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import java.io.UnsupportedEncodingException;
public class UnicodeConverter {
public static void main(String[] args) throws UnsupportedEncodingException {
String s = " \t小\u51AC";
System.out.println("Original:\t\t" + s);
s = toEncodedUnicode(s, true);
System.out.println("to unicode:\t\t" + s);
s = fromEncodedUnicode(s.toCharArray(), 0, s.length());
System.out.println("from unicode:\t" + s);
}
private static final char[] hexDigit = {
'0',
'1',
'2',
'3',
'4',
'5',
'6',
'7',
'8',
'9',
'A',
'B',
'C',
'D',
'E',
'F'
};
private static char toHex(int nibble) {
return hexDigit[(nibble & 0xF)];
}
/**
* 将字符串编码成 Unicode 形式的字符串. 如 "小" to "\u5c0f"
* Converts unicodes to encoded \\uxxxx and escapes
* special characters with a preceding slash
*
* @param theString
* 待转换成Unicode编码的字符串。
* @param escapeSpace
* 是否忽略空格，为true时在空格后面是否加个反斜杠。
* @return 返回转换后Unicode编码的字符串。
*/
public static String toEncodedUnicode(String theString, boolean escapeSpace) {
int len = theString.length();
int bufLen = len * 2;
if (bufLen < 0) {
bufLen = Integer.MAX_VALUE;
}
StringBuffer outBuffer = new StringBuffer(bufLen);
for (int x = 0; x < len; x++) {
char aChar = theString.charAt(x);
// Handle common case first, selecting largest block that
// avoids the specials below
if ((aChar > 61) && (aChar < 127)) {
if (aChar == '\\') {
outBuffer.append('\\');
outBuffer.append('\\');
continue;
}
outBuffer.append(aChar);
continue;
}
switch (aChar) {
case ' ':
if (x == 0 || escapeSpace) outBuffer.append('\\');
outBuffer.append(' ');
break;
case '\t':
outBuffer.append('\\');
outBuffer.append('t');
break;
case '\n':
outBuffer.append('\\');
outBuffer.append('n');
break;
case '\r':
outBuffer.append('\\');
outBuffer.append('r');
break;
case '\f':
outBuffer.append('\\');
outBuffer.append('f');
break;
case '=': // Fall through
case ':': // Fall through
case '#': // Fall through
case '!':
outBuffer.append('\\');
outBuffer.append(aChar);
break;
default:
if ((aChar < 0x0020) || (aChar > 0x007e)) {
// 每个unicode有16位，每四位对应的16进制从高位保存到低位
outBuffer.append('\\');
outBuffer.append('u');
outBuffer.append(toHex((aChar >> 12) & 0xF));
outBuffer.append(toHex((aChar >> 8) & 0xF));
outBuffer.append(toHex((aChar >> 4) & 0xF));
outBuffer.append(toHex(aChar & 0xF));
} else {
outBuffer.append(aChar);
}
}
}
return outBuffer.toString();
}
/**
* 从 Unicode 形式的字符串转换成对应的编码的特殊字符串。 如 "\u5c0f" to "小".
* Converts encoded \\uxxxx to unicode chars
* and changes special saved chars to their original forms
*
* @param in
* Unicode编码的字符数组。
* @param off
* 转换的起始偏移量。
* @param len
* 转换的字符长度。
* @param convtBuf
* 转换的缓存字符数组。
* @return 完成转换，返回编码前的特殊字符串。
*/
public static String fromEncodedUnicode(char[] in , int off, int len) {
char aChar;
char[] out = new char[len]; // 只短不长
int outLen = 0;
int end = off + len;
while (off < end) {
aChar = in [off++];
if (aChar == '\\') {
aChar = in [off++];
if (aChar == 'u') {
// Read the xxxx
int value = 0;
for (int i = 0; i < 4; i++) {
aChar = in [off++];
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.");
}
}
out[outLen++] = (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';
}
out[outLen++] = aChar;
}
} else {
out[outLen++] = (char) aChar;
}
}
return new String(out, 0, outLen);
}
}
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