Merge "Add StandardCoderObject to hide GSON internals"

5 files changed, 303 insertions, 1 deletions

diff --git a/utils/src/main/java/org/onap/policy/common/utils/coder/Coder.java b/utils/src/main/java/org/onap/policy/common/utils/coder/Coder.java
index 66a308f7..bb51f2b9 100644
--- a/utils/src/main/java/org/onap/policy/common/utils/coder/Coder.java
+++ b/utils/src/main/java/org/onap/policy/common/utils/coder/Coder.java
@@ -106,4 +106,22 @@ public interface Coder {
      * @throws CoderException if an error occurs
      */
     <T> T decode(File source, Class<T> clazz) throws CoderException;
+
+    /**
+     * Converts an object/POJO to a standard object.
+     *
+     * @param object object to be converted
+     * @return a new standard object representing the original object
+     * @throws CoderException if an error occurs
+     */
+    StandardCoderObject toStandard(Object object) throws CoderException;
+
+    /**
+     * Converts a standard object to an object/POJO.
+     *
+     * @param sco the standard object to be converted
+     * @return a new object represented by the standard object
+     * @throws CoderException if an error occurs
+     */
+    <T> T fromStandard(StandardCoderObject sco, Class<T> clazz) throws CoderException;
 }
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 389720f9..69a211b6 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
@@ -21,6 +21,11 @@
 package org.onap.policy.common.utils.coder;
 
 import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.JsonElement;
+import com.google.gson.TypeAdapter;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileNotFoundException;
@@ -42,7 +47,8 @@ public class StandardCoder implements Coder {
     /**
      * Gson object used to encode and decode messages.
      */
-    private static final Gson GSON = new Gson();
+    private static final Gson GSON = new GsonBuilder()
+                    .registerTypeAdapter(StandardCoderObject.class, new StandardTypeAdapter()).create();
 
     /**
      * Constructs the object.
@@ -137,6 +143,26 @@ public class StandardCoder implements Coder {
         }
     }
 
+    @Override
+    public StandardCoderObject toStandard(Object object) throws CoderException {
+        try {
+            return new StandardCoderObject(GSON.toJsonTree(object));
+
+        } catch (RuntimeException e) {
+            throw new CoderException(e);
+        }
+    }
+
+    @Override
+    public <T> T fromStandard(StandardCoderObject sco, Class<T> clazz) throws CoderException {
+        try {
+            return GSON.fromJson(sco.getData(), clazz);
+
+        } catch (RuntimeException e) {
+            throw new CoderException(e);
+        }
+    }
+
     // the remaining methods are wrappers that can be overridden by junit tests
 
     /**
@@ -223,4 +249,32 @@ public class StandardCoder implements Coder {
     protected <T> T fromJson(Reader source, Class<T> clazz) {
         return GSON.fromJson(source, clazz);
     }
+
+    /**
+     * Adapter for standard objects.
+     */
+    private static class StandardTypeAdapter extends TypeAdapter<StandardCoderObject> {
+
+        /**
+         * Used to read/write a JsonElement.
+         */
+        private static TypeAdapter<JsonElement> elementAdapter = new Gson().getAdapter(JsonElement.class);
+
+        /**
+         * Constructs the object.
+         */
+        public StandardTypeAdapter() {
+            super();
+        }
+
+        @Override
+        public void write(JsonWriter out, StandardCoderObject value) throws IOException {
+            elementAdapter.write(out, value.getData());
+        }
+
+        @Override
+        public StandardCoderObject read(JsonReader in) throws IOException {
+            return new StandardCoderObject(elementAdapter.read(in));
+        }
+    }
 }
diff --git a/utils/src/main/java/org/onap/policy/common/utils/coder/StandardCoderObject.java b/utils/src/main/java/org/onap/policy/common/utils/coder/StandardCoderObject.java
new file mode 100644
index 00000000..60c5f4ef
--- /dev/null
+++ b/utils/src/main/java/org/onap/policy/common/utils/coder/StandardCoderObject.java
@@ -0,0 +1,93 @@
+/*
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * Licensed 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.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.common.utils.coder;
+
+import com.google.gson.JsonElement;
+
+/**
+ * Object type used by the {@link StandardCoder}. Different serialization tools have
+ * different "standard objects". For instance, GSON uses {@link JsonElement}. This class
+ * wraps that object so that it can be used without exposing the object, itself.
+ */
+public class StandardCoderObject {
+
+    /**
+     * Data wrapped by this.
+     */
+    private final JsonElement data;
+
+    /**
+     * Constructs the object.
+     */
+    public StandardCoderObject() {
+        data = null;
+    }
+
+    /**
+     * Constructs the object.
+     *
+     * @param data data wrapped by this object.
+     */
+    protected StandardCoderObject(JsonElement data) {
+        this.data = data;
+    }
+
+    /**
+     * Gets the data wrapped by this.
+     *
+     * @return the data wrapped by this
+     */
+    protected JsonElement getData() {
+        return data;
+    }
+
+    /**
+     * Gets a field's value from this object, traversing the object hierarchy.
+     *
+     * @param fields field hierarchy
+     * @return the field value or {@code null} if the field does not exist or is not a
+     *         primitive
+     */
+    public String getString(String... fields) {
+
+        /*
+         * This could be relatively easily modified to allow Integer arguments, as well,
+         * which would be used to specify indices within an array.
+         */
+
+        JsonElement jel = data;
+
+        for (String field : fields) {
+            if (jel == null) {
+                return null;
+            }
+
+            if (jel.isJsonObject()) {
+                jel = jel.getAsJsonObject().get(field);
+
+            } else {
+                return null;
+            }
+        }
+
+        return (jel != null && jel.isJsonPrimitive() ? jel.getAsString() : null);
+    }
+}
diff --git a/utils/src/test/java/org/onap/policy/common/utils/coder/StandardCoderObjectTest.java b/utils/src/test/java/org/onap/policy/common/utils/coder/StandardCoderObjectTest.java
new file mode 100644
index 00000000..44086f30
--- /dev/null
+++ b/utils/src/test/java/org/onap/policy/common/utils/coder/StandardCoderObjectTest.java
@@ -0,0 +1,89 @@
+/*
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * Licensed 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.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.common.utils.coder;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+
+import com.google.gson.Gson;
+import com.google.gson.JsonElement;
+import org.junit.Before;
+import org.junit.Test;
+
+public class StandardCoderObjectTest {
+    private static final Gson gson = new Gson();
+
+    private static final String PROP1 = "abc";
+    private static final String PROP2 = "ghi";
+    private static final String PROP2b = "jkl";
+    private static final String VAL1 = "def";
+    private static final String VAL2 = "mno";
+    private static final String JSON = "{'abc':'def','ghi':{'jkl':'mno'}}".replace('\'', '"');
+
+    private StandardCoderObject sco;
+
+    /**
+     * Creates a standard object, populated with some data.
+     *
+     * @throws Exception if an error occurs
+     */
+    @Before
+    public void setUp() throws Exception {
+        sco = new StandardCoderObject(gson.fromJson(JSON, JsonElement.class));
+    }
+
+    @Test
+    public void testStandardCoderObject() {
+        assertNull(new StandardCoderObject().getData());
+    }
+
+    @Test
+    public void testStandardCoderObjectJsonElement() {
+        assertNotNull(sco.getData());
+        assertEquals(JSON, gson.toJson(sco.getData()));
+    }
+
+    @Test
+    public void testGetString() throws Exception {
+        // one field
+        assertEquals(VAL1, sco.getString(PROP1));
+
+        // multiple fields
+        assertEquals(VAL2, sco.getString(PROP2, PROP2b));
+
+        // not found
+        assertNull(sco.getString("xyz"));
+
+        // read from null object
+        assertNull(new StandardCoderObject().getString());
+        assertNull(new StandardCoderObject().getString(PROP1));
+
+        JsonElement obj = gson.fromJson("{'abc':[]}".replace('\'', '"'), JsonElement.class);
+        sco = new StandardCoderObject(obj);
+
+        // not a primitive
+        assertNull(sco.getString(PROP1));
+
+        // not a JSON object
+        assertNull(sco.getString(PROP1, PROP2));
+    }
+}
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 25cce748..7583d776 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
@@ -22,6 +22,7 @@ package org.onap.policy.common.utils.coder;
 
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
 import static org.mockito.Mockito.doThrow;
 import static org.mockito.Mockito.spy;
 import static org.mockito.Mockito.when;
@@ -196,4 +197,51 @@ public class StandardCoderTest {
         assertThatThrownBy(() -> coder.decode(file, JsonElement.class)).isInstanceOf(CoderException.class)
                         .hasCause(ioe);
     }
+
+    @Test
+    public void testToStandard() throws Exception {
+        MyObject obj = new MyObject();
+        obj.abc = "xyz";
+        StandardCoderObject sco = coder.toStandard(obj);
+        assertNotNull(sco.getData());
+        assertEquals("{'abc':'xyz'}".replace('\'', '"'), sco.getData().toString());
+
+        // class instead of object -> exception
+        assertThatThrownBy(() -> coder.toStandard(String.class)).isInstanceOf(CoderException.class);
+    }
+
+    @Test
+    public void testFromStandard() throws Exception {
+        MyObject obj = new MyObject();
+        obj.abc = "pdq";
+        StandardCoderObject sco = coder.toStandard(obj);
+
+        MyObject obj2 = coder.fromStandard(sco, MyObject.class);
+        assertEquals(obj.toString(), obj2.toString());
+
+        // null class -> exception
+        assertThatThrownBy(() -> coder.fromStandard(sco, null)).isInstanceOf(CoderException.class);
+    }
+
+    @Test
+    public void testStandardTypeAdapter() throws Exception {
+        String json = "{'abc':'def'}".replace('\'', '"');
+        StandardCoderObject sco = coder.fromJson(json, StandardCoderObject.class);
+        assertNotNull(sco.getData());
+        assertEquals(json, sco.getData().toString());
+        assertEquals(json, coder.toJson(sco));
+
+        // invalid json -> exception
+        assertThatThrownBy(() -> coder.fromJson(new StringReader("["), StandardCoderObject.class));
+    }
+
+
+    private static class MyObject {
+        private String abc;
+
+        @Override
+        public String toString() {
+            return "MyObject [abc=" + abc + "]";
+        }
+    }
 }