Author: sebb
Date: Tue Mar 19 01:16:56 2013
New Revision: 1458078
URL: http://svn.apache.org/r1458078
Log:
Simplify processing of trailing 4 bytes; this eliminates several magic numbers
Document other magic numbers and suppress the checkstyle warnings
Modified:
commons/proper/fileupload/trunk/src/main/java/org/apache/commons/fileupload/util/mime/Base64Decoder.java
Modified:
commons/proper/fileupload/trunk/src/main/java/org/apache/commons/fileupload/util/mime/Base64Decoder.java
URL:
http://svn.apache.org/viewvc/commons/proper/fileupload/trunk/src/main/java/org/apache/commons/fileupload/util/mime/Base64Decoder.java?rev=1458078&r1=1458077&r2=1458078&view=diff
==============================================================================
---
commons/proper/fileupload/trunk/src/main/java/org/apache/commons/fileupload/util/mime/Base64Decoder.java
(original)
+++
commons/proper/fileupload/trunk/src/main/java/org/apache/commons/fileupload/util/mime/Base64Decoder.java
Tue Mar 19 01:16:56 2013
@@ -103,7 +103,8 @@ final class Base64Decoder {
}
int i = off;
- int finish = end - 4;
+ // CHECKSTYLE IGNORE MagicNumber FOR NEXT 1 LINE
+ int finish = end - 4; // last set of 4 bytes might include padding
while (i < finish) {
while ((i < finish) && ignore((char) data[i])) {
@@ -130,42 +131,39 @@ final class Base64Decoder {
b4 = DECODING_TABLE[data[i++]];
- // CHECKSTYLE:OFF
- out.write((b1 << 2) | (b2 >> 4));
- out.write((b2 << 4) | (b3 >> 2));
- out.write((b3 << 6) | b4);
- // CHECKSTYLE:ON
+ // Convert 4 6-bit bytes to 3 8-bit bytes
+ // CHECKSTYLE IGNORE MagicNumber FOR NEXT 3 LINES
+ out.write((b1 << 2) | (b2 >> 4)); // 6 bits of b1 plus 2 bits of b2
+ out.write((b2 << 4) | (b3 >> 2)); // 4 bits of b2 plus 4 bits of b3
+ out.write((b3 << 6) | b4); // 2 bits of b3 plus 6 bits of b4
+ // CHECKSTYLE IGNORE MagicNumber FOR NEXT 1 LINE
outLen += 3;
}
- if (data[end - 2] == PADDING) {
- b1 = DECODING_TABLE[data[end - 4]];
- b2 = DECODING_TABLE[data[end - 3]];
-
- out.write((b1 << 2) | (b2 >> 4));
-
- outLen += 1;
- } else if (data[end - 1] == PADDING) {
- b1 = DECODING_TABLE[data[end - 4]];
- b2 = DECODING_TABLE[data[end - 3]];
- b3 = DECODING_TABLE[data[end - 2]];
-
- out.write((b1 << 2) | (b2 >> 4));
- out.write((b2 << 4) | (b3 >> 2));
-
- outLen += 2;
- } else {
- b1 = DECODING_TABLE[data[end - 4]];
- b2 = DECODING_TABLE[data[end - 3]];
- b3 = DECODING_TABLE[data[end - 2]];
- b4 = DECODING_TABLE[data[end - 1]];
-
- out.write((b1 << 2) | (b2 >> 4));
- out.write((b2 << 4) | (b3 >> 2));
- out.write((b3 << 6) | b4);
-
- outLen += 3;
+ // Get the last 4 bytes; only last two can be padding
+ b1 = DECODING_TABLE[data[i++]];
+ b2 = DECODING_TABLE[data[i++]];
+
+ // always write the first byte
+ // CHECKSTYLE IGNORE MagicNumber FOR NEXT 1 LINE
+ out.write((b1 << 2) | (b2 >> 4)); // 6 bits of b1 plus 2 bits of b2
+ outLen++;
+
+ byte p1 = data[i++];
+ byte p2 = data[i++];
+
+ b3 = DECODING_TABLE[p1]; // may be needed later
+
+ if (p1 != PADDING) { // Nothing more to do ir p1 == PADDING
+ // CHECKSTYLE IGNORE MagicNumber FOR NEXT 1 LINE
+ out.write((b2 << 4) | (b3 >> 2)); // 4 bits of b2 plus 4 bits of b3
+ outLen++;
+ } else if (p2 != PADDING) { // Nothing more to do if p2 == PADDING
+ b4 = DECODING_TABLE[p2];
+ // CHECKSTYLE IGNORE MagicNumber FOR NEXT 1 LINE
+ out.write((b3 << 6) | b4); // 2 bits of b3 plus 6 bits of b4
+ outLen++;
}
return outLen;
