GreenDao数据库简单配置和升级

最新推荐文章于 2023-08-23 15:50:41 发布

币圈小韭菜

最新推荐文章于 2023-08-23 15:50:41 发布

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分类专栏： Android

本文链接：https://blog.youkuaiyun.com/liu_qunfeng/article/details/83719697

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本文详细介绍GreenDao数据库的配置过程及数据增删改查的基本操作。通过具体代码实例，展示了如何创建数据库会话，执行查询、添加、更新和删除记录。同时，介绍了Person实体类的定义，为读者提供了实践GreenDao的全面指导。

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GreenDao数据库简单配置和升级转载于 https://blog.youkuaiyun.com/AndroidStudioo/article/details/78830569

创建数据库 DaoManager

public class DaoManager {
    private static DaoManager daoManager;
    private DaoSession daoSession;

    private DaoManager(Context context) {
        daoSession = DaoMaster.newDevSession(context, "person.db");
    }

    public static DaoManager getInstance(Context context) {
        if (daoManager == null) {
            synchronized (DaoManager.class) {
                if (daoManager == null) {
                    daoManager = new DaoManager(context);
                }
            }
        }
        return daoManager;
    }

    public DaoSession getDaoSession() {
        return daoSession;
    }
}

增删改查的方法：

public class MainActivity extends AppCompatActivity {

    private DaoSession daoSession;
    private int index;
    private PersonDao personDao;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        daoSession = DaoManager.getInstance(this).getDaoSession();
        personDao = daoSession.getPersonDao();
    }

    public void query(View view) {
        List<Person> list = personDao.queryBuilder()
                .where(PersonDao.Properties.Age.lt(500))
                .orderDesc(PersonDao.Properties.Age)
                .build()
                .list();
        for (Person person : list) {
            Log.e("tag", "query   " + person.toString());
        }
    }

    public void add(View view) {
        index++;
        Person person = new Person(null, "name" + index, index * 10);
        personDao.insert(person);
    }

    public void update(View view) {
        List<Person> list = personDao.queryBuilder()
                .where(PersonDao.Properties.Age.lt(500))
                .orderDesc(PersonDao.Properties.Age)
                .build()
                .list();
        for (Person person : list) {
            if (person.age == 20) {
                person.age = 100;
                personDao.update(person);
            }
        }
    }

    public void delete(View view) {
        Person person = personDao.queryBuilder()
                .where(PersonDao.Properties.Id.eq(2))
                .build()
                .unique();
        if (person != null) {
            personDao.delete(person);
        }
    }
}

Bean类

@Entity(nameInDb = "person_table")
public class Person {
    @Id(autoincrement = true)
    public Long id;
    @Property(nameInDb = "name")
    public String mingzi;
    public int age;
    @Transient
    public String identity;
    @Generated(hash = 244725397)
    public Person(Long id, String mingzi, int age) {
        this.id = id;
        this.mingzi = mingzi;
        this.age = age;
    }
    @Generated(hash = 1024547259)
    public Person() {
    }