Refactor codes, and add comments.

skywalking-storage-center/skywalking-routing/src/main/java/com/a/eye/skywalking/routing/http/RestfulAPIService.java

@@ -2,7 +2,6 @@ package com.a.eye.skywalking.routing.http;
 
 import com.a.eye.skywalking.logging.api.ILog;
 import com.a.eye.skywalking.logging.api.LogManager;
-import com.a.eye.skywalking.network.dependencies.com.google.gson.Gson;
 import com.a.eye.skywalking.routing.http.module.ResponseMessage;
 
 import java.io.IOException;
@@ -11,20 +10,19 @@ import java.util.Map;
 
 import fi.iki.elonen.NanoHTTPD;
 
-import static com.a.eye.skywalking.routing.http.module.ResponseMessage.REQUEST_METHOD_NOT_SUPPORT;
+import static com.a.eye.skywalking.routing.http.module.ResponseMessage.GET_NOT_SUPPORT;
 import static com.a.eye.skywalking.routing.http.module.ResponseMessage.SERVER_ERROR;
 
 public class RestfulAPIService extends NanoHTTPD {
+    public static final String JSON_MIME_TYPE = "application/json";
 
+    private static ILog logger = LogManager.getLogger(RestfulAPIService.class);
     private static final SpanStorageController spanController = new SpanStorageController();
-    public static final String JSON_MIME_TYPE = "application/json";
-    private ILog logger = LogManager.getLogger(RestfulAPIService.class);
 
     public RestfulAPIService(String host, int port) {
         super(host, port);
     }
 
-
     public void doStart() throws IOException {
         try {
             start(NanoHTTPD.SOCKET_READ_TIMEOUT, false);
@@ -39,10 +37,10 @@ public class RestfulAPIService extends NanoHTTPD {
     public Response serve(IHTTPSession session) {
         if (session.getMethod() != Method.POST) {
             return newFixedLengthResponse(Response.Status.OK, JSON_MIME_TYPE,
-                    new Gson().toJson(REQUEST_METHOD_NOT_SUPPORT));
+                    String.valueOf(GET_NOT_SUPPORT));
         }
 
-        ResponseMessage responseMessage = ResponseMessage.URL_NOT_FOUND;
+        ResponseMessage responseMessage = ResponseMessage.NOT_FOUND;
         try {
             String postData = getPostData(session);
             if (spanController.isAddAckSpanURI(session.getUri())) {
@@ -58,8 +56,7 @@ public class RestfulAPIService extends NanoHTTPD {
             responseMessage = SERVER_ERROR;
         }
 
-        return newFixedLengthResponse(Response.Status.OK, JSON_MIME_TYPE, new Gson().toJson
-                (responseMessage));
+        return newFixedLengthResponse(Response.Status.OK, JSON_MIME_TYPE, String.valueOf(responseMessage));
     }
 
     /**

skywalking-storage-center/skywalking-routing/src/main/java/com/a/eye/skywalking/routing/http/module/AckSpanModule.java

@@ -9,13 +9,16 @@ import java.util.Map;
 
 /**
  * Ack span module
+ * <p>
+ * All fields in this class will be initialized by {@link com.google.gson.Gson#fromJson(String, Class)},
+ * ignore the un-assign values warning.
  */
 public class AckSpanModule {
     private String traceId;
     private String parentLevelId = "";
-    private int levelId = 0;
+    private int    levelId       = 0;
     private long cost;
-    private int routeKey;
+    private int  routeKey;
 
     private Map<String, String> tags;
 
@@ -24,16 +27,15 @@ public class AckSpanModule {
             return null;
         }
 
-        return AckSpan.newBuilder().putAllTags(tags).setLevelId(levelId).setParentLevel
-                (parentLevelId).setRouteKey(routeKey).setCost(cost)
-                .setTraceId(TraceIdUtil.toTraceId(traceId)).build();
+        return AckSpan.newBuilder().putAllTags(tags).setLevelId(levelId).setParentLevel(parentLevelId)
+                .setRouteKey(routeKey).setCost(cost).setTraceId(TraceIdUtil.toTraceId(traceId)).build();
     }
 
     private boolean illegalAckSpan() {
         if (StringUtil.isEmpty(traceId)) {
             return true;
         }
-        if (tags.isEmpty()){
+        if (tags.isEmpty()) {
             return true;
         }
         return false;

skywalking-storage-center/skywalking-routing/src/main/java/com/a/eye/skywalking/routing/http/module/RequestSpanModule.java

@@ -9,22 +9,24 @@ import java.util.Map;
 
 /**
  * request span module
+ * <p>
+ * All fields in this class will be initialized by {@link com.google.gson.Gson#fromJson(String, Class)},
+ * ignore the un-assign values warning.
  */
 public class RequestSpanModule {
     private String traceId;
     private String parentLevelId = "";
-    private int levelId;
-    private long startTime;
-    private int routeKey;
+    private int                 levelId;
+    private long                startTime;
+    private int                 routeKey;
     private Map<String, String> tags;
 
     public RequestSpan convertToGRPCModule() {
         if (illegalRequestSpan()) {
             return null;
         }
-        return RequestSpan.newBuilder().putAllTags(tags).setLevelId(levelId).setParentLevel
-                (parentLevelId).setRouteKey(routeKey).setStartDate(startTime)
-                .setTraceId(TraceIdUtil.toTraceId(traceId)).build();
+        return RequestSpan.newBuilder().putAllTags(tags).setLevelId(levelId).setParentLevel(parentLevelId)
+                .setRouteKey(routeKey).setStartDate(startTime).setTraceId(TraceIdUtil.toTraceId(traceId)).build();
 
     }
 
@@ -32,7 +34,7 @@ public class RequestSpanModule {
         if (StringUtil.isEmpty(traceId)) {
             return true;
         }
-        if (tags.isEmpty()){
+        if (tags.isEmpty()) {
             return true;
         }
         return false;

skywalking-storage-center/skywalking-routing/src/main/java/com/a/eye/skywalking/routing/http/module/ResponseMessage.java

 package com.a.eye.skywalking.routing.http.module;
 
+import com.google.gson.JsonObject;
 
-import com.a.eye.skywalking.network.dependencies.com.google.gson.Gson;
-
-public class ResponseMessage {
-    public static final ResponseMessage OK = new ResponseMessage(200, "Store success");
-    public static final ResponseMessage REQUEST_METHOD_NOT_SUPPORT = new ResponseMessage(403, "Request method " +
-            "not support");
-    public static final ResponseMessage SERVER_ERROR = new ResponseMessage(500, "Server error");
-    public static final ResponseMessage URL_NOT_FOUND = new ResponseMessage(404, "Not found");
+/**
+ * A {@link ResponseMessage} represent a status code and response messages for http-service.
+ * <p>
+ * Created by wusheng on 2017/1/13.
+ */
+public enum ResponseMessage {
+    /**
+     * Request span or Ack Span are received and parsed without any errors.
+     */
+    OK(200, "Store success"),
+    /**
+     * Request a no-supported service.
+     */
+    GET_NOT_SUPPORT(405, "Get method not support"),
+    /**
+     * An internal error occurs.
+     */
+    SERVER_ERROR(500, "Server error"),
+    /**
+     * No service found. Also mean not provide this service.
+     */
+    NOT_FOUND(404, "Not found");
 
     /**
-     * Response code:
-     * 200 -- store success
-     * 403 -- request method not support
-     * 500 -- server error
-     * 404 -- not found
+     * The {@link String} represents the return message of the http services.
+     * It is in the JSON format, and formatted by {@link com.google.gson.Gson}.
      */
-    private int code;
     private String message;
 
     ResponseMessage(int code, String message) {
-        this.code = code;
-        this.message = message;
+        JsonObject messageFormatter = new JsonObject();
+        messageFormatter.addProperty("code", code);
+        messageFormatter.addProperty("message", message);
+        this.message = messageFormatter.toString();
     }
 
-    public int getCode() {
-        return code;
+    /**
+     * @return the return message of the http services.
+     */
+    @Override
+    public String toString() {
+        return message;
     }
 }