/**
 * 中文字符串和unicode互轉工具類 <br>
 * 
 * @author hkb <br>
 */
public class UnicodeConvertUtils {

  /**
   * 實現js的escape函數
   * 
   * @param input
   *      待傳入字符串
   * @return
   */
  public static String escape(String input) {
    int len = input.length();
    int i;
    char j;
    StringBuffer result = new StringBuffer();
    result.ensureCapacity(len * 6);
    for (i = 0; i < len; i++) {
      j = input.charAt(i);
      if (Character.isDigit(j) || Character.isLowerCase(j) || Character.isUpperCase(j)) {
        result.append(j);
      } else if (j < 256) {
        result.append("%");
        if (j < 16) {
          result.append("0");
        }
        result.append(Integer.toString(j, 16));
      } else {
        result.append("%u");
        result.append(Integer.toString(j, 16));
      }
    }
    return result.toString();

  }

  /**
   * 實現js的unescape函數
   * 
   * @param input
   *      待傳入字符串
   * @return
   */
  public static String unescape(String input) {
    int len = input.length();
    StringBuffer result = new StringBuffer();
    result.ensureCapacity(len);
    int lastPos = 0, pos = 0;
    char ch;
    while (lastPos < len) {
      pos = input.indexOf("%", lastPos);
      if (pos == lastPos) {
        if (input.charAt(pos + 1) == 'u') {
          ch = (char) Integer.parseInt(input.substring(pos + 2, pos + 6), 16);
          result.append(ch);
          lastPos = pos + 6;
        } else {
          ch = (char) Integer.parseInt(input.substring(pos + 1, pos + 3), 16);
          result.append(ch);
          lastPos = pos + 3;
        }
      } else {
        if (pos == -1) {
          result.append(input.substring(lastPos));
          lastPos = len;
        } else {
          result.append(input.substring(lastPos, pos));
          lastPos = pos;
        }
      }
    }
    return result.toString();
  }

  /**
   * unicode轉中文
   * 
   * @param input
   *      待傳入字符串
   * @return
   */
  public static String toGb2312(String input) {
    input = input.trim().replaceAll("(?i)\\\\u", "%u");
    return unescape(input);
  }

  /**
   * 中文字符串轉unicode
   * 
   * @param input
   *      待傳入字符串
   * @return
   */
  public static String toUnicode(String input) {
    input = input.trim();
    String output = escape(input).toLowerCase().replace("%u", "\\u");
    return output.replaceAll("(?i)%7b", "{").replaceAll("(?i)%7d", "}").replaceAll("(?i)%3a", ":")
        .replaceAll("(?i)%2c", ",").replaceAll("(?i)%27", "'").replaceAll("(?i)%22", "\"")
        .replaceAll("(?i)%5b", "[").replaceAll("(?i)%5d", "]").replaceAll("(?i)%3D", "=")
        .replaceAll("(?i)%20", " ").replaceAll("(?i)%3E", ">").replaceAll("(?i)%3C", "<")
        .replaceAll("(?i)%3F", "?").replaceAll("(?i)%5c", "\\");
  }

  /**
   * 測試
   * 
   * @param args
   */
  public static void main(String[] args) {
    System.out.println(toUnicode("你好"));
    System.out.println(toGb2312("\u4f60\u597d"));
    // 等同于上面
    System.out.println(toGb2312("\\u4f60\\u597d"));
  }
}