Bael 5679 json to protobuf (#12696)

* Initial Changes

* Update ProtobufUtilUnitTest.java

* Changes for JSON to Protobuf

spring-protobuf/pom.xml

@@ -20,6 +20,11 @@
             <artifactId>protobuf-java</artifactId>
             <version>${protobuf-java.version}</version>
         </dependency>
+		<dependency>
+		    <groupId>com.google.protobuf</groupId>
+		    <artifactId>protobuf-java-util</artifactId>
+		    <version>${protobuf-java.version}</version>
+		</dependency>
         <dependency>
             <groupId>com.googlecode.protobuf-java-format</groupId>
             <artifactId>protobuf-java-format</artifactId>

spring-protobuf/src/main/java/com/baeldung/protobuf/convert/ProtobuffUtil.java

@@ -0,0 +1,37 @@
+package com.baeldung.protobuf.convert;
+
+import java.io.IOException;
+
+import com.google.protobuf.AbstractMessage.Builder;
+import com.google.protobuf.Message;
+import com.google.protobuf.MessageOrBuilder;
+import com.google.protobuf.Struct;
+import com.google.protobuf.util.JsonFormat;
+
+public class ProtobuffUtil {
+
+    public static String toJson(MessageOrBuilder messageOrBuilder) throws IOException {
+        return JsonFormat.printer().print(messageOrBuilder);
+    }
+
+    @SuppressWarnings("unchecked")
+    public static <T extends Message> T fromJson(String json, Class<T> clazz) throws IOException {
+        Builder<?> builder = null;
+        try {
+            builder = (Builder<?>) clazz.getMethod("newBuilder").invoke(null);
+
+        } catch (Exception e) {
+            return null;
+        }
+        JsonFormat.parser().ignoringUnknownFields().merge(json, builder);
+        return (T) builder.build();
+    }
+
+    @SuppressWarnings("unchecked")
+    public static Message fromJson(String json) throws IOException {
+        Builder structBuilder = Struct.newBuilder();
+        JsonFormat.parser().ignoringUnknownFields().merge(json, structBuilder);
+        return structBuilder.build();
+    }
+
+}

spring-protobuf/src/test/java/com/baeldung/protobuf/convert/ProtobufUtilUnitTest.java

@@ -0,0 +1,43 @@
+package com.baeldung.protobuf.convert;
+
+import java.io.BufferedReader;
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.io.Reader;
+import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
+
+import org.junit.Assert;
+import org.junit.jupiter.api.Test;
+
+import com.google.protobuf.Message;
+
+public class ProtobufUtilUnitTest {
+
+    public static String jsonInput = "{\r\n" + "  \"boolean\": true,\r\n" + "  \"color\": \"gold\",\r\n"
+            + "  \"object\": {\r\n" + "    \"a\": \"b\",\r\n" + "    \"c\": \"d\"\r\n" + "  },\r\n"
+            + "  \"string\": \"Hello World\"\r\n" + "}";
+
+    @Test
+    public void givenProtobuf_convertToJson() throws IOException {
+        Message fromJson = ProtobuffUtil.fromJson(jsonInput);
+
+        InputStream inputStream = new ByteArrayInputStream(fromJson.toByteArray());
+
+        StringBuilder textBuilder = new StringBuilder();
+        try (Reader reader = new BufferedReader(
+                new InputStreamReader(inputStream, Charset.forName(StandardCharsets.UTF_8.name())))) {
+            int c = 0;
+            while ((c = reader.read()) != -1) {
+                textBuilder.append((char) c);
+            }
+        }
+        String json = ProtobuffUtil.toJson(fromJson);
+        Assert.assertTrue(json.contains("\"boolean\": true"));
+        Assert.assertTrue(json.contains("\"string\": \"Hello World\""));
+        Assert.assertTrue(json.contains("\"color\": \"gold\""));
+    }
+
+}