java_hibernate 框架4
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类级别查询
@Test public void func7() //------------------------------------------------------------------------ Session session = HibernateUtils.openSession(); Transaction tx = session.beginTransaction(); //!--------------------------------------------------------------------- //关联级别查询 调用时 才加载 注意:使用懒加载时要确保,调用属性加载数据时,session还是打开的.不然会抛出异常 Customer c = session.load(Customer.class, 2l); //无任何策略 Customer a = session.get(Customer.class, 2l); System.out.print(c); //!--------------------------------------------------------------------- tx.commit(); session.close();
get方法:没有任何策略. 调用即立即查询数据库加载数据.
load方法: 应用类级别的加载策略 使用才会加载
<!-- lazy 属性 决定是否延迟加载 true：延迟加载 默认 false 不延迟加载 extra 及其懒惰 fetch属性:决定加载策略 使用什么类型的sql语句加载集合数据 select 默认 join 多表查询加载集合 subselect 使用子查询加载集合 --> <!-- batch-size="3" 一次抓取几个客户的联系人 批量抓取 --> <set name="linkMans" cascade="save-update" inverse="true" lazy="true" fetch="select"> <key column="lkm_cust_id"></key> <one-to-many class="LinkMan"/> </set>
lazy属性默认是true 查询类是返回代理对象
当lazy:false. load方法会与get方法没有任何区别.调用时即加载数据.
//lazy 和 fetch 属性 //fetch select @Test public void func9() //关联级别 延迟加载 //lazy:true 使用时才加载集合数据 //fetch:select // //------------------------------------------------------------------------ Session session = HibernateUtils.openSession(); Transaction tx = session.beginTransaction(); //!--------------------------------------------------------------------- Customer c = session.load(Customer.class, 2l); Set<LinkMan> linkMans = c.getLinkMans();//关联级别 System.out.print(linkMans); //!--------------------------------------------------------------------- tx.commit(); session.close(); //lazy:false 立即加载集合数据 //fetch:select //lazy:extra 与true 懒加载差不多 只获得集合的size 只查询集合的size //fetch:select //fetch join 多表查询 //lazy:true|false|extra 失效 没有意义 都是立即加载 //fetch:subselect public void func10() //子查询 //lazy:true 懒加载 使用才加载 //fetch:subselect 子查询 // //------------------------------------------------------------------------ Session session = HibernateUtils.openSession(); Transaction tx = session.beginTransaction(); //!--------------------------------------------------------------------- String hql = "from Customer"; Query query = session.createQuery(hql); List<Customer> list = query.list(); //!--------------------------------------------------------------------- tx.commit(); session.close(); //lazy:false 立即加载 //fetch:subselect 子查询 立即加载以及子查询 //lazy:extra 懒加载效果一样 //fetch:subselect 子查询 立即加载以及子查询 public void function1() //子查询 //fatch 决定加载的sql语句 //反查询 //select 单表查询 默认 //join 多表查询 //lazy 决定加载时机 /*false 立即加载 * proxy 代理决定 默认 由一方决定 就是一放的lazy * * * proxy select 使用时加载 * * false select 全加载 * * false join 多表查询 lazy失效 * * proxy join 多表查询 lazy失效 * */ //------------------------------------------------------------------------ Session session = HibernateUtils.openSession(); Transaction tx = session.beginTransaction(); //!--------------------------------------------------------------------- LinkMan lmLinkMan = session.get(LinkMan.class, 1l); Customer customer = lmLinkMan.getCustomer(); System.out.print(customer); //!--------------------------------------------------------------------- tx.commit(); session.close(); /* * no-session问题解决 扩大session的作用范围 * 利用filter * * 创建session * * chain.dofilter(req,res); * * 销毁session * * * */
结论 用默认的就好
HQL查询 hibernate Query Language
public void hql()
Configuration configuration = new Configuration().configure(new File("src/hibernate.cfg.xml"));
SessionFactory sessionfactory = configuration.buildSessionFactory();
Session session2 = sessionfactory.openSession();
Transaction txTransaction = session2.beginTransaction();
/*取数据list customer 所有的*/
String hql = "from Customer";
Query query = session2.createQuery(hql);
//不止一个值使用list()方法 即可返回一个list
List<Customer> customers = query.list();
System.out.println(customers);
/*提交*/
txTransaction.commit();
session2.close();
sessionfactory.close();
添加where条件 使用 :变量名 来让hibernate知道这是个需要替换的变量
public void hql_rule_include_symbol()
Configuration configuration = new Configuration().configure(new File("src/hibernate.cfg.xml"));
SessionFactory sessionfactory = configuration.buildSessionFactory();
Session session2 = sessionfactory.openSession();
Transaction txTransaction = session2.beginTransaction();
/*找数据*/
/*HQL语句中 不可能出现数据库名 */
String hql2 = "from Customer where cust_id = :abc";
Query query = session2.createQuery(hql2);
//替换变量
query.setParameter("abc", 1l);
//得到唯一值 使用uniqueResult方法
Customer c = (Customer)query.uniqueResult();
System.out.println(c);
/*提交*/
txTransaction.commit();
session2.close();
sessionfactory.close();
分页
@Test
public void hql_page()
Configuration configuration = new Configuration().configure(new File("src/hibernate.cfg.xml"));
SessionFactory sessionfactory = configuration.buildSessionFactory();
Session session2 = sessionfactory.openSession();
Transaction txTransaction = session2.beginTransaction();
/*取数据*/
String hql = "from Customer";
Query query = session2.createQuery(hql);
//设置第几个开始
query.setFirstResult(0);
//数多少个
query.setMaxResults(100);
//query.setParameter("abc", 1l);
List<Customer> customers = query.list();
/*提交*/
txTransaction.commit();
session2.close();
sessionfactory.close();
跨表
public void hql_page2()
Configuration configuration = new Configuration().configure(new File("src/hibernate.cfg.xml"));
SessionFactory sessionfactory = configuration.buildSessionFactory();
Session session2 = sessionfactory.openSession();
Transaction txTransaction = session2.beginTransaction();
/*取数据 customer为1的所有linkman*/
String hql = "from Customer c,LinkMan l where l.customer = c.cust_id and c.cust_id = :id";
Query query = session2.createQuery(hql);
//设置第几个开始
query.setParameter("id", 1l);
List<Object[]> objects = query.list();
System.out.println(objects);
/*提交*/
txTransaction.commit();
session2.close();
sessionfactory.close();
排序
public void func2() //排序 Session session = HibernateUtils.openSession(); Transaction tx = session.beginTransaction(); //!--------------------------------------------------------------------- String hql = " from Customer order by cust_id desc"; //查询object子类的对象 所有注册的对象 Query query = session.createQuery(hql); List<Customer> list = query.list(); System.out.println(list); //!--------------------------------------------------------------------- tx.commit(); session.close();
count
public void func5()
//查条数
Session session = HibernateUtils.openSession();
Transaction tx = session.beginTransaction();
//!---------------------------------------------------------------------
String hql = "select count(*) from Customer";
Query query = session.createQuery(hql);
//query.setParameter("id","id");
Number count = (Number) query.uniqueResult();
System.out.println(count);
//!---------------------------------------------------------------------
tx.commit();
session.close();
查询所需要的值
public void func7() //查询所需字段的值 Session session = HibernateUtils.openSession(); Transaction tx = session.beginTransaction(); //!--------------------------------------------------------------------- String hql = "select cust_name,cust_id from Customer"; Query query = session.createQuery(hql); List<Object[]> list = query.list(); System.out.println(list); //!--------------------------------------------------------------------- tx.commit(); session.close();
封装对象
public void func8() //封装对象 Session session = HibernateUtils.openSession(); Transaction tx = session.beginTransaction(); //!--------------------------------------------------------------------- String hql = "select new Customer(cust_name,cust_id) from Customer"; Query query = session.createQuery(hql); List<Customer> list = query.list(); System.out.println(list); //!--------------------------------------------------------------------- tx.commit(); session.close();
内链接
@Test public void func9() // 内连接 //隐式连接 /* * select * from a,b where b.aid = a.id * 显示内连接 * * * 左外 * select * from A left [outer] join b on b.aid = a.id * select * from A right [outer] join b on b.aid = a.id * */ Session session = HibernateUtils.openSession(); Transaction tx = session.beginTransaction(); //---------------------------------------------------- String hql = " from Customer c inner join c.linkMans "; Query query = session.createQuery(hql); List<Object[]> list = query.list(); for(Object[] arr : list) System.out.println(Arrays.toString(arr)); //---------------------------------------------------- tx.commit(); session.close();
迫切内连接
public void func10() //HQL 迫切内连接 => 帮我们进行封装.返回值就是一个对象 Session session = HibernateUtils.openSession(); Transaction tx = session.beginTransaction(); //!--------------------------------------------------------------------- String hql = "from Customer c inner join fetch c.linkMans"; Query query = session.createQuery(hql); List<Customer> list = query.list(); System.out.println(list); //!--------------------------------------------------------------------- tx.commit(); session.close();
左外以及右外
@Test
public void func11()
/*
* 左外
* select * from A left [outer] join b on b.aid = a.id
* select * from A right [outer] join b on b.aid = a.id
* */
Session session = HibernateUtils.openSession();
Transaction tx = session.beginTransaction();
//!---------------------------------------------------------------------
String hql = "from Customer c left join c.linkMans";
String hqlString = "from Customer c right join c.linkMans";
//查询object子类的对象 所有注册的对象
Query query = session.createQuery(hqlString);
//query.setParameter("id","id");
List<Object[]> list = query.list();
for(Object[] arr : list)
System.out.println(Arrays.toString(arr));
//!---------------------------------------------------------------------
tx.commit();
session.close();
Criteria查询 可用于单表条件查询 Hibernate自创的无语句面向对象查询
查列表
@Test public void func1() Session session = HibernateUtils.openSession(); Transaction tx = session.beginTransaction(); //!--------------------------------------------------------------------- Criteria criteria = session.createCriteria(Customer.class); List<Customer> list = criteria.list(); System.out.print(list); //!--------------------------------------------------------------------- tx.commit(); session.close();
条件
public void None_Sql()
Configuration configuration = new Configuration().configure(new File("src/hibernate.cfg.xml"));
SessionFactory sessionfactory = configuration.buildSessionFactory();
Session session2 = sessionfactory.openSession();
Transaction txTransaction = session2.beginTransaction();
/*存数据*/
/*HQL语句中 不可能出现数据库名*/
Criteria criteria = session2.createCriteria(Customer.class);
/*条件查询*/
// > gt
/* >= ge
* < lt
* <= le
* == eq
* != ne
* in in
* between and between
* like like
* is not null isnotnull
* is null isNull
* or or
* and and
*
*
*
* */
//添加条件 使用Restrictions
criteria.add(Restrictions.eq("cust_id", 1l));
Customer customer =(Customer) criteria.uniqueResult();
/*提交*/
txTransaction.commit();
session2.close();
sessionfactory.close();
分页
@Test public void func3() //分页 Session session = HibernateUtils.openSession(); Transaction tx = session.beginTransaction(); //!--------------------------------------------------------------------- Criteria criteria = session.createCriteria(Customer.class); criteria.setFirstResult(0); criteria.setMaxResults(10); List<Customer> list = criteria.list(); System.out.print(list); //!--------------------------------------------------------------------- tx.commit(); session.close();
排序
@Test public void func4() //排序 Session session = HibernateUtils.openSession(); Transaction tx = session.beginTransaction(); //!--------------------------------------------------------------------- Criteria criteria = session.createCriteria(Customer.class);
//排序条件 criteria.addOrder(Order.asc("cust_id")); List<Customer> list = criteria.list(); System.out.print(list); //!--------------------------------------------------------------------- tx.commit(); session.close();
设置查询目标
@Test public void func5() //设置查询目标 Session session = HibernateUtils.openSession(); Transaction tx = session.beginTransaction(); //!--------------------------------------------------------------------- Criteria criteria = session.createCriteria(Customer.class); criteria.setProjection(Projections.rowCount()); List<Customer> list = criteria.list(); System.out.print(list); //!--------------------------------------------------------------------- tx.commit(); session.close();
离线criteria
@Test public void func6() //离线criteria DetachedCriteria dCriteria = DetachedCriteria.forClass(Customer.class); dCriteria.add(Restrictions.idEq(6l)); //------------------------------------------------------------------------ Session session = HibernateUtils.openSession(); Transaction tx = session.beginTransaction(); //!---------------------------------------------------------------------
//为离线传入session Criteria criteria = dCriteria.getExecutableCriteria(session); List<Customer> list = criteria.list(); System.out.print(list); //!--------------------------------------------------------------------- tx.commit(); session.close();
原生sql
public void origin_sql()
Configuration configuration = new Configuration().configure(new File("src/hibernate.cfg.xml"));
SessionFactory sessionfactory = configuration.buildSessionFactory();
Session session2 = sessionfactory.openSession();
Transaction txTransaction = session2.beginTransaction();
String sql = "select * from cst_customer";
SQLQuery query = session2.createSQLQuery(sql);
//制定结果集
query.addEntity(Customer.class);
//多个
List<Customer> list = query.list();
//一个
query.uniqueResult();
//条件
String sql2 = "select * from cst_customer where cust_id = ?";
SQLQuery query2 = session2.createSQLQuery(sql);
//制定结果集
query2.setParameter(0, 1);
//多个
//一个
Customer customer = (Customer) query.uniqueResult();
//分页
String sql3 = "select * from cst_customer limit ?,?";
SQLQuery query3 = session2.createSQLQuery(sql);
//制定结果集
query3.setParameter(0, 0);
query3.setParameter(1, 10);
//多个
List<Customer> list2 = query.list();
//一个
query.uniqueResult();
/*提交*/
txTransaction.commit();
session2.close();
sessionfactory.close();
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