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Question

我想下面的发送字符串作为字节数组从C＃与Java：

C＃客户：

string stringToSend = "Hello man"; 
    BinaryWriter writer = new BinaryWriter(mClientSocket.GetStream(),Encoding.UTF8); 

    //write number of bytes: 
    byte[] headerBytes = BitConverter.GetBytes(stringToSend.Length); 
    mClientSocket.GetStream().Write(headerBytes, 0, headerBytes.Length); 
    //write text: 
    byte[] textBytes = System.Text.Encoding.UTF8.GetBytes(stringToSend); 
    writer.Write(textBytes, 0, textBytes.Length); 

Java服务器：

Charset utf8 = Charset.forName("UTF-8"); 
    BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream(), utf8)); 

    while (true) { 
     //we read header first 
     int headerSize = in.read(); 
     int bytesRead = 0; 
     char[] input = new char[headerSize]; 

     while (bytesRead < headerSize) 
     {  
     bytesRead += in.read(input, bytesRead, headerSize - bytesRead); 
     } 
      String resString = new String(input); 
      System.out.println(resString); 


     if (resString.equals("!$$$")) { 
       break; 
     } 
    } 

字符串大小等于9.这两个方面都是正确的。但是，当我在Java端读取字符串iteself时，数据看起来不正确。炭缓冲液（ '输入' 可变）的含量如下：

”， “”， 'H'， 'E'， '升'， '升'， 'O'， ''

我试图通过反转字节数组来改变字节顺序。还试着改变ASCII和UTF-8之间的字符串编码格式。我仍然觉得它涉及到字节顺序问题，但不知道如何解决它。我知道我可以使用其他类型的作家为了写入文本数据的蒸汽，但我正在尝试使用原始字节数组为了学习。

Answer 1

这些

byte[] headerBytes = BitConverter.GetBytes(stringToSend.Length); 

是4个字节。它们不是字符数据，所以用BufferedReader来读取它们是没有意义的。只需直接读取字节。

byte[] headerBytes = new byte[4]; 
// shortcut, make sure 4 bytes were actually read 
in.read(headerBytes); 

现在提取文本的长度和分配足够的空间为它

int length = ByteBuffer.wrap(headerBytes).getInt(); 
byte[] textBytes = new byte[length]; 

然后读课文

int remaining = length; 
int offset = 0; 
while (remaining > 0) { 
    int count = in.read(textBytes, offset, remaining); 
    if (-1 == count) { 
     // deal with it 
     break; 
    } 
    remaining -= count; 
    offset += count; 
} 

现在为UTF-8

String text = new String(textBytes, StandardCharsets.UTF_8); 

解码你就完成了。

字节顺序必须匹配那些前4个字节。确保使用“网络顺序”（big-endian）的一种方法。所以：

C＃的客户

byte[] headerBytes = BitConverter.GetBytes(IPAddress.HostToNetworkOrder(stringToSend.Length)); 

Java服务器

int length = ByteBuffer.wrap(headerBytes).order(ByteOrder.BIG_ENDIAN).getInt(); 

Answer 2

初看起来你的索引有问题。

您的C＃代码正在发送一个整数转换为4个字节。

但是你的Java代码只读取一个字节作为字符串的长度。

从C＃发送的下一个3字节将从您的字符串长度转到三个零字节。

您的Java代码正在读取这3个零字节并将它们转换为空字符，这些空字符表示input []数组的前三个空字符。

C＃客户：

string stringToSend = "Hello man"; 
BinaryWriter writer = new BinaryWriter(mClientSocket.GetStream(),Encoding.UTF8); 

//write number of bytes: Original line was sending the entire string here. Optionally if you string is longer than 255 characters, you'll need to send another data type, perhaps an integer converted to 4 bytes. 
byte[] textBytes = System.Text.Encoding.UTF8.GetBytes(stringToSend); 
mClientSocket.GetStream().Write((byte)textBytes.Length); 
//write text the entire buffer 

writer.Write(textBytes, 0, textBytes.Length); 

Java服务器：

Charset utf8 = Charset.forName("UTF-8"); 
BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream(), utf8)); 

while (true) { 
    //we read header first 
    // original code was sending an integer as 4 bytes but was only reading a single char here. 
    int headerSize = in.read();// read a single byte from the input 
    int bytesRead = 0; 
    char[] input = new char[headerSize]; 

    // no need foe a while statement here: 
    bytesRead = in.read(input, 0, headerSize); 

    // if you are going to use a while statement, then in each loop 
    // you should be processing the input but because it will get overwritten on the next read. 
    String resString = new String(input, utf8); 
    System.out.println(resString); 


    if (resString.equals("!$$$")) { 
     break; 
    } 
}