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您好我正在尝试将消息发送到无法从 iOS 设备更改的 Java 服务器。我正在使用 AsyncSocket 并且想知道如何发送和接收附加到字符串的长度。我正在将字符串 UTF 转换为 NSData 但是我想知道这两种语言之间的原语大小是否存在差异。还有大端和小端的变化吗？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);

我知道我非常接近，但有些地方不太对劲，这就是我到目前为止所得到的：

我正在使用 NSMutableArray 来附加数据并使用 AsyncSockets 读取和写入方法。

[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);

我通常在开头附加长度，如下所示：

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

在写入结束时，我将以下内容作为终止符附加：

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

我真的很感激这方面的任何帮助。谢谢。

编辑：：

多亏了 Robadob，我已经完成了大部分工作。这是我目前试图在 Objective-C 上工作的一点 Java 片段（工作）：

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
}

这是到目前为止我在 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
}
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1 回答 1

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

以两个字节的形式将一个短路写入底层输出流，先是高字节。如果没有抛出异常，则写入的计数器加 2。

一个字节是 8 位，因此它们正在写入的值是 16 位，您使用int32_t的是 32 位。你应该写一个int16或int16_t（我不客观-c）。

于 2013-07-31T18:09:01.977 回答