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HarmonyOS应用开发数据交互--关系型数据库完整流程练习
鸿蒙时代
发布于 2021-9-13 14:53
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1收藏
1.创建一个空的java项目
2.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”,
“visible”: false,
“uri”: “dataability://com.example.rdb.Database.fristRDB”
}
3.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.DataAbilityUtils;
import ohos.data.rdb.*;
import ohos.data.resultset.ResultSet;
import ohos.data.dataability.DataAbilityPredicates;
import ohos.hiviewdfx.HiLog;
import ohos.hiviewdfx.HiLogLabel;
import ohos.utils.net.Uri;
import ohos.utils.PacMap;
import java.io.FileDescriptor;
public class fristRDB extends Ability {
// 数据库参数
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"; //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, 0xD001100, "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 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_PERSON_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);
HiLog.info(LABEL_LOG, "fristRDB 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, DataAbilityPredicates 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) {
HiLog.info(LABEL_LOG, "resultSet is null");
}
return resultSet;
}
/**
* 数据添加
* @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) {
HiLog.info(LABEL_LOG, "fristRDB insert");
String path = uri.getLastPath();
// 判断数据添加的表名称
if (!"person".equals(path)) {
HiLog.info(LABEL_LOG, "DataAbility insert path is not matched");
return -1;
}
//用于整理存储添加的数据
ValuesBucket 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_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
public 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);
HiLog.info(LABEL_LOG, "delete: " + index);
// 通知观察者数据已经修改
DataAbilityHelper.creator(this, uri).notifyChange(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 = rdbStore.update(value, rdbPredicates);
HiLog.info(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) {
return new String[0];
}
@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", 18);
long id = rdbStore.insert("person", values);
}
}
4.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.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.HiLogLabel;
import ohos.utils.net.Uri;
public class MainAbilitySlice extends AbilitySlice {
private static final HiLogLabel LABEL_LOG = new HiLogLabel(3, 0xD001100, "Demo");
private static final String BASE_URI = "dataability:///com.example.rdb.Database.fristRDB";
private static final String DATA_PATH = "/person";
private static 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 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 intent) {
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 = databaseHelper.query(Uri.parse(BASE_URI + DATA_PATH),
columns, predicates);
if (resultSet == null || resultSet.getRowCount() == 0) {
HiLog.info(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_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));
HiLog.info(LABEL_LOG, "query: Id :" + id + " Name :" + name + " 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 valuesBucket = 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);
HiLog.info(LABEL_LOG, "valuesBucket:"+valuesBucket);
try {
if (databaseHelper.insert(Uri.parse(BASE_URI + DATA_PATH), valuesBucket) != -1) {
HiLog.info(LABEL_LOG, "insert successful");
}
} catch (DataAbilityRemoteException | IllegalStateException exception) {
HiLog.error(LABEL_LOG, "insert: dataRemote exception|illegalStateException");
}
}
public void update() {
DataAbilityPredicates predicates = new DataAbilityPredicates();
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) {
HiLog.info(LABEL_LOG, "update successful");
}
} catch (DataAbilityRemoteException | IllegalStateException exception) {
HiLog.error(LABEL_LOG, "update: dataRemote exception | illegalStateException");
}
}
public void delete(int id) {
DataAbilityPredicates predicates = new DataAbilityPredicates()
.equalTo(DB_COLUMN_PERSON_ID, id);
try {
if (databaseHelper.delete(Uri.parse(BASE_URI + DATA_PATH), predicates) != -1) {
HiLog.info(LABEL_LOG, "delete successful");
}
} catch (DataAbilityRemoteException | IllegalStateException exception) {
HiLog.error(LABEL_LOG, "delete: dataRemote exception | illegalStateException");
}
}
}
5.查看结果
在虚拟机上运行后，打开Hilog，搜索查看输出的内容。
完整代码地址：
https://gitee.com/jltfcloudcn/jump_to/tree/master/HarmonyOS关系型数据库练习/HarmonyOS关系型数据库练习
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HarmonyOS应用开发--关系型数据库案例练习.docx 260.51K 52次下载
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