add some common utils

src/main/java/com/example/freshonline/constants/Constants.java

+package com.example.freshonline.constants;
+
+public class Constants {
+
+    public static final String CODE = "code";
+    public static final int SUCCESS_CODE = 0;
+    public static final int FAIL_CODE = -1;
+
+    public static final String MSG = "msg";
+    public static final String DATA = "data";
+
+
+    public static final String ADD_GOODS_SUCCESS = "add goods success";
+    public static final String UPDATE_GOODS_SUCCESS = "update goods success";
+    public static final String DELETE_GOODS_SUCCESS = "delete goods success";
+
+    public static final String ADD_GOODS_FAIL = "add goods fail";
+    public static final String UPDATE_GOODS_FAIL = "update goods fail";
+    public static final String DELETE_GOODS_FAIL = "delete goods fail";
+
+
+
+}

src/main/java/com/example/freshonline/enums/respVerifyRule/VerifyRespData.java

+package com.example.freshonline.enums.respVerifyRule;
+
+/**
+ * @author zekun
+ */
+public interface VerifyRespData {
+
+    boolean verify(Object data);
+}

src/main/java/com/example/freshonline/enums/respVerifyRule/VerifyRule.java

+package com.example.freshonline.enums.respVerifyRule;
+
+import lombok.Data;
+
+import java.util.Collection;
+
+/**
+ * rules that verify response data
+ * @author zekun
+ */
+public enum VerifyRule implements VerifyRespData {
+
+    NOT_NULL{
+        @Override
+        public boolean verify(Object data) {
+            return data != null;
+        }
+    },
+    COLLECTION_NOT_EMPTY{
+        @Override
+        public boolean verify(Object data) {
+            Collection<?> collection = (Collection<?>) data;
+            return collection != null && !collection.isEmpty();
+        }
+    },
+    GREATER_THAN_ZERO{
+        @Override
+        public boolean verify(Object data) {
+            return (Integer)data > 0;
+        }
+    },
+    TRUE{
+        @Override
+        public boolean verify(Object data) {
+            return (Boolean)data;
+        }
+    }
+    ;
+}

src/main/java/com/example/freshonline/utils/RespBuilder.java

+package com.example.freshonline.utils;
+
+import com.alibaba.fastjson.JSONObject;
+import com.example.freshonline.constants.Constants;
+import com.example.freshonline.enums.respVerifyRule.VerifyRule;
+
+/**
+ * response builder
+ * @author zekun
+ */
+public class RespBuilder {
+
+    public static JSONObject create(Object data, VerifyRule rule, String success_msg, String fail_msg) {
+        JSONObject resp = new JSONObject();
+        if (rule.verify(data)){
+            resp.put(Constants.CODE, Constants.SUCCESS_CODE);
+            resp.put(Constants.MSG, success_msg);
+            resp.put(Constants.DATA, data);
+        }else{
+            resp.put(Constants.CODE, Constants.FAIL_CODE);
+            resp.put(Constants.MSG, fail_msg);
+        }
+        return resp;
+    }
+}