GH-2997: BytesInput.fromInts

parquet-common/src/main/java/org/apache/parquet/bytes/BytesInput.java

@@ -125,6 +125,25 @@ public static BytesInput from(byte[] in, int offset, int length) {
     return new ByteArrayBytesInput(in, offset, length);
   }
 
+  /**
+   * @param intValues the ints to write
+   * @return a BytesInput that will write 4 * number of intValues bytes in little endian
+   */
+  public static BytesInput fromInts(int... intValues) {
+    int bytesLen = 4 * intValues.length;
+    CapacityByteArrayOutputStream out = CapacityByteArrayOutputStream.withTargetNumSlabs(bytesLen, bytesLen, 0);
+    try {
+      for (int i : intValues) {
+        BytesUtils.writeIntLittleEndian(out, i);
+      }
+    } catch (IOException e) {
+      // this can't happen, because CapacityByteArrayOutputStream won't throw exception
+      out.close();
+      throw new RuntimeException(e);
+    }
+    return from(out);
+  }
+
   /**
    * @param intValue the int to write
    * @return a BytesInput that will write 4 bytes in little endian

parquet-common/src/test/java/org/apache/parquet/bytes/TestBytesInput.java

@@ -197,6 +197,18 @@ public void testFromCapacityByteArrayOutputStreamMultipleSlabs() throws IOExcept
     }
   }
 
+  @Test
+  public void testFromInts() throws IOException {
+    int[] values = new int[] {1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, Integer.MIN_VALUE, Integer.MAX_VALUE};
+    ByteArrayOutputStream baos = new ByteArrayOutputStream(4 * values.length);
+    for (int value : values) {
+      BytesUtils.writeIntLittleEndian(baos, value);
+    }
+    byte[] data = baos.toByteArray();
+    Supplier<BytesInput> factory = () -> BytesInput.fromInts(values);
+    validate(data, factory);
+  }
+
   @Test
   public void testFromInt() throws IOException {
     int value = RANDOM.nextInt();