通過插座

Question

我想下面的發送字符串作爲字節數組從C＃與Java：

C＃客戶：

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服務器：

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; 
     } 
    } 

字符串大小等於9.這兩個方面都是正確的。但是，當我在Java端讀取字符串iteself時，數據看起來不正確。炭緩衝液（ '輸入' 可變）的含量如下：

」， 「」， 'H'， 'E'， '升'， '升'， 'O'， ''

我試圖通過反轉字節數組來改變字節順序。還試着改變ASCII和UTF-8之間的字符串編碼格式。我仍然覺得它涉及到字節順序問題，但不知道如何解決它。我知道我可以使用其他類型的作家爲了寫入文本數據的蒸汽，但我正在嘗試使用原始字節數組爲了學習。

Answer 1

這些

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

是4個字節。它們不是字符數據，所以用BufferedReader來讀取它們是沒有意義的。只需直接讀取字節。

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

現在提取文本的長度和分配足夠的空間爲它

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

然後讀課文

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; 
} 

現在爲UTF-8

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

解碼你就完成了。

字節順序必須匹配那些前4個字節。確保使用「網絡順序」（big-endian）的一種方法。所以：

C＃的客戶

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

Java服務器

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

Answer 2

初看起來你的索引有問題。

您的C＃代碼正在發送一個整數轉換爲4個字節。

但是你的Java代碼只讀取一個字節作爲字符串的長度。

從C＃發送的下一個3字節將從您的字符串長度轉到三個零字節。

您的Java代碼正在讀取這3個零字節並將它們轉換爲空字符，這些空字符表示input []數組的前三個空字符。

C＃客戶：

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服務器：

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; 
    } 
}