Android GreenDao with Android Studio IDE

转：http://blog.surecase.eu/using-greendao-with-android-studio-ide/

In this tutorial we will show you step by step how we have created sample application that presents our own Android Studio-GreenDao communication module. We tried to focus mainly on the implementation of database in freshly created Android Studio project and took other factors (such as layouts, modularity etc.) with a grain of salt. For those who haven‘t checked our Git yet - you can find our GreenDao module here.

So let‘s get started!

Step 1 - create new Android Project

For those who are not familiar with Android Studio IDE we recommend to go through Google tutorial - Getting Started With Android Studio.

1. To create new project please select File -> New Project. The New Project wizards pop up. Fill up fields according to your liking or do it the way we did: 
   

   1. Press next. Check "Blank Activity" and next button again.
   2. Name your first activity BoxListActivity and the layout activity_box_list.
   3. Press finish.

And it‘s done. We have our project created. Now we can go to next step which is...

Step 2 - add GreenDao Generator module to project tree

We assume you have already downloaded our module. If not please go to our Git and do it now. Add MyDaoGenerator module to your project tree as additional package.

As you can see MyDaoGenerator is recognized as Directory and not as Module like DaoExample. To change it we have to edit settings.gradle so it contains both ‘:DaoExample‘ and ‘:MyDaoGenerator‘ :

include ‘:DaoExample‘, ‘:MyDaoGenerator‘  

After doing it, please click "Sync Project with Gradle Files" button. Your directory should look like a module now in project tree.

Step 3 - connect GreenDao Generator to DaoExample (main module)

So, MyDaoGenerator is currently recognized as a module. Now we have to configure it, so we can get database files from it. The only necessary thing to be changed is outputDir parameter inbuild.gradle file of MyDaoGenerator module.

Currently our root is MyDaoGenerator. We want to access DaoExample, which needs database files. To go higher - our path will start with:

outputDir = "../"  

We are currently in GreenDaoForAndroidStudio folder. We can easly go into DaoExample and create a directory for our database files. Java files in Android Studio project are stored in ../<PROJECT NAME>/src/main/java directory. To highlight the fact, that GreenDao database files are generated and will change in future as your project develops, we decided to create separate directory for them named java-gen.

Finaly our path looks like:

outputDir = "../DaoExample/src/main/java-gen"

There is no need to create this directory manualy. After running MyDaoGenerator it will be created during build.

Your GreenDao generator is now ready to inject database files to your project.

Step 4 - configure GreenDao Generator

MyDaoGenerator consists of only one class:

Output of GreenDao Generator is deremined by content of MyDaoGenerator.class. You can create your database structure here by coding objects, relations etc. If you are not familiar with GreenDao database library, you can learn how to use it in that documentation.

We will create exemplary database with only one object. Database code needs to be placed in main method:

public class MyDaoGenerator {

    public static void main(String args[]) throws Exception {
    }
}

Create Schema object with represents database version and package. We will name the package greendao.

Schema schema = new Schema(3, "greendao");  

We create Entity - database object which will be named Box.

Entity box = schema.addEntity("Box");  

Now we can add properties/fields to our database Entity/Object. For example:

• id

box.addIdProperty();  

• String name

box.addStringProperty("name");  

• int slots

box.addIntProperty("slots");  

• String description

box.addStringProperty("description");  

Finaly we can invoke DaoGenerator object which is avaliable by default in MyDaoGenerator due to Maven tool (check gradle.build and dependencies section). DaoGenerator during run will create database java files that can be used in our main project. It takes two parameters: Schema and output directory.

new DaoGenerator().generateAll(schema, args[0]);  

When you look at gradle.build there is a run section in which outputDir parameter is being sent to main method as an argument. That‘s why args[0] will always contain output path that you have set previously in gradle. Such operation limits actions performed on MyDaoGenerator to only three steps:

• set path in gradle.build file
• create your database in MyDaoGenerator.class
• run module

Step 5 - run GreenDao Generator

Pick Gradle bookmark from the right side of Android Studio interface. Choose MyDaoGenerator module and click twice on run task.

greenDAO Generator  
Copyright 2011-2013 Markus Junginger, greenrobot.de. Licensed under GPL V3.  
This program comes with ABSOLUTELY NO WARRANTY  
Processing schema version 3...  
Written /Users/surecase/dev/examples/GreenDaoForAndroidStudio/GreenDaoForAndroidStudio/DaoExample/src/main/java-gen/greendao/BoxDao.java  
Written /Users/surecase/dev/examples/GreenDaoForAndroidStudio/GreenDaoForAndroidStudio/DaoExample/src/main/java-gen/greendao/Box.java  
Written /Users/surecase/dev/examples/GreenDaoForAndroidStudio/GreenDaoForAndroidStudio/DaoExample/src/main/java-gen/greendao/DaoMaster.java  
Written /Users/surecase/dev/examples/GreenDaoForAndroidStudio/GreenDaoForAndroidStudio/DaoExample/src/main/java-gen/greendao/DaoSession.java  
Processed 1 entities in 103ms

BUILD SUCCESSFUL

Total time: 8.802 secs  

After starting run task, you can track flow of this operation in Gradle console. When it‘s complete you can see new files in DaoExample project:

And that‘s all work connected to MyDaoGenerator. If you are familiar with it, generation of new database will take only few minutes.

Step 6 - make DaoExample aware of new files

So we have successfully created database files that are ready to be used in any Android project. The project needs to be aware where are those files located and familiar with GreenDao objects. To achieve this it is necessary to configure build.gradle file of DaoExample module. Fresh build.gradle file of a new project looks similar to this:

• We need to clean it first from features that we won‘t use in our project - buildTypes section is not needed.
• To let our project use GreenDao database, first we need to import GreenDao library. We can do it by inserting *.jar file into libs folder or by adding extra Maven dependency in gradle:

 dependencies {
    compile ‘de.greenrobot:greendao:1.3.7‘
}

• Project is still not aware of new Java files because it isn‘t located in ../<PROJECT NAME>/src/main/java directory. To fix this we must specify projects source sets. It is important to point two java file sources: /src/main/java and /src/main/java-gen. You can do it by placingsourceSets section into android section in gradle.build file:

Finaly our gradle will look like this:

When you finish editing gradle file, press "Sync Project with Gradle Files" button. Your java-gen directory will look the same as java folder in project tree.

Step 7 - start Database

Your project is ready to use previously created database. To have access to GreenDao database, you have to initialize it before using it. Right place for performing this operation is Application class which is instantiated for you when the process for your application/package is created. Initialization code can be found on GreenDao webpage. Application is avaliable from every activity, so we create DaoSession object which is avaliable during whole lifecycle of application and create getter for it.

Don‘t forget to register DaoExampleApplication class in your manifest:

<application  
    android:name=".DaoExampleApplication"
    (...)
</application>

Step 8 - simple operations on DB object

Database generated in this tutorial has only one Entity - Box. To perform create, edit, save, delete on it, we need too create helper class with those methods. We name it BoxRepository. Each Entity created in GreenDao has two classes:

• class that represents structure of object
• Dao class which is a connection of object with database

In our example those clasess are named as Box and BoxDao. So if we want start working with Box objects we need to get BoxDao object from DaoSession that was created with Application class.

private static BoxDao getBoxDao(Context c) {  
    return ((DaoExampleApplication) c.getApplicationContext()).getDaoSession().getBoxDao();
}

With access to DaoBox we can perform any operation on Box object we need. Examplary BoxRepository from our project looks like this:

Examplary use that can be used in every place where Context is avaliable:

Box box = new Box();  
box.setId(5); // if box with id 5 already exists in DB, it will be edited instead of created  
box.setName("My box");  
box.setSlots(39);  
box.setDescription("This is my box. I can put in it anything I wish.");  
BoxRepository.insertOrUpdate(context, box);  

Step 9 - rest is up to you

This is the end of this tutorial. You have all information and tools you need to start work with GreenDao database in your Android Studio project. There is no need to show you how to create views, buttons, adapters etc. If you are interested in it - whole source code and project structure of GreenDaoForAndroidStudio sample project is avaliable at SureCase git.