JAVA转化Unicode编码

package yyl.example.basic.codec;
import java.util.Locale;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class UnicodeUtil {

	//编码
	public static String encode(String string) {
		StringBuilder sbr = new StringBuilder(string.length() * 4);
		for (char ch : string.toCharArray()) {
			if (ch > 0xfff) {
				sbr.append("\\u");
				sbr.append(Integer.toHexString(ch).toUpperCase(Locale.ENGLISH));
			} else if (ch > 0xff) {
				sbr.append("\\u0");
				sbr.append(Integer.toHexString(ch).toUpperCase(Locale.ENGLISH));
			} else if (ch > 0x7f) {
				sbr.append("\\u00");
				sbr.append(Integer.toHexString(ch).toUpperCase(Locale.ENGLISH));
			} else if (ch < 32) {
				switch (ch) {
				case '\b':
					sbr.append('\\');
					sbr.append('b');
					break;
				case '\n':
					sbr.append('\\');
					sbr.append('n');
					break;
				case '\t':
					sbr.append('\\');
					sbr.append('t');
					break;
				case '\f':
					sbr.append('\\');
					sbr.append('f');
					break;
				case '\r':
					sbr.append('\\');
					sbr.append('r');
					break;
				default:
					if (ch > 0xf) {
						sbr.append("\\u00");
						sbr.append(Integer.toHexString(ch).toUpperCase(Locale.ENGLISH));
					} else {
						sbr.append("\\u000");
						sbr.append(Integer.toHexString(ch).toUpperCase(Locale.ENGLISH));
					}
					break;
				}
			} else {
				switch (ch) {
				case '\'':
					sbr.append("\\u0027");
					break;
				case '"':
				case '\\':
					sbr.append("\\");
					sbr.append(ch);
					break;
				default:
					sbr.append(ch);
					break;
				}
			}
		}
		return sbr.toString();
	}
	
	//解码
	public static String decode(String unicode) {
		char[] chars = unicode.toCharArray();
		StringBuilder buffer = new StringBuilder();
		for (int i = 0, len = chars.length; i < len;) {
			char c = chars[i++];
			switch (c) {
			case 0:
			case '\n':
			case '\r':
				break;
			case '\\':
				c = chars[i++];
				switch (c) {
				case 'b':
					buffer.append('\b');
					break;
				case 't':
					buffer.append('\t');
					break;
				case 'n':
					buffer.append('\n');
					break;
				case 'f':
					buffer.append('\f');
					break;
				case 'r':
					buffer.append('\r');
					break;
				case 'u':
					buffer.append((char) Integer.parseInt(new String(new char[] {//
							chars[i++], chars[i++], chars[i++], chars[i++] //
							}), 16));//
					break;
				case 'x':
					buffer.append((char) Integer.parseInt(new String(new char[] {//
							chars[i++], chars[i++] //
							}), 16));//
					break;
				default:
					buffer.append(c);
				}
				break;
			default:
				buffer.append(c);
			}
		}
		return buffer.toString();
	}

	/**
	 * 方法2
	 * @param unicodeStr
	 * @return
	 */
	public static String unicodeToString(String unicodeStr) {
		Pattern pattern = Pattern.compile("(\\\\u(\\p{XDigit}{4}))");
		Matcher matcher = pattern.matcher(unicodeStr);
		char ch;
		while (matcher.find()) {
			ch = (char) Integer.parseInt(matcher.group(2), 16);
			unicodeStr = unicodeStr.replace(matcher.group(1), ch + "");
		}
		return unicodeStr;
	}

	public static void main(String[] args) {
		String unicode = encode("你好Unicode");
		System.out.println(unicode);

		StringBuilder sbr = new StringBuilder();
		for (int i = 0; i < 1000; i++) {
			sbr.append(unicode);
		}
		unicode = sbr.toString();

		//System.out.println(decode(unicode));
		long l = System.currentTimeMillis();

		for (int i = 0; i < 10000; i++) {
			decode(unicode);
			//unicodeToString(unicode);
		}
		System.out.println(System.currentTimeMillis() - l);
	}
}