一、网络基础（TCP/IP详解）
1、IP协议（Internet Protocol）：网络层，支持网间数据报通信。无连接数据报传送，数据报路由选择和差错控制。
IPv4 32位（4字节），IPv6 128位（16字节）。P
ping ICMP协议
2、TCP协议、UDP协议
（1）TCP（transmission control protocol 打电话）：专门设计用于在不可靠的因特网上提供可靠的、端到端的字节流通信的协议。它是一种面向连接的协议。有三次握手。慢
（2）UDP（user data protocol 寄信）：提供了一种发送封装的原始IP数据报的方法、并且发送时无需建立连接，是一种不可靠的连接。快
二、Socket
两个Java应用程序可以通过一个双向的网络通信连接实现数据交换，这个双向链路的一端称为一个Socket。
Socket通常用来实现client-server连接。
java.net包中定义的两个类Socket和ServerSocket，分别用来实现双向连接（TCP连接）的client和server端。
建立连接时所需的寻址信息为远程计算机的IP地址和端口号（Port
number）。端口号2字节，可以区分不同的应用程序。端口号又分TCP端口和UDP端口，每个都是65536个端口。
例如：
收邮件 POP3 110
STMP 25
FTP 21
HTTP 80
1、TCP Socket通信模型
这只是练习，实际上的网络编程都是异步式的。System.in,accept(),readUTF()都是阻塞式的（非重点）
例1
import java.net.*;
import java.io.*;public class TCPServer{
public static void main(String args[]) throws Exception{
ServerSocket ss = new ServerSocket(6666);//端口号6666
while(true){
Socket s = ss.accept();
System.out.println("a client connect!");
DataInputStream dis = new DataInputStream(s.getInputStream());
System.out.println(dis.readUTF());
dis.close();
s.close();
}
}
}
import java.net.*;
import java.io.*;
public class TCPClient{
public static void main(String args[]) throws Exception{
Socket s = new Socket("127.0.0.1",6666);
OutputStream os = s.getOutputStream();
DataOutputStream dos = new DataOutputStream(os);
dos.writeUTF("hello server!");
dos.flush();
dos.close();
s.close();
}
}
例2
import java.io.*;
import java.net.*;
public class TestServer{
public static void main(String[] args){
try{
ServerSocket s = new ServerSocket(8888);//服务器端口号8888
while(true){
Socket s1 = s.accept();
OutputStream os = s1.getOutputStream();
DataOutputStream dos = new DataOutputStream(os);
dos.writeUTF("Hello,"+s1.getInetAddress()+"port#"+s1.getPort()+" byebye!");//客户端的IP地址和端口号
dos.close();
s1.close();
}
}catch(IOException e){
e.printStackTrace();
}
}
}
import java.net.*;
import java.io.*;
public class TestClient{
public static void main(String[] args){
try{
Socket s1 = new Socket("127.0.0.1",8888);//服务器地址和端口号
InputStream is = s1.getInputStream();
DataInputStream dis = new DataInputStream(is);
System.out.println(dis.readUTF());
dis.close();
s1.close();
}catch(ConnectException e){
e.printStackTrace();
}catch(IOException e){
e.printStackTrace();
}
}
}
例3
import java.io.*;
import java.net.*;
public class TestServer{
public static void main(String[] args){
InputStream in = null;
OutputStream out = null;
try{
ServerSocket ss = new ServerSocket(5888);//设置端口号
Socket s1 = ss.accept();
in = s1.getInputStream();
out = s1.getOutputStream();
DataOutputStream dos = new DataOutputStream(out);
DataInputStream dis = new DataInputStream(in);
String s = null;
if((s=dis.readUTF())!=null){
System.out.println(s);
System.out.println("from: "+s1.getInetAddress());
System.out.println("Port: "+s1.getPort());
}
dos.writeUTF("hi,hello");
dis.close();
dos.close();
s1.close();
}catch(IOException e){
e.printStackTrace();
}
}
}
import java.net.*;
import java.io.*;
public class TestClient{
public static void main(String[] args){
InputStream in = null;
OutputStream out = null;
try{
Socket s1 = new Socket("localhost",5888);//服务器地址和端口号
in = s1.getInputStream();
out = s1.getOutputStream();
DataInputStream dis = new DataInputStream(in);
DataOutputStream dos = new DataOutputStream(out);
dos.writeUTF("hey");
String s = null;
if((s=dis.readUTF())!=null){
System.out.println(s);
}
dos.close();
dis.close();
s1.close();
}catch(UnknownHostException e){
e.printStackTrace();
}catch(IOException e){
e.printStackTrace();
}
}
}
练习4：（by myself）
import java.io.*;
import java.net.*;
public class TestServer{
public static void main(String[] args){
InputStream in = null;
OutputStream out = null;
String si = null;
String so = "";
try{
ServerSocket ss = new ServerSocket(5888);//设置端口号
while(true){
Socket s1 = ss.accept();
in = s1.getInputStream();//接收数据
out = s1.getOutputStream();//发送数据
DataInputStream dis = new DataInputStream(in);
DataOutputStream dos = new DataOutputStream(out);
//从键盘读入
InputStreamReader isr2 = new InputStreamReader(System.in);
BufferedReader br2 = new BufferedReader(isr2);
while(!so.equals("exit")){
if((so=br2.readLine())!=null&&!so.equals("exit")){
System.out.println("Server:"+so);
dos.writeUTF(so);
}
if((si=dis.readUTF())!=null){
System.out.println("Client:"+si);
}
}
dis.close();
br2.close();
dos.close();
s1.close();
}
}catch(IOException e){
e.printStackTrace();
}
}
}
import java.net.*;
import java.io.*;
public class TestClient{
public static void main(String[] args){
InputStream in = null;
OutputStream out = null;
String si = null;
String so= "";
try{
Socket s1 = new Socket("127.0.0.1",5888);//服务器地址和端口号
in = s1.getInputStream();//接收
out = s1.getOutputStream();//发送
DataInputStream dis = new DataInputStream(in);
DataOutputStream dos = new DataOutputStream(out);
//从键盘读入
InputStreamReader isr2 = new InputStreamReader(System.in);
BufferedReader br2 = new BufferedReader(isr2);
while(!so.equals("exit")){
if((si=dis.readUTF())!=null){
System.out.println("Server:"+si);
}
if((so=br2.readLine())!=null&&!so.equals("exit")){
System.out.println("Client:"+so);
dos.writeUTF(so);
}
}
dis.close();
br2.close();
dos.close();
s1.close();
}catch(UnknownHostException e){
e.printStackTrace();
}catch(IOException e){
e.printStackTrace();
}
}
}
2、UDP Socket通信模型
没有server,client的概念，不区分两者的socket。receive()方法也是阻塞式的。
例1
import java.net.*;
public class TestUDPServer{
public static void main(String args[]) throws Exception{
byte buf[] = new byte[1024];
DatagramPacket dp = new DatagramPacket(buf, buf.length);
DatagramSocket ds = new DatagramSocket(5678);
while(true){
ds.receive(dp);
System.out.println(new String(buf, 0, dp.getLength()));
}
}
}
import java.net.*;
public class TestUDPClient{
public static void main(String args[]) throws Exception{
byte[] buf = (new String("Hello")).getBytes();
DatagramPacket dp = new DatagramPacket(buf, buf.length, new InetSocketAddress("127.0.0.1", 5678));
DatagramSocket ds = new DatagramSocket(9999);
ds.send(dp);
ds.close();
}
}
例2
import java.net.*;
import java.io.*;
public class TestUDPServer{
public static void main(String args[]) throws Exception{
byte buf[] = new byte[1024];
ByteArrayInputStream bais = new ByteArrayInputStream(buf);//从字节数组读数据
DataInputStream dis = new DataInputStream(bais);
DatagramPacket dp = new DatagramPacket(buf, buf.length);
DatagramSocket ds = new DatagramSocket(5678);
while(true){
ds.receive(dp);
long l = dis.readLong();
System.out.println(l);
}
}
}
import java.net.*;
import java.io.*;
public class TestUDPClient{
public static void main(String args[]) throws Exception{
long n = 10000L;
ByteArrayOutputStream baos = new ByteArrayOutputStream();
DataOutputStream dos = new DataOutputStream(baos);
dos.writeLong(n);
byte[] buf = baos.toByteArray();
System.out.println(buf.length);
DatagramPacket dp = new DatagramPacket(buf,buf.length,new InetSocketAddress("127.0.0.1",5678));
DatagramSocket ds = new DatagramSocket(9999);
ds.send(dp);
ds.close();
}
}
JAVA笔记26-网络编程（不等于网站编程）,布布扣,bubuko.com
时间： 2024-10-14 07:37:45