Java------网络编程
(1)网络编程：就是用来实现网络互连的不同计算机上运行的程序间可以进行数据交换。
(2)网络编程的三要素
A:IP地址
a:点分十进制
b:IP地址的组成
c:IP地址的分类
d:dos命令
e:InetAddress
B:端口
是应用程序的标识。范围：0-65535。其中0-1024不建议使用。
C:协议
UDP:将数据源和目的封装成数据包中，不需要建立连接；每个数据报的大小在限制在64k；因无连接，是不可靠协议；不需要建立连接，速度快
TCP:建立连接，形成传输数据的通道；在连接中进行大数据量传输；通过三次握手完成连接，是可靠协议；必须建立连接，效率会稍低
(3)Socket机制
A:通信两端都应该有Socket对象
B:所有的通信都是通过Socket间的IO进行操作的
(4)UDP协议发送和接收数据
发送：
创建UDP发送端的Socket对象
创建数据并把数据打包
发送数据
释放资源
package tongxin;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
/**
* 创建UDP发送端的Socket对象
* 创建数据并把数据打包
* 发送数据
* 释放资源
* @author moon
*
*/
public class SendDemo {
public static void main(String[] args) throws IOException {
//创建发送端的Socket对象
DatagramSocket ds = new DatagramSocket();
//封装键盘录入数据
BufferedReader bReader = new BufferedReader(new InputStreamReader(System.in));
String lineString = null;
while((lineString = bReader.readLine()) != null) {
if("886".equals(lineString)) {
break;
}
//创建数据并打包
byte[] bys = lineString.getBytes();
DatagramPacket dPacket = new DatagramPacket(bys, bys.length,
InetAddress.getByName("localhost"), 12345);
//发送数据
ds.send(dPacket);
}
//释放资源
ds.close();
}
}
接收：
创建UDP接收端的Socket对象
创建数据包用于接收数据
接收数据
解析数据包
释放资源
package tongxin;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
/**
*
* 创建UDP接收端的Socket对象
* 创建数据包用于接收数据
* 接收数据
* 解析数据包
* 释放资源
* @author moon
*
*/
public class ReceiveDemo {
public static void main(String[] args) throws IOException {
//创建接收端的Socket对象
DatagramSocket dpSocket = new DatagramSocket(999);
while(true) {
//创建一个包裹
byte[] bys = new byte[1024];
DatagramPacket dpPacket = new DatagramPacket(bys, bys.length);
//接收数据
dpSocket.receive(dpPacket);
//解析数据
String ipString = dpPacket.getAddress().getHostAddress();
String s = new String(dpPacket.getData() , 0, dpPacket.getLength());
System.out.println("from " + ipString + "data is :" + s);
}
//释放资源
//dpSocket.close();
}
}
(5)TCP协议发送和接收数据
发送：
创建TCP客户端的Socket对象
获取输出流，写数据
释放资源
package tongxin;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;
public class ClientDemo {
public static void main(String[] args) throws IOException {
Socket socket = new Socket("localhost" , 7777);
//获取输出流
OutputStream outputStream = socket.getOutputStream();
outputStream.write("你是小可爱吗".getBytes());
//获取输入流
InputStream inputStream = socket.getInputStream();
byte[] b = new byte[1024];
int len = inputStream.read(b);
String client = new String(b, 0, len);
System.out.println("client:" + client);
socket.close();
}
}
接收：
创建TCP服务器端的Socket对象
监听客户端连接
获取输入流，读取数据
释放资源
package tongxin;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;
public class ServerDemo {
public static void main(String[] args) throws IOException {
ServerSocket serverSocket = new ServerSocket(7777);
Socket socket = serverSocket.accept();
//获取输入流
InputStream is = socket.getInputStream();
byte[] b = new byte[1024];
int len = is.read(b);
String serve = new String(b, 0, len);
System.out.println("serve: " + serve);
//获取输出流
OutputStream os = socket.getOutputStream();
os.write("数据已收到".getBytes());
serverSocket.close();
socket.close();
}
}
(6)案例：
A:UDP
a:把发送数据改进为键盘录入
package lianxi;
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();
// 封装键盘录入数据
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("localhost"), 12345);
// 发送数据
ds.send(dp);
}
// 释放资源
ds.close();
}
}
package lianxi;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
public class ReceiveDemo {
public static void main(String[] args) throws IOException {
// 创建接收端的Socket对象
DatagramSocket ds = new DatagramSocket(12345);
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);
}
// 释放资源
// 接收端应该一直开着等待接收数据，是不需要关闭
// ds.close();
}
}
B:TCP
d:客户端键盘录入服务器写到文本文件
package lianxi;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.Socket;
/*
* 键盘录入,服务器端以a.txt接收
*/
public class ClientDemo {
public static void main(String[] args) throws IOException {
Socket socket = new Socket("localhost", 33333);
//键盘录入
BufferedReader bReader = new BufferedReader(new InputStreamReader(System.in));
//把通道中的流给包装一下
BufferedWriter bWriter = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
String line = null;
while((line = bReader.readLine()) != null) {
if("886".equals(line)) {
break;
}
bWriter.write(line);
bWriter.newLine();
bWriter.flush();
}
socket.close();
}
}
package lianxi;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.ServerSocket;
import java.net.Socket;
public class ServeDemo {
public static void main(String[] args) throws IOException {
ServerSocket serverSocket = new ServerSocket(33333);
//监听客户端连接
Socket socket = serverSocket.accept();
//封装通道中的流
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
//封装文本文档
BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter("a.txt"));
String lineString = null;
while((lineString = bufferedReader.readLine()) != null) {
bufferedWriter.write(lineString);
bufferedWriter.newLine();
bufferedWriter.flush();
}
bufferedWriter.close();
socket.close();
}
}