[JVM] Refactor, add filesys API

jvm-packages/xgboost4j/src/test/java/ml/dmlc/xgboost4j/java/BoosterImplTest.java

@@ -15,6 +15,10 @@
  */
 package ml.dmlc.xgboost4j.java;
 
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.util.Arrays;
 import java.util.HashMap;
 import java.util.Map;
 
@@ -67,7 +71,7 @@ public class BoosterImplTest {
   }
 
   @Test
-  public void testBoosterBasic() throws XGBoostError {
+  public void testBoosterBasic() throws XGBoostError, IOException {
     DMatrix trainMat = new DMatrix("../../demo/data/agaricus.txt.train");
     DMatrix testMat = new DMatrix("../../demo/data/agaricus.txt.test");
 
@@ -94,15 +98,20 @@ public class BoosterImplTest {
     Booster booster = XGBoost.train(paramMap, trainMat, round, watches, null, null);
 
     //predict raw output
-    float[][] predicts = booster.predict(testMat, true);
+    float[][] predicts = booster.predict(testMat, true, 0);
 
     //eval
     IEvaluation eval = new EvalError();
     //error must be less than 0.1
     TestCase.assertTrue(eval.eval(predicts, testMat) < 0.1f);
 
-    //test dump model
+    // save and load
+    File temp = File.createTempFile("temp", "model");
+    temp.deleteOnExit();
+    booster.saveModel(temp.getAbsolutePath());
 
+    Booster bst2 = XGBoost.loadModel(new FileInputStream(temp.getAbsolutePath()));
+    assert (Arrays.equals(bst2.toByteArray(), booster.toByteArray()));
   }
 
   /**