Android数据库操作--greenDAO的入门使用

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目前android经常用的orm框架主要有greenDAO、OrmLite、AndrORM。其中greenDAO的运行效率最高，内存消耗最少，性能最佳。
这里写图片描述

greenDAO是一个可以快速将Java对象映射到SQLite数据库的表单中的ORM解决方案。设计的主要目标：一个精简的库；性能最大化；内存开销最小化；易于使用的APIs；对Android进行高度优化。
GreenDAO3.0之前需要通过新建GreenDaoGenerator工程生成java数据对象（实体）和DAO对象，非常的繁琐而且也加大了使用成本。GreenDAO3.0最大的变化就是采用注解的方式通过编译生成java数据对象和DAO对象。
下面是使用步骤：

第一步，在build.gradle添加设置

buildscript {    repositories {        mavenCentral()    }    dependencies {        classpath 'org.greenrobot:greendao-gradle-plugin:3.2.0'    }}apply plugin: 'org.greenrobot.greendao'greendao {schemaVersion 1000    targetGenDir 'src/main/java'    daoPackage 'com.chinaso.greendaodemo'}dependencies {    compile 'org.greenrobot:greendao:3.2.0 '}

第二步，新建实体类，例如user：

@Entitypublic class User {    @Id    private Long id;    private String name;    private int age;   //下面省去了 setter/getter}

此时编译自动生成DAOMaster\DaoSession\Dao，默认位置build->generated->source->greenDao.如果第一步设置了greendao{}则在定义的包下生成。

第三步，第三步：通过上面使用的方式获取DAOMaster、DAOSession、DAO类，然后数据库管理者类

package com.chinaso.dagger_demo.db;import android.content.Context;import com.chinaso.dagger_demo.App;import com.chinaso.greendaodemo.DaoMaster;import com.chinaso.greendaodemo.DaoSession;import com.chinaso.greendaodemo.UserDao;import org.greenrobot.greendao.query.QueryBuilder;import java.util.List;public class DBManager {    private static DBManager mInstance;    private static DaoMaster.DevOpenHelper openHelper;    private static Context mContext;    private UserDao userDao;    private DBManager() {    }    public static DBManager getInstance(Context context) {        if (mInstance == null) {            synchronized ((DBManager.class)) {                mContext = context;                mInstance = new DBManager();                DaoSession daoSession = App.getDaoSession(mContext);                mInstance.userDao = daoSession.getUserDao();            }        }        return mInstance;    }    public void insertUser(User user) {        userDao.insert(user);    }    public void insertUserList(List<User> users) {        if (users == null || users.isEmpty()) {            return;        }        userDao.insertInTx(users);    }    public void deleteUser(User user) {        userDao.delete(user);    }    public void deleteAll() {        userDao.deleteAll();    }    public void updateUser(User user) {        userDao.update(user);    }    public List<User> queryUserList() {        QueryBuilder<User> qb = userDao.queryBuilder();        List<User> list = qb.list();        return list;    }    public List<User> queryUserList(int age) {        QueryBuilder<User> qb = userDao.queryBuilder();        qb.where(UserDao.Properties.Age.gt(age)).orderAsc(UserDao.Properties.Age);        List<User> list = qb.list();        return list;    }}

其中App：

public class App extends Application {    public final static String dbName = "test_db";    private static DaoMaster daoMaster;    private static DaoSession daoSession;    public static DaoMaster getDaoMaster(Context context)    {        if (daoMaster == null)        {            DaoMaster.OpenHelper helper = new DaoMaster.DevOpenHelper(context, dbName, null);            daoMaster = new DaoMaster(helper.getWritableDatabase());        }        return daoMaster;    }    public static DaoSession getDaoSession(Context context)    {        if (daoSession == null)        {            if (daoMaster == null)            {                daoMaster = getDaoMaster(context);            }            daoSession = daoMaster.newSession();        }        return daoSession;    }}

第四步，使用

package com.chinaso.dagger_demo;import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import android.util.Log;import android.widget.Button;import android.widget.TextView;import com.chinaso.dagger_demo.db.DBManager;import com.chinaso.dagger_demo.db.User;import java.util.List;import butterknife.BindView;import butterknife.ButterKnife;import butterknife.OnClick;public class FullscreenActivity extends AppCompatActivity {    @BindView(R.id.insertBtn)    Button insertBtn;    @BindView(R.id.queryListBtn)    Button queryListBtn;    @BindView(R.id.deleteBtn)    Button deleteBtn;    @BindView(R.id.updateBtn)    Button updateBtn;    @BindView(R.id.dbResultTV)    TextView dbResultTV;    StringBuilder result = new StringBuilder();    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_fullscreen);        ButterKnife.bind(this);        initDB();    }    private void initDB() {        result.delete(0,result.length());        DBManager dbManager = DBManager.getInstance(FullscreenActivity.this);        dbManager.deleteAll();        for (int i = 0; i < 5; i++){            User user = new User();            user.setId(new Long((long) i));            user.setAge(i * 10);            user.setName("第" + i + "人");            dbManager.insertUser(user);            result.append("insertDB:name="+user.getName()+"; age="+user.getAge() + "\n");        }        dbResultTV.setText(result.toString());    }    @OnClick(R.id.insertBtn)    public void insertDB() {        result.setLength(0);        DBManager dbManager = DBManager.getInstance(FullscreenActivity.this);        List<User> userList = dbManager.queryUserList();        int len = userList.size();        User user = new User();        user.setId(new Long((long) len));        user.setAge(len * 3);        user.setName("第" + len + "人");        dbManager.insertUser(user);        userList = dbManager.queryUserList();        int leng = userList.size();        for (int i = 0; i<leng;i++){            User u = userList.get(i);            Log.e("db", "insertDB:name="+u.getName()+"; age="+u.getAge());            result.append("insertDB:name="+u.getName()+"; age="+u.getAge() + "\n");        }        dbResultTV.setText(result.toString());    }    @OnClick(R.id.queryListBtn)    public void queryListDB() {        result.delete(0,result.length());        DBManager dbManager = DBManager.getInstance(FullscreenActivity.this);        List<User> userList = dbManager.queryUserList();        for (User user : userList) {            Log.e("db", "insertDB:name=" + user.getName() + "; age=" + user.getAge());            result.append("insertDB:name="+user.getName()+"; age="+user.getAge() + "\n");        }        dbResultTV.setText(result.toString());    }    @OnClick(R.id.deleteBtn)    public void deleteBtn() {        result.delete(0,result.length());        DBManager dbManager = DBManager.getInstance(FullscreenActivity.this);        List<User> userList = dbManager.queryUserList();        for (User user : userList) {            Log.e("db", "insertDB:name=" + user.getName() + "; age=" + user.getAge());            if (user.getId() == 0) {                dbManager.deleteUser(user);            }        }        userList = dbManager.queryUserList();        for (User user : userList) {            Log.e("db", "insertDB:name=" + user.getName() + "; age=" + user.getAge());            result.append("insertDB:name="+user.getName()+"; age="+user.getAge() + "\n");        }        dbResultTV.setText(result.toString());    }    @OnClick(R.id.updateBtn)    public void updateBtn() {        result.delete(0,result.length());        DBManager dbManager = DBManager.getInstance(FullscreenActivity.this);        List<User> userList = dbManager.queryUserList();        for (User user:userList) {            if (user.getId() == 3) {                user.setAge(10);                user.setName("张三");                dbManager.updateUser(user);            }        }        userList = dbManager.queryUserList();        for (User user : userList) {            Log.e("db", "insertDB:name=" + user.getName() + "; age=" + user.getAge());            result.append("insertDB:name="+user.getName()+"; age="+user.getAge() + "\n");        }        dbResultTV.setText(result.toString());    }}

参考：

1、官方地址：http://greenrobot.org/greendao/
2、官方demo：https://github.com/greenrobot/greenDAO 和
http://greenrobot.org/greendao/documentation/introduction/
3、Android数据存储之GreenDao 3.0 详解：http://www.cnblogs.com/whoislcj/p/5651396.html

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