Java网络通信实验小记四：Swing聊天软件

Swing聊天软件

前面做了Tcp和Udp的基本通信以及文件传输实验，是时候把这些内容整合在一起了。。
Swing就不介绍了，需要用到什么api都可以直接查。

一、基本聊天功能（服务端作中介，udp实现）

软件能够实现Windows主机和一台Linux虚拟机的通信。除此之外还需要一台Linux虚拟机作为服务端起到二者中介的作用。两个客户端与服务器的通信采用无连接的udp协议，服务器收到udp包直接向目标端口转发，不做其他任何操作。客户端在发送按钮事件里编写socket.send，同时new一个Thread并在此进程里编写socket.recieve，只有采用多线程才能保证聊天时能够同时收发信息。以上便可实现基本的聊天功能。
注意Win和Linux二者的编码有别。即

//Win客户端
byte[] buffer = text.getBytes("UTF-8");
...
//Linux客户端
byte[] buffer = text.getBytes("GBK");

二、文件传输功能（端到端，tcp实现）

文件传输采用tcp协议直接由端到端传输，这样的好处是传输效率高而且可靠、面向连接。除此之外，还需要多加一个收发信的确认功能。为了避免占用太多端口以及浪费过多线程，这里收发信还是使用原来的udp端口（而不是新建一个端口+线程）。那么就需要设计一个密文放在消息的开头以区分正常的聊天消息（我用的是三个井号"###"也可以更复杂点）。然后该密文还需要携带一些重要信息，包括：文件类型，文件名称，文件大小，主机ip以及端口号，后两者是为了告知目的主机使其与发送主机主动建立tcp连接（因为主机之间是不知道对方的ip和端口号的）。
文件传输的基本设计思路为：
发端：点击文件按钮→选择文件，获取文件、文件名等，发送密文，打开serversocket等待对方accept。
收端：收到udp消息，进行解析发现是密文，于是弹出对话框问是否接受。若选否则进行tcp连接，发送"no"消息，关闭socket。若选是则也进行tcp连接，发送"yes"消息，并准备接收文件。
发端：连接成功后，收到"no"则关闭连接，收到"yes"则准备发送文件。若是图片则使用字节流方法，文本文件则使用字符流方法。
其中传文本文件还要注意一下中文编码问题。在发端读取文件时，Win使用GBK编码，Linux使用UTF-8编码。在收端读取socket的inputStream时二者均使用UTF-8编码。

实验截图：

三、代码

1.Win客户端代码（ip：10.177.26.76，udp port：1080，tcp port：2080）

package gui;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.*;
import java.net.*;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import javax.swing.*;
import javax.swing.filechooser.FileNameExtensionFilter;public class WinClient
{public static void main(String[] args) throws Exception{JFrame f = new JFrame();f.setTitle("16010410031 陈大至");f.setSize(720, 810);f.setLocation(100, 100);f.setLayout(null);JButton button = new JButton("发送");button.setBounds(610, 650, 80, 50);f.add(button);JButton imgButton = new JButton("图片");imgButton.setBounds(10,560,70,30);f.add(imgButton);JButton fileButton = new JButton("文本文件");fileButton.setBounds(100,560,90,30);f.add(fileButton);JTextArea textArea1 = new JTextArea();textArea1.setFont(new Font("Dialog", Font.TRUETYPE_FONT,20));textArea1.setLineWrap(true);textArea1.setBounds(10, 600, 590, 150);f.add(textArea1);JTextArea textArea2 = new JTextArea();textArea2.setFont(new Font("Dialog", Font.TRUETYPE_FONT,20));textArea2.setEditable(false);textArea2.setLineWrap(true);JScrollPane scrollPane = new JScrollPane(textArea2);f.add(scrollPane);textArea2.setBounds(10,10, 680, 540);f.add(textArea2);f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);f.setVisible(true);String hostname="192.168.131.135";//192.168.131.135String localhost="10.177.26.76";DatagramSocket socket1 = new DatagramSocket(1080);ServerSocket socket2 = new ServerSocket(2080);new Thread(() -> {while (true){try {byte[] buffer = new byte[1024];DatagramPacket packet = new DatagramPacket(buffer, buffer.length);socket1.receive(packet);String text = new String(packet.getData(),0,packet.getLength());String[] strings = text.split(";");if(strings[0].equals("###")){int option;String name=strings[2];String length=strings[3];String ip=strings[4];int port=Integer.parseInt(strings[5]);option = JOptionPane.showConfirmDialog(f,"收到文件："+name+"，大小："+length+"kb，是否接收？");Socket socket = new Socket(ip,port);PrintWriter out = new PrintWriter(socket.getOutputStream(), true);if(strings[1].equals("img")){if(option==JOptionPane.OK_OPTION){out.println("yes");InputStream in = socket.getInputStream();FileOutputStream fileOut = new FileOutputStream("statics/保存图片.png");byte[] bytes = new byte[1024];int len;while((len = in.read(bytes))!=-1){fileOut.write(bytes, 0, len);}JOptionPane.showMessageDialog(f,"文件接收成功。路径：statics/保存图片.png");fileOut.close();in.close();}else{out.println("no");JOptionPane.showMessageDialog(f,"已取消接受文件。");}}else if(strings[1].equals("file")){if(option==JOptionPane.OK_OPTION){out.println("yes");BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream(),Charset.forName("UTF-8")));PrintWriter fileOut = new PrintWriter("statics/"+name);String s;while((s = in.readLine())!=null){System.out.println(s);fileOut.println(s);}fileOut.close();in.close();JOptionPane.showMessageDialog(f,"文件接收成功。路径：statics/"+name);}else{out.println("no");JOptionPane.showMessageDialog(f,"已取消接受文件。");}}out.close();socket.close();}else textArea2.append("对方："+text+"\r\n");} catch (Exception e) {e.printStackTrace();}}}).start();button.addActionListener(new ActionListener(){@Overridepublic void actionPerformed(ActionEvent e){String text = textArea1.getText();textArea2.append("你："+text+"\r\n");try {byte[] buffer = text.getBytes("UTF-8");DatagramPacket packet = new DatagramPacket(buffer, buffer.length, InetAddress.getByName(hostname),1082);socket1.send(packet);textArea1.setText("");} catch (Exception ex) {ex.printStackTrace();}}});imgButton.addActionListener(new ActionListener(){@Overridepublic void actionPerformed(ActionEvent e){try{JFileChooser fileChooser = new JFileChooser();fileChooser.setFileSelectionMode(JFileChooser.FILES_ONLY);fileChooser.setCurrentDirectory(new File("D:\\"));fileChooser.setFileFilter(new FileNameExtensionFilter("Image Files","png","jpg","gif"));int result = fileChooser.showOpenDialog(f);if(result==JFileChooser.APPROVE_OPTION){File file = fileChooser.getSelectedFile();String filename = file.getName();Long length = file.length()/1024;String message = "###;img;"+filename+";"+length.toString()+";"+localhost+";2080";byte[] buffer = message.getBytes();DatagramPacket packet = new DatagramPacket(buffer,buffer.length,InetAddress.getByName(hostname),1082);socket1.send(packet);Socket socket = socket2.accept();System.out.println("TCP连接成功");BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));if(reader.readLine().equals("yes")){FileInputStream fileIn = new FileInputStream(file);OutputStream out = socket.getOutputStream();byte[] bytes = new byte[1024];int len;while((len = fileIn.read(bytes))!= -1){out.write(bytes, 0, len);}JOptionPane.showMessageDialog(f,"文件传输成功。");fileIn.close();out.close();}else{JOptionPane.showMessageDialog(f,"文件被对方拒收。");}reader.close();socket.close();}}catch (Exception e1){e1.printStackTrace();}}});fileButton.addActionListener(new ActionListener(){@Overridepublic void actionPerformed(ActionEvent e){try{JFileChooser fileChooser = new JFileChooser();fileChooser.setFileSelectionMode(JFileChooser.FILES_ONLY);fileChooser.setCurrentDirectory(new File("D:\\"));fileChooser.setFileFilter(new FileNameExtensionFilter("Text Files","txt","doc","xls"));int result = fileChooser.showOpenDialog(f);if(result==JFileChooser.APPROVE_OPTION){File file = fileChooser.getSelectedFile();String filename = file.getName();Long length = file.length()/1024;String message = "###;file;"+filename+";"+length.toString()+";"+localhost+";2080";byte[] buffer = message.getBytes();DatagramPacket packet = new DatagramPacket(buffer,buffer.length,InetAddress.getByName(hostname),1082);socket1.send(packet);Socket socket = socket2.accept();System.out.println("TCP连接成功");BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));if(reader.readLine().equals("yes")){BufferedReader fileIn = new BufferedReader(new InputStreamReader(new FileInputStream(file), Charset.forName("GBK")));PrintWriter out = new PrintWriter(socket.getOutputStream(),true);String s;while((s = fileIn.readLine())!=null){System.out.println(s);out.println(s);}JOptionPane.showMessageDialog(f,"文件传输成功。");fileIn.close();out.close();}else{JOptionPane.showMessageDialog(f,"文件被对方拒收。");}reader.close();socket.close();}}catch (Exception e1){e1.printStackTrace();}}});}
}

2.Linux客户端代码（ip：192.168.131.131，udp port：1081，tcp port：2081）

package gui;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.*;
import java.net.*;
import java.nio.charset.Charset;
import javax.swing.*;
import javax.swing.filechooser.FileNameExtensionFilter;public class LinuxClient
{public static void main(String[] args) throws Exception{JFrame f = new JFrame();f.setTitle("16010410031 陈大至");f.setSize(700, 790);f.setLocation(900, 100);f.setLayout(null);JButton button = new JButton("发送");button.setBounds(610, 650, 80, 50);f.add(button);JButton imgButton = new JButton("图片");imgButton.setBounds(10,560,70,30);f.add(imgButton);JButton fileButton = new JButton("文本文件");fileButton.setBounds(100,560,90,30);f.add(fileButton);JTextArea textArea1 = new JTextArea();textArea1.setFont(new Font("Dialog", Font.TRUETYPE_FONT,20));textArea1.setLineWrap(true);textArea1.setBounds(10, 600, 590, 150);f.add(textArea1);JTextArea textArea2 = new JTextArea();textArea2.setFont(new Font("Dialog", Font.TRUETYPE_FONT,20));textArea2.setEditable(false);textArea2.setLineWrap(true);JScrollPane scrollPane = new JScrollPane(textArea2);f.add(scrollPane);textArea2.setBounds(10,10, 680, 540);f.add(textArea2);f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);f.setVisible(true);String hostname = "192.168.131.135";//192.168.131.135String localhost="192.168.131.131";//192.168.131.131DatagramSocket socket1 = new DatagramSocket(1081);ServerSocket socket2 = new ServerSocket(2081);new Thread(() -> {while (true){try {byte[] buffer = new byte[1024];DatagramPacket packet = new DatagramPacket(buffer, buffer.length);socket1.receive(packet);String text = new String(packet.getData(),0,packet.getLength());String[] strings = text.split(";");if(strings[0].equals("###")){int option;String name=strings[2];String length=strings[3];String ip=strings[4];int port=Integer.parseInt(strings[5]);option = JOptionPane.showConfirmDialog(f,"收到文件："+name+"，大小："+length+"kb，是否接收？");Socket socket = new Socket(ip,port);PrintWriter out = new PrintWriter(socket.getOutputStream(), true);if(strings[1].equals("img")){if(option==JOptionPane.OK_OPTION){out.println("yes");InputStream inputStream = socket.getInputStream();FileOutputStream fileOut = new FileOutputStream("statics/保存图片.png");byte[] bytes = new byte[1024];int len;while((len = inputStream.read(bytes))!=-1){fileOut.write(bytes, 0, len);}JOptionPane.showMessageDialog(f,"文件接收成功。路径：statics/保存图片.png");fileOut.close();socket.close();}else{out.println("no");JOptionPane.showMessageDialog(f,"已取消接受文件。");socket.close();}}else if(strings[1].equals("file")){if(option==JOptionPane.OK_OPTION){out.println("yes");BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream(),Charset.forName("UTF-8")));PrintWriter fileOut = new PrintWriter("statics/"+name);String s;while((s = in.readLine())!=null){System.out.println(s);fileOut.println(s);}fileOut.close();in.close();JOptionPane.showMessageDialog(f,"文件接收成功。路径：statics/"+name);}else{out.println("no");JOptionPane.showMessageDialog(f,"已取消接受文件。");}}out.close();socket.close();}else textArea2.append("对方："+text+"\r\n");} catch (Exception e) {e.printStackTrace();}}}).start();button.addActionListener(new ActionListener(){@Overridepublic void actionPerformed(ActionEvent e){String text = textArea1.getText();textArea2.append("你："+text+"\r\n");try {byte[] buffer = text.getBytes("GBK");DatagramPacket packet = new DatagramPacket(buffer, buffer.length, InetAddress.getByName(hostname),1082);socket1.send(packet);textArea1.setText("");} catch (Exception ex) {ex.printStackTrace();}}});imgButton.addActionListener(new ActionListener(){@Overridepublic void actionPerformed(ActionEvent e){try{JFileChooser fileChooser = new JFileChooser();fileChooser.setFileSelectionMode(JFileChooser.FILES_ONLY);fileChooser.setCurrentDirectory(new File("."));fileChooser.setFileFilter(new FileNameExtensionFilter("Image Files","png","jpg","gif"));int result = fileChooser.showOpenDialog(f);if(result==JFileChooser.APPROVE_OPTION){File file = fileChooser.getSelectedFile();String filename = file.getName();Long length = file.length()/1024;String message = "###;img;"+filename+";"+length.toString()+";"+localhost+";2081";byte[] buffer = message.getBytes();DatagramPacket packet = new DatagramPacket(buffer,buffer.length,InetAddress.getByName(hostname),1082);socket1.send(packet);Socket socket = socket2.accept();System.out.println("TCP连接成功");BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));if(reader.readLine().equals("yes")){FileInputStream fileIn = new FileInputStream(file);OutputStream out = socket.getOutputStream();byte[] bytes = new byte[1024];int len;while((len = fileIn.read(bytes))!= -1){out.write(bytes, 0, len);}JOptionPane.showMessageDialog(f,"文件传输成功。");fileIn.close();out.close();}else{JOptionPane.showMessageDialog(f,"文件被对方拒收。");}reader.close();socket.close();}}catch (Exception e1){e1.printStackTrace();}}});fileButton.addActionListener(new ActionListener(){@Overridepublic void actionPerformed(ActionEvent e){try{JFileChooser fileChooser = new JFileChooser();fileChooser.setFileSelectionMode(JFileChooser.FILES_ONLY);fileChooser.setCurrentDirectory(new File("."));fileChooser.setFileFilter(new FileNameExtensionFilter("Text Files","txt","doc","xls"));int result = fileChooser.showOpenDialog(f);if(result==JFileChooser.APPROVE_OPTION){File file = fileChooser.getSelectedFile();String filename = file.getName();Long length = file.length()/1024;String message = "###;file;"+filename+";"+length.toString()+";"+localhost+";2081";byte[] buffer = message.getBytes();DatagramPacket packet = new DatagramPacket(buffer,buffer.length,InetAddress.getByName(hostname),1082);socket1.send(packet);Socket socket = socket2.accept();System.out.println("TCP连接成功");BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));if(reader.readLine().equals("yes")){BufferedReader fileIn = new BufferedReader(new InputStreamReader(new FileInputStream(file), Charset.forName("UTF-8")));PrintWriter out = new PrintWriter(socket.getOutputStream(),true);String s;while((s = fileIn.readLine())!=null){System.out.print(s);out.println(s);}JOptionPane.showMessageDialog(f,"文件传输成功。");fileIn.close();out.close();}else{JOptionPane.showMessageDialog(f,"文件被对方拒收。");}reader.close();socket.close();}}catch (Exception e1){e1.printStackTrace();}}});}
}

3.Linux服务器代码（ip：192.168.131.135，udp port：1082）

package gui;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;public class Server
{public static void main(String[] args) throws Exception{String hostname="",text;DatagramSocket socket = new DatagramSocket(1082);while(true){byte[] buffer = new byte[1024];DatagramPacket packet = new DatagramPacket(buffer, buffer.length);socket.receive(packet);text = new String(packet.getData(),0,packet.getLength());int port = packet.getPort();System.out.print("端口号："+port+"，");if(port==1080){System.out.println("来自Win主机："+text);port=1081;hostname="192.168.131.131";//192.168.131.131}else if(port==1081){System.out.println("来自Ubuntu主机："+text);port=1080;hostname="10.177.26.76";}else System.out.println("端口号错误");DatagramPacket packet2 = new DatagramPacket(packet.getData(), packet.getLength(), InetAddress.getByName(hostname),port);socket.send(packet2);}}
}