RealmModules的使用

RealmModulesExample.java

/*
 * Copyright 2015 Realm Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.brucetoo.realmdemo.realmappmodules;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.widget.LinearLayout;
import android.widget.TextView;

import com.brucetoo.realmdemo.R;
import com.brucetoo.realmdemo.realmappmodules.model.Cow;
import com.brucetoo.realmdemo.realmappmodules.model.Pig;
import com.brucetoo.realmdemo.realmappmodules.model.Snake;
import com.brucetoo.realmdemo.realmappmodules.model.Spider;
import com.brucetoo.realmdemo.realmappmodules.modules.CreepyAnimalsModule;
import com.brucetoo.realmdemo.realmintro.model.Cat;
import com.brucetoo.realmdemo.realmintro.model.Dog;

import io.realm.Realm;
import io.realm.RealmConfiguration;
import io.realm.examples.librarymodules.Zoo;
import io.realm.examples.librarymodules.model.Elephant;
import io.realm.examples.librarymodules.model.Lion;
import io.realm.examples.librarymodules.model.Zebra;
import io.realm.examples.librarymodules.modules.DomesticAnimalsModule;
import io.realm.examples.librarymodules.modules.ZooAnimalsModule;
import io.realm.exceptions.RealmException;

/**
* This example demonstrates how you can use modules to control which classes belong to which Realms and how you can
 * work with multiple Realms at the same time.
*/
public class ModulesExampleActivity extends Activity {

    public static final String TAG = ModulesExampleActivity.class.getName();
    private LinearLayout rootLayout = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_modules_example);
        rootLayout = ((LinearLayout) findViewById(R.id.container));
        rootLayout.removeAllViews();
        /**
         * 在默认情况下,Realm的实例只能使用android studio主工程的Module中的类，
         * 其他的Module则不能使用,为了使用其他library Module的类,这配置Module则是必须的
         *
         * Module的定义
         1.首先必须用注解@RealModule来标识Module 参数 library = true
         2.第二个参数表示该声明的Module能使用那些Model
         allClasses = true 表示该Module能使用与其在同一个android studio Module中所有的类
        @RealmModule(library = true, allClasses = true)
           public class AllAnimalsModule {
           }
         //
         @RealmModule(library = true, classes = {Cat.class, Dog.class})
         public class DomesticAnimalsModule {
         }


         setModules(Realm.getDefaultModule(), new DomesticAnimalsModule())

         Realm.getDefaultModule() 是获取默认的Module
         上面的意思是将后者Module可使用的类加入到默认可使用的类中

         setModules(new ZooAnimalsModule(), new CreepyAnimalsModule())
         表示替换默认的Module 只使用 ZooAnimalsModule 和 ZooAnimalsModule中包含的类
         */

        // The default Realm instance implicitly knows about all classes in the realmModuleAppExample Android Studio
        // module. This does not include the classes from the realmModuleLibraryExample AS module so a Realm using this
        // configuration would know about the following classes: { Cow, Pig, Snake, Spider }
        RealmConfiguration defaultConfig = new RealmConfiguration.Builder(this).build();

        // It is possible to extend the default schema by adding additional Realm modules using setModule(). This can
        // also be Realm modules from libraries. The below Realm contains the following classes: { Cow, Pig, Snake,
        // Spider, Cat, Dog }
        RealmConfiguration farmAnimalsConfig = new RealmConfiguration.Builder(this)
                .name("farm.realm")
                .setModules(Realm.getDefaultModule(), new DomesticAnimalsModule())
                .build();

        // Or you can completely replace the default schema.
        // This Realm contains the following classes: { Elephant, Lion, Zebra, Snake, Spider }
        RealmConfiguration exoticAnimalsConfig = new RealmConfiguration.Builder(this)
                .name("exotic.realm")
                .setModules(new ZooAnimalsModule(), new CreepyAnimalsModule())
                .build();

        // Multiple Realms can be open at the same time
        /**
         * 可同时操作不同的Module
         */
        showStatus("Opening multiple Realms");
        Realm defaultRealm = Realm.getInstance(defaultConfig);
        Realm farmRealm = Realm.getInstance(farmAnimalsConfig);
        Realm exoticRealm = Realm.getInstance(exoticAnimalsConfig);

        /**
         * 默认操作Realm是使用 realm.beginTransaction(), realm.commitTransaction()
         * 也可使用代码快来代替，如下
         * realm.executeTransaction(new Realm.Transaction)
         */
        // Objects can be added to each Realm independantly
        showStatus("Create objects in the default Realm");
        defaultRealm.executeTransaction(new Realm.Transaction() {
            @Override
            public void execute(Realm realm) {
                realm.createObject(Cow.class);
                realm.createObject(Pig.class);
                realm.createObject(Snake.class);
                realm.createObject(Spider.class);
            }
        });

        showStatus("Create objects in the farm Realm");
        farmRealm.executeTransaction(new Realm.Transaction() {
            @Override
            public void execute(Realm realm) {
                realm.createObject(Cow.class);
                realm.createObject(Pig.class);
                realm.createObject(Cat.class);
                realm.createObject(Dog.class);
            }
        });

        showStatus("Create objects in the exotic Realm");
        exoticRealm.executeTransaction(new Realm.Transaction() {
            @Override
            public void execute(Realm realm) {
                realm.createObject(Elephant.class);
                realm.createObject(Lion.class);
                realm.createObject(Zebra.class);
                realm.createObject(Snake.class);
                realm.createObject(Spider.class);
            }
        });

        /**
         * 可以在不同的Module管理的Realm直接copy对象
         */
        // You can copy objects between Realms
        showStatus("Copy objects between Realms");
        showStatus("Number of pigs on the farm : " + farmRealm.where(Pig.class).count());
        showStatus("Copy pig from defaultRealm to farmRealm");
        Pig defaultPig = defaultRealm.where(Pig.class).findFirst();
        farmRealm.beginTransaction();
        farmRealm.copyToRealm(defaultPig);
        farmRealm.commitTransaction();
        showStatus("Number of pigs on the farm : " + farmRealm.where(Pig.class).count());

        // Each Realm is restricted to only accept the classes in their schema.
        /**
         * 但是每个Realm只能创建在其控制范围内的类
         */
        showStatus("Trying to add an unsupported class");
        defaultRealm.beginTransaction();
        try {
            //defaultRealm 没有包含 Elephant所以在此会抛出异常
            defaultRealm.createObject(Elephant.class);
        } catch (RealmException expected) {
            showStatus("This throws a :" + expected.toString());
        } finally {
            defaultRealm.cancelTransaction();
        }

        // And Realms in library projects are independent from Realms in the app code
        /**
         * library中的Realm操作是和主app中的操作独立开的，因此可以单独操作
         */
        showStatus("Interacting with library code that uses Realm internally");
        int animals = 5;
        Zoo libraryZoo = new Zoo(this);
        libraryZoo.open();
        showStatus("Adding animals: " + animals);
        libraryZoo.addAnimals(5);
        showStatus("Number of animals in the library Realm:" + libraryZoo.getNoOfAnimals());
        libraryZoo.close();

        // Remember to close all open Realms
        defaultRealm.close();
        farmRealm.close();
        exoticRealm.close();
    }

    private void showStatus(String txt) {
        Log.i(TAG, txt);
        TextView tv = new TextView(this);
        tv.setText(txt);
        rootLayout.addView(tv);
    }
}