public static String unicodeToUtf8(String theString) {
        if (theString == null) {
            return null;
        }
        char aChar;
        int len = theString.length();
        StringBuffer outBuffer = new StringBuffer(len);
        for (int x = 0; x < len; ) {
            aChar = theString.charAt(x++);
            if (aChar == '\\') {
                aChar = theString.charAt(x++);
                if (aChar == 'u') {
                    // Read the xxxx
                    int value = 0;
                    for (int i = 0; i < 4; i++) {
                        aChar = theString.charAt(x++);
                        switch (aChar) {
                            case '0':
                            case '1':
                            case '2':
                            case '3':
                            case '4':
                            case '5':
                            case '6':
                            case '7':
                            case '8':
                            case '9':
                                value = (value << 4) + aChar - '0';
                                break;
                            case 'a':
                            case 'b':
                            case 'c':
                            case 'd':
                            case 'e':
                            case 'f':
                                value = (value << 4) + 10 + aChar - 'a';
                                break;
                            case 'A':
                            case 'B':
                            case 'C':
                            case 'D':
                            case 'E':
                            case 'F':
                                value = (value << 4) + 10 + aChar - 'A';
                                break;
                            default:
                                //throw new IllegalArgumentException("Malformed   \\uxxxx   encoding." + value);
                                // filter this bad case
                                value = 0;
                                break;
                        }
                    }
                    outBuffer.append((char) value);
                } else {
                    if (aChar == 't') {
                        aChar = '\t';
                    } else if (aChar == 'r') {
                        aChar = '\r';
                    } else if (aChar == 'n') {
                        aChar = '\n';
                    } else if (aChar == 'f') {
                        aChar = '\f';
                    }
                    outBuffer.append(aChar);
                }
            } else {
                outBuffer.append(aChar);
            }
        }
        return outBuffer.toString();
    }
public static String unicodeToUtf8 ( String theString ) { if ( theString == null ) { return null ; } char aChar ; int len = theString . length ( ) ; StringBuffer outBuffer = new StringBuffer ( len ) ; for ( int x = 0 ; x < len ; ) { aChar = theString . charAt ( x ++ ) ; if ( aChar == '\\' ) { aChar = theString . charAt ( x ++ ) ; if ( aChar == 'u' ) { int value = 0 ; for ( int i = 0 ; i < 4 ; i ++ ) { aChar = theString . charAt ( x ++ ) ; switch ( aChar ) { case '0' : case '1' : case '2' : case '3' : case '4' : case '5' : case '6' : case '7' : case '8' : case '9' : value = ( value << 4 ) + aChar - '0' ; break ; case 'a' : case 'b' : case 'c' : case 'd' : case 'e' : case 'f' : value = ( value << 4 ) + 10 + aChar - 'a' ; break ; case 'A' : case 'B' : case 'C' : case 'D' : case 'E' : case 'F' : value = ( value << 4 ) + 10 + aChar - 'A' ; break ; default : value = 0 ; break ; } } outBuffer . append ( ( char ) value ) ; } else { if ( aChar == 't' ) { aChar = '\t' ; } else if ( aChar == 'r' ) { aChar = '\r' ; } else if ( aChar == 'n' ) { aChar = '\n' ; } else if ( aChar == 'f' ) { aChar = '\f' ; } outBuffer . append ( aChar ) ; } } else { outBuffer . append ( aChar ) ; } } return outBuffer . toString ( ) ; }
unicode 转换成 utf-8