Convert double to int when decoding via gson

Refactored MapDoubleAdapterFactory, extracting DoubleConverter to be
used by code needing to convert Double to Integer/Long after being
decoded by GSON.
Enhanced StandardCoder to automatically use the above converter if
the desired class is a generic Object.

Change-Id: I1d4e83910de41ceda383f257bfea706db2b8fbbe
Issue-ID: POLICY-1919
Signed-off-by: Jim Hahn <jrh3@att.com>

2 files changed, 29 insertions, 2 deletions

diff --git a/utils/src/main/java/org/onap/policy/common/utils/coder/StandardCoder.java b/utils/src/main/java/org/onap/policy/common/utils/coder/StandardCoder.java
index 1c65be82..80eddb86 100644
--- a/utils/src/main/java/org/onap/policy/common/utils/coder/StandardCoder.java
+++ b/utils/src/main/java/org/onap/policy/common/utils/coder/StandardCoder.java
@@ -38,6 +38,7 @@ import java.io.OutputStreamWriter;
 import java.io.Reader;
 import java.io.Writer;
 import java.nio.charset.StandardCharsets;
+import org.onap.policy.common.gson.DoubleConverter;
 import org.onap.policy.common.gson.MapDoubleAdapterFactory;
 
 /**
@@ -238,7 +239,7 @@ public class StandardCoder implements Coder {
      * @return the object represented by the given json string
      */
     protected <T> T fromJson(String json, Class<T> clazz) {
-        return GSON.fromJson(json, clazz);
+        return convertFromDouble(clazz, GSON.fromJson(json, clazz));
     }
 
     /**
@@ -249,7 +250,24 @@ public class StandardCoder implements Coder {
      * @return the object represented by the given json string
      */
     protected <T> T fromJson(Reader source, Class<T> clazz) {
-        return GSON.fromJson(source, clazz);
+        return convertFromDouble(clazz, GSON.fromJson(source, clazz));
+    }
+
+    /**
+     * Converts a value from Double to Integer/Long, walking the value's contents if it's
+     * a List/Map. Only applies if the specified class refers to the Object class.
+     * Otherwise, it leaves the value unchanged.
+     *
+     * @param clazz class of object to be decoded
+     * @param value value to be converted
+     * @return the converted value
+     */
+    private <T> T convertFromDouble(Class<T> clazz, T value) {
+        if (clazz != Object.class) {
+            return value;
+        }
+
+        return clazz.cast(DoubleConverter.convertFromDouble(value));
     }
 
     /**
diff --git a/utils/src/test/java/org/onap/policy/common/utils/coder/StandardCoderTest.java b/utils/src/test/java/org/onap/policy/common/utils/coder/StandardCoderTest.java
index e8e3bb60..2992933f 100644
--- a/utils/src/test/java/org/onap/policy/common/utils/coder/StandardCoderTest.java
+++ b/utils/src/test/java/org/onap/policy/common/utils/coder/StandardCoderTest.java
@@ -201,6 +201,15 @@ public class StandardCoderTest {
     }
 
     @Test
+    public void testConvertFromDouble() throws Exception {
+        String text = "[listA, {keyA=100}, 200]";
+        assertEquals(text, coder.decode(text, Object.class).toString());
+
+        text = "{keyB=200}";
+        assertEquals(text, coder.decode(text, Object.class).toString());
+    }
+
+    @Test
     public void testToStandard() throws Exception {
         MyObject obj = new MyObject();
         obj.abc = "xyz";