GreenDao#

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

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apply plugin: 'org.greenrobot.greendao'
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android {
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………………
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}
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dependencies {
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………………
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    //数据库操作
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    compile 'org.greenrobot:greendao-generator:3.2.0'
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    compile 'org.greenrobot:greendao:3.2.0'
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}

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@Entity(nameInDb = "t_book")
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public class Book {
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    @Id(autoincrement = true)
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    @Property(nameInDb = "id")
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    private Long id;
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    @Property(nameInDb = "f_book")
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    private String book;
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    @ToMany(referencedJoinProperty = "bookId")
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    private List<Unit> units;
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    public Long getId() {
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        return id;
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    }
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    public void setId(Long id) {
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        this.id = id;
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    }
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    public String getBook() {
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        return book;
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    }
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    public void setBook(String book) {
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        this.book = book;
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    }
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    @Generated//一定要标识这个@Generated，不要标识@Keep
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    public List<Unit> getUnits() {
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    return units;
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    }
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    @Generated//一定要标识这个@Generated，不要标识@Keep
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    public void setUnits(List<Unit> units) {
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        this.units = null;
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    }
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}

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@Id(autoincrement = true)
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    @Property(nameInDb = "id")
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    private long id;
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    @Property(nameInDb = "f_book_id")
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    private long bookId;//书籍id
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    @ToOne(joinProperty = "bookId")//请注意：joinProperty这是变量名，不是数据库字段
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    private Book book;
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    @Property(nameInDb = "f_unit")
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    private String unit;//单元
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    public long getId() {
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        return id;
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    }
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    public void setId(long id) {
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        this.id = id;
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    }
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    public long getBookId() {
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        return bookId;
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    }
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    public void setBookId(long bookId) {
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        this.bookId = bookId;
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    }
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    @Generated(hash = 8805314)//一定要标识这个@Generated，不要标识@Keep
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    public Book getBook() {
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      return book;
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    }
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    @Generated//一定要标识这个@Generated，不要标识@Keep
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    public void setBook( Book book) {
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      this.book=book;
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    }

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DaoMaster.DevOpenHelper mHelper =new DaoMaster.DevOpenHelper(App.getInstance(), DB_NAME, null);//DB_NAME，可以设置为已经存在的外部数据库，如果没有，会自动创建
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SQLiteDatabase db = mHelper.getWritableDatabase();
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DaoSession mDaoSession = mDaoMaster.newSession();//同步操作时，需要使用DaoSession
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AsyncSession mAsyncSession= mDaoSession.startAsyncSession();//异步处理时，需要使用AsyncSession

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//直接查询全部
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UnitDao unitDao = GreenDaoHelper.getDaoSession().getUnitDao();
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        unitDao.loadAll();
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//根据条件查询
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UnitDao unitDao = mDaoSession .getUnitDao();
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        WhereCondition eq = unitDao.Properties.Id.eq(1);
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        WhereCondition eq5 = unitDao.Properties.BookId.eq(1);
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        List<Unit> list = unitDao.queryBuilder().where(eq1, eq2, eq3, eq4).build().list();

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//异步数据查询
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StudyWordScoreDao studyWordScoreDao = GreenDaoHelper.getDaoSession().getStudyWordScoreDao();
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        WhereCondition eq1 = StudyWordScoreDao.Properties.BookId.eq(bookId);
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        WhereCondition eq2 = StudyWordScoreDao.Properties.UnitId.eq(unitId);
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        WhereCondition eq3 = StudyWordScoreDao.Properties.UnitId.eq(userId);
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        WhereCondition eq4 = StudyWordScoreDao.Properties.UnitId.eq(recordId);
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        Query<StudyWordScore> build = studyWordScoreDao.queryBuilder().where(eq1, eq2, eq3, eq4).build();
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//        WhereCondition and = wordDao.queryBuilder().and(eq, eq1);
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        asyncSession.queryList(build);
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        asyncSession.setListenerMainThread(asyncOperationListener);

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//根据官网的方法，说主键赋值为空，主键就会自增，但是编译器不通过，报错，因为初始为0，不是null，所以我就直接不设置主键值，果然就可以了
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new Book(null,"必修一");

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//只有使用了Generated，greenDao的插件才会将getset修改成以下代码，如果使用@keep那就保留getset代码，也就没有关联效果了
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@Generated(hash = 835179934)
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    public List<Unit> getUnits() {
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        if (units == null) {
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            final DaoSession daoSession = this.daoSession;
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            if (daoSession == null) {
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                throw new DaoException("Entity is detached from DAO context");
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            }
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            UnitDao targetDao = daoSession.getUnitDao();
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            List<Unit> unitsNew = targetDao._queryBook_Units(id);
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            synchronized (this) {
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                if (units == null) {
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                    units = unitsNew;
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                }
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            }
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        }
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        return units;
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    }
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    /** Resets a to-many relationship, making the next get call to query for a fresh result. */
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    @Generated(hash = 121816020)
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    public synchronized void resetUnits() {
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        units = null;
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    }