HarmonyOS应用开发-关系型数据库案例练习

1、 HarmonyOS应用开发数据交互-关系型数据库完整流程练习创建一个空的java项目创建data Ability如下步骤所示，创建完成后会生成相应的文件，同时会帮您修改好配置文件。配置文件（这部分自动生成，与你的目录结果、建议不要修改）： permissions: com.example.rdb.DataAbilityShellProvider.PROVIDER , name: com.example.rdb.Database.fristRDB, icon: $media:icon, description: $string:fristrdb_description, type: data,

2、 visible: false, uri: dataability:/com.example.rdb.Database.fristRDB编写创建数据库代码编写的fristRDB.java文件：package com.example.rdb.Database;import ohos.aafwk.ability.Ability;import ohos.aafwk.ability.DataAbilityHelper;import ohos.aafwk.content.Intent;import ohos.data.DatabaseHelper;import ohos.data.dataability

3、.DataAbilityUtils;import ohos.data.rdb.*;import ohos.data.resultset.ResultSet;import ohos.data.dataability.DataAbilityPredicates;import ohos.hiviewdfx.HiLog;import ohos.hiviewdfx.HiLogLabel;import .Uri;import ohos.utils.PacMap;import java.io.FileDescriptor;public class fristRDB extends Ability / 数据库

4、参数 private static final String DB_NAME = persondataability.db; /数据库名称 private static final String DB_TAB_NAME = person; /表名称 private static final String DB_COLUMN_PERSON_ID = id; /列 id private static final String DB_COLUMN_NAME = name; /列 name private static final String DB_COLUMN_GENDER = gender; /

5、列 gender private static final String DB_COLUMN_AGE = age; /列 age private static final int DB_VERSION = 1; /版本 private static final HiLogLabel LABEL_LOG = new HiLogLabel(3, 0 xD001100, Demo); private StoreConfig config = StoreConfig.newDefaultConfig(DB_NAME); /通过指定数据库名称使用默认配置创建数据库配置。 private RdbStore

6、 rdbStore; /提供管理关系数据库 (RDB) 的方法。 / RdbOpenCallback 管理数据库创建、升级和降级。 private RdbOpenCallback rdbOpenCallback = new RdbOpenCallback() Override public void onCreate(RdbStore store) / 数据库创建时被回调，开发者可以在该方法中初始化表结构，并添加一些应用使用到的初始化数据。 store.executeSql(create table if not exists + DB_TAB_NAME + ( + DB_COLUMN_PER

7、SON_ID + integer primary key, + DB_COLUMN_NAME + text not null, + DB_COLUMN_GENDER + text not null, + DB_COLUMN_AGE + integer); Override public void onUpgrade(RdbStore store, int oldVersion, int newVersion) ; Override public void onStart(Intent intent) super.onStart(intent); HiL(LABEL_LOG, fristRDB

8、onStart); DatabaseHelper databaseHelper = new DatabaseHelper(this); / 根据配置创建或打开数据库。 rdbStore = databaseHelper.getRdbStore(config, DB_VERSION, rdbOpenCallback, null); /* * 数据查询 * param uri * param columns * param predicates * return */ Override public ResultSet query(Uri uri, String columns, DataAbil

9、ityPredicates predicates) / 拼装查询语句 RdbPredicates rdbPredicates = DataAbilityUtils.createRdbPredicates(predicates, DB_TAB_NAME); / 查询表中数据 根据 查询语句 + 查找的列 ResultSet resultSet = rdbStore.query(rdbPredicates, columns); if (resultSet = null) HiL(LABEL_LOG, resultSet is null); return resultSet; /* * 数据添加 *

10、 param uri 插入的目标路径 * param value 插入的数据值 * return */ Override public int insert(Uri uri, ValuesBucket value) HiL(LABEL_LOG, fristRDB insert); String path = uri.getLastPath(); / 判断数据添加的表名称 if (!person.equals(path) HiL(LABEL_LOG, DataAbility insert path is not matched); return -1; /用于整理存储添加的数据 ValuesBu

11、cket values = new ValuesBucket(); values.putInteger(DB_COLUMN_PERSON_ID, value.getInteger(DB_COLUMN_PERSON_ID); values.putString(DB_COLUMN_NAME, value.getString(DB_COLUMN_NAME); values.putString(DB_COLUMN_GENDER, value.getString(DB_COLUMN_GENDER); values.putInteger(DB_COLUMN_AGE, value.getInteger(DB

12、_COLUMN_AGE); int index = (int) rdbStore.insert(DB_TAB_NAME, values); / 当表格数据插入成功时，可执行DataAbilityHelper.creator(this, uri).notifyChange(uri)，通知该表格数据的订阅者 DataAbilityHelper.creator(this, uri).notifyChange(uri); return index; /* * 数据删除 * param uri 删除的目标路径 * param predicates 删除条件 * return */ Override pu

13、blic int delete(Uri uri, DataAbilityPredicates predicates) / 解析出要删除的数据 RdbPredicates rdbPredicates = DataAbilityUtils.createRdbPredicates(predicates, DB_TAB_NAME); int index = rdbStore.delete(rdbPredicates); HiL(LABEL_LOG, delete: + index); / 通知观察者数据已经修改 DataAbilityHelper.creator(this, uri).notifyCh

14、ange(uri); return index; /* * 数据修改 * param uri * param value * param predicates * return */ Override public int update(Uri uri, ValuesBucket value, DataAbilityPredicates predicates) / 解析出要修改的数据 RdbPredicates rdbPredicates = DataAbilityUtils.createRdbPredicates(predicates, DB_TAB_NAME); int index = r

15、dbStore.update(value, rdbPredicates); HiL(LABEL_LOG, update: + index); / 通知观察者数据已经修改 DataAbilityHelper.creator(this, uri).notifyChange(uri); return index; Override public FileDescriptor openFile(Uri uri, String mode) return null; Override public String getFileTypes(Uri uri, String mimeTypeFilter) re

16、turn new String0; Override public PacMap call(String method, String arg, PacMap extras) return null; Override public String getType(Uri uri) return null; public void myInsert() ValuesBucket values = new ValuesBucket(); values.putInteger(id, 1); values.putString(name, zhangsan); values.putInteger(age

17、, 18); long id = rdbStore.insert(person, values); 编写数据操作代码为了方便在在MainAbility上编写数据库操作代码。package com.example.rdb.slice;import com.example.rdb.Database.MyDataAbilityHelper;import com.example.rdb.ResourceTable;import ohos.aafwk.ability.AbilitySlice;import ohos.aafwk.ability.DataAbilityHelper;import ohos.

18、aafwk.ability.DataAbilityRemoteException;import ohos.aafwk.content.Intent;import ohos.app.Context;import ohos.data.dataability.DataAbilityPredicates;import ohos.data.rdb.RdbStore;import ohos.data.rdb.ValuesBucket;import ohos.data.resultset.ResultSet;import ohos.hiviewdfx.HiLog;import ohos.hiviewdfx.

19、HiLogLabel;import .Uri;public class MainAbilitySlice extends AbilitySlice private static final HiLogLabel LABEL_LOG = new HiLogLabel(3, 0 xD001100, Demo); private static final String BASE_URI = dataability:/com.example.rdb.Database.fristRDB; private static final String DATA_PATH = /person; private s

20、tatic final String DB_COLUMN_PERSON_ID = id; private static final String DB_COLUMN_NAME = name; private static final String DB_COLUMN_GENDER = gender; private static final String DB_COLUMN_AGE = age; private DataAbilityHelper databaseHelper = DataAbilityHelper.creator(Context) this); Override public

21、 void onStart(Intent intent) super.onStart(intent); super.setUIContent(ResourceTable.Layout_ability_main); databaseHelper = DataAbilityHelper.creator(this); insert(33, Tom, man, 20); query(); delete(33); Override public void onActive() super.onActive(); Override public void onForeground(Intent inten

22、t) super.onForeground(intent); public void query() String columns = new String DB_COLUMN_PERSON_ID, DB_COLUMN_NAME, DB_COLUMN_GENDER, DB_COLUMN_AGE; / 构造查询条件 DataAbilityPredicates predicates = new DataAbilityPredicates(); predicates.between(DB_COLUMN_AGE, 15, 40); try ResultSet resultSet = databaseH

23、elper.query(Uri.parse(BASE_URI + DATA_PATH), columns, predicates); if (resultSet = null | resultSet.getRowCount() = 0) HiL(LABEL_LOG, query: resultSet is null or no result found); return; /移动到第一行 resultSet.goToFirstRow(); do int id = resultSet.getInt(resultSet.getColumnIndexForName(DB_COLUMN_PERSON_

24、ID); String name = resultSet.getString(resultSet.getColumnIndexForName(DB_COLUMN_NAME); String gender = resultSet.getString(resultSet.getColumnIndexForName(DB_COLUMN_GENDER); int age = resultSet.getInt(resultSet.getColumnIndexForName(DB_COLUMN_AGE); HiL(LABEL_LOG, query: Id : + id + Name : + name +

25、Gender : + gender + Age : + age); while (resultSet.goToNextRow();/移动到下一行一行 catch (DataAbilityRemoteException | IllegalStateException exception) HiLog.error(LABEL_LOG, query: dataRemote exception | illegalStateException); public void insert(int id, String name, String gender, int age) ValuesBucket va

26、luesBucket = new ValuesBucket(); valuesBucket.putInteger(DB_COLUMN_PERSON_ID, id); valuesBucket.putString(DB_COLUMN_NAME, name); valuesBucket.putString(DB_COLUMN_GENDER, gender); valuesBucket.putInteger(DB_COLUMN_AGE, age); HiL(LABEL_LOG, valuesBucket:+valuesBucket); try if (databaseHelper.insert(Ur

27、i.parse(BASE_URI + DATA_PATH), valuesBucket) != -1) HiL(LABEL_LOG, insert successful); catch (DataAbilityRemoteException | IllegalStateException exception) HiLog.error(LABEL_LOG, insert: dataRemote exception|illegalStateException); public void update() DataAbilityPredicates predicates = new DataAbil

28、ityPredicates(); predicates.equalTo(DB_COLUMN_PERSON_ID, 102); ValuesBucket valuesBucket = new ValuesBucket(); valuesBucket.putString(DB_COLUMN_NAME, ZhangSanPlus); valuesBucket.putInteger(DB_COLUMN_AGE, 28); try if (databaseHelper.update(Uri.parse(BASE_URI + DATA_PATH), valuesBucket, predicates) != -1) HiL(LABEL_LOG, update successful); catch (DataAbilityRemoteException | I