#3904 Inheritance support java client retrofit gson (#4729)

* merge with master

* remove zoo specific artifact names

* fix duplicate doublequote

* #3904 add samples for retrofit2

* #3904 clean json field retrieval

* #3904 allow non-abstract parent class

samples/client/petstore/java/retrofit2/build.gradle

@@ -99,6 +99,7 @@ ext {
     swagger_annotations_version = "1.5.15"
     junit_version = "4.12"
     threetenbp_version = "1.3.5"
+    json_fire_version = "1.8.0"
 }
 
 dependencies {
@@ -107,6 +108,7 @@ dependencies {
     compile "com.squareup.retrofit2:converter-gson:$retrofit_version"
     compile "io.swagger:swagger-annotations:$swagger_annotations_version"
     compile "org.apache.oltu.oauth2:org.apache.oltu.oauth2.client:$oltu_version"
+    compile "io.gsonfire:gson-fire:$json_fire_version"
     compile "org.threeten:threetenbp:$threetenbp_version"
 
     testCompile "junit:junit:$junit_version"

samples/client/petstore/java/retrofit2/build.sbt

@@ -15,6 +15,7 @@ lazy val root = (project in file(".")).
       "io.swagger" % "swagger-annotations" % "1.5.15" % "compile",
       "org.apache.oltu.oauth2" % "org.apache.oltu.oauth2.client" % "1.0.1" % "compile",
       "org.threeten" % "threetenbp" % "1.3.5" % "compile",
+      "io.gsonfire" % "gson-fire" % "1.8.0" % "compile",
       "junit" % "junit" % "4.12" % "test",
       "com.novocode" % "junit-interface" % "0.11" % "test"
     )

samples/client/petstore/java/retrofit2/pom.xml

@@ -194,6 +194,11 @@
       <artifactId>org.apache.oltu.oauth2.client</artifactId>
       <version>${oltu-version}</version>
     </dependency>
+    <dependency>
+      <groupId>io.gsonfire</groupId>
+      <artifactId>gson-fire</artifactId>
+      <version>${gson-fire-version}</version>
+    </dependency>
     <dependency>
       <groupId>org.threeten</groupId>
       <artifactId>threetenbp</artifactId>
@@ -215,6 +220,7 @@
     <java.version>1.7</java.version>
     <maven.compiler.source>${java.version}</maven.compiler.source>
     <maven.compiler.target>${java.version}</maven.compiler.target>
+    <gson-fire-version>1.8.0</gson-fire-version>
     <swagger-core-version>1.5.15</swagger-core-version>
     <retrofit-version>2.3.0</retrofit-version>
     <threetenbp-version>1.3.5</threetenbp-version>

samples/client/petstore/java/retrofit2/src/main/java/io/swagger/client/ApiClient.java

@@ -2,6 +2,7 @@ package io.swagger.client;
 
 import com.google.gson.Gson;
 import com.google.gson.JsonParseException;
+import com.google.gson.JsonElement;
 import okhttp3.Interceptor;
 import okhttp3.OkHttpClient;
 import okhttp3.RequestBody;
@@ -25,6 +26,7 @@ import java.lang.reflect.Type;
 import java.text.DateFormat;
 import java.util.LinkedHashMap;
 import java.util.Map;
+import java.util.HashMap;
 
 public class ApiClient {
 

samples/client/petstore/java/retrofit2/src/main/java/io/swagger/client/JSON.java

@@ -20,10 +20,15 @@ import com.google.gson.TypeAdapter;
 import com.google.gson.internal.bind.util.ISO8601Utils;
 import com.google.gson.stream.JsonReader;
 import com.google.gson.stream.JsonWriter;
+import com.google.gson.JsonElement;
+import io.gsonfire.GsonFireBuilder;
+import io.gsonfire.TypeSelector;
 import org.threeten.bp.LocalDate;
 import org.threeten.bp.OffsetDateTime;
 import org.threeten.bp.format.DateTimeFormatter;
 
+import io.swagger.client.model.*;
+
 import java.io.IOException;
 import java.io.StringReader;
 import java.lang.reflect.Type;
@@ -31,6 +36,8 @@ import java.text.DateFormat;
 import java.text.ParseException;
 import java.text.ParsePosition;
 import java.util.Date;
+import java.util.Map;
+import java.util.HashMap;
 
 public class JSON {
     private Gson gson;
@@ -39,8 +46,42 @@ public class JSON {
     private OffsetDateTimeTypeAdapter offsetDateTimeTypeAdapter = new OffsetDateTimeTypeAdapter();
     private LocalDateTypeAdapter localDateTypeAdapter = new LocalDateTypeAdapter();
 
+    public static GsonBuilder createGson() {
+        GsonFireBuilder fireBuilder = new GsonFireBuilder()
+          .registerTypeSelector(Animal.class, new TypeSelector() {
+            @Override
+            public Class getClassForElement(JsonElement readElement) {
+                Map classByDiscriminatorValue = new HashMap();
+                classByDiscriminatorValue.put("Cat".toUpperCase(), Cat.class);
+                classByDiscriminatorValue.put("Dog".toUpperCase(), Dog.class);
+                classByDiscriminatorValue.put("Animal".toUpperCase(), Animal.class);
+                return getClassByDiscriminator(
+                            classByDiscriminatorValue,
+                            getDiscriminatorValue(readElement, "className"));
+            }
+          })
+        ;
+        return fireBuilder.createGsonBuilder();
+    }
+
+    private static String getDiscriminatorValue(JsonElement readElement, String discriminatorField) {
+        JsonElement element = readElement.getAsJsonObject().get(discriminatorField);
+        if(null == element) {
+            throw new IllegalArgumentException("missing discriminator field: <" + discriminatorField + ">");
+        }
+        return element.getAsString();
+    }
+
+    private static Class getClassByDiscriminator(Map classByDiscriminatorValue, String discriminatorValue) {
+        Class clazz = (Class) classByDiscriminatorValue.get(discriminatorValue.toUpperCase());
+        if(null == clazz) {
+            throw new IllegalArgumentException("cannot determine model class of name: <" + discriminatorValue + ">");
+        }
+        return clazz;
+    }
+
     public JSON() {
-        gson = new GsonBuilder()
+        gson = createGson()
             .registerTypeAdapter(Date.class, dateTypeAdapter)
             .registerTypeAdapter(java.sql.Date.class, sqlDateTypeAdapter)
             .registerTypeAdapter(OffsetDateTime.class, offsetDateTimeTypeAdapter)