add Payload(Block block)

src/main/java/component/Payload.java

@@ -16,7 +16,14 @@ public class Payload implements TlvComponentBase,InitialAble, IEncodingAble {
     // 成员变量
     private byte[] value;
 
-    // 函数
+    /**
+     * 构造函数
+     * @param block
+     */
+    public Payload(Block block){
+        this.buildPayloadByBlock(block);
+    }
+
     /**
      * 根据 TLV Block 初始化一个 Payload
      * @param block