2589     /**

  2590      * Escape invalid URI characters.

  2591      *

  2592      * Passed a URI that contains invalid characters (like spaces, non-ASCII Unicode characters, and the like),

  2593      * this function percent encodes the invalid characters per the URI specification (i.e., as a sequence of

  2594      * %-encoded UTF-8 octets).

  2595      *

  2596      * N.B. There are two problems. If the URI contains a '%' character, that might be an indication that

  2597      * the URI has already been escaped by the author, or it might be an invalid '%'. In the former case,

  2598      * it's important not to escape it, or we'll wind up with invalid, doubly-escaped '%'s. In the latter,

  2599      * the URI is broken if we don't encode it. Similarly, a '#' character might be the start of a fragment

  2600      * identifier or it might be an invalid '#'.

  2601      *

  2602      * Given that the former is vastly more likely than the latter in each case (most users are familiar with

  2603      * the magic status of '%' and '#' and they occur relatively infrequently in filenames, and if the user parses

  2604      * a proper Java File, we will already have %-escaped the URI), we simply assume that %'s and #'s are legit.

  2605      *

  2606      * Very rarely, we may be wrong. If so, tell the user to fix the clearly broken URI.

  2607      */

  2608     protected static String escapeNonUSAscii(String str) {

  2609         if (str == null) {

  2610             return str;

  2611         }

  2612         int len = str.length(), i=0, ch;

  2613         for (; i < len; i++) {

  2614             ch = str.charAt(i);

  2615             // if it's not an ASCII 7 character, break here, and use UTF-8 encoding

  2616             if (ch >= 128)

  2617                 break;

  2618         }

  2619 

  2620         // we saw no non-ascii-7 character

  2621         if (i == len) {

  2622             return str;

  2623         }

  2624 

  2625         // get UTF-8 bytes for the string

  2626         StringBuffer buffer = new StringBuffer();

  2627         byte[] bytes = null;

  2628         byte b;

  2629         try {

  2630             bytes = str.getBytes("UTF-8");

  2631         } catch (java.io.UnsupportedEncodingException e) {

  2632             // should never happen

  2633             return str;

  2634         }

  2635 

  2636         len = bytes.length;

  2637 

  2638         // for each byte

  2639         for (i = 0; i < len; i++) {

  2640             b = bytes[i];

  2641             // for non-ascii character: make it positive, then escape

  2642             if (b < 0) {

  2643                 ch = b + 256;

  2644                 buffer.append('%');

  2645                 buffer.append(gHexChs[ch >> 4]);

  2646                 buffer.append(gHexChs[ch & 0xf]);

  2647             }

  2648             else if (b != '%' && b != '#' && gNeedEscaping[b]) {

  2649                 buffer.append('%');

  2650                 buffer.append(gAfterEscaping1[b]);

  2651                 buffer.append(gAfterEscaping2[b]);

  2652             }

  2653             else {

  2654                 buffer.append((char)b);

  2655             }

  2656         }

  2657         return buffer.toString();

  2658     }