javaSE实现文件上传下载操作

文件的上传下载要保证文件的完整性，所以采用TCP连接
TCP连接是面向连接的、稳定的、安全的传输协议，在OSI的传输层

用户信息类
用户上传文件和下载文件，服务器需要获取用户的信息，这个信息可以封装成用户类

public class HostsMsg {private String ip;private int port;private String hostname;public HostsMsg(String ip, int port, String hostname) {this.ip = ip;this.port = port;this.hostname = hostname;}public String getIp() {return ip;}public void setIp(String ip) {this.ip = ip;}public int getPort() {return port;}public void setPort(int port) {this.port = port;}public String getHostname() {return hostname;}public void setHostname(String hostname) {this.hostname = hostname;}@Overridepublic String toString() {return "HostsMsg{" +"ip='" + ip + '\'' +", port=" + port +", hostname='" + hostname + '\'' +'}';}
}

文件工具类
文件上传和下载有很多重复的代码，可以封装成一个工具类

public class FileUtils {//发送文件public static void sendMsg(Socket socket,String msg) throws IOException {DataOutputStream dataOutputStream = new DataOutputStream(socket.getOutputStream());dataOutputStream.writeUTF(msg);}//接收文件public static String receiveMsg(Socket socket) throws IOException {DataInputStream dataInputStream = new DataInputStream(socket.getInputStream());String s = dataInputStream.readUTF();return s;}//发送文件public static void sendFile(Socket socket, File file) throws IOException {FileInputStream fileInputStream = new FileInputStream(file);OutputStream outputStream = socket.getOutputStream();byte[] bytes = new byte[1024];int len = 0;while ((len = fileInputStream.read(bytes)) != -1){outputStream.write(bytes,0,len);}}//接收文件public static void receiveFile(Socket socket, File file) throws IOException {FileOutputStream fileOutputStream = new FileOutputStream(file);InputStream inputStream = socket.getInputStream();byte[] bytes = new byte[1024];int len = 0;while ((len = inputStream.read(bytes)) != -1){fileOutputStream.write(bytes,0,len);}}//发送操作类型public static void sendOperation(Socket socket,OperationType operationType) throws IOException {ObjectOutputStream objectOutputStream = new ObjectOutputStream(socket.getOutputStream());objectOutputStream.writeObject(operationType);}//接收操作类型public static OperationType receiveOperation(Socket socket,OperationType operationType) throws IOException, ClassNotFoundException {ObjectInputStream objectInputStream = new ObjectInputStream(socket.getInputStream());OperationType operation = ((OperationType) objectInputStream.readObject());return operation;}
}

文件操作枚举类
用户上传下载文件需要操作相关指令，可以用1，2，3进行相应操作，但是要转换，这里采用枚举类，直接将操作类型发送给服务端

public enum OperationType {UPLOAD,DOWNLOAD,DELETE
}

服务端

public class Server_File {private ServerSocket serverSocket = null;private boolean isRun = true;public Server_File(int port) throws IOException {serverSocket = new ServerSocket(port);}public void start() throws IOException, ClassNotFoundException {while (isRun) {System.out.println("服务器启动");Socket socket = connection();OperationType operation = receiveOperation(socket);if (operation == null) continue;HostsMsg clientMsg = getClientMsg(socket);File dirOwn = createDirOwn(clientMsg);if (!dirOwn.exists()) continue;printHosts(clientMsg, operation);}}public File createDirOwn(HostsMsg hostsMsg){File file = new File("F:/云盘存储",hostsMsg.getHostname());if (!file.exists()) {file.mkdirs();}return file;}public void action(Socket socket,OperationType operationType,File file) throws IOException {if (operationType == null) return;switch (operationType){case UPLOAD:upload(socket,file);break;case DOWNLOAD:delete(socket,file);break;}}private OperationType receiveOperation(Socket socket) throws IOException, ClassNotFoundException {ObjectInputStream inputStream = (ObjectInputStream) socket.getInputStream();OperationType operationType = ((OperationType) inputStream.readObject());return operationType;}private void delete(Socket socket,File file) throws IOException {DataInputStream inputStream = (DataInputStream) socket.getInputStream();String s = inputStream.readUTF();}private void download(Socket socket,File dir) throws IOException {File[] files = dir.listFiles();if (files == null || files.length == 0){FileUtils.sendMsg(socket,"no");System.out.println("下载失败，没有该文件");return;}//将文件列表发送给客户端String msg = filesToString(files);//接收客户端需要下载文件信息String filename = FileUtils.receiveMsg(socket);File file = new File(dir,filename);//判断该文件是否存在if (file.exists()){FileUtils.sendMsg(socket,"yes");}else {FileUtils.sendMsg(socket,"no");}if (file.exists()){FileUtils.sendFile(socket,file);System.out.println(filename+"下载成功");}else {FileUtils.sendFile(socket,file);System.out.println("文件不存在");}}private String filesToString(File[] files){//将多个文件的名字，拼接成一个字符串StringBuilder stringBuilder = new StringBuilder("");for (int i = 0; i < files.length; i++) {stringBuilder.append(i+1).append(".").append(files[i].getName()).append("\r\n");}return stringBuilder.toString();}private void upload(Socket socket,File dir) throws IOException {//获得文件名字String fileName = receiveFileName(socket);if (fileName == null)return;//判断该文件是否存在boolean flag = checkFileExists(dir, fileName);//发送信息给客户端，告知上传的文件名是否重复if (flag){FileUtils.sendMsg(socket,"yes");}else {FileUtils.sendMsg(socket,"no");}if (flag){}else {File file = new File(dir,fileName);FileUtils.receiveFile(socket,file);}}private boolean checkFileExists(File dir, String fileName) {File file = new File(dir,fileName);return file.exists();}private String receiveFileName(Socket socket){String s = null;try {s = FileUtils.receiveMsg(socket);} catch (IOException e) {System.out.println(socket + "传输上传文件的名字的时候出错");}return s;}private void printHosts(HostsMsg clientMsg,OperationType operationType) {System.out.println("用户 == " + clientMsg + " == 已登录，进行了 " + operationType);}private HostsMsg getClientMsg(Socket socket) {String ip = socket.getInetAddress().getHostAddress();int port = socket.getPort();String hostName = socket.getInetAddress().getHostName();return new HostsMsg(ip,port,hostName);}public Socket connection() {try {Socket accept = serverSocket.accept();return accept;} catch (IOException e) {System.err.println("一个客户端已下线");}return null;}
}

客户端

public class Client_File {private String ip;private int port;public Client_File() {}public void start() throws IOException {Socket socket = connection(ip,port);}public Socket connection(String ip,int port) throws IOException {Socket socket = new Socket(ip,port);return socket;}public void sendMsg(Socket socket,String msg) throws IOException {FileUtils.sendMsg(socket,msg);}public String receiveMsg(Socket socket) throws IOException {String s = FileUtils.receiveMsg(socket);return s;}public void sendFile(Socket socket, File file) throws IOException {FileUtils.sendFile(socket,file);}public void receiveFile(Socket socket,File file) throws IOException {FileUtils.receiveFile(socket,file);}public void upload(Socket socket,File file) throws IOException, ClassNotFoundException {sendOperation(socket,OperationType.UPLOAD);sendMsg(socket,file.getName());boolean flag = receiveMsg(socket).equals("yes")?true:false;if (flag){}else {sendFile(socket,file);}}private Scanner scanner = new Scanner(System.in);public void download(Socket socket,File file) throws Exception {sendOperation(socket,OperationType.DOWNLOAD);String dir = scanner.next();String filename = scanner.next();sendMsg(socket,filename);boolean flag = receiveMsg(socket).equals("yes") ? true:false;if (flag){}else {receiveFile(socket,new File(dir,filename));}}public void delete(Socket socket,File file) throws IOException {DataOutputStream outputStream = (DataOutputStream) socket.getOutputStream();outputStream.writeUTF(file.getName());}public void sendOperation(Socket socket,OperationType operationType) throws IOException, ClassNotFoundException {FileUtils.sendOperation(socket,operationType);}public OperationType ReceiveOperation(Socket socket,OperationType operationType) throws IOException, ClassNotFoundException {OperationType operationType_02 = FileUtils.receiveOperation(socket, operationType);return operationType_02;}
}

开启服务端

**public class Server_Main {public static void main(String[] args) throws IOException, ClassNotFoundException {Server_File server_file = new Server_File(9999);server_file.start();}
}**

开启客户端

public class Client_Main {public static void main(String[] args) throws IOException, ClassNotFoundException {Client_File client_file = new Client_File();Socket connection = client_file.connection("127.0.0.1", 9999);File file = new File("D:/a.txt");client_file.upload(connection,file);}
}

效果

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