通过AsyncSocket向objective-c中的java服务器发送消息

Question

嗨，我正在尝试向Java服务器发送无法从iOS设备更改的消息。我正在使用AsyncSocket，想知道如何发送和接收附加到字符串的长度。我正在进行字符串到NSData的UTF转换，但我想知道这两种语言之间的原语大小是否存在差异。还有大端序和小端序的变体吗？基本上，我需要能够转换以下java方法：

inStream.readUTF();
inStream.readInt();
inStream.readChar();
inStream.readShort();
inStream.readFully(recvBuff, 0, recvLen);
outStream.writeInt();
outStream.writeUTF();
outStream.writeChars();
outStream.writeShort();
outStream.write(sendBytes, 0, sendBytes.length);

我知道我很接近，但有些地方不太对劲，这就是我到目前为止所得到的：

我使用NSMutableArray来附加数据，并使用AsyncSockets读写方法。

[theSocket readDataToData:[AsyncSocket ZeroData] withTimeout:timeout buffer:buffer bufferOffset:offset tag:tag]; // inStream.readUTF();
[theSocket readDataToLength:sizeof(int32_t) withTimeout:timeout buffer:buffer bufferOffset:offset tag:tag]; // inStream.readInt();
[theSocket readDataToLength:sizeof(unichar) withTimeout:timeout buffer:buffer bufferOffset:offset tag:tag]; // inStream.readChar();
[theSocket readDataToLength:sizeof(int16_t) withTimeout:timeout tag:tag]; // inStream.readShort();
[theSocket readDataWithTimeout:timeout buffer:buffer bufferOffset:offset maxLength:maxLength tag:tag]; // inStream.readFully(recvBuff, 0, recvLen);
[outputBufferStream appendBytes:&[sendString length] length:sizeof([sendString length])]; // outStream.writeInt();
[outputBufferStream appendData:[sendString dataUsingEncoding:NSUTF8StringEncoding]] // outStream.writeUTF();
char array[5];
[outputBufferStream appendBytes:array length:sizeof(array)]; // outStream.writeChars();
int16_t _short;
[outputBufferStream appendBytes:&_short length:sizeof(_short)]; // outStream.writeShort();
unsigned char *sendBytes;
[outputBufferStream appendBytes:sendBytes length:sendBytesLength]; // outStream.write(sendBytes, 0, sendBytes.length);

我通常在开头加上这样的长度：

int32_t sendStringLength = [sendString length];
[outputBufferStream appendBytes:&sendStringLength length:sizeof(sendStringLength)];

在写的最后，我将添加以下内容作为终止符：

[outputBufferStream appendData:[@"n" dataUsingEncoding:NSUTF8StringEncoding]];

我真的很感激在这方面的任何帮助。谢谢

编辑：：

多亏了Robadob，我大部分时间都在工作。以下是我目前在Objective-C上工作时遇到的一个小java片段：

private int sendData(String stringToSend) {
    if (theSocket==null) {
        lastError="sendData() called before socket was set up.";
        return 1; // Error
    }
    try {
        System.out.println("Sending "+stringToSend.length()+" chars  ["+ stringToSend.length()*2+" bytes]");
        System.out.println("'" + stringToSend + "'");
        outStream.writeInt(stringToSend.length()*2);
        outStream.writeChars(stringToSend);
        outStream.flush();
    } catch (IOException e) {
        lastError="sendData() exception: "+e;
        System.out.println(lastError);
        return 2; // Error
    }
    return 0; // Ok
}

以下是我在Objective-C中得到的一个片段：

- (int32_t)sendData:(NSString *)stringToSend {
    if (theSocket == nil) {
        lastError = @"sendData called before socket was set up";
        return 1; // Error
    }
    @try {
        NSLog(@"Sending %d chars  [%d bytes]", [stringToSend length], ([stringToSend length] * 2));
        NSLog(@"'%@'", stringToSend);
        uint32_t stringToSendInt = ([stringToSend length] * 2);
        uint32_t stringToSendIntBigE = CFSwapInt32HostToBig(stringToSendInt);
        [outputBufferStream appendBytes:&stringToSendIntBigE length:sizeof(stringToSendIntBigE)];
        stringToSend = [stringToSend stringByAppendingString:@"n"];
        for (int i = 0; i < ([stringToSend length]); i++) {
            unichar characterTmp = [stringToSend characterAtIndex:i];
            unichar character = characterTmp << 8;
            [outputBufferStream appendBytes:&character length:sizeof(character)];
        }
        [self syncWriteData:outputBufferStream withTimeout:socketTimeout tag:kSendDataSocketTag];
        outputBufferStream = [NSMutableData data];
    }
    @catch (NSException *e) {
        lastError = [NSString stringWithFormat:@"sendData exception: %@", [e reason]];
        NSLog(@"%@", lastError);
        return 2; // Error
    }
    return 0; // Ok
}

Answer 1

如果您阅读了writeUTF的文档，它会说它使用writeShort写入前2个字节。上面写着

将short作为两个字节（高字节）写入基础输出流第一如果未引发异常，则写入的计数器将递增乘以2。

一个字节是8位，所以他们写入的值是16位，您使用的是int32_t，即32位。你应该写一个int16或int16_t（我不是objective-c）。