Java InputStream编码/字符集

问题描述

运行以下（示例）代码

import java.io.*;

public class test {
    public static void main(String[] args) throws Exception {
        byte[] buf = {-27};
        InputStream is = new ByteArrayInputStream(buf);
        BufferedReader r = new BufferedReader(
                new InputStreamReader(is, "ISO-8859-1"));
        String s = r.readLine();
        System.out.println("test.java:9 [byte] (char)" + (char)s.getBytes()[0] +
                " (int)" + (int)s.getBytes()[0]);
        System.out.println("test.java:10 [char] (char)" + (char)s.charAt(0) +
                " (int)" + (int)s.charAt(0));
        System.out.println("test.java:11 string below");
        System.out.println(s);
        System.out.println("test.java:13 string above");
    }
}

给我这个输出

test.java:9 [byte] (char)? (int)63
test.java:10 [char] (char)? (int)229
test.java:11 string below
?
test.java:13 string above

如何在第9行保留正确的字节值（-27）打印？并因此收到 System.out.println（s）命令（å）的预期输出。

How do I retain the correct byte value (-27) in the line-9 printout? And consequently receive the expected output of the System.out.println(s) command (å).

推荐答案

如果要保留字节值，最好不要使用阅读器。为了在文本中表示任意的二进制数据，稍后将其转换回二进制数据，您应该使用base16或base64编码。

If you want to retain byte values, don't use a Reader at all, ideally. To represent arbitrary binary data in text and convert it back to binary data later, you should use base16 or base64 encoding.

然而，为了解释发生了什么，当您调用 s.getBytes（）使用默认字符编码，这显然不包括Unicode字符U + 00E5。

However, to explain what's going on, when you call s.getBytes() that's using the default character encoding, which apparently doesn't include Unicode character U+00E5.

如果您调用 s.getBytes（ISO-8859-1），而不是 s.getBytes（ ）我怀疑你会得到正确的字节值...但依靠ISO-8859-1这样做是有点脏的IMO。

If you call s.getBytes("ISO-8859-1") everywhere instead of s.getBytes() I suspect you'll get back the right byte value... but relying on ISO-8859-1 for this is kinda dirty IMO.

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