Android(安卓)ORM系列之GreenDao最佳实践

GreenDAO是一个可以帮助Android开发者快速将Java对象映射到SQLite数据库的表单中的ORM解决方案，通过使用一个简单的面向对象API，开发者可以对Java对象进行存储、更新、删除和查询。

GreenDao有两个项目，一个是生成dao和model的generator的项目，该项目是java项目，一个是用于android的核心jar包。在使用前，我们必须先生成dao和model。

首先加入依赖。

compile 'de.greenrobot:greendao:2.0.0'compile 'de.greenrobot:greendao-generator:2.0.0'

然后在我们的包名之下新建一个db的包，在db下新建dao和model的包以及一个generator的包，就像下图。

在generator包下，新建一个生成dao和model的类GreenDaoGenerator，在里面加入代码

public class GreenDaoGenerator {    public static void main(String[] args) throws Exception {        Schema schema = new Schema(1, "cn.edu.zafu.greendao.db.model");        schema.setDefaultJavaPackageDao("cn.edu.zafu.greendao.db.dao");        schema.enableKeepSectionsByDefault();        //schema.enableActiveEntitiesByDefault();        //ActiveRecord        addEntity(schema);        new DaoGenerator().generateAll(schema, "./app/src/main/java");    }    private static void addEntity(Schema schema) {        Entity person = schema.addEntity("Person");        person.addIdProperty().primaryKey();        person.addStringProperty("name");        person.addDoubleProperty("height");        person.addDoubleProperty("weight");        Entity card = schema.addEntity("Card");        card.addIdProperty().primaryKey();        card.addStringProperty("num");        card.addStringProperty("address");        Property idcardPK = person.addLongProperty("cardId").getProperty();        person.addToOne(card, idcardPK);        Property personPK = card.addLongProperty("personId").getProperty();        card.addToOne(person,personPK);    }}

Schema schema = new Schema(1, “cn.edu.zafu.greendao.db.model”); 代表创建的数据库的版本号以及默认的java package，如果不修改默认的包名，生成的dao和model都会在该包下，这里我们修改了dao的包名schema.setDefaultJavaPackageDao(“cn.edu.zafu.greendao.db.dao”);，生成的model中，我们可能需要加入自己的一些信息，但是又不希望下次生成的时候消失，所以可以使用schema.enableKeepSectionsByDefault();，使用后会在model类中有如下这些标示

// KEEP INCLUDES - put your custom includes here// KEEP INCLUDES END// KEEP FIELDS - put your custom fields here// KEEP FIELDS END // KEEP METHODS - put your custom methods here// KEEP METHODS END

你只需将你需要的信息添加到这三个之间，分布代表引入的包，字段，方法。之后重新生成这些信息将会被保留。

schema.enableActiveEntitiesByDefault();代表实体类是否支持active，用过php中yii框架的都应该清楚，实体类可以直接进行crud操作。我们不开启就好了，如果开启了的话，实体类将之间支持update, refresh, deleted 等操作。

之后就使用 schema.addEntity()函数增加Entity 对象，即对应的实体类，通过添加属性方法addProperty系列方法增加字段，最后调用new DaoGenerator().generateAll(schema, “./app/src/main/java”);方法生成dao和model。

生成的步骤也很简单，在该类上右键，点run即可。

生成之后控制台就会输出

然后我们编写一个核心辅助类。用于获取DaoMaster和DaoSession

public class DbCore {    private static final String DEFAULT_DB_NAME = "default.db";    private static DaoMaster daoMaster;    private static DaoSession daoSession;    private static Context mContext;    private static String DB_NAME;    public static void init(Context context) {        init(context, DEFAULT_DB_NAME);    }    public static void init(Context context, String dbName) {        if (context == null) {            throw new IllegalArgumentException("context can't be null");        }        mContext = context.getApplicationContext();        DB_NAME = dbName;    }    public static DaoMaster getDaoMaster() {        if (daoMaster == null) {            DaoMaster.OpenHelper helper = new DaoMaster.DevOpenHelper(mContext, DB_NAME, null);            daoMaster = new DaoMaster(helper.getWritableDatabase());        }        return daoMaster;    }    public static DaoSession getDaoSession() {        if (daoSession == null) {            if (daoMaster == null) {                daoMaster = getDaoMaster();            }            daoSession = daoMaster.newSession();        }        return daoSession;    }    public static void enableQueryBuilderLog(){        QueryBuilder.LOG_SQL = true;        QueryBuilder.LOG_VALUES = true;    }}

接下来就是基础的泛型Service

public class BaseService<T, K> {    private AbstractDao<T, K> mDao;    public BaseService(AbstractDao dao) {        mDao = dao;    }    public void save(T item) {        mDao.insert(item);    }    public void save(T... items) {        mDao.insertInTx(items);    }    public void save(List<T> items) {        mDao.insertInTx(items);    }    public void saveOrUpdate(T item) {        mDao.insertOrReplace(item);    }    public void saveOrUpdate(T... items) {        mDao.insertOrReplaceInTx(items);    }    public void saveOrUpdate(List<T> items) {        mDao.insertOrReplaceInTx(items);    }    public void deleteByKey(K key) {        mDao.deleteByKey(key);    }    public void delete(T item) {        mDao.delete(item);    }    public void delete(T... items) {        mDao.deleteInTx(items);    }    public void delete(List<T> items) {        mDao.deleteInTx(items);    }    public void deleteAll() {        mDao.deleteAll();    }    public void update(T item) {        mDao.update(item);    }    public void update(T... items) {        mDao.updateInTx(items);    }    public void update(List<T> items) {        mDao.updateInTx(items);    }    public  T query(K key) {        return  mDao.load(key);    }    public List<T> queryAll() {        return mDao.loadAll();    }    public List<T> query(String where, String... params) {        return mDao.queryRaw(where, params);    }    public QueryBuilder<T> queryBuilder() {        return mDao.queryBuilder();    }    public long count() {        return mDao.count();    }    public void refresh(T item) {        mDao.refresh(item);    }    public void detach(T item) {        mDao.detach(item);    }}

一个实现类，第二个泛型参数是主键类型

public class CardService extends BaseService<Card,Long> {    public CardService(CardDao dao) {        super(dao);    }}public class PersonService extends BaseService<Person,Long> {    public PersonService(PersonDao dao) {        super(dao);    }}

编写一个工具类获得service

public class DbUtil {    private static CardService cardService;    private static PersonService personService;    private static PersonDao getPersonDao() {        return DbCore.getDaoSession().getPersonDao();    }    private static CardDao getCardDao() {        return DbCore.getDaoSession().getCardDao();    }    public static CardService getCardService() {        if (cardService == null) {            cardService = new CardService(getCardDao());        }        return cardService;    }    public static PersonService getPersonService() {        if (personService == null) {            personService = new PersonService(getPersonDao());        }        return personService;    }}

在Application中初始化，并设置在清单文件中

public class App extends Application{    @Override    public void onCreate() {        super.onCreate();        DbCore.init(this);    }}

增删改查，下面为单元测试的方法

public class ApplicationTest extends ApplicationTestCase<Application> {    private PersonService mPersonService;    private CardService mCardService;    public ApplicationTest() {        super(Application.class);    }    @Override    protected void setUp() throws Exception {        super.setUp();        DbCore.init(getContext());        DbCore.enableQueryBuilderLog();        mPersonService = DbUtil.getPersonService();        mCardService = DbUtil.getCardService();    }    public void testSave(){        Card c=new Card();        c.setNum("3303241646813416463468");        c.setAddress("杭州");        mCardService.save(c);        Person p=new Person();        p.setName("张三");        p.setHeight(178.00);        p.setWeight(65.00);        p.setCard(c);        mPersonService.save(p);        c.setPerson(p);        mCardService.saveOrUpdate(c);    }    public void testSave1(){        Card c=new Card();        c.setNum("3303241646813416463468");        c.setAddress("杭州");        Card c1=new Card();        c1.setNum("12121646813416463468");        c1.setAddress("温州");        mCardService.save(c, c1);        c.setNum("11111");        mCardService.saveOrUpdate(c, c1);    }    public void testSave2(){        Card c=new Card();        c.setNum("3303241646813416463468");        c.setAddress("杭州");        Card c1=new Card();        c1.setNum("12121646813416463468");        c1.setAddress("温州");        List<Card> cards=new ArrayList<Card>();        cards.add(c);        cards.add(c1);        mCardService.save(cards);        c1.setNum("22222");        mCardService.saveOrUpdate(cards);    }    public void testDelete(){        Card c=new Card();        c.setNum("333333333333333");        c.setAddress("3333");        mCardService.save(c);        mCardService.delete(c);        c=new Card();        c.setNum("444444");        c.setAddress("44444444");        mCardService.save(c);        mCardService.deleteByKey(c.getId());    }    public void testDelete1(){        Card c=new Card();        c.setNum("55555");        c.setAddress("5555");        Card c1=new Card();        c1.setNum("666666");        c1.setAddress("66666666");        mCardService.save(c,c1);        mCardService.delete(c, c1);    }    public void testDelete2(){        Card c=new Card();        c.setNum("55555");        c.setAddress("5555");        Card c1=new Card();        c1.setNum("666666");        c1.setAddress("66666666");        List<Card> cards=new ArrayList<Card>();        cards.add(c);        cards.add(c1);        mCardService.save(cards);        mCardService.delete(cards);    }    public  void testDelete3(){        mCardService.deleteAll();    }    public void testUpdate(){        Card c=new Card();        c.setNum("55555");        c.setAddress("5555");        mCardService.save(c);        c.setNum("123456");        mCardService.update(c);    }    public void testUpdate1(){        Card c=new Card();        c.setNum("55555");        c.setAddress("5555");        mCardService.save(c);        c.setNum("123456");        Card c1=new Card();        c1.setNum("6666");        c1.setAddress("66666");        mCardService.save(c1);        c1.setNum("654321");        mCardService.update(c,c1);    }    public void testUpdate2(){        Card c=new Card();        c.setNum("aaaaa");        c.setAddress("aaaaaaaaaa");        mCardService.save(c);        c.setNum("bbbbbbbbb");        Card c1=new Card();        c1.setNum("ccccc");        c1.setAddress("cccccccc");        mCardService.save(c1);        c1.setNum("dddddddddd");        List<Card> cards=new ArrayList<Card>();        cards.add(c);        cards.add(c1);        mCardService.update(cards);    }    public void testQuery(){        Card c=new Card();        c.setNum("aaaaa111");        c.setAddress("aaaaaaaa11111aa");        mCardService.save(c);        List<Card> cards = mCardService.queryAll();        Log.e("TAG", cards + "");        Card query = mCardService.query(c.getId());        Log.e("TAG", query + "");        List<Card> query1 = mCardService.query("where NUM=?", c.getNum());        Log.e("TAG", query1 + "");        long count = mCardService.count();        Log.e("TAG", count + "");        List<Card> list = mCardService.queryBuilder().where(CardDao.Properties.Num.eq(c.getNum())).list();        Log.e("TAG", list + "");    }}

关于关联关系的映射，下一篇文章细说。

源码下载。

http://download.csdn.net/detail/sbsujjbcy/9070059

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