说起greendao的就要将3.0版本，3.0之前是通过java类的main方法来生成一些操作数据库的类；3.0之后是直接用注解来写实体生成对应的数据库表和操作类。我下面的字段可能写的有点随意，但是我最后都会附上源码连接，包含ToOne和ToMany的基本使用；
我写的demo代码：greenDao Demo代码，里面写的特别详细。
以下是3.2需要导入的依赖：
compile 'org.greenrobot:greendao:3.2.0'
compile 'org.greenrobot:greendao-generator:3.2.0'我下面会贴出3.0之前和3.0之后的greendao的一些基本用法：
用Java类的main方法来生成相关需要的类。如下是生成1V1的外键关联代码：
Schema schema = new Schema(1, "greendao.database");//在下面的那个路径下，生成的时候生成的包名
Entity son = schema.addEntity("Son");//设置表名
son.addIdProperty();
son.addLongProperty("carId").primaryKey().autoincrement();//设置自增加的主键，跟上面那句代码其实是等效的
son.addStringProperty("name").notNull();//设置字段不允许为null
son.addIntProperty("age");
//设置一个字段来作为关联外键的时候使用
Property fatherId = son.addLongProperty("fatherId").getProperty();
Entity father = schema.addEntity("Father");
father.addIdProperty();
father.addStringProperty("name");
father.addIntProperty("age");
//关联外键
son.addToOne(father, fatherId);
try {
new DaoGenerator().generateAll(schema, "greendao3/src/main/java");//在那个项目的那个文件夹下生成文件夹，文件夹的名称是new Schema的第二个参数
} catch (Exception e) {
e.printStackTrace();
}注意：这里面的两个路径我加了注解，您看着可能还不是很理解，您自己多试几次就懂了。
如下是生成1V多的代码：
Entity son1 = schema.addEntity("Son");
son1.addIdProperty().primaryKey().autoincrement();
son1.addStringProperty("name").notNull();
son1.addIntProperty("age");
Entity father1 = schema.addEntity("Father");
father1.addIdProperty().primaryKey().autoincrement();
father1.addStringProperty("name").notNull();
father1.addIntProperty("age");
Property sonId = father1.addLongProperty("sonId").getProperty();
father1.addToOne(son1, sonId);
son1.addToMany(father1, sonId).setName("fathers");
try {
new DaoGenerator().generateAll(schema, "greendao3/src/main/java");//在那个项目的那个文件夹下生成文件夹，文件夹的名称是new Schema的第二个参数
} catch (Exception e) {
e.printStackTrace();
}下面是用注解来生成1v1（ToOne）的代码：字段不一样请包涵一下，，，我随便从几个Demo里面扣除来的代码
扫描二维码关注公众号，回复：
2990516 查看本文章
@Entity(nameInDb = "son_profile")
public class Son {
@Id(autoincrement = true)
private Long id;
@NotNull
@Unique
private String userName;
private int age;
private String address;
private long fatherId;
@ToOne(joinProperty = "fatherId")
private Father father;
/** Used to resolve relations */
@Generated(hash = 2040040024)
private transient DaoSession daoSession;
/** Used for active entity operations. */
@Generated(hash = 1926509084)
private transient SonDao myDao;
@Generated(hash = 1929761275)
public Son(Long id, @NotNull String userName, int age, String address,
long fatherId) {
this.id = id;
this.userName = userName;
this.age = age;
this.address = address;
this.fatherId = fatherId;
}
@Generated(hash = 1259336981)
public Son() {
}
public Long getId() {
return this.id;
}
public void setId(Long id) {
this.id = id;
}
public String getUserName() {
return this.userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public int getAge() {
return this.age;
}
public void setAge(int age) {
this.age = age;
}
public String getAddress() {
return this.address;
}
public void setAddress(String address) {
this.address = address;
}
public long getFatherId() {
return this.fatherId;
}
public void setFatherId(long fatherId) {
this.fatherId = fatherId;
}
@Generated(hash = 2100996716)
private transient Long father__resolvedKey;
/** To-one relationship, resolved on first access. */
@Generated(hash = 614506380)
public Father getFather() {
long __key = this.fatherId;
if (father__resolvedKey == null || !father__resolvedKey.equals(__key)) {
final DaoSession daoSession = this.daoSession;
if (daoSession == null) {
throw new DaoException("Entity is detached from DAO context");
}
FatherDao targetDao = daoSession.getFatherDao();
Father fatherNew = targetDao.load(__key);
synchronized (this) {
father = fatherNew;
father__resolvedKey = __key;
}
}
return father;
}
/** called by internal mechanisms, do not call yourself. */
@Generated(hash = 1018445113)
public void setFather(@NotNull Father father) {
if (father == null) {
throw new DaoException(
"To-one property 'fatherId' has not-null constraint; cannot set to-one to null");
}
synchronized (this) {
this.father = father;
fatherId = father.getId();
father__resolvedKey = fatherId;
}
}
/**
* Convenient call for {@link org.greenrobot.greendao.AbstractDao#delete(Object)}.
* Entity must attached to an entity context.
*/
@Generated(hash = 128553479)
public void delete() {
if (myDao == null) {
throw new DaoException("Entity is detached from DAO context");
}
myDao.delete(this);
}
/**
* Convenient call for {@link org.greenrobot.greendao.AbstractDao#refresh(Object)}.
* Entity must attached to an entity context.
*/
@Generated(hash = 1942392019)
public void refresh() {
if (myDao == null) {
throw new DaoException("Entity is detached from DAO context");
}
myDao.refresh(this);
}
/**
* Convenient call for {@link org.greenrobot.greendao.AbstractDao#update(Object)}.
* Entity must attached to an entity context.
*/
@Generated(hash = 713229351)
public void update() {
if (myDao == null) {
throw new DaoException("Entity is detached from DAO context");
}
myDao.update(this);
}
/** called by internal mechanisms, do not call yourself. */
@Generated(hash = 838735897)
public void __setDaoSession(DaoSession daoSession) {
this.daoSession = daoSession;
myDao = daoSession != null ? daoSession.getSonDao() : null;
}
}
1V多（ToMany）注解生成代码：
@Entity(nameInDb = "user_profile")
public class User {
@Id(autoincrement = true)
private Long id;
@NotNull
@Unique
private String userNamer;
private int age;
private String address;
@ToMany(referencedJoinProperty = "sonId")
private List<Father> fathers;
/** Used to resolve relations */
@Generated(hash = 2040040024)
private transient DaoSession daoSession;
/** Used for active entity operations. */
@Generated(hash = 1507654846)
private transient UserDao myDao;
@Generated(hash = 1459575629)
public User(Long id, @NotNull String userNamer, int age, String address) {
this.id = id;
this.userNamer = userNamer;
this.age = age;
this.address = address;
}
@Generated(hash = 586692638)
public User() {
}
public Long getId() {
return this.id;
}
public void setId(Long id) {
this.id = id;
}
public String getUserNamer() {
return this.userNamer;
}
public void setUserNamer(String userNamer) {
this.userNamer = userNamer;
}
public int getAge() {
return this.age;
}
public void setAge(int age) {
this.age = age;
}
public String getAddress() {
return this.address;
}
public void setAddress(String address) {
this.address = address;
}
/**
* To-many relationship, resolved on first access (and after reset).
* Changes to to-many relations are not persisted, make changes to the target entity.
*/
@Generated(hash = 1959132710)
public List<Father> getFathers() {
if (fathers == null) {
final DaoSession daoSession = this.daoSession;
if (daoSession == null) {
throw new DaoException("Entity is detached from DAO context");
}
FatherDao targetDao = daoSession.getFatherDao();
List<Father> fathersNew = targetDao._queryUser_Fathers(id);
synchronized (this) {
if (fathers == null) {
fathers = fathersNew;
}
}
}
return fathers;
}
/** Resets a to-many relationship, making the next get call to query for a fresh result. */
@Generated(hash = 590801454)
public synchronized void resetFathers() {
fathers = null;
}
/**
* Convenient call for {@link org.greenrobot.greendao.AbstractDao#delete(Object)}.
* Entity must attached to an entity context.
*/
@Generated(hash = 128553479)
public void delete() {
if (myDao == null) {
throw new DaoException("Entity is detached from DAO context");
}
myDao.delete(this);
}
/**
* Convenient call for {@link org.greenrobot.greendao.AbstractDao#refresh(Object)}.
* Entity must attached to an entity context.
*/
@Generated(hash = 1942392019)
public void refresh() {
if (myDao == null) {
throw new DaoException("Entity is detached from DAO context");
}
myDao.refresh(this);
}
/**
* Convenient call for {@link org.greenrobot.greendao.AbstractDao#update(Object)}.
* Entity must attached to an entity context.
*/
@Generated(hash = 713229351)
public void update() {
if (myDao == null) {
throw new DaoException("Entity is detached from DAO context");
}
myDao.update(this);
}
/** called by internal mechanisms, do not call yourself. */
@Generated(hash = 2059241980)
public void __setDaoSession(DaoSession daoSession) {
this.daoSession = daoSession;
myDao = daoSession != null ? daoSession.getUserDao() : null;
}
}
@Entity(nameInDb = "father_profile")
public class Father {
@Id(autoincrement = true)
private Long id;
@Unique
private String userName;
private int age;
private Long sonId;
@Generated(hash = 2066595481)
public Father(Long id, String userName, int age, Long sonId) {
this.id = id;
this.userName = userName;
this.age = age;
this.sonId = sonId;
}
@Generated(hash = 383274692)
public Father() {
}
public Long getId() {
return this.id;
}
public void setId(Long id) {
this.id = id;
}
public String getUserName() {
return this.userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public int getAge() {
return this.age;
}
public void setAge(int age) {
this.age = age;
}
public Long getSonId() {
return this.sonId;
}
public void setSonId(Long sonId) {
this.sonId = sonId;
}
}
下面是一些调用代码，3.0前后的增删改查代码都基本一样：
先要初始化，我选择在DbManager里面来进行初始化，然后在application里面来初始化一下就可以了。
public class DbManager {
private UserDao mUserDao;
private FatherDao mFatherDao;
private DbManager() {
}
private static final class Holder {
private static final DbManager INSTANCE = new DbManager();
}
public static DbManager getInstance() {
return Holder.INSTANCE;
}
public DbManager init(Context context) {
initDao(context);
return this;
}
private void initDao(Context context) {
final DaoMaster.OpenHelper helper = new DaoMaster.DevOpenHelper(context, "person.db");
final Database db = helper.getWritableDb();
DaoSession mDaoSession = new DaoMaster(db).newSession();
mUserDao = mDaoSession.getUserDao();
mFatherDao = mDaoSession.getFatherDao();
}
public UserDao getUserDao() {
return mUserDao;
}
public FatherDao getFatherDao() {
return mFatherDao;
}
}
public class App extends Application {
public static Context shareInstance;
@Override
public void onCreate() {
super.onCreate();
shareInstance = this;
DbManager.getInstance().init(shareInstance);
}
}