java基础笔记(7)
阅读原文时间:2023年07月15日阅读:1

Socket编程

通信基础:ip地址(位置)、协议(语言)、端口(软件程序);

java提供网络功能的四大类:

InetAddress没有构造函数,不够里面有一些方法是可以返回实例,如:

InetAddress.getLocalHost();返回本机的实例;

InetAddress.getByName(String NAME);根据主机名或ip返回实例;

URL类实例化后可以获取URL的主机名、端口、文件的路径、文件名等等信息,需要注意的是,如果URL在实例化时没有指定端口号,会传入默认端口号,通过url.getPort()获取的端口号是-1而不是80;

URL提供了一个openStream(),用来获取URL的输入流,例:

public void urlTest() throws IOException {
URL baidu = new URL("http://www.baidu.com");
InputStream in = baidu.openStream();//获取URL的输入流,此时输入流是字节数组
InputStreamReader isr = new InputStreamReader(in,"utf-8");//将输入流转换为字符输入流
BufferedReader br = new BufferedReader(isr);//为字符流添加缓冲
String data = br.readLine();
while(data!=null) {
System.out.println(data);
data = br.readLine();
}
br.close();
isr.close();
in.close();
}

给予TCP协议实现网络通信的类:

客户端:Socket类

服务器端;ServerSocket类

Socket实现通信的步骤:

常用的创建构造方法及常用方法:

ServerSocket类:

构造方法:

ServerSocket(int port);指定端口号创建ServerSocket类;

调用方法:

accept();监听并接收此套接字的连接,返回一个Socket;

close();关闭套接字

getInetAddress(),返回InetAddress类,返回服务器的本地地址;

getLocalPort(),返回int类,返回套接字监听的接口;

Socket类:

构造方法:

Socket(String host,int port);指定主机地址和端口创建Socket类;

调用方法;

close();关闭套接字

getInetAddress(),返回InetAddress类,返回套接字的本地地址;

getLocalPort(),返回int类,返回套接字绑定的接口;

getInputStream(),返回InputStream类,获取套接字的输入流

getOutputStream(),返回OutputStream类,获取套接字的输出流

通过Socket编码演示实现服务器端和客户端之间的通讯:

服务器端:

package com.Socket;

import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;

public class server {
public static void main(String[] args) throws IOException {
ServerSocket serversocket = new ServerSocket(8889);//创建服务器套接字
System.out.println("===服务器即将启动,正在等待客户端的连接===");
Socket socket = serversocket.accept();//开始监听,等待客户端的连接
InputStream in = socket.getInputStream();//获取输入流
InputStreamReader inr = new InputStreamReader(in);//将字节输入流转为字符输入流
BufferedReader binr = new BufferedReader(inr);//将输入流添加到缓冲流
String info =null;
while((info = binr.readLine())!=null) {
System.out.println("我是服务器,客户端说:"+info);
}
socket.shutdownInput();
OutputStream output = socket.getOutputStream();
PrintWriter pw = new PrintWriter(output);
pw.write("欢迎您");
pw.flush();
pw.close();
binr.close();
inr.close();in.close();
socket.close();
serversocket.close();
}
}

客户端:

package com.Socket;

import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.Socket;
import java.net.UnknownHostException;

public class client {
public static void main(String[] args) throws UnknownHostException, IOException {
Socket socket = new Socket("localhost",8889);//创建客户端Socket套接字
OutputStream output = socket.getOutputStream();//创建字节输出流
PrintWriter pw = new PrintWriter(output);//将输出流包装为打印流
pw.write("用户名:admin;密码:123");
pw.flush();
socket.shutdownOutput();
InputStream in = socket.getInputStream();
BufferedReader br = new BufferedReader(new InputStreamReader(in));
String info;
while((info = br.readLine())!=null) {
System.out.print("客户端对我说:"+info);
}
br.close();
in.close();
pw.close();
output.close();
socket.close();
}

}

多线程的通信:

建立一个线程类:

package com.Socket;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.Socket;

public class ServerThread extends Thread {
Socket socket = null;
public ServerThread(Socket socket) {
this.socket = socket;
}
public void run() {
try {
InputStream in = socket.getInputStream();//获取输入流
InputStreamReader inr = new InputStreamReader(in);//将字节输入流转为字符输入流
BufferedReader binr = new BufferedReader(inr);//将输入流添加到缓冲流
String info =null;
while((info = binr.readLine())!=null) {
System.out.println("我是服务器,客户端说:"+info);
}
socket.shutdownInput();
OutputStream output = socket.getOutputStream();
PrintWriter pw = new PrintWriter(output);
pw.write("欢迎您");
pw.flush();
if(pw!=null)
pw.close();
if(binr!=null)
binr.close();
if(inr!=null)
inr.close();
if(in!=null)
in.close();
if(socket!=null)
socket.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}

在服务器类中循环调用accept()方法并不断实例化线程类,在accept()连接返回一个Socket后又继续调用进行监听:

package com.Socket;

import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;

public class server {
public static void main(String[] args) throws IOException {
ServerSocket serversocket = new ServerSocket(8889);//创建服务器套接字
Socket socket = null;
int count = 0;
System.out.println("===服务器即将启动,正在等待客户端的连接===");
while(true) {
socket = serversocket.accept();
//开始监听,等待客户端的连接
ServerThread serverthread = new ServerThread(socket);
serverthread.start();
count++;
System.out.println("客户端的数量:"+count);
InetAddress address =socket.getInetAddress();
System.out.println("客户端的IP:"+address);
}
}
}

这样既可实现多客户端的多次连接;

UDP信息传输

DatagramPacket:表示数据报包

DatagramSocket:表示端到端通信的类

服务器端:

package com.Socket;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;

public class Udpserver {
public static void main(String[] args) throws IOException {
DatagramSocket socket = new DatagramSocket(8887);//创建Socket
byte[] data = new byte[1024];//创建数组,在创建数据报的时候需将该字节数组传入
DatagramPacket packet = new DatagramPacket(data, data.length);//创建数据报,将数据传入数组中
System.out.println("服务器已经启动,正在等待客户端的连接=====");
socket.receive(packet);//等待接收数据报,在接收前会一直阻塞
String info = new String(data,0,packet.getLength());
System.out.println("我是服务器,客户端发来信息:"+info);
//向客户端相应数据
InetAddress address = packet.getAddress();//根据传过来的数据报获取客户端的地址
int port = packet.getPort();//获取客户端端口
byte[] data2 = "欢迎您".getBytes();
DatagramPacket packet2 = new DatagramPacket(data2, data2.length,address,port);
socket.send(packet2);
socket.close();
}
}

客户端:

package com.Socket;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
import java.net.UnknownHostException;

public class Udpclient {
public static void main(String[] args) throws IOException {
InetAddress adress = InetAddress.getByName("localhost");
int port = 8887;
byte[] data = "用户名:admin;密码:123".getBytes();//定义发送信息并存到字节数组中
DatagramPacket packet =new DatagramPacket(data,data.length,adress,port);//将定义好的字节数组和传送的目标地址,目标端口封装成数据报
DatagramSocket socket = new DatagramSocket();//创建socket套接字
socket.send(packet);//发送数据报
byte[] data3 = new byte[1024];
DatagramPacket packet3 =new DatagramPacket(data3,data3.length);
socket.receive(packet3);
String info2 = new String(data3,0,packet3.getLength());
System.out.println("服务器对我说:"+info2);
socket.close();
}
}