数据库升级与创建操作

common/src/main/ets/db/util/AbstractDbOption.ets

+import relationalStore from '@ohos.data.relationalStore';
+
+/**
+ * 数据库操作
+ */
+export abstract class AbstractDbOption {
+
+  /**
+   * 数据库对象-创建
+   */
+  abstract onCreate(db: relationalStore.RdbStore)
+
+  /**
+   * 数据库对象-版本
+   */
+  abstract onUpgrade(db: relationalStore.RdbStore, oldVersion: number, newVersion: number)
+}
\ No newline at end of file

common/src/main/ets/db/util/DbHelper.ets

+import relationalStore from '@ohos.data.relationalStore';
+import dataPreferences from '@ohos.data.preferences'
+import { AbstractDbOption } from './AbstractDbOption';
+import { Logger } from '../../utils/Logger';
+
+
+/**
+ * 数据工具类
+ */
+class DbHelper {
+  dbContext: Context;
+  dbName: string = '';
+  dbVersion: number = 0;
+  rdbStore: relationalStore.RdbStore;
+
+  /**
+   * 初始化数据库
+   * @param context
+   * @param dbName
+   * @param dbVersion
+   * @param dbOpts
+   */
+  async initDb(context: Context, dbName: string, dbVersion: number, dbOpts: AbstractDbOption) {
+    if (dbVersion <= 0) {
+      throw new Error("数据库版本必须大于0");
+    }
+    this.dbContext = context;
+    this.dbName = dbName;
+    this.dbVersion = dbVersion;
+    if (this.rdbStore) {
+      this.rdbStore = null;
+    }
+    //定义Preference缓存键
+    let dbPreferenceKey = `junmp_db_preference`;
+    let dbVersionKey = `junmp_db_version_${dbName}`;
+    //去当前的缓存
+    let preferences = await dataPreferences.getPreferences(context, dbPreferenceKey);
+    let oldVersion = (await preferences.get(dbVersionKey, 0)) as number
+    if (this.dbVersion < oldVersion) {
+      this.dbVersion = oldVersion;
+    }
+    //获取RDB对象
+    await this.getRdbStore();
+
+    if (oldVersion != this.dbVersion) {
+      await dbOpts.onCreate(this.rdbStore);
+      if (oldVersion < this.dbVersion) {
+        this.beginTransaction();
+        await dbOpts.onUpgrade(this.rdbStore, oldVersion, this.dbVersion);
+        this.commit();
+      }
+      //把新的版本信息刷进缓存
+      await preferences.put(dbVersionKey, this.dbVersion);
+      await preferences.flush();
+    }
+  }
+
+  /**
+   * 获取RDB对象
+   */
+  getRdbStore(): Promise<relationalStore.RdbStore> {
+    return new Promise((resolve, reject) => {
+      if (this.rdbStore) {
+        resolve(this.rdbStore);
+      } else {
+        relationalStore.getRdbStore(this.dbContext, {
+          name: this.dbName,
+          securityLevel: relationalStore.SecurityLevel.S1
+        }).then((store) => {
+          this.rdbStore = store;
+          resolve(store)
+        }).catch(e => {
+          Logger.error(this, '初始化RDB异常', e);
+          reject(e)
+        })
+      }
+    })
+  }
+
+  beginTransaction() {
+    if (this.rdbStore) {
+      Logger.info(this, "事务开始")
+      this.rdbStore.beginTransaction()
+    }
+  }
+
+  commit() {
+    if (this.rdbStore) {
+      Logger.info(this, "事务提交")
+      this.rdbStore.commit()
+    }
+  }
+
+  rollBack() {
+    if (this.rdbStore) {
+      Logger.info(this, "事务回滚")
+      this.rdbStore.rollBack()
+    }
+  }
+}
+
+export default new DbHelper();
\ No newline at end of file