更新

src/guide/uniqueIDGen.md

@@ -0,0 +1,41 @@
+# 唯一id
+基于表来完成分布式ID生成
+
+原理参考[美团点评分布式ID](https://tech.meituan.com/2017/04/21/mt-leaf.html)
+```java
+@Table(value = "leaf_alloc", comment = "唯一id分配")
+public class LeafAllocEntity  extends BaseEntity<LeafAllocEntity> {
+
+    @UniIndex
+    @ColumnDefine(comment = "业务key ，比如orderId", length = 20, notNull = true)
+    private String key;
+
+    @ColumnDefine(comment = "当前最大id", defaultValue = "1", notNull = true)
+    private Long maxId;
+
+    @ColumnDefine(comment = "步长", defaultValue = "500", notNull = true)
+    private Integer step;
+
+    @ColumnDefine(comment = "描述")
+    private String description;
+}
+```
+用法
+```
+// 注入service
+private final IDGenService idGenService;
+// 获取id，入参为key: orderId 需要提取初始化到上面那个
+Long orderId = idGenService.next("orderId");
+```
+项目启动自动插入数据参考 [数据初始化](/src/guide/initData.md)
+
+```json
+{
+  "leaf_alloc": [{
+    "key": "orderId",
+    "max_id": 1,
+    "step": 500,
+    "description": "订单ID"
+  }]
+}
+```