HZPHYT的博客

OneToMany:在One一方添加外键，比如Message和Comment，就在Message这一方添加set   Message.hbm.xml： <hibernate-mapping> <class name="model.Message" table="MESSAGE"> <id name="id" type="int"

1.导入struts-2.3.36-all\struts-2.3.36\apps\struts2-blank-2.3.36\WEB-INF\lib中的包以及struts2-spring-plugin-2.3.36 2.配置struts.xml <struts> <constant name="struts.action.extension" value="action,do...

 统计每一个专业的人数: void test17() { Session s=null; try { s=HibernateUtil.getSession(); List<Object[]> objs=s.createQuery("select spe.name,count(stu.classroom.special.id)...

1.SELECT * FROM classroom t1 LEFT JOIN student t2 ON (t1.`id`=t2.`c_id`) 左连接:左边有的，右边没有的也连接上去 2.SELECT * FROM classroom t1 RIGHT JOIN student t2 ON (t1.`id`=t2.`c_id`) 右连接 3.SELECT t2.id,t2.`name`,...

@Entity public class Classroom { private int id; private String name; private int grade; private Set<Student> stus; private Special special; public Classroom() { } public Classroom(in...

第一种方式（manytomany）： @Entity @Table(name="t_admin") public class Admin { private int id; private String name; private Set<Role> roles; public Admin() { roles=new HashSet<>(); } pub...

@Entity @Table(name="t_person") public class Person { private int id; private String name; private IdCard idcard; @OneToOne(mappedBy="person") public IdCard getIdcard() { return idcard; } public vo...

1.通过在两个类中分别设置set完成MnayToMany:  public class Admin { private int id; private String name; private Set<Role> roles; public Admin() { roles=new HashSet<>(); } public void add(Role r...

@Entity @Table(name="t_cla") public class Classroom { private int id; private String name; private int grade; private Set<Student> stus; @OneToMany(mappedBy="cla")//表示由对方即多的一方(stu)的cla属性维护关系 @L...

1.在Classroom.java增加Set<Student> stus: public class Classroom { private int id; private String name; private int grade; private Set<Student> stus; public Set<Student> getStus() { ...

many2one:在many一方添加外键，比如classroom和student，就在student这一方添加外键   先添加1: void test() { Session s=null; try { s=HibernateUtil.getSession(); s.beginTransaction(); Classroom cla=new Classroom()...

assigned:不会自动生成，需要由用户指定，第一次没传入默认为0，第二次没传入也是0，id重复就会报错 uuid:自动生成一个字符串，id必须设置为String类型，适用于添加，不需要从数据库查id最大值，然后+1，但是由于字符串较长，所以查询id效率偏低 native:自动生成一个递增的id，查询效率高，但是添加的时候需要从数据库判断最大值然后加1，没有uuid方便   总结:由于开...

void test01() { Session session=null; try { session=HibernateUtil.getSession(); session.beginTransaction(); User u1=(User)session.load(User.class, 1); System.out.println(u1.g...

HibernateUtil： package util; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.cfg.Configuration; public class HibernateUtil { private final static SessionFac...

Hibernate的安装: 1.打开 http://tools.jboss.org/downloads/jbosstools/photon/4.6.0.Final.html#update_site，找到如下链接， 然后在JBoss Application Development中选上Hibernate Tools以及在J2EE中选上Hibernate 下载hibernate-rele...

瞬时状态(transient):刚new出来的对象就属于瞬时状态 持久化状态(persistent):对象存进数据库，被session所管理就是持久化状态 离线状态(detached):数据库有，但是没有被session管理就是离线状态   1.test01: void test01() { Session session=null; try { session=Hibe...

首先在person类加入idcard: public class Person { private int id; private String name; private IdCard idcard; public IdCard getIdcard() { return idcard; } public void setIdcard(IdCard idcard) { this.idc...

OneToOne单向:即Person和Idcard(身份证)，一个人只能有一张身份证，单向的话在那一端设置外键都可以，下面在idcard这一端设置外键 Person： public class Person { private int id; private String name; public int getId() { return id; } public void setId(i...