17_网络编程

时间：2019-06-07 14:22:18 阅读：69 评论：0 收藏：0 [点我收藏+]

标签：oracl exce send shu puts poi 交换 socket 常见

网络编程

网络

把多台终端(计算机)通过物理线路连接起来，形成网络。便于交换数据、共享信息、组成更强大的逻辑体。

网络通信三要素

【1】IP地址:唯一标识网络上的每一台计算机

 两台计算机之间通信的必备有素

【2】端口号:计算机中应用的标号(代表一个应用程序)

 0-1024系统使用或保留端口 ，

 有效端口0-65536

常见的端口http协议80端口、mysql(3306) oracle(1521)

【3】通信协议:通信的规则

 TCP,UDP

TCP/IP参考模型

IP地址分类

127.0.0.1 表示本机IP地址

InetAddress

表示IP地址信息

package cn.net01;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.Arrays;
public class Test02 {
 public static void main(String[] args) throws UnknownHostException {
 
 // 通过IP地址构建InetAddress对象
 byte[] ip = new byte[] {(byte) 192,(byte) 168,7,(byte)189};
 InetAddress ip1 = InetAddress.getByAddress(ip);
 System.out.println(ip1.toString());
 
 
 System.out.println(ip1.getHostName());
 System.out.println(ip1.getHostAddress());
 // 给定名称www.baidu.com 获取地址
 InetAddress ip3 = InetAddress.getByName("www.baidu.com");
 System.out.println(ip3.toString());
 
 InetAddress[] ips = InetAddress.getAllByName("www.baidu.com");
 System.out.println(Arrays.toString(ips));
 
 }
}

TCP编程(A)

案例:服务器向客户端完成一次单向通信

package cn.net02;
import java.io.IOException;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;
public class Server01 {
 public static void main(String[] args){
 System.out.println("server running....");
 
 // 【1】创建serversocket
 ServerSocket serverSocket = null;
 try {
 serverSocket = new ServerSocket(8000);
 } catch (IOException e) {
 e.printStackTrace();
 }
 
 // 【2】等待客户端链入
 Socket clientSocket = null;
 try {
 // accept 阻塞式方法
 clientSocket = serverSocket.accept();
 System.out.println("客户端"+clientSocket.getInetAddress().getHostAddress()+"链入");
 } catch (IOException e) {
 // TODO Auto-generated catch block
 e.printStackTrace();
 }
 
 // 【3】服务器给客户端发信息
 OutputStream out = null;
 try {
 out = clientSocket.getOutputStream();
 
 String msg = "hello!";
 byte[] buf = msg.getBytes();
 out.write(buf);
 
 clientSocket.shutdownOutput();
 out.close();
 } catch (IOException e) {
 e.printStackTrace();
 }
 
 }
}

package cn.net02;
import java.io.IOException;
import java.io.InputStream;
import java.net.Socket;
import java.net.UnknownHostException;
import com.sun.org.apache.bcel.internal.generic.NEW;
public class Client01 {
 public static void main(String[] args) {
 System.out.println("client running...");
 // 【1】创建客户端socket
 Socket socket=null;
 try {
 socket = new Socket("192.168.7.194",8000);
 } catch (UnknownHostException e) {
 e.printStackTrace();
 } catch (IOException e) {
 e.printStackTrace();
 }
 
 // 【2】接收服务器发来的信息
 InputStream in = null;
 try {
 in = socket.getInputStream();
 byte[] buf = new byte[4];
 int len;
 StringBuilder sb = new StringBuilder();
 while( (len=in.read(buf)) != -1) {
 sb.append(new String(buf,0,len));
 }
 
 System.out.println("来自服务器的消息："+sb.toString());
 
 } catch (IOException e) {
 e.printStackTrace();
 }
 
 }
}

常见异常

[1]端口被占用

java.net.BindException: Address already in use: JVM_Bind
 at java.net.DualStackPlainSocketImpl.bind0(Native Method)
 at java.net.DualStackPlainSocketImpl.socketBind(DualStackPlainSocketImpl.java:106)
 at java.net.AbstractPlainSocketImpl.bind(AbstractPlainSocketImpl.java:387)
 at java.net.PlainSocketImpl.bind(PlainSocketImpl.java:190)
 at java.net.ServerSocket.bind(ServerSocket.java:375)
 at java.net.ServerSocket.<init>(ServerSocket.java:237)
 at java.net.ServerSocket.<init>(ServerSocket.java:128)
 at cn.net02.Server01.main(Server01.java:15)
Exception in thread "main" java.lang.NullPointerException
 at cn.net02.Server01.main(Server01.java:24)

[2]服务器没启动

java.net.ConnectException: Connection refused: connect
 at java.net.DualStackPlainSocketImpl.connect0(Native Method)
 at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:79)
 at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
 at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
 at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
…

[3] SocketTimeoutException 连接超时异常。

案例:服务器和客户端双向通信

package cn.net03;
import java.io.DataInput;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;
public class Server01 {
 public static void main(String[] args) throws IOException {
 
 System.out.println("server running....");
 
 ServerSocket serverSocket = new ServerSocket(8000);
 Socket clientSocket = serverSocket.accept();
 
 // send msg to client
 OutputStream out = clientSocket.getOutputStream();
 String msg = "hello client";
 DataOutputStream dos = new DataOutputStream(out);
 dos.writeUTF(msg);
 clientSocket.shutdownOutput();
 
 // receive msg2 from client
 InputStream in = clientSocket.getInputStream();
 DataInputStream dis = new DataInputStream(in);
 String msg2 = dis.readUTF();
 System.out.println("来自客户端消息:"+msg2);
 clientSocket.shutdownInput();
 
 
 dos.close();
 out.close();
 in.close();
 dis.close();
 
 
 }
}

package cn.net03;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;
import java.net.UnknownHostException;
import javax.print.Doc;
public class Client01 {
 public static void main(String[] args) throws UnknownHostException, IOException {
 System.out.println("client running...");
 
 Socket socket = new Socket("127.0.0.1",8000);
 
 // receive msg from server
 InputStream in = socket.getInputStream();
 DataInputStream dis = new DataInputStream(in);
 String msg = dis.readUTF();
 System.out.println(msg);
 socket.shutdownInput();
 
 
 // send msg to server
 OutputStream out = socket.getOutputStream();
 DataOutputStream dos = new DataOutputStream(out);
 String msg2 = "hello server";
 dos.writeUTF(msg2);
 socket.shutdownOutput();
 
 in.close();
 dis.close();
 out.close();
 dos.close();
 
 }
}

需求:请发送一张图片到服务器。

需求:c/s模式验证用户名密码。

User序列化是客户端和服务器端的全路径一定要一致。

UDP编程(B)

需求:客户端A向客户端B发信息

客户端A

package cn.net06;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.util.Scanner;
public class ClientA {
 public static void main(String[] args) throws IOException {
 // 客户端A
 DatagramSocket ds = new DatagramSocket(8000);
 while(true) {
 //System.out.println("请输入");
 Scanner sc = new Scanner(System.in);
 String msg = sc.nextLine();
 // --send msg to ClientB --
 System.out.println("开始发送数据:"+msg);
 byte[] buf = msg.getBytes();
 InetAddress toIp = InetAddress.getLocalHost();
 DatagramPacket dp = new DatagramPacket(buf, buf.length, toIp, 9000);
 // 构造一个数据报包socket，通过8000用于发送数据报
 ds.send(dp);
 
 // --receive msg from clientA--
 byte[] recBuf = new byte[1024];
 DatagramPacket recDp = new DatagramPacket(recBuf, recBuf.length);
 ds.receive(recDp);
 
 String recMsg = new String(recBuf, 0, recDp.getLength());
 System.out.println("clientB说:"+recMsg);
 }
 
 // ds.close();
 }
}

客户端B

package cn.net06;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
import java.util.Scanner;
public class ClientB {
 public static void main(String[] args) throws IOException {
 // 创建一个datagram socket用于结束clientA 传入的数据
 DatagramSocket ds = new DatagramSocket(9000);
 while (true) {
// System.out.println("正在接收信息...");
 // --receive msg from clinetA--
 byte[] buf = new byte[1024];
 DatagramPacket dp = new DatagramPacket(buf, buf.length);
 ds.receive(dp);
 // 从dp中获取接收的内容
 String msg = new String(buf, 0, dp.getLength());
 System.out.println("clientA说:" + msg);
 // --send msg to clientA--
 Scanner sc = new Scanner(System.in);
 String sendMsg = sc.nextLine();
 byte[] sendBuf = sendMsg.getBytes();
 InetAddress toIp = InetAddress.getLocalHost();
 DatagramPacket sendPd = new DatagramPacket(sendBuf, sendBuf.length, toIp, 8000);
 // DatagramSocket sendDs = new DatagramSocket(9000);
 ds.send(sendPd);
 }
 }
}

17_网络编程

标签：oracl exce send shu puts poi 交换 socket 常见

原文地址：https://www.cnblogs.com/aknife/p/10988095.html

踩

(0)

评论一句话评论（0）

分享档案

更多>

2021年07月29日 (22)
2021年07月28日 (40)
2021年07月27日 (32)
2021年07月26日 (79)
2021年07月23日 (29)
2021年07月22日 (30)
2021年07月21日 (42)
2021年07月20日 (16)
2021年07月19日 (90)
2021年07月16日 (35)

周排行