From 8168b0b14dee8ac314dc32ac92ab907f89637384 Mon Sep 17 00:00:00 2001
From: ascrutae <ascrutae@gmail.com>
Date: Sat, 4 Jun 2016 09:13:20 +0800
Subject: [PATCH] =?UTF-8?q?=E6=8F=90=E4=BA=A4ProtocolPackager?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../skywalking/util/ProtocolPackager.java     | 73 +++++++++++++++++++
 1 file changed, 73 insertions(+)
 create mode 100644 skywalking-protocol/src/main/java/com/ai/cloud/skywalking/util/ProtocolPackager.java

diff --git a/skywalking-protocol/src/main/java/com/ai/cloud/skywalking/util/ProtocolPackager.java b/skywalking-protocol/src/main/java/com/ai/cloud/skywalking/util/ProtocolPackager.java
new file mode 100644
index 000000000..e162612c0
--- /dev/null
+++ b/skywalking-protocol/src/main/java/com/ai/cloud/skywalking/util/ProtocolPackager.java
@@ -0,0 +1,73 @@
+package com.ai.cloud.skywalking.util;
+
+import java.util.Arrays;
+
+public class ProtocolPackager {
+    public static byte[] pack(byte[] data) {
+        // 对协议格式进行修改
+        // | check sum(4 byte) |  data
+        byte[] dataPackage = new byte[data.length + 4];
+
+        packDataText(data, dataPackage);
+        packCheckSum(data, dataPackage);
+
+        return dataPackage;
+    }
+
+    private static void packCheckSum(byte[] data, byte[] dataPackage) {
+        byte[] checkSumArray = generateChecksum(data, 0);
+        System.arraycopy(checkSumArray, 0, dataPackage, 0, 4);
+    }
+
+    private static void packDataText(byte[] data, byte[] dataPackage) {
+        System.arraycopy(data, 0, dataPackage, 4, data.length);
+    }
+
+
+    public static byte[] unpack(byte[] dataPackage) {
+        if (validateCheckSum(dataPackage)) {
+            return unpackDataText(dataPackage);
+        } else {
+            return null;
+        }
+
+    }
+
+    private static byte[] unpackDataText(byte[] dataPackage) {
+        byte[] data = new byte[dataPackage.length - 4];
+        System.arraycopy(dataPackage, 4, data, 0, data.length);
+        return data;
+    }
+
+    private static boolean validateCheckSum(byte[] dataPackage){
+        byte[] checkSum = generateChecksum(dataPackage, 4);
+        byte[] originCheckSum = new byte[4];
+        System.arraycopy(dataPackage, 0, originCheckSum, 0, 4);
+        return Arrays.equals(checkSum, originCheckSum);
+    }
+
+    /**
+     * 生成校验和参数
+     *
+     * @param data
+     * @return
+     */
+    private static byte[] generateChecksum(byte[] data, int offset) {
+        int result = data[0];
+        for (int i = offset; i < data.length; i++) {
+            result ^= data[i];
+        }
+
+        return intToBytes(result);
+    }
+
+    private static byte[] intToBytes(int value) {
+        byte[] src = new byte[4];
+        src[0] = (byte) ((value >> 24) & 0xFF);
+        src[1] = (byte) ((value >> 16) & 0xFF);
+        src[2] = (byte) ((value >> 8) & 0xFF);
+        src[3] = (byte) (value & 0xFF);
+        return src;
+    }
+
+}