将UTF-8 Unicode字符串转换为ASCII Unicode转义的字符串

Question

I need to convert unicode string to string which have non-ascii characters encoded in unicode. For example, string "漢字 Max" should be presented as "\漢\字 Max".

What I have tried:

1. Differenct combinations of

   new String(sourceString.getBytes(encoding1), encoding2)

2. Apache StringEscapeUtils which escapes also ascii chars like double-quote

   StringEscapeUtils.escapeJava(source)

Is there an easy way to encode such string? Ideally only Java 6 SE or Apache Commons should be used to achieve desired result.

Answer 1

This is the kind of simple code Jon Skeet had in mind in his comment:

final String in = "šđčćasdf";
final StringBuilder out = new StringBuilder();
for (int i = 0; i < in.length(); i++) {
  final char ch = in.charAt(i);
  if (ch <= 127) out.append(ch);
  else out.append("\\u").append(String.format("%04x", (int)ch));
}
System.out.println(out.toString());

As Jon said, surrogate pairs will be represented as a pair of \\u\u003c/code> escapes.

Answer 2

Guava Escaper Based Solution:

This escapes any non-ASCII characters into Unicode escape sequences.

import static java.lang.String.format;    
import com.google.common.escape.CharEscaper;

public class NonAsciiUnicodeEscaper extends CharEscaper
{
    @Override
    protected char[] escape(final char c)
    {
        if (c >= 32 && c <= 127) { return new char[]{c}; }
        else { return format("\\u%04x", (int) c).toCharArray(); }
    }
}