我有两个文件,一个正在发送,一个正在接收。 我有两者之间的联系。
可以发送带有以下内容的文本:
// Prepare a message
messageToSend = "text that is sent";
lengthMessageToSend = messageToSend.length();
sendingBuffer = messageToSend.getBytes();
// Send the message
myLink.sendFrame(sendingBuffer, lengthMessageToSend);
System.out.println(lengthMessageToSend);
并接收:
// Display the message
messageReceived = new String(receivingBuffer, 0, lengthMessageReceived);
System.out.println("Message received is: [" + messageReceived + "]");
// Prepare a message
messageToSend = "1";
lengthMessageToSend = messageToSend.length();
sendingBuffer = messageToSend.getBytes();
// Send the message
myLink.sendFrame(sendingBuffer, lengthMessageToSend);
我现在尝试发送的文本来自.txt,但只是在有效负载中一次发送 16 个字节:
[ 序列 |林 |有效载荷 |校验和 ] --> 表示总标头为 19 个字节。
最好的方法是什么?
一次只读取 16 个字节(8 个字符)??如果是这样,如何?
并递增 16 i
,此i
表示messageToSend.getBytes()
偏移量的开始 - 然后将接下来的 16 个字节(从 i
到 i+16
,处理剩余少于 16 个字节的情况)放入"数据包"并将其发送出去。
此外,对getBytes()
或环境设置使用显式编码可能会导致"意外的行为更改"。
这样的基本实现可能如下所示:
byte[] data = messageToSend.getBytes("UTF-8"); // Specify encoding!
// "For all data, stepping by 16 bytes at a time.."
for (int i = 0; i < data.length; i += 16) {
// How many bytes actually remain (or 16 if more than 16 remain)
var frameSize = Math.min(16, data.length - i);
// Construct frame data from data in i..i+frameSize and send.
// If you want to ALWAYS send 16 bytes, update as appropriate.
byte[] frameData = new byte[frameSize];
System.arraycopy(data, i, frameData, 0, frameSize);
sendFrame(frameData, frameSize);
}
必须调整代码以添加序列号,但这应该不难,因为它总是递增 1。
读取发生类似:使用数据包标头并根据长度/成帧数据处理剩余的缓冲区(可能包括下一个数据包的开始)。
// Assuming new frames are always copied-to-start and that there
// if a complete frame ready (can be determined from frame size with)
// two reads. If not, keep reading..
byte[] receivingBuffer = ..;
int offset = 0;
int seq = receivingBuffer[offset++];
int frameSize = receivingBuffer[offset++];
// Again, use an encoding
String content = new String(receivingBuffer, offset, frameSize, "UTF-8");
offset += frameSize;
int checksum = receivingBuffer[offset++];
// Use offset to move extra data in receivingBuffer to start
// of buffer to make it easy to reset offset to 0 and repeat above.