Ftr: add json generalizer (#1343)

* Ftr: add json generalizer

Fix: go fmt

* Fix: hessian pojo

* fix: restart ci

* Fix: imports format

common/constant/key.go

@@ -314,4 +314,5 @@ const (
 	GenericSerializationDefault = "true"
 	// disable "protobuf-json" temporarily
 	//GenericSerializationProtobuf = "protobuf-json"
+	GenericSerializationGson = "gson"
 )

filter/generic/generalizer/gson.go

@@ -0,0 +1,99 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package generalizer
+
+import (
+	"encoding/json"
+	"reflect"
+	"sync"
+)
+
+import (
+	hessian "github.com/apache/dubbo-go-hessian2"
+	perrors "github.com/pkg/errors"
+)
+
+import (
+	"dubbo.apache.org/dubbo-go/v3/common/logger"
+	"dubbo.apache.org/dubbo-go/v3/protocol/dubbo/hessian2"
+)
+
+var (
+	jsonGeneralizer     Generalizer
+	jsonGeneralizerOnce sync.Once
+)
+
+func GetGsonGeneralizer() Generalizer {
+	jsonGeneralizerOnce.Do(func() {
+		jsonGeneralizer = &GsonGeneralizer{}
+	})
+	return jsonGeneralizer
+}
+
+type GsonGeneralizer struct{}
+
+func (GsonGeneralizer) Generalize(obj interface{}) (interface{}, error) {
+	newObj, ok := obj.(hessian.POJO)
+	if !ok {
+		return nil, perrors.Errorf("unexpected type of obj(=%T), wanted is hessian pojo", obj)
+	}
+
+	jsonbytes, err := json.Marshal(newObj)
+	if err != nil {
+		return nil, err
+	}
+
+	return string(jsonbytes), nil
+}
+
+func (GsonGeneralizer) Realize(obj interface{}, typ reflect.Type) (interface{}, error) {
+	jsonbytes, ok := obj.(string)
+	if !ok {
+		return nil, perrors.Errorf("unexpected type of obj(=%T), wanted is string", obj)
+	}
+
+	// create the target object
+	ret, ok := reflect.New(typ).Interface().(hessian.POJO)
+	if !ok {
+		return nil, perrors.Errorf("the type of obj(=%s) should be hessian pojo", typ)
+	}
+
+	err := json.Unmarshal([]byte(jsonbytes), ret)
+	if err != nil {
+		return nil, err
+	}
+
+	return ret, nil
+}
+
+func (GsonGeneralizer) GetType(obj interface{}) (typ string, err error) {
+	typ, err = hessian2.GetJavaName(obj)
+	// no error or error is not NilError
+	if err == nil || err != hessian2.NilError {
+		return
+	}
+
+	typ = "java.lang.Object"
+	if err == hessian2.NilError {
+		logger.Debugf("the type of nil object couldn't be inferred, use the default value(\"%s\")", typ)
+		return
+	}
+
+	logger.Debugf("the type of object(=%T) couldn't be recognized as a POJO, use the default value(\"%s\")", obj, typ)
+	return
+}

filter/generic/generalizer/gson_test.go

@@ -0,0 +1,97 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package generalizer
+
+import (
+	"reflect"
+	"testing"
+)
+
+import (
+	"github.com/stretchr/testify/assert"
+)
+
+var mockGsonGeneralizer = GetGsonGeneralizer()
+
+type mockGsonParent struct {
+	Gender, Email, Name string
+	Age                 int
+	Child               *mockGsonChild
+}
+
+func (p mockGsonParent) JavaClassName() string {
+	return "org.apache.dubbo.mockGsonParent"
+}
+
+type mockGsonChild struct {
+	Gender, Email, Name string
+	Age                 int
+}
+
+func (p mockGsonChild) JavaClassName() string {
+	return "org.apache.dubbo.mockGsonChild"
+}
+
+func TestGsonGeneralizer(t *testing.T) {
+	c := &mockGsonChild{
+		Age:    20,
+		Gender: "male",
+		Email:  "childName@example.com",
+		Name:   "childName",
+	}
+	p := mockGsonParent{
+		Age:    30,
+		Gender: "male",
+		Email:  "enableasync@example.com",
+		Name:   "enableasync",
+		Child:  c,
+	}
+
+	m, err := mockGsonGeneralizer.Generalize(p)
+	assert.Nil(t, err)
+	assert.Equal(t, "{\"Gender\":\"male\",\"Email\":\"enableasync@example.com\",\"Name\":\"enableasync\",\"Age\":30,\"Child\":{\"Gender\":\"male\",\"Email\":\"childName@example.com\",\"Name\":\"childName\",\"Age\":20}}", m)
+
+	r, err := mockGsonGeneralizer.Realize(m, reflect.TypeOf(p))
+	assert.Nil(t, err)
+	rMockParent, ok := r.(*mockGsonParent)
+	assert.True(t, ok)
+	// parent
+	assert.Equal(t, "enableasync", rMockParent.Name)
+	assert.Equal(t, 30, rMockParent.Age)
+	// child
+	assert.Equal(t, "childName", rMockParent.Child.Name)
+	assert.Equal(t, 20, rMockParent.Child.Age)
+}
+
+func TestGsonPointer(t *testing.T) {
+	c := &mockGsonChild{
+		Age:    20,
+		Gender: "male",
+		Email:  "childName@example.com",
+		Name:   "childName",
+	}
+
+	m, err := mockMapGeneralizer.Generalize(c)
+	assert.Nil(t, err)
+	newC, err := mockMapGeneralizer.Realize(m, reflect.TypeOf(c))
+	assert.Nil(t, err)
+	rMockChild, ok := newC.(*mockGsonChild)
+	assert.True(t, ok)
+	assert.Equal(t, "childName", rMockChild.Name)
+	assert.Equal(t, 20, rMockChild.Age)
+}

filter/generic/util.go

@@ -69,6 +69,9 @@ func getGeneralizer(generic string) (g generalizer.Generalizer) {
 	switch strings.ToLower(generic) {
 	case constant.GenericSerializationDefault:
 		g = generalizer.GetMapGeneralizer()
+	case constant.GenericSerializationGson:
+		g = generalizer.GetGsonGeneralizer()
+
 	default:
 		logger.Debugf("\"%s\" is not supported, use the default generalizer(MapGeneralizer)", generic)
 		g = generalizer.GetMapGeneralizer()