HarmonyOS基础技术赋能之对象关系映射数据库的使用 原创 精华

引言
HarmonyOS对象关系映射（Object Relational Mapping，ORM）数据库是一款基于SQLite的数据库框架，屏蔽了底层SQLite数据库的SQL操作，针对实体和关系提供了增删改查等一系列的面向对象接口。应用开发者不必再去编写复杂的SQL语句， 以操作对象的形式来操作数据库，提升效率的同时也能聚焦于业务开发。

功能介绍
对象关系映射数据库目前可以支持数据库和表的创建，对象数据的增删改查、对象数据变化回调、数据库升降级和备份等功能。

开发指南
1. 配置“build.gradle”文件。

//在ohos节点中添加以下配置：

compileOptions{        

    annotationEnabled true    

} 

2. 构造数据库。

//例如，定义了一个数据库类BookStore.java，数据库包含了“User”一张表，版本号为“1”。数据库类的getVersion方法和getHelper方法不需要实现，直接将数据库类设为虚类即可。

@Database(entities = {User.class}, version = 1)
public abstract class BookStore extends OrmDatabase {

}

3．构造数据表。

//创建数据库实体类并配置对应的属性（如对应表的主键，外键等

 @Entity(tableName = "user")
public class User extends OrmObject {
// 此处将userId设为了自增的主键。注意只有在数据类型为包装类型时，自增主键才能生效。
  @PrimaryKey(autoGenerate = true)
  private Integer userId;
  private String userName;
  private int userAge;
  private String userRole;

  public User() {
  }

  // 需添加各字段的getter和setter方法。
  ……
  ……
}

4. 使用对象数据操作接口OrmContext创建数据库。

// context入参类型为ohos.app.Context，注意不要使用slice.getContext()来获取context，请直接传入slice，否则会出现找不到类的报错。
DatabaseHelper helper = new DatabaseHelper(this); 
OrmContext context = helper.getOrmContext("BookStore", "BookStore.db", BookStore.class); 

5. 使用对象数据操作接口OrmContext对数据库进行增删改查、注册观察者、备份数据库等。

1）首先需要创建一个DataAbility. 右键项目包名→New→Ability→Empty Data Ability，点击进入configure Ability，然后自己定义Data Name，例如：UserDataAbilty。

2）然后在UserDataAbilty类中重写增删改查的方法：

//先在onstart()方法中创建OrmContext对象，context入参类型为ohos.app.Context，注意不要使用slice.getContext()来获取context，请直接传入slice，否则会出现找不到类的报错。
DatabaseHelper helper = new DatabaseHelper(this); 
OrmContext context = helper.getOrmContext("BookStore", "BookStore.db", BookStore.class); 
// 然后重新增删改查方法 query()/insert()/update()/delete()
@Override
public ResultSet query(Uri uri, String[] columns, DataAbilityPredicates predicates) {
  if(ormContext == null){
    HiLog.error(LABEL_LOG,"failed to query, ormContext is null");
    return null;
  }
  //查询数据库
  OrmPredicates ormPredicates = DataAbilityUtils.createOrmPredicates(predicates, User.class);
  ResultSet resultSet = ormContext.query(ormPredicates,columns);
  if (resultSet == null){
    HiLog.info(LABEL_LOG,"resultSet is null");
  }
  return resultSet;
}

@Override
public int insert(Uri uri, ValuesBucket value) {
  // 参数校验
  if (ormContext == null) {
    HiLog.error(LABEL_LOG, "failed to insert, ormContext is null");
    return -1;
  }

  // 构造插入数据
  User user = new User();
  user.setUserId(value.getInteger("userId"));
  user.setUserName(value.getString("userName"));
  user.setUserAge(value.getInteger("userAge"));
  user.setUserRole(value.getString("userRole"));

  // 插入数据库
  boolean isSuccessed;
  isSuccessed = ormContext.insert(user);
  if (!isSuccessed) {
    HiLog.error(LABEL_LOG, "failed to insert");
    return -1;
  }
  isSuccessed = ormContext.flush();
  if (!isSuccessed) {
    HiLog.error(LABEL_LOG, "failed to insert flush");
    return -1;
  }
  DataAbilityHelper.creator(this, uri).notifyChange(uri);
  //返回的id，为数据表自增主键id
  int id = Math.toIntExact(user.getRowId());
  HiLog.debug(LABEL_LOG, "success to insert id="+id);
  return id;
}

@Override
public int delete(Uri uri, DataAbilityPredicates predicates) {
  if (ormContext == null) {
    HiLog.error(LABEL_LOG, "failed to delete, ormContext is null");
    return -1;
  }

  OrmPredicates ormPredicates = DataAbilityUtils.createOrmPredicates(predicates,User.class);
  int result = ormContext.delete(ormPredicates);
  DataAbilityHelper.creator(this, uri).notifyChange(uri);
  // result>0 表示删除成功，result<=0 表示删除失败
  if(result>0){
    HiLog.debug(LABEL_LOG, "UserDataAbility  success to delete value="+result);
  }else {
    HiLog.debug(LABEL_LOG, "UserDataAbility  failed to delete value="+result);
  }

  return result;
}

@Override
public int update(Uri uri, ValuesBucket value, DataAbilityPredicates predicates) {
  if (ormContext == null) {
    HiLog.error(LABEL_LOG, "failed to update, ormContext is null");
    return -1;
  }

  OrmPredicates ormPredicates = DataAbilityUtils.createOrmPredicates(predicates,User.class);
  int result = ormContext.update(ormPredicates, value);
  // result>0 表示更新成功，result<=0 表示更新失败
  if(result>0){
    HiLog.info(LABEL_LOG, "UserDataAbility success to update value:" + result);
  }else {
    HiLog.info(LABEL_LOG, "UserDataAbility failed to update value:" + result);

  }
  DataAbilityHelper.creator(this, uri).notifyChange(uri);
  return result;
}

6.在需要调用的地方，例如MainAbilitySlice中，先创建DataAbilityHelper 对象，然后调用DataAbilityHelper的增、删、改、查方法。

//创建DataAbilityHelper
DataAbilityHelper helper = DataAbilityHelper.creator(this);

//插入数据
//其中Uri uri = Uri.parse(String Uri);里面的配置字符串Uri就是用于读取关系映射数据库的路径，来自于创建DataAbility后，在config.json中的Uri标签,本案例中的String Uri= “dataability://com.isoftstone.ormdatebase.UserDataAbility”

helper.insert(uri, valuesBucket);

//删除数据
helper.delete(uri,predicates);

//修改数据
helper.update(uri, valuesBucket, predicates)

//查询数据
ResultSet resultSet = helper.query(uri, columns, predicates)

操作步骤

App打开之后:

 

1.点击QueryAll时，打印的log。（查询插入的“ZhangSan”、“LiSi”）

08-25 15:50:00.966 10496-10496/com.isoftstone.ormdatebase I 01100/Demo: userId=1; userName=ZhangSan; userAge=22; userRole=teacher

08-25 15:50:00.967 10496-10496/com.isoftstone.ormdatebase I 01100/Demo: userId=2; userName=LiSi; userAge=23; userRole=programmer

 

 

2.点击QueryByCondition时，打印的log。（条件查询“userRole=programmer”）

08-25 15:51:29.031 10496-10496/com.isoftstone.ormdatebase I 01100/Demo: userId=2; userName=LiSi; userAge=23; userRole=programmer

 

 

3.点击Insert后，再点击QueryAll时，打印的log。（插入“WangWu”）

08-25 15:52:26.426 10496-10496/com.isoftstone.ormdatebase D 01100/Demo: success to insert id=3

08-25 15:52:31.466 10496-10496/com.isoftstone.ormdatebase I 01100/Demo: userId=1; userName=ZhangSan; userAge=22; userRole=teacher

08-25 15:52:31.466 10496-10496/com.isoftstone.ormdatebase I 01100/Demo: userId=2; userName=LiSi; userAge=23; userRole=programmer

08-25 15:52:31.467 10496-10496/com.isoftstone.ormdatebase I 01100/Demo: userId=3; userName=WangWu; userAge=18; userRole=police

 

 

4.点击Update后，再点击QueryAll时，打印的log。（把“WangWu”修改为“ZhaoLiu”）

08-25 15:53:42.641 10496-10496/com.isoftstone.ormdatebase I 01100/Demo: UserDataAbility success to update value:1

08-25 15:53:42.643 10496-10496/com.isoftstone.ormdatebase I 01100/Demo: 1

08-25 15:54:35.062 10496-10496/com.isoftstone.ormdatebase I 01100/Demo: userId=1; userName=ZhangSan; userAge=22; userRole=teacher

08-25 15:54:35.063 10496-10496/com.isoftstone.ormdatebase I 01100/Demo: userId=2; userName=LiSi; userAge=23; userRole=programmer

08-25 15:54:35.063 10496-10496/com.isoftstone.ormdatebase I 01100/Demo: userId=3; userName=ZhaoLiu; userAge=26; userRole=doctor

 

 

5.点击Delete后，在点击QueryAll时，打印的log。（删除“ZhaoLiu”）

08-25 15:55:26.885 10496-10496/com.isoftstone.ormdatebase D 01100/Demo: UserDataAbility  success to delete value=1

08-25 15:55:29.157 10496-10496/com.isoftstone.ormdatebase I 01100/Demo: userId=1; userName=ZhangSan; userAge=22; userRole=teacher

08-25 15:55:29.158 10496-10496/com.isoftstone.ormdatebase I 01100/Demo: userId=2; userName=LiSi; userAge=23; userRole=programmer

提供源码

1. BookStore

@Database(entities = {User.class}, version = 1)
public abstract class BookStore extends OrmDatabase {

}

2. User

@Entity(tableName = "user")
public class User extends OrmObject {
  @PrimaryKey(autoGenerate = true)
  private Integer userId;
  private String userName;
  private int userAge;
  private String userRole;

  public User() {
  }

  public Integer getUserId() {
    return userId;
  }

  public void setUserId(Integer userId) {
    this.userId = userId;
  }

  public String getUserName() {
    return userName;
  }

  public void setUserName(String userName) {
    this.userName = userName;
  }

  public int getUserAge() {
    return userAge;
  }

  public void setUserAge(int userAge) {
    this.userAge = userAge;
  }

  public String getUserRole() {
    return userRole;
  }

  public void setUserRole(String userRole) {
    this.userRole = userRole;
  }

  @Override
  public String toString() {
    return "User{" +
        "userId=" + userId +
        ", userName='" + userName + '\'' +
        ", userAge=" + userAge +
        ", userRole='" + userRole + '\'' +
        '}';
  }
}

3. UserDataAbility

public class UserDataAbility extends Ability {
  private static final String DATABASE_NAME ="BookStore.db";
  private static final String DATABASE_NAME_ALIAS = "BookStore";
  private static OrmContext ormContext = null;
  private static final HiLogLabel LABEL_LOG = new HiLogLabel(3, 0xD001100, "Demo");

  @Override
  public void onStart(Intent intent) {
    super.onStart(intent);

    DatabaseHelper helper = new DatabaseHelper(this);
    ormContext = helper.getOrmContext(DATABASE_NAME_ALIAS, DATABASE_NAME, BookStore.class);
    User user1 = new User();
    user1.setUserName("ZhangSan");
    user1.setUserAge(22);
    user1.setUserRole("teacher");
    ormContext.insert(user1);
    User user2 = new User();
    user2.setUserName("LiSi");
    user2.setUserAge(23);
    user2.setUserRole("programmer");
    ormContext.insert(user2);
    ormContext.flush();
  }

  @Override
  public ResultSet query(Uri uri, String[] columns, DataAbilityPredicates predicates) {
    if(ormContext == null){
      HiLog.error(LABEL_LOG,"failed to query, ormContext is null");
      return null;
    }
    //查询数据库
    OrmPredicates ormPredicates = DataAbilityUtils.createOrmPredicates(predicates, User.class);
    ResultSet resultSet = ormContext.query(ormPredicates,columns);
    if (resultSet == null){
      HiLog.info(LABEL_LOG,"resultSet is null");
    }
    return resultSet;
  }

  @Override
  public int insert(Uri uri, ValuesBucket value) {
    // 参数校验
    if (ormContext == null) {
      HiLog.error(LABEL_LOG, "failed to insert, ormContext is null");
      return -1;
    }

    // 构造插入数据
    User user = new User();
    user.setUserId(value.getInteger("userId"));
    user.setUserName(value.getString("userName"));
    user.setUserAge(value.getInteger("userAge"));
    user.setUserRole(value.getString("userRole"));

    // 插入数据库
    boolean isSuccessed;
    isSuccessed = ormContext.insert(user);
    if (!isSuccessed) {
      HiLog.error(LABEL_LOG, "failed to insert");
      return -1;
    }
    isSuccessed = ormContext.flush();
    if (!isSuccessed) {
      HiLog.error(LABEL_LOG, "failed to insert flush");
      return -1;
    }
    DataAbilityHelper.creator(this, uri).notifyChange(uri);
    //返回的id，为数据表自增主键id
    int id = Math.toIntExact(user.getRowId());
    HiLog.debug(LABEL_LOG, "success to insert id="+id);
    return id;
  }

  @Override
  public int delete(Uri uri, DataAbilityPredicates predicates) {
    if (ormContext == null) {
      HiLog.error(LABEL_LOG, "failed to delete, ormContext is null");
      return -1;
    }

    OrmPredicates ormPredicates = DataAbilityUtils.createOrmPredicates(predicates,User.class);
    int result = ormContext.delete(ormPredicates);
    DataAbilityHelper.creator(this, uri).notifyChange(uri);
    // result>0 表示删除成功，result<=0 表示删除失败
    if(result>0){
      HiLog.debug(LABEL_LOG, "UserDataAbility  success to delete value="+result);
    }else {
      HiLog.debug(LABEL_LOG, "UserDataAbility  failed to delete value="+result);
    }

    return result;
  }

  @Override
  public int update(Uri uri, ValuesBucket value, DataAbilityPredicates predicates) {
    if (ormContext == null) {
      HiLog.error(LABEL_LOG, "failed to update, ormContext is null");
      return -1;
    }

    OrmPredicates ormPredicates = DataAbilityUtils.createOrmPredicates(predicates,User.class);
    int result = ormContext.update(ormPredicates, value);
    // result>0 表示更新成功，result<=0 表示更新失败
    if(result>0){
      HiLog.info(LABEL_LOG, "UserDataAbility success to update value:" + result);
    }else {
      HiLog.info(LABEL_LOG, "UserDataAbility failed to update value:" + result);

    }
    DataAbilityHelper.creator(this, uri).notifyChange(uri);
    return result;
  }


}

4. MainAbilitySlice

public class MainAbilitySlice extends AbilitySlice implements ClickedListener {
  private String uriString = "dataability:///com.isoftstone.ormdatebase.UserDataAbility";
  private static final HiLogLabel LABEL_LOG = new HiLogLabel(3, 0xD001100, "Demo");
  private DataAbilityHelper helper;
  @Override
  public void onStart(Intent intent) {
    super.onStart(intent);
    super.setUIContent(ResourceTable.Layout_ability_main);
    helper = DataAbilityHelper.creator(this);
    Button queryAll = (Button) findComponentById(ResourceTable.Id_query_all);
    Button queryByCondition = (Button) findComponentById(ResourceTable.Id_query_by_condition);
    Button insert = (Button) findComponentById(ResourceTable.Id_insert);
    Button update = (Button) findComponentById(ResourceTable.Id_update);
    Button delete = (Button) findComponentById(ResourceTable.Id_delete);
    queryAll.setClickedListener(this);
    queryByCondition.setClickedListener(this);
    insert.setClickedListener(this);
    update.setClickedListener(this);
    delete.setClickedListener(this);
  }
  @Override
  public void onClick(Component component) {
    switch (component.getId()){
      case ResourceTable.Id_query_all:
        try {
          queryAll();
        } catch (Exception e) {
          e.printStackTrace();
        }
        break;
      case ResourceTable.Id_query_by_condition:
        try {
          queryByCondition();
        } catch (Exception e) {
          e.printStackTrace();
        }
        break;
      case ResourceTable.Id_insert:
        try {
          insert();
        } catch (Exception e) {
          e.printStackTrace();
        }
        break;
      case ResourceTable.Id_update:
        try {
          update();
        } catch (Exception e) {
          e.printStackTrace();
        }
        break;
      case ResourceTable.Id_delete:
        try {
          delete();
        } catch (Exception e) {
          e.printStackTrace();
        }
    }
  }
  public void queryAll() throws DataAbilityRemoteException {
    // 构造查询条件
    DataAbilityPredicates predicates = new DataAbilityPredicates();
    String[] columns = new String[]{"userId", "userName", "userAge", "userRole"};
    Uri uri = Uri.parse(uriString);
    ResultSet resultSet = helper.query(uri, columns, predicates);
    // 处理结果
    resultSet.goToFirstRow();
    do {
      // 在此处理ResultSet中的记录;
      HiLog.info(LABEL_LOG,
          "userId=" + resultSet.getString(0)
              + "; userName=" + resultSet.getString(1)
              + "; userAge=" + resultSet.getString(2)
              + "; userRole=" + resultSet.getString(3));
    } while (resultSet.goToNextRow());
  }
  public void queryByCondition() throws DataAbilityRemoteException {
    // 构造查询条件
    DataAbilityPredicates predicates = new DataAbilityPredicates();
    predicates.equalTo("userRole", "programmer");
    String[] columns = new String[]{"userId", "userName", "userAge", "userRole"};
    Uri uri = Uri.parse(uriString);
    ResultSet resultSet = helper.query(uri, columns, predicates);
    // 处理结果
    resultSet.goToFirstRow();
    do {
      // 在此处理ResultSet中的记录;
      HiLog.info(LABEL_LOG,
          "userId=" + resultSet.getString(0)
              + "; userName=" + resultSet.getString(1)
              + "; userAge=" + resultSet.getString(2)
              + "; userRole=" + resultSet.getString(3));
    } while (resultSet.goToNextRow());
  }
  public void insert() throws DataAbilityRemoteException {

    DataAbilityHelper helper = DataAbilityHelper.creator(this);
    Uri uri = Uri.parse(uriString);
    ValuesBucket valuesBucket = new ValuesBucket();
    valuesBucket.putString("userName", "WangWu");
    valuesBucket.putInteger("userAge", 18);
    valuesBucket.putString("userRole", "police");
    helper.insert(uri, valuesBucket);
  }
  public void update() throws DataAbilityRemoteException {
    // 构造插入数据
    DataAbilityHelper helper = DataAbilityHelper.creator(this);

    // 构造更新条件
    DataAbilityPredicates predicates = new DataAbilityPredicates();
    predicates.equalTo("userName", "WangWu");

    // 构造更新数据
    ValuesBucket valuesBucket = new ValuesBucket();
    valuesBucket.putString("userName", "ZhaoLiu");
    valuesBucket.putInteger("UserAge", 26);
    valuesBucket.putString("userRole", "doctor");
    Uri uri = Uri.parse(uriString);
    int update = helper.update(uri, valuesBucket, predicates);
  }
  public void delete() throws DataAbilityRemoteException {
    DataAbilityHelper helper = DataAbilityHelper.creator(this);
    Uri uri = Uri.parse(uriString);
    // 构造删除条件
    DataAbilityPredicates predicates = new DataAbilityPredicates();
    predicates.equalTo("userName", "ZhaoLiu");
    helper.delete(uri,predicates);
  }
}

5. 页面布局ability_main.xml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:orientation="vertical" >

  <Button
    ohos:id="$+id:query_all"
    ohos:width="match_content"
    ohos:height="match_content"
    ohos:text="QueryAll"
    ohos:text_size="19fp"
    ohos:text_color="#FFFFFF"
    ohos:top_margin="30vp"
    ohos:top_padding="8vp"
    ohos:bottom_padding="8vp"
    ohos:right_padding="70vp"
    ohos:left_padding="70vp"
    ohos:background_element="$graphic:background_button"
    ohos:center_in_parent="true"
    ohos:align_parent_bottom="true"
    ohos:bottom_margin="40vp"
    ohos:layout_alignment="center"
    />
  <Button
    ohos:id="$+id:query_by_condition"
    ohos:width="match_content"
    ohos:height="match_content"
    ohos:text="queryByCondition"
    ohos:text_size="19fp"
    ohos:text_color="#FFFFFF"
    ohos:top_padding="8vp"
    ohos:bottom_padding="8vp"
    ohos:right_padding="70vp"
    ohos:left_padding="70vp"
    ohos:background_element="$graphic:background_button"
    ohos:center_in_parent="true"
    ohos:align_parent_bottom="true"
    ohos:bottom_margin="40vp"
    ohos:layout_alignment="center"
    />
  <Button
    ohos:id="$+id:insert"
    ohos:width="match_content"
    ohos:height="match_content"
    ohos:text="Insert"
    ohos:text_size="19fp"
    ohos:text_color="#FFFFFF"
    ohos:top_padding="8vp"
    ohos:bottom_padding="8vp"
    ohos:right_padding="70vp"
    ohos:left_padding="70vp"
    ohos:background_element="$graphic:background_button"
    ohos:center_in_parent="true"
    ohos:align_parent_bottom="true"
    ohos:bottom_margin="40vp"
    ohos:layout_alignment="center"
    />
  <Button
    ohos:id="$+id:update"
    ohos:width="match_content"
    ohos:height="match_content"
    ohos:text="Update"
    ohos:text_size="19fp"
    ohos:text_color="#FFFFFF"
    ohos:top_padding="8vp"
    ohos:bottom_padding="8vp"
    ohos:right_padding="70vp"
    ohos:left_padding="70vp"
    ohos:background_element="$graphic:background_button"
    ohos:center_in_parent="true"
    ohos:align_parent_bottom="true"
    ohos:bottom_margin="40vp"
    ohos:layout_alignment="center"
    />
  <Button
    ohos:id="$+id:delete"
    ohos:width="match_content"
    ohos:height="match_content"
    ohos:text="Delete"
    ohos:text_size="19fp"
    ohos:text_color="#FFFFFF"
    ohos:top_padding="8vp"
    ohos:bottom_padding="8vp"
    ohos:right_padding="70vp"
    ohos:left_padding="70vp"
    ohos:background_element="$graphic:background_button"
    ohos:center_in_parent="true"
    ohos:align_parent_bottom="true"
    ohos:bottom_margin="40vp"
    ohos:layout_alignment="center"
    />


</DirectionalLayout>

6.圆角背景图形background_button.xml文件：

<?xml version="1.0" encoding="utf-8"?>
<shape
    xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:shape="rectangle">
    <corners
        ohos:radius="100"/>
    <solid
        ohos:color="#007DFF"/>
</shape>

7.config.json

{
  "app": {
    "bundleName": "com.isoftstone.ormdatebase",
    "vendor": "isoftstone",
    "version": {
      "code": 1000000,
      "name": "1.0"
    },
    "apiVersion": {
      "compatible": 4,
      "target": 5,
      "releaseType": "Release"
    }
  },
  "deviceConfig": {},
  "module": {
    "package": "com.isoftstone.ormdatebase",
    "name": ".MyApplication",
    "deviceType": [
      "phone"
    ],
    "distro": {
      "deliveryWithInstall": true,
      "moduleName": "entry",
      "moduleType": "entry"
    },
    "abilities": [
      {
        "skills": [
          {
            "entities": [
              "entity.system.home"
            ],
            "actions": [
              "action.system.home"
            ]
          }
        ],
        "orientation": "unspecified",
        "name": "com.isoftstone.ormdatebase.MainAbility",
        "icon": "$media:icon",
        "description": "$string:mainability_description",
        "label": "$string:app_name",
        "type": "page",
        "launchType": "standard"
      },
      {
        "visible": true,
        "permissions": [
          "com.isoftstone.ormdatebase.DataAbilityShellProvider.PROVIDER"
        ],
        "name": "com.isoftstone.ormdatebase.UserDataAbility",
        "icon": "$media:icon",
        "description": "$string:userdataability_description",
        "type": "data",
        "uri": "dataability://com.isoftstone.ormdatebase.UserDataAbility"
      }
    ]
  }
}

8.build.gradle

apply plugin: 'com.huawei.ohos.hap'
ohos {
    compileSdkVersion 5
    defaultConfig {
        compatibleSdkVersion 4
    }
    compileOptions{
        annotationEnabled true
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar', '*.har'])
    testCompile 'junit:junit:4.12'
}

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