objectbox 在android开发中的配置和使用

Myth丶恋晨 2023-07-08 11:29 1阅读 0赞

介绍：ObjectBox是一个超快的面向对象数据库，专为物联网和移动设备而构建。我们为小型设备提供边缘计算，允许在本地存储和处理数据，以实现高效，快速和安全的数据管理。

ObjectBox是nosql数据库，如果接触过java开发，那么ObjectBox有点类似redis。

本文主要介绍一下在安卓环境下怎么使用ObjectBox。

一、配置：

首先在android工程的 build.gradle 文件中加入

classpath "io.objectbox:objectbox-gradle-plugin:2.5.1"

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在 module的 build.gradle 文件中引用

apply plugin: 'io.objectbox'

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引用ObjectBox 的jar包

implementation "io.objectbox:objectbox-android:2.4.1"

到这里基本上配置就做好了。

二、使用

先初始化ObjectBox

import android.content.Context;
    import com.gettyio.gim.db.entity.MyObjectBox;
    import io.objectbox.BoxStore;
    
    public class ObjectBox {
    
        private static BoxStore boxStore;
    
        public static void init(Context context){
            boxStore = MyObjectBox.builder().androidContext(context).build();
        }
    
        public static BoxStore getBoxStore() {
            return boxStore;
        }
    }

在工程的 Application中初始化

public class MyApplication extends Application {
    
        private static Context mContext;
    
    
        @Override
        public void onCreate() {
            super.onCreate();
            mContext = getApplicationContext();
            ObjectBox.init(this);
        }
    
        public static Context getContext() {
            return mContext;
        }
    
    }

这里提供一个增删改查的公共工具类，方便使用

import io.objectbox.Box;
    import io.objectbox.Property;
    import io.objectbox.query.QueryBuilder;
    
    import java.util.ArrayList;
    import java.util.Iterator;
    import java.util.List;
    import java.util.Map;
    
    public class CommonDao {
    
        private static CommonDao commonDao;
    
    
        public static CommonDao getInstance() {
            if (commonDao == null) {
                synchronized (CommonDao.class) {
                    commonDao = new CommonDao();
                }
            }
            return commonDao;
        }
    
        private CommonDao() {
    
        }
    
    
        /**
         * 获取列表
         *
         * @return java.util.List<T>
         * @params [tClass]
         */
        public <T> List<T> getList(Class<T> tClass) {
            List<T> list = new ArrayList<>();
            Box<T> box = ObjectBox.getBoxStore().boxFor(tClass);
            list.addAll(box.query().build().find());
            return list;
        }
    
    
        /**
         * 获取单个对象
         *
         * @return T
         * @params [tClass]
         */
        public <T> T getFirst(Class<T> tClass) {
            Box<T> box = ObjectBox.getBoxStore().boxFor(tClass);
            return box.query().build().findFirst();
        }
    
    
        /**
         * 多条件查询
         *
         * @param tClass            查询对象
         * @param propertyObjectMap 查询条件集合 key查询条件，value具体值
         **/
        public <T> List<T> getList(Class<T> tClass, Map<Property, Object> propertyObjectMap) {
    
            if (propertyObjectMap == null) {
                throw new NullPointerException("propertyObjectMap is not null and value is not null.");
            }
    
            if (propertyObjectMap.isEmpty()) {
    
                throw new IllegalStateException("propertyObjectMap is not empty and value is not empty.");
            }
            List<T> list = new ArrayList<>();
            Box<T> box = ObjectBox.getBoxStore().boxFor(tClass);
            QueryBuilder queryBuilder = box.query();
    
            Iterator<Map.Entry<Property, Object>> iterator = propertyObjectMap.entrySet().iterator();
            while (iterator.hasNext()) {
                Map.Entry<Property, Object> entry = iterator.next();
                queryBuilder.equal(entry.getKey(), entry.getValue().toString());
            }
    
            //PropertyQuery propertyQuery=queryBuilder.build().property();
    
            list.addAll(queryBuilder.build().find());
            return list;
        }
    
    
        /**
         * 统计
         *
         * @return java.lang.Long
         * @params [tClass, propertyObjectMap]
         */
        public <T> Long count(Class<T> tClass, Map<Property, Object> propertyObjectMap) {
    
            if (propertyObjectMap == null) {
                throw new NullPointerException("propertyObjectMap is not null and value is not null.");
            }
    
            if (propertyObjectMap.isEmpty()) {
    
                throw new IllegalStateException("propertyObjectMap is not empty and value is not empty.");
            }
            Box<T> box = ObjectBox.getBoxStore().boxFor(tClass);
            QueryBuilder queryBuilder = box.query();
            Iterator<Map.Entry<Property, Object>> iterator = propertyObjectMap.entrySet().iterator();
            while (iterator.hasNext()) {
                Map.Entry<Property, Object> entry = iterator.next();
                queryBuilder.equal(entry.getKey(), entry.getValue().toString());
            }
    
            return queryBuilder.build().count();
        }
    
    
        /**
         * 多条件模糊查找
         *
         * @param tClass            查询对象
         * @param propertyObjectMap 查询条件集合 key查询条件，value具体值
         **/
        public <T> List<T> getListContains(Class<T> tClass, Map<Property, Object> propertyObjectMap) {
    
            if (propertyObjectMap == null) {
                throw new NullPointerException("propertyObjectMap is not null and value is not null.");
            }
    
            if (propertyObjectMap.isEmpty()) {
    
                throw new IllegalStateException("propertyObjectMap is not empty and value is not empty.");
            }
    
            List<T> list = new ArrayList<>();
            Box<T> box = ObjectBox.getBoxStore().boxFor(tClass);
    
            QueryBuilder queryBuilder = box.query();
            Iterator<Map.Entry<Property, Object>> iterator = propertyObjectMap.entrySet().iterator();
            while (iterator.hasNext()) {
                Map.Entry<Property, Object> entry = iterator.next();
                queryBuilder.contains(entry.getKey(), entry.getValue().toString());
            }
    
            list.addAll(queryBuilder.build().find());
            return list;
        }
    
    
        /**
         * 保存一个数据
         *
         * @return void
         * @params [clazz, value]
         */
        public <T> void putData(Class<T> clazz, Object value) {
            Box<T> box = ObjectBox.getBoxStore().boxFor(clazz);
            box.put((T) value);
    
        }
    
    
        /**
         * 删除数据
         *
         * @return void
         * @params [clazz, value]
         */
        public <T> void deleteData(Class<T> clazz, Object value) {
            Box<T> box = ObjectBox.getBoxStore().boxFor(clazz);
            box.remove((T) value);
        }
    
    
        /**
         * 删除全部
         *
         * @return void
         * @params [clazz]
         */
        public <T> void deleteAllData(Class<T> clazz) {
            Box<T> box = ObjectBox.getBoxStore().boxFor(clazz);
            box.removeAll();
        }
    }

三、需要注意的问题：

使用 objectbox 之前要先创建对应的实体类，实体类必须要用 @Entity 注解标明，且必须要指定一个 long类型的id，用@Id 注解标明。且属性必须要有对应的get/set方法。

import io.objectbox.annotation.Entity;
    import io.objectbox.annotation.Id;
    
    //必须要加注解@Entity
    @Entity
    public class MessageInfo {
    
        public MessageInfo(){
    
        }
    
        //必须要指定@id
        @Id
        private long id;
    
        private String identify;
    
    
        //属性必须要有对应的get/set方法，否则无法生成MyObjectBox
         public long getId() {
            return id;
        }
    
        public void setId(long id) {
            this.id = id;
        }
    
        public String getIdentify() {
            return identify;
        }
    
        public void setIdentify(String identify) {
            this.identify = identify;
        }
    
    }

最后点击 Build -> build project ，即可生成对应的配置正常使用。

完

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