From 8c2246cc852ffd272a9eb6498e8d235a0064fb12 Mon Sep 17 00:00:00 2001
From: qi <qi_liang_gz@163.com>
Date: Tue, 4 Aug 2020 11:40:17 +0800
Subject: [PATCH] =?UTF-8?q?=E6=96=B0=E5=A2=9E=E4=B8=BB=E9=94=AEID=E7=94=9F?=
 =?UTF-8?q?=E6=88=90=E5=99=A8?=
MIME-Version: 1.0
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---
 .../java/org/panda/jdbc/id/IdGenerate.java    |  14 ++
 .../panda/jdbc/id/SnowflakeIdGenerate.java    | 138 ++++++++++++++++++
 .../java/org/panda/jdbc/id/UUIdGenerate.java  |  14 ++
 3 files changed, 166 insertions(+)
 create mode 100644 panda-jdbc/src/main/java/org/panda/jdbc/id/IdGenerate.java
 create mode 100644 panda-jdbc/src/main/java/org/panda/jdbc/id/SnowflakeIdGenerate.java
 create mode 100644 panda-jdbc/src/main/java/org/panda/jdbc/id/UUIdGenerate.java

diff --git a/panda-jdbc/src/main/java/org/panda/jdbc/id/IdGenerate.java b/panda-jdbc/src/main/java/org/panda/jdbc/id/IdGenerate.java
new file mode 100644
index 0000000..e4a90d8
--- /dev/null
+++ b/panda-jdbc/src/main/java/org/panda/jdbc/id/IdGenerate.java
@@ -0,0 +1,14 @@
+package org.panda.jdbc.id;
+
+/**
+ * 数据库主键ID生成器
+ * @author qi
+ */
+public interface IdGenerate<T> {
+
+    /**
+     *
+     * @return 主键ID
+     */
+    T nextId();
+}
diff --git a/panda-jdbc/src/main/java/org/panda/jdbc/id/SnowflakeIdGenerate.java b/panda-jdbc/src/main/java/org/panda/jdbc/id/SnowflakeIdGenerate.java
new file mode 100644
index 0000000..431bce3
--- /dev/null
+++ b/panda-jdbc/src/main/java/org/panda/jdbc/id/SnowflakeIdGenerate.java
@@ -0,0 +1,138 @@
+package org.panda.jdbc.id;
+
+/**
+ * @Description 雪花主键ID生成
+ * @Author qi
+ **/
+public class SnowflakeIdGenerate implements IdGenerate<Long> {
+
+    /**
+     * 开始时间戳
+     */
+    private final long twepoch = 1420041600000L;
+
+    /**
+     * 机器id所占的位数
+     */
+    private final long workerIdBits = 5L;
+
+    /**
+     * 数据标识id所占的位数
+     */
+    private final long dataCenterIdBits = 5L;
+
+    /**
+     * 支持的最大机器ID,结果是31(位移算法可以很快计算出二进制所能表示的最大十进制数)
+     */
+    private final long maxWorkerId = -1L^(-1L<<workerIdBits);
+
+    /**
+     * 支持的最大数据标识DI,结果是31
+     */
+    private final long maxDataCenterId = -1L^(-1L<<dataCenterIdBits);
+
+    /**
+     * 序列在id中咱的位数
+     */
+    private final long sequenceBits = 12L;
+
+    /**
+     * 机器ID向左位移12位
+     */
+    private final long workerIdShift = sequenceBits;
+
+    /**
+     * 数据标识ID向左位移17位(12+5)
+     */
+    private final long dataCenterIdShift = sequenceBits+workerIdBits;
+
+    /**
+     * 时间戳向左位移22位(12+5+5)
+     */
+    private final long timestampLeftShift =sequenceBits+workerIdBits+dataCenterIdShift;
+
+    /**
+     * 生成序列的掩码,这里为4095
+     */
+    private final long sequenceMask = -1L^(-1L<<sequenceBits);
+
+    /**
+     * 工作机器ID(0-31)
+     */
+    private long workerId;
+    /**
+     * 数据中心ID(0-31)
+     */
+    private long dataCenterId;
+    /**
+     * 毫秒内序列（0-4095）
+     */
+    private long sequence = 0L;
+    /**
+     * 上次生成ID的时间戳
+     */
+    private long lastTimeStamp = -1L;
+
+    /**
+     * 构造方法
+     * @param workerId 机器ID
+     * @param dataCenterId 数据中心ID
+     */
+    public SnowflakeIdGenerate(long workerId, long dataCenterId) {
+        if (workerId>maxWorkerId||workerId<0){
+            throw new IllegalArgumentException();
+        }
+        if (dataCenterId>maxDataCenterId||dataCenterId<0){
+            throw new IllegalArgumentException();
+        }
+        this.workerId = workerId;
+        this.dataCenterId = dataCenterId;
+    }
+
+    @Override
+    public synchronized Long nextId() {
+
+        long timestamp = timeGen();
+        if (timestamp<lastTimeStamp){
+            throw new RuntimeException(
+                    String.format("Clock moved backwards.  Refusing to generate id for %d milliseconds", lastTimeStamp - timestamp));
+        }
+        if (lastTimeStamp == timestamp){
+            sequence = (sequence+1)&sequenceMask;
+            if (sequenceMask == 0){
+                timestamp = tilNextMillis(lastTimeStamp);
+            }
+        }else {
+            sequence = 0L;
+        }
+        //上次生成ID的时间戳
+        lastTimeStamp = timestamp;
+        return ((timestamp-twepoch)<<timestampLeftShift)
+                |(dataCenterId<<dataCenterIdShift)
+                |(workerId<<workerIdShift)
+                |sequence;
+    }
+
+    /**
+     * 阻塞到下一个毫秒,知道获取新的时间戳
+     * @param lastTimestamp
+     * @return
+     */
+    private long tilNextMillis(long lastTimestamp){
+        long timestamp = timeGen();
+        while (timestamp<=lastTimestamp){
+            timestamp = timeGen();
+        }
+        return timestamp;
+    }
+
+    /**
+     * 获取当前时间戳
+     * @return
+     */
+    private long timeGen(){
+
+        return System.currentTimeMillis();
+    }
+
+}
diff --git a/panda-jdbc/src/main/java/org/panda/jdbc/id/UUIdGenerate.java b/panda-jdbc/src/main/java/org/panda/jdbc/id/UUIdGenerate.java
new file mode 100644
index 0000000..f6035f2
--- /dev/null
+++ b/panda-jdbc/src/main/java/org/panda/jdbc/id/UUIdGenerate.java
@@ -0,0 +1,14 @@
+package org.panda.jdbc.id;
+
+import java.util.UUID;
+
+/**
+ * @Description uuid主键生成
+ * @Author qi
+ **/
+public class UUIdGenerate implements IdGenerate<String> {
+    @Override
+    public String nextId() {
+        return UUID.randomUUID().toString();
+    }
+}