support dynamic map key

Author: taowen

src/main/java/com/jsoniter/output/CodegenImplMap.java

@@ -13,7 +13,7 @@ public static CodegenResult genMap(String cacheKey, ClassInfo classInfo) {
         if (cacheKey.endsWith("__value_not_nullable")) {
             isCollectionValueNullable = false;
         }
-        Type keyType = String.class;
+        Type keyType = Object.class;
         Type valueType = Object.class;
         if (typeArgs.length == 2) {
             keyType = typeArgs[0];

src/main/java/com/jsoniter/output/MapKeyEncoders.java

@@ -22,6 +22,9 @@ private static Encoder createDefaultEncoder(Type mapKeyType) {
         if (mapKeyType == String.class) {
             return new StringKeyEncoder();
         }
+        if (mapKeyType == Object.class) {
+            return new DynamicKeyEncoder();
+        }
         if (mapKeyType instanceof Class) {
             if (Number.class.isAssignableFrom((Class<?>) mapKeyType)) {
                 return new NumberKeyEncoder();
@@ -47,4 +50,17 @@ public void encode(Object obj, JsonStream stream) throws IOException {
             stream.write('"');
         }
     }
+
+    private static class DynamicKeyEncoder implements Encoder {
+
+        @Override
+        public void encode(Object obj, JsonStream stream) throws IOException {
+            Class<?> clazz = obj.getClass();
+            if (clazz == Object.class) {
+                throw new JsonException("map key type is Object.class, can not be encoded");
+            }
+            Encoder mapKeyEncoder = registerOrGetExisting(clazz);
+            mapKeyEncoder.encode(obj, stream);
+        }
+    }
 }

src/main/java/com/jsoniter/output/ReflectionMapEncoder.java

@@ -14,7 +14,7 @@ class ReflectionMapEncoder implements Encoder.ReflectionEncoder {
     private final Encoder mapKeyEncoder;
 
     public ReflectionMapEncoder(Class clazz, Type[] typeArgs) {
-        Type keyType = String.class;
+        Type keyType = Object.class;
         Type valueType = Object.class;
         if (typeArgs.length == 2) {
             keyType = typeArgs[0];

src/test/java/com/jsoniter/output/TestMap.java

@@ -1,6 +1,9 @@
 package com.jsoniter.output;
 
-import com.jsoniter.spi.*;
+import com.jsoniter.spi.Config;
+import com.jsoniter.spi.Encoder;
+import com.jsoniter.spi.JsoniterSpi;
+import com.jsoniter.spi.TypeLiteral;
 import junit.framework.TestCase;
 
 import java.io.ByteArrayOutputStream;
@@ -124,4 +127,10 @@ public void test_int_as_map_key() {
         assertEquals("{\"1\":2}", JsonStream.serialize(new TypeLiteral<Map<Integer, Integer>>(){
         }, m));
     }
+
+    public void test_int_obj_as_map_key() {
+        HashMap<Integer, Integer> m = new HashMap<Integer, Integer>();
+        m.put(1, 2);
+        assertEquals("{\"1\":2}", JsonStream.serialize(m));
+    }
 }