Diff of /lucene/nutch/trunk/src/java/org/apache/nutch/util/StringUtil.java

Parent Directory | Revision Log | Patch

--- lucene/nutch/trunk/src/java/org/apache/nutch/util/StringUtil.java	2005/12/29 15:25:20	359821
+++ lucene/nutch/trunk/src/java/org/apache/nutch/util/StringUtil.java	2005/12/29 15:28:30	359822
@@ -49,6 +49,79 @@ public class StringUtil {
     return sb.toString();
   }
 
+
+  private static final char[] HEX_DIGITS =
+  {'0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f'};
+
+  /**
+   * Convenience call for {@link #toHexString(byte[], String, int)}, where
+   * <code>sep = null; lineLen = Integer.MAX_VALUE</code>.
+   * @param buf
+   * @return
+   */
+  public static String toHexString(byte[] buf) {
+    return toHexString(buf, null, Integer.MAX_VALUE);
+  }
+
+  /**
+   * Get a text representation of a byte[] as hexadecimal String, where each
+   * pair of hexadecimal digits corresponds to consecutive bytes in the array.
+   * @param buf input data
+   * @param sep separate every pair of hexadecimal digits with this separator, or
+   * null if no separation is needed.
+   * @param lineLen break the output String into lines containing output for lineLen
+   * bytes.
+   */
+  public static String toHexString(byte[] buf, String sep, int lineLen) {
+    if (buf == null) return null;
+    if (lineLen <= 0) lineLen = Integer.MAX_VALUE;
+    StringBuffer res = new StringBuffer(buf.length * 2);
+    for (int i = 0; i < buf.length; i++) {
+      int b = buf[i];
+      res.append(HEX_DIGITS[(b >> 4) & 0xf]);
+      res.append(HEX_DIGITS[b & 0xf]);
+      if (i > 0 && (i % lineLen) == 0) res.append('\n');
+      else if (sep != null && i < lineLen - 1) res.append(sep); 
+    }
+    return res.toString();
+  }
+  
+  /**
+   * Convert a String containing consecutive (no inside whitespace) hexadecimal
+   * digits into a corresponding byte array. If the number of digits is not even,
+   * a '0' will be appended in the front of the String prior to conversion.
+   * Leading and trailing whitespace is ignored.
+   * @param text input text
+   * @return converted byte array, or null if unable to convert
+   */
+  public static byte[] fromHexString(String text) {
+    text = text.trim();
+    if (text.length() % 2 != 0) text = "0" + text;
+    int resLen = text.length() / 2;
+    int loNibble, hiNibble;
+    byte[] res = new byte[resLen];
+    for (int i = 0; i < resLen; i++) {
+      int j = i << 1;
+      hiNibble = charToNibble(text.charAt(j));
+      loNibble = charToNibble(text.charAt(j + 1));
+      if (loNibble == -1 || hiNibble == -1) return null;
+      res[i] = (byte)(hiNibble << 4 | loNibble);
+    }
+    return res;
+  }
+  
+  private static final int charToNibble(char c) {
+    if (c >= '0' && c <= '9') {
+      return c - '0';
+    } else if (c >= 'a' && c <= 'f') {
+      return 0xa + (c - 'a');
+    } else if (c >= 'A' && c <= 'F') {
+      return 0xA + (c - 'A');
+    } else {
+      return -1;
+    }
+  }
+
   /**
    * Parse the character encoding from the specified content type header.
    * If the content type is null, or there is no explicit character encoding,