.lesson01;
import java.net.InetSocketAddress;
public class TesyInetSocketAddress {
public static void main(String[] args) {
InetSocketAddress socketAddress = new InetSocketAddress("127.0.0.1", 8080);
InetSocketAddress socketAddress1 = new InetSocketAddress("localhost", 8080);
System.out.println(socketAddress);
System.out.println(socketAddress1);
System.out.println("====================");
System.out.println(socketAddress.getAddress());//ip地址
System.out.println(socketAddress.getHostName());//主机名称
System.out.println(socketAddress.getHostString());
System.out.println(socketAddress.getPort());//端口
}
}
4.通信协议
TCP:用户传输协议
UDP:用户数据报协议
TCP和UDP 对比:
TCP:
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
1.不连接,不稳定
2.客户端、服务端:没有明确的界限
3.不管有没有准备好,都可以发给你…
/* 客户端*/
package cn.bloghut.lesson02;
import java.io.IOException;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.Socket;
public class TcpClientDemo1 {
public static void main(String[] args) throws Exception{
Socket socket = null;
OutputStream os = null;
//要知道服务器地址
try {
InetAddress serverIp = InetAddress.getByName("localhost");
int port = 9999;
//2.创建连接
socket = new Socket(serverIp,port);
//3.发生消息 IO流
os = socket.getOutputStream();
os.write("你好".getBytes());
} catch (IOException e) {
e.printStackTrace();
}finally {
if (os != null) {
os.close();
}
if (socket != null) {
socket.close();
}
}
}
}
/*服务器*/
package cn.bloghut.lesson02;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.ServerSocket;
import java.net.Socket;
public class TcpServerDemo01 {
public static void main(String[] args) throws Exception {
ServerSocket serverSocket = null;
Socket accept = 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
accept = serverSocket.accept();
//3.读取客户端消息
is = accept.getInputStream();
/*byte[] buf = new byte[1024];
int len;
while ((len = is.read(buf)) != -1 ){
String s = new String(buf, 0, len);
System.out.println(s);
}*/
//管道流
baos = new ByteArrayOutputStream();
byte[] buff = new byte[1024];
int len = -1;
while ((len = is.read(buff)) != -1) {
baos.write(buff, 0, len);
}
System.out.println(baos.toString());
} catch (IOException e) {
e.printStackTrace();
} finally {
if (baos != null) {
baos.close();
}
if (is != null) {
is.close();
}
if (accept != null) {
accept.close();
}
if (serverSocket != null) {
serverSocket.close();
}
}
}
}