added play-framework project (#678)

* made changes to java reflection

* removed redundant method makeSound in Animal abstract class

* added project for play-framework article

play-framework/student-api/app/controllers/StudentController.java

@@ -0,0 +1,56 @@
+package controllers;
+import models.*;
+import util.*;
+import play.mvc.*;
+import play.libs.Json;
+import play.libs.Json.*;
+import com.fasterxml.jackson.databind.JsonNode;           
+import com.fasterxml.jackson.databind.ObjectMapper;
+import java.util.List;
+
+public class StudentController extends Controller {
+    public Result create() {
+		JsonNode json = request().body().asJson();
+		if(json == null)
+			return badRequest(Util.createResponse("Expecting Json data",false));
+		Student student=StudentStore.getInstance().addStudent((Student)Json.fromJson(json,Student.class));
+		JsonNode jsonObject=Json.toJson(student);
+        return created(Util.createResponse(jsonObject,true));
+    }
+	public Result update() {
+        JsonNode json = request().body().asJson();
+		if(json == null)
+			return badRequest(Util.createResponse("Expecting Json data",false));
+		Student student=StudentStore.getInstance().updateStudent((Student)Json.fromJson(json,Student.class));
+		if(student==null){
+		return notFound(Util.createResponse("Student not found",false));
+		}
+
+		JsonNode jsonObject=Json.toJson(student);
+        return ok(Util.createResponse(jsonObject,true));
+    }
+	public Result retrieve(int id) {
+		Student student=StudentStore.getInstance().getStudent(id);
+		if(student==null){
+		return notFound(Util.createResponse("Student with id:"+id+" not found",false));
+		}
+		JsonNode jsonObjects=Json.toJson(student);
+        return ok(Util.createResponse(jsonObjects,true));
+    }
+	public Result listStudents() {
+		List<Student> result=StudentStore.getInstance().getAllStudents();
+		    	ObjectMapper mapper = new ObjectMapper();
+
+		JsonNode jsonData=mapper.convertValue(result, JsonNode.class);
+        return ok(Util.createResponse(jsonData,true));
+
+    }
+	public Result delete(int id) {
+		boolean status=StudentStore.getInstance().deleteStudent(id);
+		if(!status){
+		return notFound(Util.createResponse("Student with id:"+id+" not found",false));
+		}
+        return ok(Util.createResponse("Student with id:"+id+" deleted",true));
+    }
+
+}