零基础学鸿蒙编程轻量级数据库

轻量级数据库是一种以键值对形式保存数据的存储方式.每条数据都需要指定一个唯一键名来进行区分.可以存储布尔型、整型、字符串等基础数据类型.其特点为简单、轻量,适合保存少量简单类型的数据,不适合保存大批量或复杂类型的数据.，我来为大家科普一下关于零基础学鸿蒙编程轻量级数据库?以下内容希望对你有帮助!

零基础学鸿蒙编程轻量级数据库

什么是轻量级数据库

轻量级数据库是一种以键值对形式保存数据的存储方式.每条数据都需要指定一个唯一键名来进行区分.可以存储布尔型、整型、字符串等基础数据类型.其特点为简单、轻量,适合保存少量简单类型的数据,不适合保存大批量或复杂类型的数据.

基础样例

1. 写入和读取数据

1. java代码

public class MainAbilitySlice extends AbilitySlice { private Preferences preferences; @Override public void onStart(Intent intent) { super.onStart(intent); super.setUIContent(ResourceTable.Layout_ability_main); DatabaseHelper databaseHelper = new DatabaseHelper(getContext()); String filename = "pdb"; preferences = databaseHelper.getPreferences(filename); findComponentById(ResourceTable.Id_writeText).setClickedListener(component -> write()); findComponentById(ResourceTable.Id_readText).setClickedListener(component -> read()); findComponentById(ResourceTable.Id_modifyText).setClickedListener(component -> modify()); findComponentById(ResourceTable.Id_delText).setClickedListener(component -> del()); } private void write() { preferences.putString("name", "花生皮编程"); preferences.flush(); } private void read() { String name = preferences.getString("name", "数据不存在"); new ToastDialog(getContext()).setText(name).show(); } private void modify() { preferences.putString("name", "花生皮编程2"); preferences.flush(); } private void del() { preferences.delete("name"); }}

2. 对应页面布局文件:

<?xml version="1.0" encoding="utf-8"?><DirectionalLayout xmlns:ohos="http://schemas.huawei.com/res/ohos" ohos:height="match_parent" ohos:width="match_parent" ohos:alignment="center" ohos:orientation="vertical"> <Text ohos:id="$ id:writeText" ohos:height="match_content" ohos:width="match_content" ohos:text="写数据" ohos:text_size="20fp"/> <Text ohos:id="$ id:readText" ohos:height="match_content" ohos:width="match_content" ohos:text="读数据" ohos:text_size="20fp"/> <Text ohos:id="$ id:modifyText" ohos:height="match_content" ohos:width="match_content" ohos:text="修改数据" ohos:text_size="20fp"/> <Text ohos:id="$ id:delText" ohos:height="match_content" ohos:width="match_content" ohos:text="删除数据" ohos:text_size="20fp"/></DirectionalLayout>

常用函数说明

完整源代码

http://gitee.com/hspbc/harmonyos_demos/tree/master/preferenceDemo