greenDAO: Android ORM for your SQLite database

一.什么是GreenDao

Demo鏈接: https://github.com/liumaomao0209/GreenDaoDemo
GreenDAO是一個開源的AndroidORM，使SQLite數(shù)據(jù)庫的開發(fā)再次變得有趣。它在節(jié)省開發(fā)時間的同時，減輕了開發(fā)人員對低級別數(shù)據(jù)庫需求的處理。SQLite是一個令人敬畏的嵌入式關(guān)系數(shù)據(jù)庫。盡管如此，編寫SQL和解析查詢結(jié)果仍然是非常繁瑣和耗時的任務(wù)。GreenDAO通過將Java對象映射到數(shù)據(jù)庫表(稱為奧姆，“對象/關(guān)系映射”)。通過這種方式，您可以使用簡單的面向?qū)ο驛PI來存儲、更新、刪除和查詢Java對象。

二.GreenDao的特點

GreenDAO的特點一目了然

• 性能強大 (可能是Android最快的ORM)
• 易用 有強大的API
• 極小內(nèi)存消耗
• 體積小 GreenDAO小于100KB，所以對于應(yīng)用程序APK的大小影響很小。
• 數(shù)據(jù)庫加密 支持SQLCiPHER，以確保用戶數(shù)據(jù)的安全

當(dāng)性能很重要時（數(shù)據(jù)訪問頻繁），GreenDao是一個很快的解決方案，它能夠支持數(shù)千條記錄的CRUD每秒，和OrmLite相比，GreenDAO要快幾乎4.5倍。（準(zhǔn)確數(shù)據(jù)請自行benchmark）。

greenDAO vs OrmLite

三.GreenDao的配置

1.導(dǎo)入插件
在project:build.gradle添加如下兩行(位置已注釋)

base.png

// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {
    
    repositories {
        google()
        jcenter()
        mavenCentral() // 添加
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.1.2'
        classpath 'org.greenrobot:greendao-gradle-plugin:3.2.2' // 添加
    }
}

allprojects {
    repositories {
        google()
        jcenter()
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

2.添加依賴和數(shù)據(jù)庫配置
(1)在app:build.gradle添加library和plugin(位置已經(jīng)注釋為// apply plugin // add library)
(2)數(shù)據(jù)庫配置信息,在android節(jié)點下

app.build.gradle

apply plugin: 'com.android.application'
apply plugin: 'org.greenrobot.greendao' // apply plugin

android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "com.maomao.technology.greendaodemo"
        minSdkVersion 27
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
    greendao {
        schemaVersion 1 //數(shù)據(jù)庫版本號，數(shù)據(jù)庫升級使用
        daoPackage 'com.maomao.technology.greendaodemo.greendao' //代表GreenDao自動生成的有關(guān)數(shù)據(jù)庫操作工具類所要存放的包名
        targetGenDir 'src/main/java' //路徑
    }

}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
    implementation 'org.greenrobot:greendao:3.2.2' // add library
}

四.GreenDao的使用

首先大概看一下整體構(gòu)建的樣子:

base:數(shù)據(jù)庫操作的基類
db:對用戶表專門自定義的操作類.
greendao:建表時自動生成的類.

目錄

1.創(chuàng)建一個用戶類

Generated之下是build后自動生成的.
項目的build目錄下或者自己設(shè)定的目錄下還可以看到自動生成的三個類文件：
DaoMaster
DaoSession
UserDao

@Entity
public class UserBean {
    @Id(autoincrement = true)
    long id;
    @NotNull
    String name;
    String age;
    @Generated(hash = 47803367)
    public UserBean(long id, @NotNull String name, String age) {
        this.id = id;
        this.name = name;
        this.age = age;
    }
    @Generated(hash = 1203313951)
    public UserBean() {
    }
    public long getId() {
        return this.id;
    }
    public void setId(long id) {
        this.id = id;
    }
    public String getName() {
        return this.name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getAge() {
        return this.age;
    }
    public void setAge(String age) {
        this.age = age;
    }
}

創(chuàng)建好后.png

注解說明：

@Id 注解選擇 long / Long 屬性作為實體ID。在數(shù)據(jù)庫術(shù)語中，它是主鍵。參數(shù)自動增量，是使ID值不斷增加（不會選用舊值）的標(biāo)志。
@Property 讓你定義一個非默認的列名，其屬性映射到。如果不存在，greenDAO將在SQL雜交方式使用字段名（大寫，下劃線，而不是駱駝情況下，例如 customName將成為 CUSTOM_NAME）。注意：您目前只能使用內(nèi)聯(lián)常量來指定列名。
@Transient 表明這個字段不會被寫入數(shù)據(jù)庫，只是作為一個普通的java類字段，用來臨時存儲數(shù)據(jù)的，不會被持久化
@Entity 定義實體
@nameInDb 在數(shù)據(jù)庫中的名字，如不寫則為實體中類名
@indexes 索引
@schema 指定架構(gòu)名稱為實體
@active 無論是更新生成都刷新
@NotNull 不為null
@Unique 唯一約束
@ToMany 一對多
@OrderBy 排序
@ToOne 一對一
@Transient 不存儲在數(shù)據(jù)庫中
@generated 由greendao產(chǎn)生的構(gòu)造函數(shù)或方法

2.構(gòu)建兩個管理DB的基類

1.BaseDBManager 所有的數(shù)據(jù)庫操作類都繼承自此

public class BaseDBManager<T, K> {

    private AbstractDao<T, K> mDao;

    public BaseDBManager(AbstractDao dao) {
        this.mDao = dao;
    }

    public void insert(T item) {
        mDao.insert(item);
    }

    public void insert(T... items) {
        mDao.insertInTx(items);
    }

    public void insert(List<T> items) {
        mDao.insertInTx(items);
    }

    public void insertOrUpdate(T item) {
        mDao.insertOrReplace(item);
    }

    public void insertOrUpdate(T... items) {
        mDao.insertOrReplaceInTx(items);
    }

    public void insertOrUpdate(List<T> items) {
        mDao.insertOrReplaceInTx(items);
    }

    public void deleteByKey(K key) {
        mDao.deleteByKey(key);
    }

    public void delete(T item) {
        mDao.delete(item);
    }

    public void delete(T... items) {
        mDao.deleteInTx(items);
    }

    public void delete(List<T> items) {
        mDao.deleteInTx(items);
    }

    public void deleteAll() {
        mDao.deleteAll();
    }

    public void update(T item) {
        mDao.update(item);
    }

    public void update(T... items) {
        mDao.updateInTx(items);
    }

    public void update(List<T> items) {
        mDao.updateInTx(items);
    }

    /**
     * 根據(jù)主鍵查詢數(shù)據(jù)  如果沒有涉及主鍵 則會報錯
     *
     * @param key 主鍵
     * @return T
     */
    public T query(K key) {
        return mDao.load(key);
    }

    public List<T> queryAll() {
        return mDao.loadAll();
    }

    public List<T> query(String where, String... params) {
        return mDao.queryRaw(where, params);
    }

    public QueryBuilder<T> getQueryBuilder() {
        return mDao.queryBuilder();
    }

    public long count() {
        return mDao.count();
    }

    public void refresh(T item) {
        mDao.refresh(item);
    }

    public void detach(T item) {
        mDao.detach(item);
    }

}

2.庫名類

public interface DBConfig {
    String DB_NAME = "User.db";
}

3.編寫USER庫的操作類

操作類

三個類分別為

UserDBFactory 用戶數(shù)據(jù)庫工廠類 通過這個類統(tǒng)一下面兩個類的功能,使用時調(diào)用這個類.
UserDBManage 數(shù)據(jù)庫管理類,用于創(chuàng)建 刪除 關(guān)閉數(shù)據(jù)庫 獲取session
UserInfoManage 用戶信息管理類 對用戶列表的增刪改查放這里

public class UserDBFactory {
    private static UserDBFactory mInstance = null;
    private UserInfoManage userInfoManage;

    public static UserDBFactory getInstance() {
        if (mInstance == null) {
            synchronized (UserDBFactory.class) {
                if (mInstance == null) {
                    mInstance = new UserDBFactory();
                }
            }
        }
        return mInstance;
    }

    public UserInfoManage getUserInfoManage() {
        if (userInfoManage == null) {
            userInfoManage = new UserInfoManage(UserDBManage.getInstance(MyApplication.getApplication()).getDaoSession().getUserBeanDao());
        }
        return userInfoManage;
    }
}

public class UserDBManage {
    private static UserDBManage dbManage;
    private Context context;
    public static UserDBManage getInstance(Context context) {
        if (dbManage == null) {
            synchronized (UserDBManage.class) {
                if (dbManage == null) {
                    dbManage = new UserDBManage(context);
                }
            }
        }
        return dbManage;
    }
    private UserDBManage(Context context) {
        this.context = context;
    }
    private DaoMaster.DevOpenHelper mHelper;
    private DaoMaster mDaoMaster;
    private DaoSession mDaoSession;
    /**
     * 獲取DaoSession * * @return
     */
    public synchronized DaoSession getDaoSession() {
        if (null == mDaoSession) {
            mDaoSession = getDaoMaster().newSession();
        }
        return mDaoSession;
    }
    /**
     * 關(guān)閉數(shù)據(jù)庫
     */
    public synchronized void closeDataBase() {
        closeHelper();
        closeDaoSession();
    }
    /**
     * 判斷數(shù)據(jù)庫是否存在，如果不存在則創(chuàng)建 * * @return
     */
    private DaoMaster getDaoMaster() {
        if (null == mDaoMaster) {
            mHelper = new DaoMaster.DevOpenHelper(context, DBConfig.DB_NAME, null);
            mDaoMaster = new DaoMaster(mHelper.getWritableDb());
        }
        return mDaoMaster;
    }
    private void closeDaoSession() {
        if (null != mDaoSession) {
            mDaoSession.clear();
            mDaoSession = null;
        }
    }
    private void closeHelper() {
        if (mHelper != null) {
            mHelper.close();
            mHelper = null;
        }
    }
}

/**
 * Describe：DB操作類
 */

public class UserInfoManage extends BaseDBManager<UserBean, String> {
    public UserInfoManage(AbstractDao dao) {
        super(dao);
    }
}

五.增刪改查功能實現(xiàn)

1.布局和代碼目錄展示

增刪改查功能.png

布局和條目布局代碼我就不寫在這里了,各位自行定義.列表使用的是recyclerview;
2.自定義適配器

package com.maomao.technology.greendaodemo;

import android.content.Context;
import android.support.annotation.NonNull;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import java.util.List;

/**
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 * 創(chuàng)建日期:2019/4/19 on 15:45
 * 作   者:劉喵喵
 * 郵   箱:915850672@qq.com
 * 描   述:
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */
public class MyAdapter extends RecyclerView.Adapter {

    private final int mLayoutId;
    private final List<UserBean> mData;
    private final Context mContext;
    private final LayoutInflater inflater;

    public MyAdapter(List<UserBean> mData, int mLayoutId, Context mContext) {
        this.mData = mData;
        this.mLayoutId = mLayoutId;
        this.mContext = mContext;
        inflater = LayoutInflater.from(mContext);
    }


    @NonNull
    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int i) {
        View view = inflater.inflate(mLayoutId, parent, false);
        return new MyViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull RecyclerView.ViewHolder viewHolder, int i) {
        MyViewHolder holder = (MyViewHolder) viewHolder;
        holder.key.setText(mData.get(i).getId()+"");
        holder.name.setText(mData.get(i).getName()+"");
        holder.age.setText(mData.get(i).getAge()+"");

    }

    @Override
    public int getItemCount() {
        return mData.size();
    }

    public class MyViewHolder extends RecyclerView.ViewHolder {

        private final TextView age;
        private final TextView name;
        private final TextView key;
        public MyViewHolder(View v) {
            super(v);
            name = v.findViewById(R.id.name);
            age = v.findViewById(R.id.age);
            key = v.findViewById(R.id.key);

        }


    }
}

3.主要功能邏輯

public class MainActivity extends Activity implements View.OnClickListener {

    private UserInfoManage userInfoManage;
    private List<UserBean> userBeanList = new ArrayList<>();
    private RecyclerView recyclerView;
    private MyAdapter myAdapter;
    private EditText keyEdit;
    private EditText valueEdit;
    private TextView add;
    private TextView delete;
    private TextView search;
    private TextView show;
    private TextView update;
    private UserBean userBean;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initview();
        initdata();
        UserDBFactory userDBFactory = new UserDBFactory();
        userInfoManage = userDBFactory.getUserInfoManage();
    }

    private void initdata() {
        myAdapter = new MyAdapter(userBeanList, R.layout.user_item, this);
        recyclerView.setAdapter(myAdapter);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
    }

    private void initview() {
        add = findViewById(R.id.add_btn);
        delete = findViewById(R.id.delete_btn);
        search = findViewById(R.id.search_btn);
        show = findViewById(R.id.show_btn);
        recyclerView = findViewById(R.id.recyclerView);
        keyEdit = findViewById(R.id.key_edt);
        valueEdit = findViewById(R.id.value_edt);
        update = findViewById(R.id.update_btn);
        add.setOnClickListener(this);
        delete.setOnClickListener(this);
        search.setOnClickListener(this);
        show.setOnClickListener(this);
        update.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        Random mRandom = new Random();
        String key = keyEdit.getText().toString();
        switch (v.getId()) {
            case R.id.add_btn:
                //添加數(shù)據(jù)
                for (int i = 0; i < 10; i++) {
                    userBean = new UserBean();
                    userBean.setId(i + "");
                    int age = mRandom.nextInt(10) + 10;
                    userBean.setAge(age + "");
                    userBean.setName("瑤瑤" + i);
                    userInfoManage.insertOrUpdate(userBean);//插入或替換
                }
                myAdapter.notifyDataSetChanged();
                //顯示
                show.performClick();
                break;
            case R.id.delete_btn:
                //刪除key為..的數(shù)據(jù)
                userInfoManage.deleteByKey(key);
                show.performClick();
                break;
            case R.id.show_btn:
                userBeanList.clear();
                //查詢所有并顯示
                List<UserBean> userBeans = userInfoManage.queryAll();
                userBeanList.addAll(userBeans);
                myAdapter.notifyDataSetChanged();
                break;
            case R.id.search_btn:
                //搜索key為..的數(shù)據(jù)
                UserBean query = userInfoManage.query(key);
                if (query != null) {
                    userBeanList.clear();
                    userBeanList.add(query);
                    myAdapter.notifyDataSetChanged();
                } else {
                    Toast.makeText(this, "沒有該條數(shù)據(jù)", Toast.LENGTH_SHORT).show();
                }
        break;
        case R.id.update_btn:
        //使用主鍵查詢需要修改的數(shù)據(jù)
        UserBean userBean = userInfoManage.query(key);
        if (userBean != null) {
            userBean.setName(valueEdit.getText().toString());
            //修改
            userInfoManage.update(userBean);
            show.performClick();
        } else {
            Toast.makeText(this, "沒有該條數(shù)據(jù)", Toast.LENGTH_SHORT).show();
        }
        break;
    }
}
}

4.全局context

public class MyApplication extends Application {

    //全局唯一的context
    private static MyApplication application;
    @Override
    protected void attachBaseContext(Context base) {
        super.attachBaseContext(base);
        application = this;
    }
    public static Context getContext() {
        return application;
    }

    @Override
    public void onCreate() {
        super.onCreate();
    }
    /**
     * 獲取全局唯一上下文
     *
     * @return BaseApplication
     */
    public static MyApplication getApplication() {
        return application;
    }
}

最后再放一次我的Demo鏈接

https://github.com/liumaomao0209/GreenDaoDemo
官方網(wǎng)站：http://greendao-orm.com/