通过alljoyn传输文件(2)

    上一篇文章介绍了使用alljoyn的raw方式进行文件的传输，其实那种方法不是很实用，并不是一种好的方式，这篇文章介绍一下使用alljoyn的signal方式进行文件的传输。

     在alljoyn的sdk里面有个chat的例子，这个例子就是使用signal传输手机间的聊天信息的。我们所要做的就是将其修改一下来传输我们的文件。

     首先修改ChatInterface.java里面的接口，将参数从string 类型改成byte[]类型，如下所示：

public void Chat(byte[] str) throws Bu***ception;

    这就表示我们传输的不是字符串而是byte数组了。所以接下来的问题就是将文件内容转换成一系列的byte数组发出去然后接收这些byte数组并重新组成文件就可以了。首先来看发送，发送时在AllJoynService.java的doSendMessages()方法。

try {
                if (mJoinedToSelf) {
                    if (mHostChatInterface != null) {
                        // mHostChatInterface.Chat(message);

                    }
                } else {
                    SimpleDateFormat formatter = new SimpleDateFormat("yyyy年MM月dd日 HH:mm:ss ");
                    Date curDate = new Date(System.currentTimeMillis());// 获取当前时间

                    String str = formatter.format(curDate);
                    Log.d("test", "start:" + str+"::::");
                    String filepath = "/sdcard/Picture/100ANDRO/MOV_0426.mp4";
                    File file = new File(filepath);
                    InputStream in = null;
                    try {
                        in = new FileInputStream(file);
                    } catch (FileNotFoundException e1) {
                        // TODO Auto-generated catch block

                        e1.printStackTrace();
                    }
                    byte[] buffer = new byte[102400];
                    int read = 0;
                    while ((read = in.read(buffer)) != -1) {
                        mChatInterface.Chat(buffer);
                        buffer = new byte[102400];
                    }
                    in.close();
                    curDate = new Date(System.currentTimeMillis());// 获取当前时间

                    str = formatter.format(curDate);
                    Log.d("test", "end:" + str+"::::");
                }
            } catch (Bu***ception ex) {
                mChatApplication.alljoynError(ChatApplication.Module.USE,
                        "Bus exception while sending message: (" + ex + ")");
            } catch (IOException e) {
                Log.d("test", e.toString());
            }

     在发送的前后加上系统的时间这样就可以测试发送文件花费的时间。接收是在Chat(byte[] string) 方法里面。

public void Chat(byte[] string) {

        /*
         * See the long comment in doJoinSession() for more explanation of why
         * this is needed.
         *
         * The only time we allow a signal from the hosted session ID to pass
         * through is if we are in mJoinedToSelf state. If the source of the
         * signal is us, we also filter out the signal since we are going to
         * locally echo the signal.
         */
        String uniqueName = mBus.getUniqueName();
        MessageContext ctx = mBus.getMessageContext();
        Log.i(TAG, "Chat(): use sessionId is " + mUseSessionId);
        Log.i(TAG, "Chat(): message sessionId is " + ctx.sessionId);

        /*
         * Always drop our own signals which may be echoed back from the system.
         */
        if (ctx.sender.equals(uniqueName)) {
            Log.i(TAG, "Chat(): dropped our own signal received on session "
                    + ctx.sessionId);
            return;
        }

        /*
         * Drop signals on the hosted session unless we are joined-to-self.
         */
        if (mJoinedToSelf == false && ctx.sessionId == mHostSessionId) {
            Log.i(TAG, "Chat(): dropped signal received on hosted session "
                    + ctx.sessionId + " when not joined-to-self");
            return;
        }

        /*
         * To keep the application simple, we didn't force users to choose a
         * nickname. We want to identify the message source somehow, so we just
         * use the unique name of the sender's bus attachment.
         */
        String nickname = ctx.sender;
        nickname = nickname
                .substring(nickname.length() - 10, nickname.length());

        // Log.i(TAG, "Chat(): signal " + string + " received from nickname " +

        // nickname);

//        mChatApplication.newRemoteUserMessage(nickname, "get message");

        try {
            try {
                if (file == null) {
                    file = new File("/mnt/sdcard/abc.mp4");
                }
                fos = new FileOutputStream(file, true);
            } catch (Exception e) {
                Log.e(TAG, "creat file error");
            }
            try {
                fos.write(string, 0, string.length);
            } catch (IOException e) {
                Log.e(TAG, "write file error");
            }

        } finally {
            if (fos != null) {
                try {
                    fos.close();
                } catch (IOException e) {
                    Log.e(TAG, e.toString());
                }
            }
            fos = null;
        }
    }

      这样就可以进行文件的传输了，测试表明这个方法比上个方法更快更稳定了。