add some more useful byte operations

git-svn-id: https://svn.code.sf.net/p/jackcess/code/jackcess/trunk@616 f203690c-595d-4dc9-a70b-905162fa7fd2

5 files changed, 49 insertions, 14 deletions

diff --git a/src/java/com/healthmarketscience/jackcess/ByteUtil.java b/src/java/com/healthmarketscience/jackcess/ByteUtil.java
index b39898a..b500268 100644
--- a/src/java/com/healthmarketscience/jackcess/ByteUtil.java
+++ b/src/java/com/healthmarketscience/jackcess/ByteUtil.java
@@ -290,6 +290,48 @@ public final class ByteUtil {
     }
   }
 
+  /**
+   * Reads an array of bytes from the given buffer
+   * @param buffer Buffer containing the desired bytes
+   * @param len length of the desired bytes
+   * @return a new buffer with the given number of bytes from the current
+   *         position in the given buffer
+   */
+  public static byte[] getBytes(ByteBuffer buffer, int len)
+  {
+      byte[] bytes = new byte[len];
+      buffer.get(bytes);    
+      return bytes;
+  }
+
+  /**
+   * Reads an array of bytes from the given buffer at the given offset
+   * @param buffer Buffer containing the desired bytes
+   * @param offset Offset at which to read the bytes
+   * @param len length of the desired bytes
+   * @return a new buffer with the given number of bytes from the given
+   *         position in the given buffer
+   */
+  public static byte[] getBytes(ByteBuffer buffer, int offset, int len)
+  {
+    int origPos = buffer.position();
+    try {
+      buffer.position(offset);
+      return getBytes(buffer, len);
+    } finally {
+      buffer.position(origPos);
+    }
+  }
+
+  /**
+   * Concatenates and returns the given byte arrays.
+   */
+  public static byte[] concat(byte[] b1, byte[] b2) {
+    byte[] out = new byte[b1.length + b2.length];
+    System.arraycopy(b1, 0, out, 0, b1.length);
+    System.arraycopy(b2, 0, out, b1.length, b2.length);
+    return out;
+  }
   
   /**
    * Sets all bits in the given remaining byte range to 0.
diff --git a/src/java/com/healthmarketscience/jackcess/Column.java b/src/java/com/healthmarketscience/jackcess/Column.java
index 6023c26..cd28621 100644
--- a/src/java/com/healthmarketscience/jackcess/Column.java
+++ b/src/java/com/healthmarketscience/jackcess/Column.java
@@ -1011,8 +1011,7 @@ public class Column implements Comparable<Column> {
   {
     boolean negate = (buffer.get() != 0);
 
-    byte[] tmpArr = new byte[16];
-    buffer.get(tmpArr);
+    byte[] tmpArr = ByteUtil.getBytes(buffer, 16);
 
     if(buffer.order() != ByteOrder.BIG_ENDIAN) {
       fixNumericByteOrder(tmpArr);
@@ -1155,8 +1154,7 @@ public class Column implements Comparable<Column> {
   private static String readGUIDValue(ByteBuffer buffer, ByteOrder order)
   {
     if(order != ByteOrder.BIG_ENDIAN) {
-      byte[] tmpArr = new byte[16];
-      buffer.get(tmpArr);
+      byte[] tmpArr = ByteUtil.getBytes(buffer, 16);
 
         // the first 3 guid components are integer components which need to
         // respect endianness, so swap 4-byte int, 2-byte int, 2-byte int
diff --git a/src/java/com/healthmarketscience/jackcess/IndexData.java b/src/java/com/healthmarketscience/jackcess/IndexData.java
index 637f763..c51a016 100644
--- a/src/java/com/healthmarketscience/jackcess/IndexData.java
+++ b/src/java/com/healthmarketscience/jackcess/IndexData.java
@@ -1690,8 +1690,7 @@ public abstract class IndexData {
       int colEntryLen = entryLen - (4 + extraTrailingLen);
 
       // read the entry bytes
-      _entryBytes = new byte[colEntryLen];
-      buffer.get(_entryBytes);
+      _entryBytes = ByteUtil.getBytes(buffer, colEntryLen);
 
       // read the rowId
       int page = ByteUtil.get3ByteInt(buffer, ENTRY_BYTE_ORDER);
diff --git a/src/java/com/healthmarketscience/jackcess/PropertyMaps.java b/src/java/com/healthmarketscience/jackcess/PropertyMaps.java
index 2120b56..51853ee 100644
--- a/src/java/com/healthmarketscience/jackcess/PropertyMaps.java
+++ b/src/java/com/healthmarketscience/jackcess/PropertyMaps.java
@@ -236,8 +236,7 @@ public class PropertyMaps implements Iterable<PropertyMap>
         String propName = propNames.get(nameIdx);
         PropColumn col = getColumn(dataType, propName, dataSize);
 
-        byte[] data = new byte[dataSize];
-        bbBlock.get(data);
+        byte[] data = ByteUtil.getBytes(bbBlock, dataSize);
         Object value = col.read(data);
 
         map.put(propName, dataType, flag, value);
@@ -253,8 +252,7 @@ public class PropertyMaps implements Iterable<PropertyMap>
      */
     private String readPropName(ByteBuffer buffer) { 
       int nameLength = buffer.getShort();
-      byte[] nameBytes = new byte[nameLength];
-      buffer.get(nameBytes);
+      byte[] nameBytes = ByteUtil.getBytes(buffer, nameLength);
       return Column.decodeUncompressedText(nameBytes, _database.getCharset());
     }
 
diff --git a/src/java/com/healthmarketscience/jackcess/Table.java b/src/java/com/healthmarketscience/jackcess/Table.java
index df53a88..2a00126 100644
--- a/src/java/com/healthmarketscience/jackcess/Table.java
+++ b/src/java/com/healthmarketscience/jackcess/Table.java
@@ -715,9 +715,8 @@ public class Table
       }
 
       // grab the column data
-      columnData = new byte[colDataLen];
       rowBuffer.position(colDataPos);
-      rowBuffer.get(columnData);
+      columnData = ByteUtil.getBytes(rowBuffer, colDataLen);
 
       if((rawVarValues != null) && column.isVariableLength()) {
         // caller wants raw value as well
@@ -1322,8 +1321,7 @@ public class Table
    */
   private String readName(ByteBuffer buffer) { 
     int nameLength = readNameLength(buffer);
-    byte[] nameBytes = new byte[nameLength];
-    buffer.get(nameBytes);
+    byte[] nameBytes = ByteUtil.getBytes(buffer, nameLength);
     return Column.decodeUncompressedText(nameBytes, 
                                          getDatabase().getCharset());
   }