utf 8在Java中将UTF8转换为ISO88591如何将其保持为单字节

Question

我正在尝试将UTF-8中java编码的字符串转换为ISO-8859-1。例如，在字符串“–abcd”中，ISO-8859-1将–表示为E2。在UTF-8中，它表示为两个字节。我相信。当我执行getbytes（编码）并使用ISO-8859-1编码中的字节创建一个新字符串时，我会得到两个不同的字符。â. 是否有其他方法来保持角色不变，即–abcd

Answer 1

如果您处理的是UTF-16以外的字符编码，那么不应该使用java.lang.String或char原语——您应该只使用byte[]数组或ByteBuffer对象。然后，可以使用^{}在编码之间进行转换：

Charset utf8charset = Charset.forName("UTF-8");
Charset iso88591charset = Charset.forName("ISO-8859-1");

ByteBuffer inputBuffer = ByteBuffer.wrap(new byte[]{(byte)0xC3, (byte)0xA2});

// decode UTF-8
CharBuffer data = utf8charset.decode(inputBuffer);

// encode ISO-8559-1
ByteBuffer outputBuffer = iso88591charset.encode(data);
byte[] outputData = outputBuffer.array();

Answer 2

对于文件编码

public class FRomUtf8ToIso {
        static File input = new File("C:/Users/admin/Desktop/pippo.txt");
        static File output = new File("C:/Users/admin/Desktop/ciccio.txt");


    public static void main(String[] args) throws IOException {

        BufferedReader br = null;

        FileWriter fileWriter = new FileWriter(output);
        try {

            String sCurrentLine;

            br = new BufferedReader(new FileReader( input ));

            int i= 0;
            while ((sCurrentLine = br.readLine()) != null) {
                byte[] isoB =  encode( sCurrentLine.getBytes() );
                fileWriter.write(new String(isoB, Charset.forName("ISO-8859-15") ) );
                fileWriter.write("\n");
                System.out.println( i++ );
            }

        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                fileWriter.flush();
                fileWriter.close();
                if (br != null)br.close();
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }

    }


    static byte[] encode(byte[] arr){
        Charset utf8charset = Charset.forName("UTF-8");
        Charset iso88591charset = Charset.forName("ISO-8859-15");

        ByteBuffer inputBuffer = ByteBuffer.wrap( arr );

        // decode UTF-8
        CharBuffer data = utf8charset.decode(inputBuffer);

        // encode ISO-8559-1
        ByteBuffer outputBuffer = iso88591charset.encode(data);
        byte[] outputData = outputBuffer.array();

        return outputData;
    }

}

Answer 3

这就是我需要的：

public static byte[] encode(byte[] arr, String fromCharsetName) {
    return encode(arr, Charset.forName(fromCharsetName), Charset.forName("UTF-8"));
}

public static byte[] encode(byte[] arr, String fromCharsetName, String targetCharsetName) {
    return encode(arr, Charset.forName(fromCharsetName), Charset.forName(targetCharsetName));
}

public static byte[] encode(byte[] arr, Charset sourceCharset, Charset targetCharset) {

    ByteBuffer inputBuffer = ByteBuffer.wrap( arr );

    CharBuffer data = sourceCharset.decode(inputBuffer);

    ByteBuffer outputBuffer = targetCharset.encode(data);
    byte[] outputData = outputBuffer.array();

    return outputData;
}

Answer 4

从使用UTF-8对字符串进行编码的一组字节开始，从该数据创建一个字符串，然后获取一些以不同编码对字符串进行编码的字节：

    byte[] utf8bytes = { (byte)0xc3, (byte)0xa2, 0x61, 0x62, 0x63, 0x64 };
    Charset utf8charset = Charset.forName("UTF-8");
    Charset iso88591charset = Charset.forName("ISO-8859-1");

    String string = new String ( utf8bytes, utf8charset );

    System.out.println(string);

    // "When I do a getbytes(encoding) and "
    byte[] iso88591bytes = string.getBytes(iso88591charset);

    for ( byte b : iso88591bytes )
        System.out.printf("%02x ", b);

    System.out.println();

    // "then create a new string with the bytes in ISO-8859-1 encoding"
    String string2 = new String ( iso88591bytes, iso88591charset );

    // "I get a two different chars"
    System.out.println(string2);

这将正确输出字符串和iso88591字节：

âabcd 
e2 61 62 63 64 
âabcd

因此，您的字节数组没有与正确的编码配对：

    String failString = new String ( utf8bytes, iso88591charset );

    System.out.println(failString);

输出

âabcd

（或者，您只是将utf8字节写入一个文件，并将它们作为iso88591读取到其他位置）

Answer 5

如果字符串中有正确的编码，则无需执行更多操作来获取另一种编码的字节

public static void main(String[] args) throws Exception {
    printBytes("â");
    System.out.println(
            new String(new byte[] { (byte) 0xE2 }, "ISO-8859-1"));
    System.out.println(
            new String(new byte[] { (byte) 0xC3, (byte) 0xA2 }, "UTF-8"));
}

private static void printBytes(String str) {
    System.out.println("Bytes in " + str + " with ISO-8859-1");
    for (byte b : str.getBytes(StandardCharsets.ISO_8859_1)) {
        System.out.printf("%3X", b);
    }
    System.out.println();
    System.out.println("Bytes in " + str + " with UTF-8");
    for (byte b : str.getBytes(StandardCharsets.UTF_8)) {
        System.out.printf("%3X", b);
    }
    System.out.println();
}

输出：

Bytes in â with ISO-8859-1
 E2
Bytes in â with UTF-8
 C3 A2
â
â

Answer 6

byte[] iso88591Data = theString.getBytes("ISO-8859-1");

我会成功的。从您的描述来看，似乎您正在尝试“存储ISO-8859-1字符串”。Java中的字符串对象总是以UTF-16隐式编码。没有办法改变这种编码

不过，您可以做的是获取构成它的其他编码的字节（使用.getBytes()方法，如上所示）