Android Studio 简单使用 GreenDao3.0

Android Studio 简单使用 GreenDao3.0

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• • 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

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• 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.
 */
@Entity
public 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

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 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>... daoClasses) {
        generateTempTables(db, daoClasses);
        DaoMaster.dropAllTables(db, true);
        DaoMaster.createAllTables(db, false);
        restoreData(db, daoClasses);
    }
    private void generateTempTables(Database db, Class>... 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 properties = new ArrayList();
            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>... 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 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 getColumns(Database db, String tableName) {
        List columns = new ArrayList();
        Cursor cursor = null;
        try {
            cursor = db.rawQuery("SELECT * FROM " + tableName + " limit 1", null);
            if (cursor != null) {
                columns = new ArrayList(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
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