# DataAbilityRDBDemo

**Repository Path**: cxshu/data-ability-rdbdemo

## Basic Information

- **Project Name**: DataAbilityRDBDemo
- **Description**: 本示例通过DataAbility对关系型数据库（RDB）进行增加、删除、更新、查询
- **Primary Language**: Unknown
- **License**: Not specified
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2021-09-10
- **Last Updated**: 2021-09-11

## Categories & Tags

**Categories**: Uncategorized

**Tags**: HarmonyOS, dataability

## README


# 一、概述
使用Data模板的Ability（以下简称“Data”）有助于应用管理其自身和其他应用存储数据的访问，并提供与其他应用共享数据的方法。Data既可用于同设备不同应用的数据共享，也支持跨设备不同应用的数据共享。

数据的存放形式多样，可以是数据库，也可以是磁盘上的文件。
Data对外提供对数据的增、删、改、查，以及打开文件等接口，这些接口的具体实现由开发者提供。

本篇文章详细讲述了通过DataAbility来对关系型数据库进行操作。
![image](screenshots/phone/Snipaste_2021-09-11_14-31-01.png)
# 二、开发步骤：
## 1. 创建DataAbility
1. 新建一个Empty DataAbility，创建完成后，会在config.json里生成如下配置
```json
{
    "permissions": [
      "com.cxs.rdbdemo.DataAbilityShellProvider.PROVIDER"
    ],
    "name": "com.cxs.rdbdemo.DataAbility",
    "icon": "$media:icon",
    "description": "$string:dataability_description",
    "type": "data",
    "uri": "dataability://com.cxs.rdbdemo.DataAbility"
}
```
2. 申请访问该DataAbility时需要的权限
```json
"reqPermissions": [
  {
    "name": "com.cxs.rdbdemo.DataAbilityShellProvider.PROVIDER"
  }
]
```
## 2. DataAbiliy操作数据库
1. __创建数据库__  
在DataAbility的onStart()方法中创建关系型数据库，在数据库中新增两个表（user和book）
```java
public class DataAbility extends Ability {
    private RdbStore rdbStore;
    RdbOpenCallback callback = new RdbOpenCallback() {
        @Override
        public void onCreate(RdbStore rdbStore) {
            // 创建数据库时被回调，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
            rdbStore.executeSql("CREATE TABLE IF NOT EXISTS user" +
                    "(id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, age INTEGER, salary REAL)");
            rdbStore.executeSql("CREATE TABLE IF NOT EXISTS book" +
                    "(id INTEGER PRIMARY KEY AUTOINCREMENT, title TEXT NOT NULL, price REAL)");
        }

        @Override
        public void onUpgrade(RdbStore rdbStore, int i, int i1) {}
    };

    @Override
    public void onStart(Intent intent) {
        super.onStart(intent);
        DatabaseHelper helper = new DatabaseHelper(this);
        StoreConfig config = StoreConfig.newDefaultConfig("rdbstoretest.db");
        rdbStore = helper.getRdbStore(config, 1, callback);
    }
}
```

2. __插入数据__  
重写 DataAbility 中的插入方法
```java
@Override
public int insert(Uri uri, ValuesBucket value) {
    if (rdbStore == null) {
        return -1;
    }
    long index = rdbStore.insert(uri.getLastPath(), value);
    return (int)index;
}
```
3. __查询数据__  
重写 DataAbility 中的查询方法
```java
@Override
public ResultSet query(Uri uri, String[] columns, DataAbilityPredicates predicates) {
    // 把DataAbilityPredicates转换为RdbPredicates
    RdbPredicates rdbPredicates = DataAbilityUtils.createRdbPredicates(predicates, uri.getLastPath());
    ResultSet query = rdbStore.query(rdbPredicates, columns);
    return query;
}
```

4. __更新数据__
```java
@Override
public int update(Uri uri, ValuesBucket value, DataAbilityPredicates predicates) {
    RdbPredicates rdbPredicates = DataAbilityUtils.createRdbPredicates(predicates, uri.getLastPath());
    int update = rdbStore.update(value, rdbPredicates);
    return update;
}
```

5. __删除数据__
```java
@Override
public int delete(Uri uri, DataAbilityPredicates predicates) {
    RdbPredicates rdbPredicates = DataAbilityUtils.createRdbPredicates(predicates, uri.getLastPath());
    int delete = rdbStore.delete(rdbPredicates);
    return delete;
}
```

## 3. 访问DataAbility
开发者可以通过DataAbilityHelper类来访问当前应用或其他应用提供的共享数据。
```java
private static final String BASE_URI = "dataability:///com.cxs.rdbdemo.DataAbility/";
private static final String TABLE_USER = "user";
private static final String TABLE_BOOK = "book";
Uri userUri, bookUri;
DataAbilityHelper helper;

@Override
public void onStart(Intent intent) {
    ...
    helper = DataAbilityHelper.creator(this);
    userUri = Uri.parse(BASE_URI + TABLE_USER);
    bookUri = Uri.parse(BASE_URI + TABLE_BOOK);
}
```
1. 查询数据
```java
DataAbilityPredicates predicates = new DataAbilityPredicates();
try {
    ResultSet query = helper.query(userUri,
            new String[]{"name", "age", "salary"}, predicates);
    while (query.goToNextRow()) {
        System.out.println(query.getString(query.getColumnIndexForName("name")));
        System.out.println(query.getInt(query.getColumnIndexForName("age")));
        System.out.println(query.getDouble(query.getColumnIndexForName("salary")));
    }
} catch (DataAbilityRemoteException e) {
    e.printStackTrace();
}
```
2. 插入数据
```java
ValuesBucket valuesBucket = new ValuesBucket();
valuesBucket.putString("name", "zhangsan");
valuesBucket.putInteger("age", 20);
valuesBucket.putDouble("salary", 567.34);
try {
    helper.insert(userUri, valuesBucket);
} catch (DataAbilityRemoteException e) {
    e.printStackTrace();
}   
```

3. 更新数据
```java
ValuesBucket valuesBucket = new ValuesBucket();
valuesBucket.putString("name", "张三");
DataAbilityPredicates predicates = new DataAbilityPredicates().equalTo("name", "zhangsan");

try {
    int update = helper.update(userUri, valuesBucket, predicates);
} catch (DataAbilityRemoteException e) {
    e.printStackTrace();
}
```

4. 删除数据
```java
DataAbilityPredicates predicates = new DataAbilityPredicates()
        .greaterThan("age", 18);
try {
    helper.delete(userUri, predicates);
} catch (DataAbilityRemoteException e) {
    e.printStackTrace();
}
```