db 的简单使用

各种导

classpath 'org.greenrobot:greendao-gradle-plugin:3.2.2'

apply plugin: 'org.greenrobot.greendao'

greendao {
    schemaVersion 1 //数据库版本号
    daoPackage '包名.database' //设置时生成代码的目录
    targetGenDir 'src/main/java' //设置DaoMaster、DaoSession、Dao目录
}

底部依赖

compile 'org.greenrobot:greendao:3.2.2'

《-----------------------------------------------------------》

自定义一个单例模式不是一定的但是优化不是每次都创建数据库等数据

MyDao.....

private static   DaoMyMaster daoMyMaster;
private DaoSession daoSession;
public DaoMyMaster(Context context) {
    daoSession= DaoMaster.newDevSession(context,"zhang.db");
}
public static DaoMyMaster insers(Context context){

     if (daoMyMaster==null){
         synchronized (DaoMyMaster.class){

          if (daoMyMaster==null){

              daoMyMaster=  new DaoMyMaster(context);
          }
         }
     }

    return daoMyMaster;

}
public  DaoSession  getDaoSession(){
    return  daoSession;
}

《-----------------------------------------------------------》

MainActivity

private  DaoSession daoSession;
private UserDao userDao;
daoSession = DaoMyMaster.insers(this).getDaoSession();
userDao=daoSession.getUserDao();

//增删改查

public void add(View view) {
        index++;
        personDao.insert(new Person(null, "wang" + index, index));
    }

    public void delete(View view) {
        Person person = personDao.queryBuilder()
                .where(PersonDao.Properties.Id.eq(1))
                .build().unique();
        personDao.delete(person);
    }

    public void update(View view) {
        Person person = personDao.queryBuilder()
                .where(PersonDao.Properties.Id.eq(1))
                .build().unique();
        person.setAge(1000);
        personDao.update(person);
    }

    public void query(View view) {
        List<Person> list = personDao.queryBuilder()
                .where(PersonDao.Properties.Id.ge(5))
                .build().list();
        Log.e("tag", "query" + list.get(0).getId());
    }

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