GreenDao的初次使用--號稱Android最快的關係型數據庫

1、準備工做

一、項目build.gradle文件下的dependencies中引入插件：

classpath 'org.greenrobot:greendao-gradle-plugin:3.2.1'

二、在module的build.gradle文件下頂部依賴插件：

apply plugin: 'org.greenrobot.greendao'

三、在module的build.gradle文件下的dependencies中引入依賴：

compile 'org.greenrobot:greendao:3.2.0'

2、GreenDao的註解

一、實體@Entity註解：

  schema：告知GreenDao當前實體屬於哪一個schema

  active：標記一個實體處於活動狀態，活動實體有更新、刪除和刷新方法

  nameInDb：在數據中使用的別名，默認使用的是實體的類名

  indexes：定義索引，能夠跨越多個列

  createInDb：標記建立數據庫表

二、基礎屬性註解

  @Id :主鍵 Long型，能夠經過@Id(autoincrement = true)設置自增加

  @Property：設置一個非默認關係映射所對應的列名，默認是的使用字段名 舉例：@Property (nameInDb="name")

  @NotNul：設置數據庫表當前列不能爲空

  @Transient ：添加次標記以後不會生成數據庫表的列

三、索引註解

  @Index：使用@Index做爲一個屬性來建立一個索引，經過name設置索引別名，也能夠經過unique給索引添加約束

  @Unique：向數據庫列添加了一個惟一的約束

四、關係註解

  @ToOne：定義與另外一個實體（一個實體對象）的關係

  @ToMany：定義與多個實體對象的關係

3、簡單使用----使用管理類DBManager，操做名稱爲test_db的數據庫，完成數據庫中用戶實體類User的增刪改查等操做

一、建立實體用戶類User，使用GreenDao進行註解，ReBuild項目。

/**
 * <p>Description:
 */
@Entity
public class User {

    @Id(autoincrement = true)
    private Long id ;
    private String name ;
    private int age ;

    public User(String name,int age){
        this.name = name ;
        this.age = age ;
    }


    @Generated(hash = 1309193360)
    public User(Long id, String name, int age) {
        this.id = id;
        this.name = name;
        this.age = age;
    }
    @Generated(hash = 586692638)
    public User() {
    }
    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 int getAge() {
        return this.age;
    }
    public void setAge(int age) {
        this.age = age;
    }
}

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二、建立管理類DBManager，完成對User的增刪改查方法

public class DBManager {

    private static DBManager instance ;
    private final static String dbName = "test_db";

    private Context mContext ;

    private DBManager(Context context){
        this.mContext = context ;
        openHelper = new DaoMaster.DevOpenHelper(context,dbName);
    }


    private DaoMaster.DevOpenHelper openHelper = null ;

    public static DBManager getInstance(Context context){
        if(instance == null){
            synchronized (DBManager.class){
                if(instance == null){
                    instance = new DBManager(context);
                }
            }
        }
        return instance ;
    }

    private SQLiteDatabase getWriteableDatabase(){
        if(openHelper == null){
            openHelper = new DaoMaster.DevOpenHelper(mContext,dbName);
        }
        return openHelper.getWritableDatabase();
    }
    private SQLiteDatabase getRedadableDatabase(){
        if(openHelper == null){
            openHelper = new DaoMaster.DevOpenHelper(mContext,dbName);
        }
        return openHelper.getReadableDatabase() ;
    }


    public void saveUser(User user){
        DaoMaster daoMaster = new DaoMaster(getWriteableDatabase());
        DaoSession daoSession = daoMaster.newSession();
        UserDao userDao = daoSession.getUserDao();
        //存入user對象
        userDao.save(user);

    }

    public void saveUsers(List<User> users){
        DaoMaster daoMaster = new DaoMaster(getWriteableDatabase());
        DaoSession daoSession = daoMaster.newSession();
        UserDao userDao = daoSession.getUserDao();
        userDao.saveInTx(users);
    }

    public void delteUser(User user){
        DaoMaster daoMaster = new DaoMaster(getWriteableDatabase());
        DaoSession daoSession = daoMaster.newSession();
        UserDao userDao = daoSession.getUserDao();
        userDao.delete(user);
    }

    public void updateUser(User user){
        DaoMaster daoMaster = new DaoMaster(getWriteableDatabase());
        DaoSession daoSession = daoMaster.newSession();
        UserDao userDao = daoSession.getUserDao();
        userDao.update(user);
    }

    public List<User> queryUser(){
        DaoMaster daoMaster = new DaoMaster(getRedadableDatabase());
        DaoSession daoSession = daoMaster.newSession();
        UserDao userDao = daoSession.getUserDao();
        QueryBuilder<User> qb = userDao.queryBuilder();
        List<User> list = qb.list();
        return list ;
    }

    public List<User> queryUser(int age){
        DaoMaster daoMaster = new DaoMaster(getRedadableDatabase());
        DaoSession daoSession = daoMaster.newSession();
        UserDao userDao = daoSession.getUserDao();
        QueryBuilder<User> qb = userDao.queryBuilder();
        //添加查詢條件
        qb.where(UserDao.Properties.Age.eq(age));
        List<User> list = qb.list();
        return list ;
    }

}

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