功能实现流程为：

1.文件发送方用户登录

2.确定文件的接收方和待发送文件路径

3.获取连接

4.根据连接获取文件接收方的完整jid（例如user@192.168.1.34/MiniQQ 2.3.6），其中MiniQQ 2.3.6为文件接收方用户客户端的resource，必须获取到，否则文件无法发送

5.发送文件

实现代码为：

public int TransFile(String toUser, String fileDir) {		// final int flag[] = new int[] { 0 };		Connection conn = this.connection;		ServiceDiscoveryManager serviceDiscoveryManager = new ServiceDiscoveryManager(				conn);		// System.out.println(conn.toString());		// System.out.println(this.sessionManager.getConnection().toString());		if (!toUser.contains("@")) {			toUser = toUser + "@" + this.connection.getServiceName();		}		// toUser = toUser +"/Spark 2.6.3";		Roster roster = connection.getRoster();		Presence pre = roster.getPresence(toUser);		toUser = pre.getFrom();		if (!toUser.contains("/")) {			//toUser = toUser + "/MiniQQ 2.3.6";			toUser = toUser + "/MiniQQ 2.3.6";		}		System.out.println("向发送文件：" + toUser);		// System.out.println(toUser);		if (pre == null) {			System.out.println("用户不存在");			return -1;		}		FileTransferManager transferManager = new FileTransferManager(conn);		final File file = new File(fileDir);		final OutgoingFileTransfer transfer = transferManager				.createOutgoingFileTransfer(toUser);		// FutureTask
     
       task = new FutureTask
      
       ();		FutureTask
       
         task = new FutureTask<>(new Callable
        
         () {			@Override			public Integer call() throws Exception {				int flag = 0;				try {					transfer.sendFile(file, "Sending");					while (!transfer.isDone()) {						try {							Thread.sleep(10L);						} catch (InterruptedException e) {							e.printStackTrace();						}						if (transfer.getStatus() == FileTransfer.Status.in_progress) {							System.out.println(transfer.getProgress());							// flag[0] = 0;						} else {							if (transfer.getStatus() == FileTransfer.Status.error) {								System.out.println("file transport failed");//								// flag[0] = -1;								flag = -1;								// return ;							}							if (transfer.getStatus() == FileTransfer.Status.refused) {								System.out										.println("file transport was refused");								// flag[0] = -1;								flag = -1;								// return ;							}						}					}				} catch (XMPPException e1) {					e1.printStackTrace();					// return ;				}				return flag;			}		});		SwingUtilities.invokeLater(task);		int flagRes = 0;		while (true) {			if (task.isDone()) {				try {					flagRes = task.get();				} catch (InterruptedException e) {					e.printStackTrace();				} catch (ExecutionException e) {					e.printStackTrace();				}				break;			}		}		return flagRes;	}