每一台计算机通过网络连接起来,达到了数据互动的效果,而网络编程所解决的问题就是如何让程序与程序之间实现数据的通讯与互动 在吗?你是GG还是MM?
网络模型一般是指:
我们应该或多或少都有见过IP地址的格式 xxx.xxx.xxx.xxx大致应该是类似这样的,但是计算机不是只能识别二进制的数据,但是很显然,我们的IP地址确实不是二进制的,这是什么原因呢?
我们先随便拿一个IP地址举个例子看看
IP:192.168.1.100
换算:11000000 10101000 00000001 01100100
但是如果我们日后需要用到这个IP地址的时候,记忆起来就比较麻烦,所以,为了方便表示IP地址,我们就把IP地址的每一个字节上的数据换算成十进制,然后用 ' . ' 分开来表示:"点分十进制"
A类:第一号段为网络号段+后三段的主机号段,一个网络号:256256256 = 16777216
B类:前二号段为网络号段+后二段的主机号段,一个网络号:256*256 = 65536
C类:前三号段为网络号段+后一段的主机号段,一个网络号:256
C:IP地址的分类
A类
1.0.0.1---127.255.255.254
(1)10.X.X.X是私有地址(私有地址就是在互联网上不使用,而被用在局域网络中的地址)
(2)127.X.X.X是保留地址,用做循环测试用的
B类
128.0.0.1---191.255.255.254
172.16.0.0---172.31.255.255是私有地址
169.254.X.X是保留地址
C类
192.0.0.1---223.255.255.254 192.168.X.X是私有地址
D类
224.0.0.1---239.255.255.254
E类
240.0.0.1---247.255.255.254
两个DOS命令
ipconfig 查看本机ip地址
ping 后面跟ip地址, 测试本机与指定的ip地址间的通信是否有问题
特殊IP地址
127.0.0.1 回环地址(表示本机)//也就是说,ping本机的IP地址相当于ping 127.0.0.1
x.x.x.255 广播地址
x.x.x.0 网络地址
InetAddress的成员方法
//根据主机名或者IP地址的字符串表示得到IP地址对象
public static InetAddress getByName(String host):
import java.net.InetAddress;
import java.net.UnknownHostException;
public class InetAddressDemo {
public static void main(String[] args) throws UnknownHostException {
InetAddress address = InetAddress.getByName("192.168.24.1");
//获取两个东西:主机名,IP地址
String name = address.getHostName();
String ip = address.getHostAddress();
System.out.println(name + "---" + ip);
}
}
//运行结果
LAPTOP-5T03DV1G---192.168.24.1
TCP:传输控制协议,传输效率低,可靠性强,用于传输可靠性要求高,数据量大的数据
UDP:用户数据报协议,与TCP特性恰恰相反,用于传输可靠性要求不高,数据量小的数据,如QQ微信聊天数据就是通过这种方式传输的
简单总结:
TCP:建立数据通道,无限制,效率低,可靠
UDP:数据打包,有限制,不连接,效率高,不可靠
import java.io.IOException;
import java.net.*;
/* UDP协议发送数据:
* A:创建发送端Socket对象
* B:创建数据,并把数据打包
* C:调用Socket对象的发送方法发送数据包
* D:释放资源
*/
public class SendDemo {
public static void main(String[] args) throws IOException {
//创建socket对象
DatagramSocket ds = new DatagramSocket();
//创建数据,并把数据打包
//DatagramPacket(byte[] buf, int length, InetAddress address, int port)
byte[] bys = "Hello,BWH!".getBytes();//把字符串转换成字符数组
int length = bys.length;
InetAddress address = InetAddress.getByName("192.168.24.1");
int port = 10086; //自拟
DatagramPacket dp = new DatagramPacket(bys, length, address, port);
//调用Socket对象的方法发送数据包
//public void send(DatagramPacket p)
ds.send(dp);
//释放资源
ds.close(); //底层依赖IO流,所以要释放资源
}
}
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
/*
* UDP协议接收数据:
* A:创建接收端Socket对象
* B:创建一个数据包(接收容器)
* C:调用Socket对象的接收方法接收数据
* D:解析数据包,并显示在控制台
* E:释放资源
*/
public class ReceiveDemo {
public static void main(String[] args) throws IOException {
// 创建接收端Socket对象
// DatagramSocket(int port)
DatagramSocket ds = new DatagramSocket(10086);
// 创建一个数据包(接收容器)
// DatagramPacket(byte[] buf, int length)
byte[] bys = new byte[1024];
int length = bys.length;
DatagramPacket dp = new DatagramPacket(bys, length);
// 调用Socket对象的接收方法接收数据
// public void receive(DatagramPacket p)
ds.receive(dp);
// 解析数据包,并显示在控制台
// 获取对方的ip
// public InetAddress getAddress()
InetAddress address = dp.getAddress();
String ip = address.getHostAddress();
// public byte[] getData():获取数据缓冲区
// public int getLength():获取数据的实际长度
byte[] bys2 = dp.getData();
int len = dp.getLength();
String s = new String(bys2, 0, len);
System.out.println(ip + ": " + s);
// 释放资源
ds.close();
}
}
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
public class SendDemo {
public static void main(String[] args) throws IOException {
//创建发送端的Socket对象
DatagramSocket ds = new DatagramSocket();
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
String line = null;
while ((line = br.readLine()) != null) {
if ("886".equals(line)) {
break;
}
//创建数据并打包
byte[] bys = line.getBytes();
DatagramPacket dp = new DatagramPacket(bys, bys.length, InetAddress.getByName("192.168.24.1"), 10086);
//发送数据
ds.send(dp);
}
//释放资源
ds.close();
}
}
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
public class ReceiveDemo {
public static void main(String[] args) throws IOException {
//创建接受端的Socket对象
DatagramSocket ds = new DatagramSocket(10086);
while (true) {
//创建一个包裹
byte[] bys = new byte[1024];
DatagramPacket dp = new DatagramPacket(bys, bys.length);
//接收数据
ds.receive(dp);
//解析数据
String ip = dp.getAddress().getHostAddress();
String s = new String(dp.getData(), 0, dp.getLength());
System.out.println(ip + ": " + s);
}
// 释放资源,但是接收端是服务器应该一直开启
//ds.close();
}
}
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
public class SendThread implements Runnable {
private DatagramSocket ds;
public SendThread(DatagramSocket ds) {
this.ds = ds;
}
@Override
public void run() {
try {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
String line = null;
while ((line = br.readLine()) != null) {
if ("886".equals(line)) {
break;
}
// 创建数据并打包
byte[] bys = line.getBytes();
DatagramPacket dp = new DatagramPacket(bys, bys.length, InetAddress.getByName("192.168.24.1"), 10086);
// 发送数据
ds.send(dp);
}
// 释放资源
ds.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
public class ReceiveThread implements Runnable {
private DatagramSocket ds;
public ReceiveThread(DatagramSocket ds) {
this.ds = ds;
}
@Override
public void run() {
try {
while (true) {
//创建一个包裹
byte[] bys = new byte[1024];
DatagramPacket dp = new DatagramPacket(bys, bys.length);
//接收数据
ds.receive(dp);
//解析数据
String ip = dp.getAddress().getHostAddress();
String s = new String(dp.getData(), 0, dp.getLength());
System.out.println("from " + ip + " data is : " + s);
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
import java.net.DatagramSocket;
import java.net.SocketException;
public class ChatRoom {
public static void main(String[] args) throws SocketException {
DatagramSocket dsSend = new DatagramSocket();
DatagramSocket dsReceive = new DatagramSocket(10086);
SendThread st = new SendThread(dsSend);
ReceiveThread rt = new ReceiveThread(dsReceive);
Thread t1 = new Thread(st);
Thread t2 = new Thread(rt);
t1.start();
t2.start();
}
}
package cn.bwh_06_TCP2;
import java.io.*;
import java.net.Socket;
public class Clietn {
public static void main(String[] args) throws IOException {
Socket s = new Socket("192.168.24.1", 22222);
//键盘录入对象
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
//把通道内的流包装一下
BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));
String line = null;
while ((line = br.readLine()) != null) {
if ("886".equals(line)) {
break;
}
bw.write(line);
bw.newLine();
bw.flush();
}
s.close();
}
}
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.ServerSocket;
import java.net.Socket;
public class Server {
public static void main(String[] args) throws IOException {
ServerSocket ss = new ServerSocket(22222);
Socket s = ss.accept();
BufferedReader br = new BufferedReader(new InputStreamReader(s.getInputStream()));
String line = null;
while ((line = br.readLine()) != null) {
System.out.println(line);
}
s.close();
}
}
//封装通道内的数据
BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));
//封装文本文件
BufferedWriter bw = new BufferedWriter(new FileWriter("a.txt"));
//封装文本文件
BufferedReader br = new BufferedReader(new FileReader("Demo.java"));
//封装通道内的数据
BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));
String line = null;
while ((line = br.readLine()) != null) {
bw.write(line);
bw.newLine();
bw.flush();
}