Android GreenDao数据库

1、在app的Gradle中配置：

apply plugin: 'org.greenrobot.greendao'

添加依赖：

dependencies {
    compile 'org.greenrobot:greendao:3.2.0'
}

2、在project的Gradle中配置：

buildscript {
    repositories {
        jcenter()
        mavenCentral()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:2.3.3'
        classpath 'org.greenrobot:greendao-gradle-plugin:3.2.1'
        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

3、在app的Gradle配置 数据库 版本等信息（android下）

greendao {
    schemaVersion 1
    daoPackage 'com.bwie.greendao.gen'
    targetGenDir 'src/main/java'
}

4、在项目中定义实体类

//标识实体类
@Entity
public class User {
    //标识主键（autoincrement = true表示自动增长）
    @Id(autoincrement = true)
        private Long id;
        private String name;
        private int age;
}

5、新建一个类，实例化greenDAO所需要的几个关键对象，DaoMaster，DaoSession，代码如下：

public class GreenDaoManager {
    private DaoMaster mDaoMaster;
    private DaoSession mDaoSession;
    private static volatile GreenDaoManager mInstance = null;

    private GreenDaoManager() {
        if (mInstance == null) {
            DaoMaster.DevOpenHelper devOpenHelper = new DaoMaster.DevOpenHelper(Myapp.getContext(), "user.db");
            mDaoMaster = new DaoMaster(devOpenHelper.getWritableDatabase());
            mDaoSession = mDaoMaster.newSession();
        }
    }

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

    public DaoMaster getMaster() {
        return mDaoMaster;
    }

    public DaoSession getSession() {
        return mDaoSession;
    }

    public DaoSession getNewSession() {
        mDaoSession = mDaoMaster.newSession();
        return mDaoSession;
    }
}

然后在Application中初始化：

GreenDaoManager.getInstance();

现在就可以操作数据库了。

6、数据库的增、删、改、查

首先获得UserDao的对象

UserDao userDao = GreenDaoManager.getInstance().getNewSession().getUserDao();

增:

user = new User(null, "唐1", 22);
userDao.insert(user);

删:

(按照id删除)

userDao.deleteByKey(id);

(全部删除)

userDao.deleteAll();

查:

(查询全部数据)

List<User> users = userDao.loadAll();
String name = "";
for (int i = 0; i < users.size(); i++) {
    name+=user.getName()+",";
}
Toast.makeText(this , "查詢"+ name,Toast.LENGTH_SHORT).show();

改:

(按照id查找)

user = new User((long)2,"唐唐");
UserDao.update(user);