Hibernate DAO中的幾個方法
阿新 • • 發佈：2019-01-31
* save()方法提供了向資料庫中新增資料的功能,但只能新增,這個DAO沒有生成Update()的方法
* 但你可以簡單的八save()方法改稱具有Update功能:將getSession().save * (transientInstance);這句改成
* getSession().merge(transientInstance);或者getSession().saveOrUpdate
* (transientInstance);
public void save(User transientInstance) {
log.debug("saving User instance");
try {
Session session=getSession();
Transaction tx=session.beginTransaction();
session.save(transientInstanc);
tx.commit();
session.close();
log.debug("save successful");
} catch (RuntimeException re) {
log.error("save failed", re);
throw re;
}
}
delete()方法用來刪除的 實際上我們會用下邊的這個方法進行刪除
public void delete(Integer id){
log.debug("deleting User instance...");
User user=findById(id);
delete(user);
}
public void delete(User persistentInstance) {
log.debug("deleting User instance");
try {
Session session=getSession();
Transaction tx=session.beginTransaction();
session.delete(persistentInstance);
tx.commit();
session.close();
log.debug("delete successful");
} catch (RuntimeException re) {
log.error("delete failed", re);
throw re;
}
}
根據編號進行查詢
public User findById(java.lang.Integer id) {
log.debug("getting User instance with id: " + id);
try {
User instance = (User) getSession().get("hbm.User", id);
return instance;
} catch (RuntimeException re) {
log.error("get failed", re);
throw re;
}
}
findByExample()方法實現的功能相當於"select * from Usertable"實現的功能就是查詢所有 資料.
public List findByExample(User instance) {
log.debug("finding User instance by example");
try {
List results = getSession().createCriteria("hbm.User").add(
Example.create(instance)).list();
log.debug("find by example successful, result size: "
+ results.size());
return results;
} catch (RuntimeException re) {
log.error("find by example failed", re);
throw re;
}
}
findByProperty()方法用來靈活的提供一種按條件查詢的方法,你可以自己定義要按什麼樣的方 式查詢.
public List findByProperty(String propertyName, Object value) {
log.debug("finding User instance with property: " + propertyName
+ ", value: " + value);
try {
String queryString = "from User as model where model."
+ propertyName + "= ?";
Query queryObject = getSession().createQuery(queryString);
queryObject.setParameter(0, value);
return queryObject.list();
} catch (RuntimeException re) {
log.error("find by property name failed", re);
throw re;
}
}
public List findByName(Object name) {
return findByProperty(NAME, name);
}
public List findBySex(Object sex) {
return findByProperty(SEX, sex);
}
public List findByAge(Object age) {
return findByProperty(AGE, age);
}
public List findAll() {
log.debug("finding all User instances");
try {
String queryString = "from User";
Query queryObject = getSession().createQuery(queryString);
return queryObject.list();
} catch (RuntimeException re) {
log.error("find all failed", re);
throw re;
}
}
將傳入的detached狀態的物件的屬性複製到持久化物件中，並返回該持久化物件 如果該session中沒有關聯的持久化物件，載入一個，如果傳入物件未儲存，儲存一個副本並作為持久物件返回，傳入物件依然保持detached狀態。
可以用作更新資料
public User merge(User detachedInstance) {
log.debug("merging User instance");
try {
Session session=getSession();
Transaction tx=session.beginTransaction();
User result = (User) session.merge(detachedInstance);
tx.commit();
session.close();
log.debug("merge successful");
return result;
} catch (RuntimeException re) {
log.error("merge failed", re);
throw re;
}
}
將傳入的物件持久化並儲存。 如果物件未儲存（Transient狀態），呼叫save方法儲存。如果物件已儲存（Detached狀態），呼叫update方法將物件與Session重新關聯。
public void attachDirty(User instance) {
log.debug("attaching dirty User instance");
try {
getSession().saveOrUpdate(instance);
log.debug("attach successful");
} catch (RuntimeException re) {
log.error("attach failed", re);
throw re;
}
}
將傳入的物件狀態設定為Transient狀態
public void attachClean(User instance) {
log.debug("attaching clean User instance");
try {
getSession().lock(instance, LockMode.NONE);
log.debug("attach successful");
} catch (RuntimeException re) {
log.error("attach failed", re);
throw re;
}
}
* 但你可以簡單的八save()方法改稱具有Update功能:將getSession().save * (transientInstance);這句改成
* getSession().merge(transientInstance);或者getSession().saveOrUpdate
* (transientInstance);
public void save(User transientInstance) {
log.debug("saving User instance");
try {
Session session=getSession();
Transaction tx=session.beginTransaction();
session.save(transientInstanc);
tx.commit();
session.close();
log.debug("save successful");
} catch (RuntimeException re) {
log.error("save failed", re);
throw re;
}
}
delete()方法用來刪除的 實際上我們會用下邊的這個方法進行刪除
public void delete(Integer id){
log.debug("deleting User instance...");
User user=findById(id);
delete(user);
}
public void delete(User persistentInstance) {
log.debug("deleting User instance");
try {
Session session=getSession();
Transaction tx=session.beginTransaction();
session.delete(persistentInstance);
tx.commit();
session.close();
log.debug("delete successful");
} catch (RuntimeException re) {
log.error("delete failed", re);
throw re;
}
}
根據編號進行查詢
public User findById(java.lang.Integer id) {
log.debug("getting User instance with id: " + id);
try {
User instance = (User) getSession().get("hbm.User", id);
return instance;
} catch (RuntimeException re) {
log.error("get failed", re);
throw re;
}
}
findByExample()方法實現的功能相當於"select * from Usertable"實現的功能就是查詢所有 資料.
public List findByExample(User instance) {
log.debug("finding User instance by example");
try {
List results = getSession().createCriteria("hbm.User").add(
Example.create(instance)).list();
log.debug("find by example successful, result size: "
+ results.size());
return results;
} catch (RuntimeException re) {
log.error("find by example failed", re);
throw re;
}
}
findByProperty()方法用來靈活的提供一種按條件查詢的方法,你可以自己定義要按什麼樣的方 式查詢.
public List findByProperty(String propertyName, Object value) {
log.debug("finding User instance with property: " + propertyName
+ ", value: " + value);
try {
String queryString = "from User as model where model."
+ propertyName + "= ?";
Query queryObject = getSession().createQuery(queryString);
queryObject.setParameter(0, value);
return queryObject.list();
} catch (RuntimeException re) {
log.error("find by property name failed", re);
throw re;
}
}
public List findByName(Object name) {
return findByProperty(NAME, name);
}
public List findBySex(Object sex) {
return findByProperty(SEX, sex);
}
public List findByAge(Object age) {
return findByProperty(AGE, age);
}
public List findAll() {
log.debug("finding all User instances");
try {
String queryString = "from User";
Query queryObject = getSession().createQuery(queryString);
return queryObject.list();
} catch (RuntimeException re) {
log.error("find all failed", re);
throw re;
}
}
將傳入的detached狀態的物件的屬性複製到持久化物件中，並返回該持久化物件 如果該session中沒有關聯的持久化物件，載入一個，如果傳入物件未儲存，儲存一個副本並作為持久物件返回，傳入物件依然保持detached狀態。
可以用作更新資料
public User merge(User detachedInstance) {
log.debug("merging User instance");
try {
Session session=getSession();
Transaction tx=session.beginTransaction();
User result = (User) session.merge(detachedInstance);
tx.commit();
session.close();
log.debug("merge successful");
return result;
} catch (RuntimeException re) {
log.error("merge failed", re);
throw re;
}
}
將傳入的物件持久化並儲存。 如果物件未儲存（Transient狀態），呼叫save方法儲存。如果物件已儲存（Detached狀態），呼叫update方法將物件與Session重新關聯。
public void attachDirty(User instance) {
log.debug("attaching dirty User instance");
try {
getSession().saveOrUpdate(instance);
log.debug("attach successful");
} catch (RuntimeException re) {
log.error("attach failed", re);
throw re;
}
}
將傳入的物件狀態設定為Transient狀態
public void attachClean(User instance) {
log.debug("attaching clean User instance");
try {
getSession().lock(instance, LockMode.NONE);
log.debug("attach successful");
} catch (RuntimeException re) {
log.error("attach failed", re);
throw re;
}
}