Android开源：数据库ORM框架GreenDao封装工具类使用

Android开源：数据库ORM框架GreenDao封装工具类使用。

一、使用QureyBuilder实现表的增删改查

增删改查相当方便，完全的面向对象，不需要涉及到任何的sql语言。

1.查询

范例1：查询某个表是否包含某个id:

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publicbooleanisSaved(intID){

QueryBuilderqb=saveListDao.queryBuilder();

qb.where(Properties.Id.eq(ID));

qb.buildCount().count();

returnqb.buildCount().count()>0?true:false;

}

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/**通过图片id查找其目录id*/

publicintgetTypeId(intpicId)

{

QueryBuilderqb=photoGalleryDao.queryBuilder();

qb.where(Properties.Id.eq(picId));

if(qb.list().size()>0)

{

returnqb.list().get(0).getTypeId();

}else{

return-1;

}

}

Listjoes=userDao.queryBuilder()

where(Properties.FirstName.eq("Joe"))

orderAsc(Properties.LastName)

list();

范例5：多重条件查询

(1)获取id为cityId并且infotype为HBContant.CITYINFO_SL的数据集合：

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publicListgetSupportingList(intcityId){

QueryBuilderqb=cityInfoDao.queryBuilder();

qb.where(qb.and(Properties.CityId.eq(cityId),Properties.InfoType.eq(HBContant.CITYINFO_SL)));

qb.orderAsc(Properties.Id);//排序依据

returnqb.list();

}

(2)获取firstname为“Joe”并且出生于1970年10月以后的所有user集合:

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QueryBuilderqb=userDao.queryBuilder();

qb.where(Properties.FirstName.eq("Joe"),

qb.or(Properties.YearOfBirth.gt(1970),

qb.and(Properties.YearOfBirth.eq(1970),Properties.MonthOfBirth.ge(10))));

ListyoungJoes=qb.list();

picJsonDao.loadByRowId(picId);

publicvoidaddToPhotoTable(Photop){

photoDao.insert(p);

}

插入时需要new一个新的对象，范例如下:

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DevOpenHelperhelper=newDaoMaster.DevOpenHelper(this,"notes-db",null);

db=helper.getWritableDatabase();

daoMaster=newDaoMaster(db);

daoSession=daoMaster.newSession();

noteDao=daoSession.getNoteDao();

Notenote=newNote(null,noteText,comment,newDate());

noteDao.insert(note);

photoDao.insertOrReplace(photo);

photoDao.insertInTx(photo);

/**清空相册图片列表的数据*/

publicvoidclearPhoto(){

photoDao.deleteAll();

}

(2)删除某个对象

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publicvoiddeleteCityInfo(intcityId){

QueryBuilderqb=cityInfoDao.queryBuilder();

DeleteQuerybd=qb.where(Properties.CityId.eq(cityId)).buildDelete();

bd.executeDeleteWithoutDetachingEntities();

}

参考：https://github.com/greenrobot/greenDAO/issues/34

由上可见，使用greenDAO进行数据库的增删改查时及其方便，而且性能极佳。

(三)常用方法笔记

1.在Application实现得到DaoMaster和DaoSession的方法：

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privatestaticDaoMasterdaoMaster;

privatestaticDaoSessiondaoSession;

/**

*取得DaoMaster

*

*@paramcontext

*@return

*/

publicstaticDaoMastergetDaoMaster(Contextcontext)

{

if(daoMaster==null){

OpenHelperhelper=newDaoMaster.DevOpenHelper(context,ontant.DATABASE_NAME,null);

daoMaster=newDaoMaster(helper.getWritableDatabase());

}

returndaoMaster;

}

/**

*取得DaoSession

*

*@paramcontext

*@return

*/

publicstaticDaoSessiongetDaoSession(Contextcontext){

if(daoSession==null){

if(daoMaster==null){

daoMaster=getDaoMaster(context);

}

daoSession=daoMaster.newSession();

}

returndaoSession;

}

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publicclassDBHelper{

privatestaticContextmContext;

privatestaticDBHelperinstance;

privateCityInfoDBDaocityInfoDao;

privateDBHelper(){

}

publicstaticDBHelpergetInstance(Contextcontext){

if(instance==null){

instance=newDBHelper();

if(mContext==null){

mContext=context;

}

//数据库对象

DaoSessiondaoSession=HBApplication.getDaoSession(mContext);

instance.cityInfoDao=daoSession.getCityInfoDBDao();

}

returninstance;

}

/**添加数据*/

publicvoidaddToCityInfoTable(CityInfoitem){

cityInfoDao.insert(item);

}

/**查询*/

publicListgetCityInfoList(){

QueryBuilderqb=cityInfoDao.queryBuilder();

returnqb.list();

}

/**查询*/

publicListgetCityInfo(){

returncityInfoDao.loadAll();//查找图片相册

}

/**查询*/

publicbooleanisSaved(intId){

QueryBuilderqb=cityInfoDao.queryBuilder();

qb.where(Properties.Id.eq(Id));

qb.buildCount().count();

returnqb.buildCount().count()>0?true:false;//查找收藏表

}

/**删除*/

publicvoiddeleteCityInfoList(intId){

QueryBuilderqb=cityInfoDao.queryBuilder();

DeleteQuerybd=where(Properties.Id.eq(Id)).buildDelete();

bd.executeDeleteWithoutDetachingEntities();

}

/**删除*/

publicvoidclearCityInfo(){

cityInfoDao.deleteAll();

}

/**通过城市id查找其类型id*/

publicintgetTypeId(intcityId){

QueryBuilderqb=cityInfoDao.queryBuilder();

qb.where(Properties.Id.eq(cityId));

if(qb.list().size()>0){

returnqb.list().get(0).getTypeId();

}else{

return0;

}

}

/**多重查询*/

publicListgetIphRegionList(intcityId){

QueryBuilderqb=cityInfoDao.queryBuilder();

qb.where(qb.and(Properties.CityId.eq(cityId),perties.InfoType.eq(HBContant.CITYINFO_IR)));

qb.orderAsc(Properties.Id);//排序依据

returnqb.list();

}

}