Java学习日记——DAY23

今天我针对Java网络编程展开了学习，学习内容如下：

1.OSI（开放式系统互连）七层模型：

物理层：传输原始二进制比特流，常见设备如：双绞线、光纤、集线器、中继器；

数据链路层：在同一局域网内提供可靠的数据帧传输，处理物理地址，差错检验；

网络层：负责逻辑寻址和路由选择（决定数据包如何从源目的跨网络传输），IP；

传输层：提供端到端的可靠或不可靠传输、负责流量控制、错误检测与恢复，UDP、TCP；

会话层：建立管理和终止对话；

表示层：完成数据的格式转换、加密解密、压缩解压（确保不同系统间能理解数据）；

应用层：为用户提供网络服务接口；

2.TCP/IP

基于TCP实现聊天服务：

public class Test1 { public static void main(String[] args) throws IOException { ServerSocket serverSocket = new ServerSocket(1235); System.out.println("等待客户端连接中..."); Socket socket = serverSocket.accept(); System.out.println("成功连接客户端..."); OutputStream outputStream = socket.getOutputStream(); PrintWriter printWriter = new PrintWriter(outputStream); Scanner scanner = new Scanner(System.in); InputStreamReader inputStreamReader = new InputStreamReader(socket.getInputStream()); BufferedReader bufferedReader = new BufferedReader(inputStreamReader); System.out.println("请输入内容："); String line; while(true){ line = scanner.nextLine(); printWriter.println(line); printWriter.flush(); if("bye".equals(line)){ break; } line = bufferedReader.readLine(); System.out.println("[客户端]:"+line); if("bye".equals(line)){ break; } } bufferedReader.close(); printWriter.close(); socket.close(); serverSocket.close(); } } public class Test2 { public static void main(String[] args) throws IOException { Socket socket = new Socket("localhost",1235); System.out.println("客户端连接"); InputStream is = socket.getInputStream(); InputStreamReader isr = new InputStreamReader(is); BufferedReader br = new BufferedReader(isr); OutputStream os = socket.getOutputStream(); PrintWriter pw = new PrintWriter(os); Scanner sc = new Scanner(System.in); while(true){ String line = br.readLine(); System.out.println("[服务端]:"+line); if("bye".equals(line)){ break; } line = sc.nextLine(); pw.println(line); pw.flush(); if("bye".equals(line)){ break; } } br.close(); pw.close(); socket.close(); } }

基于UDP实现消息快报：

public class Test5 { public static void main(String[] args) throws IOException { DatagramSocket socket = new DatagramSocket(1234); Scanner in = new Scanner(System.in); String str = in.nextLine(); byte[] data = str.getBytes(); DatagramPacket packet =new DatagramPacket(data,0,data.length, InetAddress.getByName("localhost"),1235); socket.send(packet); socket.close(); } } public class Test6 { public static void main(String[] args) throws IOException { DatagramSocket socket = new DatagramSocket(1235); byte[] buf = new byte[1024]; DatagramPacket packet = new DatagramPacket(buf, buf.length); socket.receive(packet); String data = new String(buf, 0, packet.getLength(), StandardCharsets.UTF_8); System.out.println(data); socket.close(); } }

URL同一资源定位符：

public class Test7 { public static void main(String[] args) throws IOException { URL url = new URL("https://inews.gtimg.com/om_bt/Ojkpad4ytS_JDeu___pZIxZ50fz1ISSAl4AH6PShWSFmYAA/641"); URLConnection con = url.openConnection(); BufferedInputStream bis = new BufferedInputStream(con.getInputStream()); BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream("tu.jpg")); byte[] buf = new byte[1024]; int len; while((len = bis.read(buf)) != -1) { bos.write(buf, 0, len); } bos.flush(); bos.close(); bis.close(); } }public class Test8 { public static void main(String[] args) throws IOException { URL url = new URL("https://news.qq.com/rain/a/20260211A0306900"); URLConnection conn = url.openConnection(); BufferedInputStream bis = new BufferedInputStream(conn.getInputStream()); BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream("tu.html")); byte[] buf = new byte[1024]; int len; while ((len = bis.read(buf)) != -1) { bos.write(buf, 0, len); } bos.flush(); bos.close(); bis.close(); } }

学习内容如上，如有错误或者意见请评论讨论。