Remove jdk.charset module dependency for spreadsheets generation

Move double byte charset utility code to scratchpad...hwpf that is the
only code that currently requires them. This allows using spreadsheet
related code without pulling jdk.charset to custom built JREs using
jlink.

src/java/org/apache/poi/util/CodePageUtil.java

@@ -31,8 +31,6 @@ Licensed to the Apache Software Foundation (ASF) under one or more
 public class CodePageUtil
 {
 
-    public static final Set<Charset> DOUBLE_BYTE_CHARSETS = Collections.singleton(StringUtil.BIG5);
-
     /** <p>Codepage 037, a special case</p> */
     public static final int CP_037 = 37;
 
@@ -446,27 +444,4 @@ public static String codepageToEncoding(final int codepage, boolean javaLangForm
                 return "cp" + codepage;
         }
     }
-
-    /**
-     * This tries to convert a LE byte array in cp950
-     * (Microsoft's dialect of Big5) to a String.
-     * We know MS zero-padded ascii, and we drop those.
-     * There may be areas for improvement in this.
-     *
-     * @param data
-     * @param offset
-     * @param lengthInBytes
-     * @return Decoded String
-     */
-    public static String cp950ToString(byte[] data, int offset, int lengthInBytes) {
-        StringBuilder sb = new StringBuilder();
-        LittleEndianCP950Reader reader = new LittleEndianCP950Reader(data, offset, lengthInBytes);
-        int c = reader.read();
-        while (c != -1) {
-            sb.append((char)c);
-            c = reader.read();
-        }
-        reader.close();
-        return sb.toString();
-    }
 }

src/java/org/apache/poi/util/StringUtil.java

@@ -34,7 +34,6 @@ public final class StringUtil {
     public static final Charset UTF16LE = StandardCharsets.UTF_16LE;
     public static final Charset UTF8 = StandardCharsets.UTF_8;
     public static final Charset WIN_1252 = Charset.forName("cp1252");
-    public static final Charset BIG5 = Charset.forName("Big5");
 
     private StringUtil() {
         // no instances of this class

src/scratchpad/src/org/apache/poi/hwpf/HWPFOldDocument.java

@@ -37,7 +37,7 @@ Licensed to the Apache Software Foundation (ASF) under one or more
 import org.apache.poi.hwpf.usermodel.Range;
 import org.apache.poi.poifs.filesystem.DirectoryNode;
 import org.apache.poi.poifs.filesystem.POIFSFileSystem;
-import org.apache.poi.util.CodePageUtil;
+import org.apache.poi.hwpf.util.DoubleByteUtil;
 import org.apache.poi.util.IOUtils;
 import org.apache.poi.util.LittleEndian;
 import org.apache.poi.util.NotImplemented;
@@ -176,7 +176,7 @@ private TextPiece buildTextPiece(Charset guessedCharset) throws IllegalStateExce
               _fib.getFibBase().getFcMac()-_fib.getFibBase().getFcMin(), MAX_RECORD_LENGTH);
 
         int numChars = textData.length;
-        if (CodePageUtil.DOUBLE_BYTE_CHARSETS.contains(guessedCharset)) {
+        if (DoubleByteUtil.DOUBLE_BYTE_CHARSETS.contains(guessedCharset)) {
             numChars /= 2;
         }
 

src/scratchpad/src/org/apache/poi/hwpf/model/OldTextPieceTable.java

@@ -20,7 +20,7 @@ Licensed to the Apache Software Foundation (ASF) under one or more
 import java.util.ArrayList;
 import java.util.Collections;
 
-import org.apache.poi.util.CodePageUtil;
+import org.apache.poi.hwpf.util.DoubleByteUtil;
 import org.apache.poi.util.IOUtils;
 import org.apache.poi.util.Internal;
 
@@ -73,7 +73,7 @@ public OldTextPieceTable(byte[] documentStream, byte[] tableStream,
             boolean unicode = pieces[x].isUnicode();
             int multiple = 1;
             if (unicode ||
-                    (charset != null && CodePageUtil.DOUBLE_BYTE_CHARSETS.contains(charset))) {
+                    (charset != null && DoubleByteUtil.DOUBLE_BYTE_CHARSETS.contains(charset))) {
                 multiple = 2;
             }
 
@@ -106,7 +106,7 @@ protected TextPiece newTextPiece(int nodeStartChars, int nodeEndChars, byte[] bu
     @Override
     protected int getEncodingMultiplier(TextPiece textPiece) {
         Charset charset = textPiece.getPieceDescriptor().getCharset();
-        if (charset != null && CodePageUtil.DOUBLE_BYTE_CHARSETS.contains(charset)) {
+        if (charset != null && DoubleByteUtil.DOUBLE_BYTE_CHARSETS.contains(charset)) {
             return 2;
         }
         return 1;

src/scratchpad/src/org/apache/poi/hwpf/model/TextPiece.java

@@ -20,7 +20,7 @@ Licensed to the Apache Software Foundation (ASF) under one or more
 
 import java.nio.charset.Charset;
 
-import org.apache.poi.util.CodePageUtil;
+import org.apache.poi.hwpf.util.DoubleByteUtil;
 import org.apache.poi.util.Internal;
 import org.apache.poi.util.StringUtil;
 
@@ -77,8 +77,8 @@ public TextPiece(int start, int end, byte[] text, PieceDescriptor pd) {
      * Create the StringBuilder from the text and unicode flag
      */
     private static StringBuilder buildInitSB(byte[] text, PieceDescriptor pd) {
-        if (StringUtil.BIG5.equals(pd.getCharset())) {
-            return new StringBuilder(CodePageUtil.cp950ToString(text, 0, text.length));
+        if (DoubleByteUtil.BIG5.equals(pd.getCharset())) {
+            return new StringBuilder(DoubleByteUtil.cp950ToString(text, 0, text.length));
         }
 
         String str = new String(text, 0, text.length, (pd.isUnicode()) ? StringUtil.UTF16LE : pd.getCharset());

src/scratchpad/src/org/apache/poi/hwpf/util/DoubleByteUtil.java

@@ -0,0 +1,59 @@
+/* ====================================================================
+   Licensed to the Apache Software Foundation (ASF) under one or more
+   contributor license agreements.  See the NOTICE file distributed with
+   this work for additional information regarding copyright ownership.
+   The ASF licenses this file to You under the Apache License, Version 2.0
+   (the "License"); you may not use this file except in compliance with
+   the License.  You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+==================================================================== */
+
+package org.apache.poi.hwpf.util;
+
+import java.nio.charset.Charset;
+import java.util.Collections;
+import java.util.Set;
+
+/**
+ * Utilities for working with double byte CodePages.
+ *
+ * <p>Provides constants for understanding numeric codepages,
+ *  along with utilities to translate these into Java Character Sets.</p>
+ */
+public class DoubleByteUtil
+{
+
+    public static final Charset BIG5 = Charset.forName("Big5");
+
+    public static final Set<Charset> DOUBLE_BYTE_CHARSETS = Collections.singleton(BIG5);
+
+    /**
+     * This tries to convert a LE byte array in cp950
+     * (Microsoft's dialect of Big5) to a String.
+     * We know MS zero-padded ascii, and we drop those.
+     * There may be areas for improvement in this.
+     *
+     * @param data
+     * @param offset
+     * @param lengthInBytes
+     * @return Decoded String
+     */
+    public static String cp950ToString(byte[] data, int offset, int lengthInBytes) {
+        StringBuilder sb = new StringBuilder();
+        LittleEndianCP950Reader reader = new LittleEndianCP950Reader(data, offset, lengthInBytes);
+        int c = reader.read();
+        while (c != -1) {
+            sb.append((char)c);
+            c = reader.read();
+        }
+        reader.close();
+        return sb.toString();
+    }
+}

src/java/org/apache/poi/util/LittleEndianCP950Reader.java → src/scratchpad/src/org/apache/poi/hwpf/util/LittleEndianCP950Reader.java

@@ -15,13 +15,18 @@ Licensed to the Apache Software Foundation (ASF) under one or more
    limitations under the License.
 ==================================================================== */
 
-package org.apache.poi.util;
+package org.apache.poi.hwpf.util;
+
 import java.io.IOException;
 import java.io.Reader;
 import java.nio.ByteBuffer;
 import java.nio.CharBuffer;
 import java.nio.charset.CharsetDecoder;
 
+import org.apache.poi.util.Internal;
+import org.apache.poi.util.POILogFactory;
+import org.apache.poi.util.POILogger;
+
 /**
  * Stream that converts CP950 (MSOffice's dialect of Big5), with
  * zero-byte padding for ASCII and in LittleEndianOrder.
@@ -31,11 +36,10 @@ public class LittleEndianCP950Reader extends Reader {
 
     private static final POILogger LOGGER = POILogFactory.getLogger(LittleEndianCP950Reader.class);
 
-
     private static final char UNMAPPABLE = '?';
     private final ByteBuffer doubleByteBuffer = ByteBuffer.allocate(2);
     private final CharBuffer charBuffer = CharBuffer.allocate(2);
-    private final CharsetDecoder decoder = StringUtil.BIG5.newDecoder();
+    private final CharsetDecoder decoder = DoubleByteUtil.BIG5.newDecoder();
 
     //https://en.wikipedia.org/wiki/Code_page_950
     //see private use area

src/testcases/org/apache/poi/util/TestLittleEndianCP950Reader.java → src/scratchpad/testcases/org/apache/poi/hwpf/util/TestLittleEndianCP950Reader.java

@@ -15,8 +15,7 @@ Licensed to the Apache Software Foundation (ASF) under one or more
    limitations under the License.
 ==================================================================== */
 
-package org.apache.poi.util;
-
+package org.apache.poi.hwpf.util;
 
 import static org.junit.Assert.assertEquals;