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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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