Issue zxing#105 avoid accessing Charset Cp437 until absolutely necess…

…ary, as it won't work on Android sometimes
gdellamonica · Mar 28, 2014 · b09290c · b09290c
1 parent 699471b
commit b09290c
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Showing 2 changed files with 28 additions and 5 deletions.
diff --git a/core/src/main/java/com/google/zxing/pdf417/encoder/PDF417.java b/core/src/main/java/com/google/zxing/pdf417/encoder/PDF417.java
@@ -528,7 +528,7 @@ public PDF417() {
   public PDF417(boolean compact) {
     this.compact = compact;
     compaction = Compaction.AUTO;
-    encoding = PDF417HighLevelEncoder.DEFAULT_ENCODING;
+    encoding = null; // Use default
     minCols = 2;
     maxCols = 30;
     maxRows = 30;

diff --git a/core/src/main/java/com/google/zxing/pdf417/encoder/PDF417HighLevelEncoder.java b/core/src/main/java/com/google/zxing/pdf417/encoder/PDF417HighLevelEncoder.java
@@ -25,7 +25,9 @@
 
 import java.math.BigInteger;
 import java.nio.charset.Charset;
+import java.nio.charset.UnsupportedCharsetException;
 import java.util.Arrays;
+import java.util.List;
 
 /**
  * PDF417 high-level encoder following the algorithm described in ISO/IEC 15438:2001(E) in
@@ -125,7 +127,7 @@ final class PDF417HighLevelEncoder {
   private static final byte[] MIXED = new byte[128];
   private static final byte[] PUNCTUATION = new byte[128];
 
-  static final Charset DEFAULT_ENCODING = Charset.forName("Cp437");
+  private static final List<String> DEFAULT_ENCODING_NAMES = Arrays.asList("Cp437", "IBM437");
 
   private PDF417HighLevelEncoder() {
   }
@@ -154,14 +156,17 @@ private PDF417HighLevelEncoder() {
    * is used.
    *
    * @param msg the message
+   * @param compaction compaction mode to use
+   * @param encoding character encoding used to encode in default or byte compaction
+   *  or {@code null} for default / not applicable
    * @return the encoded message (the char values range from 0 to 928)
    */
   static String encodeHighLevel(String msg, Compaction compaction, Charset encoding) throws WriterException {
 
     //the codewords 0..928 are encoded as Unicode characters
     StringBuilder sb = new StringBuilder(msg.length());
 
-    if (!DEFAULT_ENCODING.equals(encoding)) {
+    if (encoding != null || !DEFAULT_ENCODING_NAMES.contains(encoding.name())) {
       CharacterSetECI eci = CharacterSetECI.getCharacterSetECIByName(encoding.name());
       if (eci != null) {
         encodingECI(eci.getValue(), sb);
@@ -178,7 +183,7 @@ static String encodeHighLevel(String msg, Compaction compaction, Charset encodin
       encodeText(msg, p, len, sb, textSubMode);
 
     } else if (compaction == Compaction.BYTE) {
-      bytes = msg.getBytes(encoding);
+      bytes = toBytes(msg, encoding);
       encodeBinary(bytes, p, bytes.length, BYTE_COMPACTION, sb);
 
     } else if (compaction == Compaction.NUMERIC) {
@@ -207,7 +212,7 @@ static String encodeHighLevel(String msg, Compaction compaction, Charset encodin
             p += t;
           } else {
             if (bytes == null) {
-              bytes = msg.getBytes(encoding);
+              bytes = toBytes(msg, encoding);
             }
             int b = determineConsecutiveBinaryCount(msg, bytes, p);
             if (b == 0) {
@@ -231,6 +236,24 @@ static String encodeHighLevel(String msg, Compaction compaction, Charset encodin
     return sb.toString();
   }
 
+  private static byte[] toBytes(String msg, Charset encoding) throws WriterException {
+    // Defer instantiating default Charset until needed, since it may be for an unsupported
+    // encoding. For example the default of Cp437 doesn't seem to exist on Android.
+    if (encoding == null) {
+      for (String encodingName : DEFAULT_ENCODING_NAMES) {
+        try {
+          encoding = Charset.forName(encodingName);
+        } catch (UnsupportedCharsetException uce) {
+          // continue
+        }
+      }
+      if (encoding == null) {
+        throw new WriterException("No support for any encoding: " + DEFAULT_ENCODING_NAMES);
+      }
+    }
+    return msg.getBytes(encoding);
+  }
+
   /**
    * Encode parts of the message using Text Compaction as described in ISO/IEC 15438:2001(E),
    * chapter 4.4.2.