NSNonLossyASCIIStringEncoding等效于Android

Question

我需要将一些聊天代码从iOS移植到Android.在将聊天消息发送到套接字之前,iOS代码使用NSNonLossyASCIIStringEncoding该类作为NSString :: dataUsingEncoding的参数.

你会如何在Android中做到这一点？关于相反解码的相同问题.

例如,如果不这样做,换行符就会消失在另一个移动设备上收到的消息中.

iOS上的代码:

NSData *data1 = [myStringTosend dataUsingEncoding:NSNonLossyASCIIStringEncoding];
NSString *goodValue = [[[NSString alloc] initWithData:data1 encoding:NSUTF8StringEncoding] autorelease];

并解码:

NSData *data = [[NSData alloc] initWithData:[response dataUsingEncoding:NSASCIIStringEncoding]];

到目前为止(并且不正确),在Android端进行编码:

OutputStream os = socket.getOutputStream();
os.write(request.getBytes("UTF-8"));
os.flush();

并解码:

while ((bytesRead = is.read(buffer, 0, BUFFER_SIZE)) >= 0) {
    if (bytesRead > 0) response.append(new String(buffer, 0, bytesRead, "UTF-8"));
    if (bytesRead < BUFFER_SIZE) break;
}

Answer 1

@portforwardpodcast是绝对正确的,如果可能的话,你应该避免对你的utf8进行ASCII编码,而是设置你的堆栈来直接处理/存储utf8.也就是说,如果您无法更改行为,则以下代码可能会有所帮助.

虽然没有公布的解释如何NSNonLossyASCIIStringEncoding工作,但根据其输出,它看起来像:

• 扩展ASCII范围(十进制值128 - 255)中的字节使用八进制编码进行转义(例如,ñ使用十进制值241 - > \361)
• 非ASCII代码点使用十六进制编码以两个字节的块进行转义(例如,它占用32位,十进制值128549 - > \ud83d\ude25)

所以编码:

public static String encodeToNonLossyAscii(String original) {
    Charset asciiCharset = Charset.forName("US-ASCII");
    if (asciiCharset.newEncoder().canEncode(original)) {
        return original;
    }
    StringBuffer stringBuffer = new StringBuffer();
    for (int i = 0; i < original.length(); i++) {
        char c = original.charAt(i);
        if (c < 128) {
            stringBuffer.append(c);
        } else if (c < 256) {
            String octal = Integer.toOctalString(c);
            stringBuffer.append("\\");
            stringBuffer.append(octal);
        } else {
            String hex = Integer.toHexString(c);
            stringBuffer.append("\\u");
            stringBuffer.append(hex);
        }
    }
    return stringBuffer.toString();
}

并进行解码(通过在锁定步骤中解析两种类型的编码,而不是两次单独的传递,可以提高效率):

private static final Pattern UNICODE_HEX_PATTERN = Pattern.compile("\\\\u([0-9A-Fa-f]{4})");
private static final Pattern UNICODE_OCT_PATTERN = Pattern.compile("\\\\([0-7]{3})");

public static String decodeFromNonLossyAscii(String original) {
    Matcher matcher = UNICODE_HEX_PATTERN.matcher(original);
    StringBuffer charBuffer = new StringBuffer(original.length());
    while (matcher.find()) {
        String match = matcher.group(1);
        char unicodeChar = (char) Integer.parseInt(match, 16);
        matcher.appendReplacement(charBuffer, Character.toString(unicodeChar));
    }
    matcher.appendTail(charBuffer);
    String parsedUnicode = charBuffer.toString();

    matcher = UNICODE_OCT_PATTERN.matcher(parsedUnicode);
    charBuffer = new StringBuffer(parsedUnicode.length());
    while (matcher.find()) {
        String match = matcher.group(1);
        char unicodeChar = (char) Integer.parseInt(match, 8);
        matcher.appendReplacement(charBuffer, Character.toString(unicodeChar));
    }
    matcher.appendTail(charBuffer);
    return charBuffer.toString();
}