Android Studio 简单使用 GreenDao3.0

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Android Studio 简单使用 GreenDao3.0

- 据说现在很流行GreenDao框架，所以也抽空了解一下，可恨啊，刚看到的时候在百度上查询的就是GreenDao，然后很不幸的去走老版本的套路，麻麻烦烦的创建java工程，生成那四个文件，还为此查找了网上留存的不少的方法，今天的时候，再次搜索GreenDao的时候，发现有一个信息后面带了3.0这个版本号，查阅之后，只能暗自拍一拍大腿…………坑啊

GreenDao的使用

1、首先需要引入到工程中，在as中导入相关的jar，

compile 'org.greenrobot:greendao:3.0.1'compile 'org.greenrobot:greendao-generator:3.0.0'

2、在app的build.gradle文件中声明greendao的路径、版本、名称的设置

greendao {    /**     * 版本号     */    schemaVersion 1    /**     * greendao输出dao的数据库操作实体类文件夹（相对路径 包名+自定义路径名称，包将创建于包名的直接路径下）     */    daoPackage 'com.qiufeng.greendao.greendao.gen'    /**     * greenDao实体类包文件夹     */    targetGenDir 'src/main/java'}

3、在project的build.gradle中添加代码，apply plugin 的声明可以放到app的 build.gradle中

apply plugin: 'org.greenrobot.greendao'buildscript {      repositories {          jcenter()          mavenCentral()      }       dependencies {        classpath 'com.android.tools.build:gradle:2.2.1'        classpath 'org.greenrobot:greendao-gradle-plugin:3.0.0'       }    }

4、创建实体类，以@Entity注解标注,其中需添加id列，类型必须为Long类型，为其索引，如下：

/** * 用户信息 * Created by 秋风 on 2016/10/12. */@Entitypublic class UserInfo {    @Id    private Long id;    /**     * 用户名     */    private String userName;    /**     * 别名     */    private String nickName;    /**     * 密码     */    private String password;    /**     * 年龄     */    private int age;    /**     * 卡号     */    private String card;    /**     * 性别     */    private String gender;}

5、创建完成实体类之后点击Build–>MarkProject，会自动在配置的路径下生成DaoMaster、DaoSession、以及UserInfoDao文件（如果拥有多个实体类，则会生成多个实体类Dao文件），并且，刚才编写的实体类文件UserInfo会自动生成get、set方法跟无参构造以及完整参数的构造方法
MarkProject之后

6、目前测试前的环境基本搭建完成了，下面就开始进行测试，首先初始化我们的设置，在Application中

public class App extends Application {    private DaoMaster.DevOpenHelper dbHelper;    private SQLiteDatabase db;    private DaoMaster mDaoMaster;    private DaoSession mDaoSession;    public static App instance;    @Override    public void onCreate() {        super.onCreate();        init();        initDatabass();    }    public static App getInstance(){        return instance;    }    private void initDatabass() {        //这里之后会修改，关于升级数据库        dbHelper = new DaoMaster.DevOpenHelper(this, "notes-db", null);        db = dbHelper.getWritableDatabase();        mDaoMaster = new DaoMaster(db);        mDaoSession = mDaoMaster.newSession();    }    public DaoSession getSession(){        return mDaoSession;    }    public SQLiteDatabase getDb(){        return db;    }    private void init() {        instance = this;    }}

7、使用GreenDao3.0的功能，只需要声明我们要操作的Dao，然后进行使用就好，这里就不一一介绍了，统一贴出代码

package com.qiufeng.greendao;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.util.Log;import android.widget.TextView;import android.widget.Toast;import com.qiufeng.greendao.application.App;import com.qiufeng.greendao.entity.UserInfo;import com.qiufeng.greendao.greendao.gen.UserInfoDao;import java.util.List;public class MainActivity extends AppCompatActivity {    private UserInfoDao dao;    private TextView id_userinfo;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        initView();        dao = App.getInstance().getSession().getUserInfoDao();//        dao.deleteAll();//        insert();        update();        select();    }    /**     * 修改     */    private void update() {    //通过多种方式获取实例//        UserInfo userInfo = dao.queryBuilder().where(UserInfoDao.Properties.UserName.eq("qiufeng4")).build().unique();        UserInfo userInfo = dao.load((long)1);        if (userInfo != null) {            userInfo.setNickName("秋风哈哈");            dao.update(userInfo);            Toast.makeText(this, "修改成功", Toast.LENGTH_SHORT).show();        } else {            Toast.makeText(this, "修改失败", Toast.LENGTH_SHORT).show();        }    }    /**     * 初始化视图组件     */    private void initView() {        id_userinfo = (TextView) findViewById(R.id.id_userinfo);    }    /**     * 查询     */    private void select() {        List<UserInfo> userInfos = dao.loadAll();        if (userInfos == null) {            return;        }        UserInfo userInfo = userInfos.get(userInfos.size() - 1);        Log.e("qiufeng", "select: " + userInfos.size());        id_userinfo.setText("ID:" + userInfo.getId()                + "\n userName:" + userInfo.getUserName()                + "\n nichName:" + userInfo.getNickName()                + "\n age:" + userInfo.getAge() + "card:"                + userInfo.getCard() + "\n gender:"                + userInfo.getGender());    }    /**     * 数据库添加信息     */    private void insert() {        UserInfo userInfo = new UserInfo(null, "qiufeng4", "junyou4", "444444", 28, "3700000000000004", "男");        dao.insert(userInfo);    }}

到这里基本的增删改查都可以完成，删除方法没有写，不过也是很简单，大家只要同过获取的dao实例“点”一下都能找到，框架的好处就是降低使用门槛跟减少繁琐的代码逻辑嘛，好吧贴图,其实跟修改差不多的条件，对象，或者是key（id）

8、数据库的升级，这个估计是很多人比较关注的，我也是从网上其他博贴中寻找的方法，当然是跟GreenDao匹配的了，建议直接粘贴，因为有几处其他的地方用的数据库类型不一致

package com.qiufeng.greendao.helper;import android.database.Cursor;import android.text.TextUtils;import android.util.Log;import com.qiufeng.greendao.greendao.gen.DaoMaster;import org.greenrobot.greendao.AbstractDao;import org.greenrobot.greendao.database.Database;import org.greenrobot.greendao.internal.DaoConfig;import java.util.ArrayList;import java.util.Arrays;import java.util.List;/** * 数据库升级 */public class MigrationHelper {    private static final String CONVERSION_CLASS_NOT_FOUND_EXCEPTION = "MIGRATION HELPER - CLASS DOESN'T MATCH WITH THE CURRENT PARAMETERS";    private static MigrationHelper instance;    public static MigrationHelper getInstance() {        if(instance == null) {            instance = new MigrationHelper();        }        return instance;    }    public void migrate(Database db, Class<? extends AbstractDao<?, ?>>... daoClasses) {        generateTempTables(db, daoClasses);        DaoMaster.dropAllTables(db, true);        DaoMaster.createAllTables(db, false);        restoreData(db, daoClasses);    }    private void generateTempTables(Database db, Class<? extends AbstractDao<?, ?>>... daoClasses) {        for(int i = 0; i < daoClasses.length; i++) {            DaoConfig daoConfig = new DaoConfig(db, daoClasses[i]);            String divider = "";            String tableName = daoConfig.tablename;            String tempTableName = daoConfig.tablename.concat("_TEMP");            ArrayList<String> properties = new ArrayList<String>();            StringBuilder createTableStringBuilder = new StringBuilder();            createTableStringBuilder.append("CREATE TABLE ").append(tempTableName).append(" (");            for(int j = 0; j < daoConfig.properties.length; j++) {                String columnName = daoConfig.properties[j].columnName;                if(getColumns(db, tableName).contains(columnName)) {                    properties.add(columnName);                    String type = null;                    try {                        type = getTypeByClass(daoConfig.properties[j].type);                    } catch (Exception exception) {                    }                createTableStringBuilder.append(divider).append(columnName).append(" ").append(type);                    if(daoConfig.properties[j].primaryKey) {                        createTableStringBuilder.append(" PRIMARY KEY");                    }                    divider = ",";                }            }            createTableStringBuilder.append(");");            db.execSQL(createTableStringBuilder.toString());            StringBuilder insertTableStringBuilder = new StringBuilder();            insertTableStringBuilder.append("INSERT INTO ").append(tempTableName).append(" (");            insertTableStringBuilder.append(TextUtils.join(",", properties));            insertTableStringBuilder.append(") SELECT ");            insertTableStringBuilder.append(TextUtils.join(",", properties));            insertTableStringBuilder.append(" FROM ").append(tableName).append(";");            db.execSQL(insertTableStringBuilder.toString());        }    }    private void restoreData(Database db, Class<? extends AbstractDao<?, ?>>... daoClasses) {        for(int i = 0; i < daoClasses.length; i++) {            DaoConfig daoConfig = new DaoConfig(db, daoClasses[i]);            String tableName = daoConfig.tablename;            String tempTableName = daoConfig.tablename.concat("_TEMP");            ArrayList<String> properties = new ArrayList();            for (int j = 0; j < daoConfig.properties.length; j++) {                String columnName = daoConfig.properties[j].columnName;                if(getColumns(db, tempTableName).contains(columnName)) {                    properties.add(columnName);                }            }            StringBuilder insertTableStringBuilder = new StringBuilder();            insertTableStringBuilder.append("INSERT INTO ").append(tableName).append(" (");            insertTableStringBuilder.append(TextUtils.join(",", properties));            insertTableStringBuilder.append(") SELECT ");            insertTableStringBuilder.append(TextUtils.join(",", properties));            insertTableStringBuilder.append(" FROM ").append(tempTableName).append(";");            StringBuilder dropTableStringBuilder = new StringBuilder();            dropTableStringBuilder.append("DROP TABLE ").append(tempTableName);            db.execSQL(insertTableStringBuilder.toString());            db.execSQL(dropTableStringBuilder.toString());        }    }    private String getTypeByClass(Class<?> type) throws Exception {        if(type.equals(String.class)) {            return "TEXT";        }        if(type.equals(Long.class) || type.equals(Integer.class) || type.equals(long.class)) {            return "INTEGER";        }        if(type.equals(Boolean.class)) {            return "BOOLEAN";        }        Exception exception = new Exception(CONVERSION_CLASS_NOT_FOUND_EXCEPTION.concat(" - Class: ").concat(type.toString()));        throw exception;    }    private static List<String> getColumns(Database db, String tableName) {        List<String> columns = new ArrayList<String>();        Cursor cursor = null;        try {            cursor = db.rawQuery("SELECT * FROM " + tableName + " limit 1", null);            if (cursor != null) {                columns = new ArrayList<String>(Arrays.asList(cursor.getColumnNames()));            }        } catch (Exception e) {            Log.v(tableName, e.getMessage(), e);            e.printStackTrace();        } finally {            if (cursor != null)                cursor.close();        }        return columns;    }}

然后添加一个OpenHelper的帮助类，继承DaoMaster.OpenHelper，并重写onUpgrade方法

package com.qiufeng.greendao.helper;import android.content.Context;import android.database.sqlite.SQLiteDatabase;import com.qiufeng.greendao.greendao.gen.DaoMaster;import com.qiufeng.greendao.greendao.gen.UserInfoDao;import org.greenrobot.greendao.database.Database;/** * 自定义OpenHelper */public class QFOpenHelper extends DaoMaster.OpenHelper {    public QFOpenHelper(Context context, String name, SQLiteDatabase.CursorFactory factory) {        super(context, name, factory);    }    /**     * 升级数据库     * @param db     * @param oldVersion     * @param newVersion     */    @Override    public void onUpgrade(Database db, int oldVersion, int newVersion) {        //操作数据库的更新        MigrationHelper.getInstance().migrate(db,UserInfoDao.class);    }}

最后修改我们在application中的引用，将DaoMaster.DevOpenHelper修改为QFOpenHelper，
好吧，重新贴下代码

package com.qiufeng.greendao.application;import android.app.Application;import android.database.sqlite.SQLiteDatabase;import com.qiufeng.greendao.greendao.gen.DaoMaster;import com.qiufeng.greendao.greendao.gen.DaoSession;import com.qiufeng.greendao.helper.QFOpenHelper;/** * Created by 秋风 on 2016/10/12. */public class App extends Application {    private DaoMaster.DevOpenHelper dbHelper;    private QFOpenHelper helper;    private SQLiteDatabase db;    private DaoMaster mDaoMaster;    private DaoSession mDaoSession;    public static App instance;    @Override    public void onCreate() {        super.onCreate();        init();        initDatabass();    }    public static App getInstance(){        return instance;    }    private void initDatabass() {//        dbHelper = new DaoMaster.DevOpenHelper(this, "notes-db", null);        helper=new QFOpenHelper(this, "notes-db", null);        db = helper.getWritableDatabase();        mDaoMaster = new DaoMaster(db);        mDaoSession = mDaoMaster.newSession();    }    public DaoSession getSession(){        return mDaoSession;    }    public SQLiteDatabase getDb(){        return db;    }    /**     * 初始化App     */    private void init() {        instance = this;    }}

总结，没啥好说的，对于脑力不太够的我们，成长就需要多“跟风”，但凡是好的，即使不是最好的，但相比我们用的东西，子要是优于当前，就需要多查，多看，多了解
多谢费时浏览

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