一.背景
之前用dbFlow,但是因为某些原因不适合所有机型，所以准备用GreenDao,所以现在写篇文章记录一下使用的基本要点。
二.基本知识点和坑
- 增
mUser = new User((long)2,"anye3");
mUserDao.insert(mUser);//添加一个
- 删
mUserDao.deleteByKey(id);
- 改
mUser = new User((long)2,"anye0803");
mUserDao.update(mUser);
- 查
List<User> users = mUserDao.loadAll();
String userName = "";
for (int i = 0; i < users.size(); i++) {
userName += users.get(i).getName()+",";
}
mContext.setText("查询全部数据==>"+userName);
- 实体@Entity注解
schema：告知GreenDao当前实体属于哪个schema
active：标记一个实体处于活动状态，活动实体有更新、删除和刷新方法
nameInDb：在数据中使用的别名，默认使用的是实体的类名
indexes：定义索引，可以跨越多个列
createInDb：是否创建表，默认为true,false时不创建
- 基础属性注解
@Id :主键 Long型，可以通过@Id(autoincrement = true)设置自增长
@Property：设置一个非默认关系映射所对应的列名，默认是的使用字段名 举例：@Property (nameInDb="name")
@NotNul：设置数据库表当前列不能为空
@Transient ：添加次标记之后不会生成数据库表的列
- 索引注解
@Index：使用@Index作为一个属性来创建一个索引，通过name设置索引别名，也可以通过unique给索引添加约束
@Unique：向数据库列添加了一个唯一的约束
@OrderBy 排序
@generated 由greendao产生的构造函数或方法
- 关系注解
@ToOne：定义与另一个实体（一个实体对象）的关系
@ToMany：定义与多个实体对象的关系
- 坑one
greendao的关联关系是通过主外键（对象之间关联的id）来构建的。realm是直接通过对象关系来自动构建的。
- 坑two
如果属性是List<> xx, greendao不会自动调用设置xx的值，只有手动调用getXX的时候获取.我在打印log的时候被坑惨了，无论怎么样都是为null.
- 数据库升级
如果某张表修改了字段，或者新增了一张表，必须要修改build.gradle中的schemaVersion，否则当你升级app的时候，如果进行了数据库操作，会发现列不匹配或者表不存在等问题，直接会导致app闪退。但是如果仅仅是将schemaVersion加1，虽然程序不会崩溃，并且数据表的结构也会更新成功，但是之前表中的数据会全部清空。我们需要进行手动操作来进行数据库里面的数据迁移，大致的思路是：创建临时表（结构与上一版本的表结构相同），将旧数据移到临时表中，删除旧版本的表，创建新版本的表，将临时表中的数据转移到新表中，最后再删除临时表。详细方法见链接：
http://stackoverflow.com/a/30334668/5995409
- 自定义sql语句
ChatHistoryDao dao = GreenDaoManager.getInstance().getSession().getChatHistoryDao();
Cursor cursor = dao.getDatabase().rawQuery("select t.sales_wx_nick_name,t.wx_nick_name,count(*),t.talker_id,t.sales_wx_account from chat_history t group by t.talker_id,t.sales_wx_account order by t.created_at desc", null);
while (cursor.moveToNext()) {
String salesWxNickName = cursor.getString(0);
String clientWxNickName = cursor.getString(1);
int chatCount = cursor.getInt(2);
int talkerId = cursor.getInt(3);
String salesWxAccount = cursor.getString(4);
}
有的时候需要用到group by或者left join等复杂的语句，可以调用android原生的sqlite去进行查询。
三.例子（oneToone,oneTomany,manyTomany）
- 一对一
一个人只有一个职业(socialRole)
我们用 @ToOne(joinProperty = "socialRoleId"),然后把SocialRole的Id设置给Person的socialRoleId就建立联系了，不需setSocialRole!!!!!!
Person.java
@Entity
public class Person {
@Id
private Long id;
@Property(nameInDb = "address")
private String personAddress;
private Long socialRoleId;
private String name;
@ToOne(joinProperty = "socialRoleId")
private SocialRole socialRole;
@ToMany(referencedJoinProperty = "authorId")
private List<Article> articleList;
/** Used to resolve relations */
@Keep
private transient com.rebase.greendao.entity.DaoSession daoSession;
/** Used for active entity operations. */
@Keep
private transient com.rebase.greendao.entity.PersonDao myDao;
@Keep
public Person(Long id, String personAddress, Long socialRoleId, String name) {
this.id = id;
this.personAddress = personAddress;
this.socialRoleId = socialRoleId;
this.name = name;
}
@Keep
public Person() {
}
public Long getId() {
return this.id;
}
public void setId(Long id) {
this.id = id;
}
public String getPersonAddress() {
return this.personAddress;
}
public void setPersonAddress(String personAddress) {
this.personAddress = personAddress;
}
public Long getSocialRoleId() {
return this.socialRoleId;
}
public void setSocialRoleId(Long socialRoleId) {
this.socialRoleId = socialRoleId;
}
@Keep
private transient Long socialRole__resolvedKey;
/** To-one relationship, resolved on first access. */
@Keep
public SocialRole getSocialRole() {
Long __key = this.socialRoleId;
if (socialRole__resolvedKey == null || !socialRole__resolvedKey.equals(__key)) {
final com.rebase.greendao.entity.DaoSession daoSession = this.daoSession;
if (daoSession == null) {
throw new DaoException("Entity is detached from DAO context");
}
com.rebase.greendao.entity.SocialRoleDao targetDao = daoSession.getSocialRoleDao();
SocialRole socialRoleNew = targetDao.load(__key);
synchronized (this) {
socialRole = socialRoleNew;
socialRole__resolvedKey = __key;
}
}
return socialRole;
}
/** called by internal mechanisms, do not call yourself. */
@Keep
public void setSocialRole(SocialRole socialRole) {
synchronized (this) {
this.socialRole = socialRole;
socialRoleId = socialRole == null ? null : socialRole.getId();
socialRole__resolvedKey = socialRoleId;
}
}
/**
* To-many relationship, resolved on first access (and after reset).
* Changes to to-many relations are not persisted, make changes to the target entity.
*/
@Keep
public List<Article> getArticleList() {
if (articleList == null) {
final com.rebase.greendao.entity.DaoSession daoSession = this.daoSession;
if (daoSession == null) {
throw new DaoException("Entity is detached from DAO context");
}
com.rebase.greendao.entity.ArticleDao targetDao = daoSession.getArticleDao();
List<Article> articleListNew = targetDao._queryPerson_ArticleList(id);
synchronized (this) {
if (articleList == null) {
articleList = articleListNew;
}
}
}
return articleList;
}
/** Resets a to-many relationship, making the next get call to query for a fresh result. */
@Keep
public synchronized void resetArticleList() {
articleList = null;
}
/**
* Convenient call for {@link org.greenrobot.greendao.AbstractDao#delete(Object)}.
* Entity must attached to an entity context.
*/
@Keep
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.
*/
@Keep
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.
*/
@Keep
public void update() {
if (myDao == null) {
throw new DaoException("Entity is detached from DAO context");
}
myDao.update(this);
}
public String getName() {
return this.name;
}
public void setName(String name) {
this.name = name;
}
/** called by internal mechanisms, do not call yourself. */
@Keep
public void __setDaoSession(com.rebase.greendao.entity.DaoSession daoSession) {
this.daoSession = daoSession;
myDao = daoSession != null ? daoSession.getPersonDao() : null;
}
}
SocialRole.java
@Entity
public class SocialRole {
@Id
private Long id;
@Property(nameInDb = "job")
private String jobDesc;
private int salary;
@Generated(hash = 764507058)
public SocialRole(Long id, String jobDesc, int salary) {
this.id = id;
this.jobDesc = jobDesc;
this.salary = salary;
}
@Generated(hash = 508250821)
public SocialRole() {
}
public Long getId() {
return this.id;
}
public void setId(Long id) {
this.id = id;
}
public String getJobDesc() {
return this.jobDesc;
}
public void setJobDesc(String jobDesc) {
this.jobDesc = jobDesc;
}
public int getSalary() {
return this.salary;
}
public void setSalary(int salary) {
this.salary = salary;
}
@Override
public String toString() {
return "SocialRole{" +
"id=" + id +
", jobDesc='" + jobDesc + '\'' +
", salary=" + salary +
'}';
}
}
然后初始化
mPerson = mDaoSession.getPersonDao().queryBuilder().where(PersonDao.Properties.Name.eq("Jason")).unique();
if (mPerson == null) {
Person person = new Person();
person.setPersonAddress("shanghai");
person.setName("Jason");
mPerson = person;
}
System.out.println("xcqw person"+mPerson.getName());
// 一般一个人就一个职业
mSocial = (SocialRole) mDaoSession.getSocialRoleDao().queryBuilder().unique();
if (mSocial == null) {
System.out.println("xcqw mSocial == null");
SocialRole social = new SocialRole();
social.setJobDesc("法师");
social.setSalary(1000);
mDaoSession.getSocialRoleDao().insert(social);
mSocial = social;
}
System.out.println("xcqw social"+mSocial.getJobDesc());
// Person 跟 socialRole 关联起来!!!!!!!!111
// 只需要关联socialRoleId
mPerson.setSocialRoleId(mSocial.getId());
mDaoSession.getPersonDao().insertOrReplace(mPerson);
// 开始查person的里的socialRole
System.out.println("xcqw oneToone" + mPerson.getSocialRole().toString());
- 一对多
一个人写个多篇文章
@ToMany(referencedJoinProperty = "authorId")
然后把person中的id设置给article中的authorId就建立关系了
Article.java
@Entity
public class Article {
@Id
private Long id;
private String content;
private Long authorId;
@Generated(hash = 2128110276)
public Article(Long id, String content, Long authorId) {
this.id = id;
this.content = content;
this.authorId = authorId;
}
@Generated(hash = 742516792)
public Article() {
}
public Long getId() {
return this.id;
}
public void setId(Long id) {
this.id = id;
}
public String getContent() {
return this.content;
}
public void setContent(String content) {
this.content = content;
}
public Long getAuthorId() {
return this.authorId;
}
public void setAuthorId(Long authorId) {
this.authorId = authorId;
}
@Override
public String toString() {
return "Article{" +
"id=" + id +
", content='" + content + '\'' +
", authorId=" + authorId +
'}';
}
}
初始化
List<Article> articleList = mDaoSession.getArticleDao().queryBuilder().list();
if(articleList.size() >0) {
for (int i = 0; i < articleList.size(); i++) {
if (articleList.get(i).equals("我是第1个篇")) {
firstArticle = true;
} else if (articleList.get(i).equals("我是第2个篇")) {
secondArticle = true;
} else {
firstArticle = false;
secondArticle = false;
}
}
}
if (!firstArticle) {
articleOne = new Article();
articleOne.setContent("我是第1个篇");
//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!建立关系
articleOne.setAuthorId(mPerson.getId());
}
if (!secondArticle) {
articleTwo = new Article();
articleTwo.setContent("我是第2个篇");
//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!建立关系
articleTwo.setAuthorId(mPerson.getId());
mDaoSession.getArticleDao().insertInTx(articleOne,articleTwo);
}
System.out.println("xcqw oneToMany"+mPerson.getArticleList().get(1).toString());
- 多对多
一个学生有多个老师，一个老师有多个学生
Student.java
@Entity
public class Student {
@Id
private Long id;
private String name;
// 对多，@JoinEntity注解：entity 中间表；sourceProperty 实体属性；targetProperty 外链实体属性
@ToMany
@JoinEntity(
entity = JoinStudentToTeacher.class,
sourceProperty = "sId",
targetProperty = "tId"
)
private List<Teacher> teacherList;
/** Used to resolve relations */
@Keep
private transient com.rebase.greendao.entity.DaoSession daoSession;
/** Used for active entity operations. */
@Keep
private transient com.rebase.greendao.entity.StudentDao myDao;
@Keep
public Student(Long id, String name) {
this.id = id;
this.name = name;
}
@Keep
public Student() {
}
@Override
public String toString() {
return "Student{" +
"id=" + id +
", name='" + name + '\'' +
", teacherList=" + teacherList +
'}';
}
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;
}
/**
* To-many relationship, resolved on first access (and after reset).
* Changes to to-many relations are not persisted, make changes to the target entity.
*/
@Keep
public List<Teacher> getTeacherList() {
if (teacherList == null) {
final com.rebase.greendao.entity.DaoSession daoSession = this.daoSession;
if (daoSession == null) {
throw new DaoException("Entity is detached from DAO context");
}
com.rebase.greendao.entity.TeacherDao targetDao = daoSession.getTeacherDao();
List<Teacher> teacherListNew = targetDao._queryStudent_TeacherList(id);
synchronized (this) {
if (teacherList == null) {
teacherList = teacherListNew;
}
}
}
return teacherList;
}
/** Resets a to-many relationship, making the next get call to query for a fresh result. */
@Keep
public synchronized void resetTeacherList() {
teacherList = null;
}
/**
* Convenient call for {@link org.greenrobot.greendao.AbstractDao#delete(Object)}.
* Entity must attached to an entity context.
*/
@Keep
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.
*/
@Keep
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.
*/
@Keep
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. */
@Keep
public void __setDaoSession(com.rebase.greendao.entity.DaoSession daoSession) {
this.daoSession = daoSession;
myDao = daoSession != null ? daoSession.getStudentDao() : null;
}
}
Teacher.java
@Entity
public class Teacher {
@Id
private Long id;
private String name;
// 对多，@JoinEntity注解：entity 中间表；sourceProperty 实体属性；targetProperty 外链实体属性
@ToMany
@JoinEntity(
entity = JoinStudentToTeacher.class,
sourceProperty = "tId",
targetProperty = "sId"
)
private List<Student> studentList;
/** Used to resolve relations */
@Keep
private transient com.rebase.greendao.entity.DaoSession daoSession;
/** Used for active entity operations. */
@Keep
private transient com.rebase.greendao.entity.TeacherDao myDao;
@Keep
public Teacher(Long id, String name) {
this.id = id;
this.name = name;
}
@Keep
public Teacher() {
}
@Override
public String toString() {
return "Teacher{" +
"id=" + id +
", name='" + name + '\'' +
", studentList=" + studentList +
'}';
}
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;
}
/**
* To-many relationship, resolved on first access (and after reset).
* Changes to to-many relations are not persisted, make changes to the target entity.
*/
@Keep
public List<Student> getStudentList() {
if (studentList == null) {
final com.rebase.greendao.entity.DaoSession daoSession = this.daoSession;
if (daoSession == null) {
throw new DaoException("Entity is detached from DAO context");
}
com.rebase.greendao.entity.StudentDao targetDao = daoSession.getStudentDao();
List<Student> studentListNew = targetDao._queryTeacher_StudentList(id);
synchronized (this) {
if (studentList == null) {
studentList = studentListNew;
}
}
}
return studentList;
}
/** Resets a to-many relationship, making the next get call to query for a fresh result. */
@Keep
public synchronized void resetStudentList() {
studentList = null;
}
/**
* Convenient call for {@link org.greenrobot.greendao.AbstractDao#delete(Object)}.
* Entity must attached to an entity context.
*/
@Keep
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.
*/
@Keep
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.
*/
@Keep
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. */
@Keep
public void __setDaoSession(com.rebase.greendao.entity.DaoSession daoSession) {
this.daoSession = daoSession;
myDao = daoSession != null ? daoSession.getTeacherDao() : null;
}
}
初始化
List<Student> studentList = mDaoSession.getStudentDao().queryBuilder().list();
if (studentList.size() == 0) {
Student studentOne = new Student();
studentOne.setId(1l);
studentOne.setName("stu1");
Student studentTwo = new Student();
studentTwo.setId(2l);
studentTwo.setName("stu2");
Teacher teachOne = new Teacher();
teachOne.setId(1l);
teachOne.setName("tech1");
Teacher teachTwo = new Teacher();
teachTwo.setId(2l);
teachTwo.setName("tech2");
// 模拟 多对多关系
//Student1有teacher1 teacher2
JoinStudentToTeacher stOne = new JoinStudentToTeacher();
stOne.setSId(1l);
stOne.setTId(1l);
JoinStudentToTeacher stTwo = new JoinStudentToTeacher();
stTwo.setSId(1l);
stTwo.setTId(2l);
//teacher1 有stu1 stu2
JoinStudentToTeacher stThree = new JoinStudentToTeacher();
stThree.setSId(1l);
stThree.setTId(1l);
JoinStudentToTeacher stFour = new JoinStudentToTeacher();
stFour.setSId(2l);
stFour.setTId(1l);
mDaoSession.getJoinStudentToTeacherDao().insertOrReplaceInTx(stOne, stTwo, stThree, stFour);
mDaoSession.getStudentDao().insertOrReplaceInTx(studentOne, studentTwo);
mDaoSession.getTeacherDao().insertOrReplaceInTx(teachOne, teachTwo);
}
// List<Student> students = mDaoSession.getStudentDao().queryBuilder().list();
// for(int i = 0;i<students.size();i++){
// for(int j= 0;j<students.get(i).getTeacherList().size();j++){
// System.out.println("xcqw teacher i--"+i+"--j--"+j+students.get(i).getTeacherList().get(j).toString());
// }
// }
List<Teacher> teachers = mDaoSession.getTeacherDao().queryBuilder().list();
for(int i = 0;i<teachers.size();i++){
for(int j= 0;j<teachers.get(i).getStudentList().size();j++){
System.out.println("xcqw student i--"+i+"--j--"+j+teachers.get(i).getStudentList().get(j).toString());
}
}
System.out.println("xcqw asdsad");
注意！！！
mDaoSession.getTeacherDao().queryBuilder().list();如果在这个地方打断点，下属的students是null,只有走完两个for循环调用get方法才会有值
