GreenDao 学习笔记 7

最新推荐文章于 2019-10-31 19:12:31 发布

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最新推荐文章于 2019-10-31 19:12:31 发布

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分类专栏： Android GreenDao 文章标签： Android GreenDao

本文链接：https://blog.youkuaiyun.com/ivolianer/article/details/39155827

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Active & Interface

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

        Schema schema = new Schema(1, "com.example.GreenDao6");

        Entity personEntity = schema.addEntity("Person");
        personEntity.addIdProperty();
        personEntity.addStringProperty("name").notNull();
        personEntity.setActive(false);
        personEntity.implementsSerializable();

        new DaoGenerator().generateAll(schema, "D:\\");
    }

当 setActive(false) 时，生成是实体类将不会用 update，delete，refresh 的方法，变成最简单的实体。

而 implementsSerializable 则可以让实体类实现序列化接口，这是为了满足 Activity 之间传值的需要。

GreenDao 该以何种形式结合到应用中

What’s a good place to store SQLiteDatabase/DaoMaster/DaoSession?
As a rule of thumb it’s a good idea to store database related objects in Application scope. This way use can use the database/DAO objects across Activities. Leaving the database open for the life time of the application’s process makes things simple and efficient.

既然我都用 GreenDao，为何不能听从作者的意见。

Db，DaoMaster，DaoSession 都为作为单列的存在，实现方式可以随意。

Db 连接在应用生命周期中始终开放。

查询

如果你认为拼写 SQL 语句不麻烦，你可以用原生的查询。

否则，你可以使用 queryBuilder 来查询，非常的简便。

MyActivity.java

public class MyActivity extends Activity implements View.OnClickListener {

    private PersonDao personDao;

    private ListViewAdapter listViewAdapter;

    private EditText etPersonName;

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.my_activity);

        initDao();
        initView();

        refreshListView(null);
    }

    @Override
    public void onClick(View v) {

        onBtnQueryClick();
    }

    private void initDao() {

        DaoMaster.DevOpenHelper helper = new DaoMaster.DevOpenHelper(this, "person-db", null);
        SQLiteDatabase db = helper.getWritableDatabase();

        DaoMaster daoMaster = new DaoMaster(db);
        DaoSession daoSession = daoMaster.newSession();
        personDao = daoSession.getPersonDao();

        // initData();
    }

    private void initData() {

        personDao.insert(new Person(null, "Mary", "female", new Date()));
        personDao.insert(new Person(null, "Mike", "male", new Date()));
        personDao.insert(new Person(null, "John", "male", new Date()));
    }

    private void initView() {

        etPersonName = (EditText) findViewById(R.id.etPersonName);

        findViewById(R.id.btnQuery).setOnClickListener(this);

        ListView listView = (ListView) findViewById(R.id.lvNote);
        listViewAdapter = new ListViewAdapter(this);
        listView.setAdapter(listViewAdapter);
    }

    private void onBtnQueryClick() {

        String personName = etPersonName.getText().toString();
        if (personName.equals("")) {
            refreshListView(null);
            return;
        }

        List<Person> result = personDao.queryBuilder()
                .where(PersonDao.Properties.Name.like("%"+personName+"%"))
                .listLazy();

        refreshListView(result);
    }

    private void refreshListView(List<Person> dataFromDb) {

        if (dataFromDb == null) {
            dataFromDb = personDao.loadAll();
        }

        List<Person> listViewData = listViewAdapter.getData();
        listViewData.clear();
        listViewData.addAll(dataFromDb);
        listViewAdapter.notifyDataSetChanged();
    }

}