注解代替了我们用的*.hbm.xml文件。简少了我们的代码量；应用简单。

@Override

用途：重写父类的同名方法

单元测试注解

@Test

用途：用于测试

@Before

用途：单测方法走之前执行

@After

用途：单测方法走之后执行

注解的目标：替换小配置。

替换hbm文件

@Entity  :标识实体类（被持久化）

@Table  ：DB层表的名称

@Transient ：不持久化某个属性

@Column：数据表中的字段名

@GenerateValue ：主键生成策略

-----------------关联-------------------------------------------------------------------------------------------------------

@OneToMany ：

@ManyToMany

@OneToOne

@JoinColumn

@JoinTable

Hibernate提供了Hibernate Annotations扩展包，使用注解完成映射。

在Hibernate3.3之前，需单独下载注解开发包。

配置持久化类

Hibernate 注解可以替代hbm文件

看完了注解的意思我们用注解配置一对一；（我用的是idea;MyEclipse应该是一样的。）

先看实体类

员工实体类

package cn.curry.entity2;

import javax.persistence.*;

/**

 * Created by Curry on 2017/2/16.

 */

@Entity

@Table(name = "Emp2")

public class Emp {

    private Integer eid;

    @Column

    private String ename;

    private Idcard idcard;

    @OneToOne

    @JoinColumn(name = "iid")

    public Idcard getIdcard() {

        return idcard;

    }

    public void setIdcard(Idcard idcard) {

        this.idcard = idcard;

    }

    @Id

    @GeneratedValue

    public Integer getEid() {

        return eid;

    }

    public void setEid(Integer eid) {

        this.eid = eid;

    }

    public String getEname() {

        return ename;

    }

    public void setEname(String ename) {

        this.ename = ename;

    }

}

身份证实体类

package cn.curry.entity2;

import javax.persistence.*;

/**

 * Created by Curry on 2017/2/16.

 */

@Entity

@Table(name = "Idcard2")

public class Idcard {

    @Id

    @GeneratedValue

    private Integer iid;

    private String inum;

    @OneToOne(mappedBy = "idcard",cascade = CascadeType.ALL)

    private Emp emp;

    public Integer getIid() {

        return iid;

    }

    public void setIid(Integer iid) {

        this.iid = iid;

    }

    public String getInum() {

        return inum;

    }

    public void setInum(String inum) {

        this.inum = inum;

    }

    public Emp getEmp() {

        return emp;

    }

    public void setEmp(Emp emp) {

        this.emp = emp;

    }

}

然后我们再看hibernate.cfg.xml文件

<?xml version="1.0" encoding="utf-8"?>

<!DOCTYPE hibernate-configuration PUBLIC

        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"

        "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

<hibernate-configuration>

    <session-factory>

        <property name="connection.driver_class">oracle.jdbc.driver.OracleDriver</property>

        <property name="connection.url">jdbc:oracle:thin:@localhost::orcl</property>

        <property name="connection.username">curry</property>

        <property name="connection.password">curry</property>

        <property name="dialect">org.hibernate.dialect.Oracle10gDialect</property>

        <property name="show_sql">true</property>

        <property name="hbm2ddl.auto">update</property>

        <!--和当前线程绑定 -->

        <property name="current_session_context_class">thread</property>

        <!--<mapping resource="cn/curry/entity/Grade.hbm.xml"/>

        <mapping resource="cn/curry/entity/Student.hbm.xml"/>-->

       <!-- 一对一-->

        <mapping class="cn.curry.entity2.Emp"/>

        <mapping class="cn.curry.entity2.Idcard"/>

       <!-- 一对多双向关联-->

        <mapping class="cn.curry.entity3.Emp"/>

        <mapping class="cn.curry.entity3.Dept"/>

        <!--多对多双向关联-->

        <mapping class="cn.curry.entity4.Game"/>

        <mapping class="cn.curry.entity4.Palyer"/>

    </session-factory>

</hibernate-configuration>

最后测试一下

package cn.curry.test;

import cn.curry.entity2.Emp;

import cn.curry.entity2.Idcard;

import org.hibernate.Session;

import org.hibernate.Transaction;

import org.junit.After;

import org.junit.Before;

import org.junit.Test;

/**

 * Created by Curry on 2017/2/16.

 */

public class MyTest2 {

    Session session=null;

    Transaction tx;

    @Before

    public void before(){

        session = HibernateUtil.currentSession();

        tx=session.beginTransaction();

    }

    @After

    public void after(){

        tx.commit();

        HibernateUtil.closeSession();

    }

    @Test

    public void testOneToOne(){

        Emp emp=new Emp();

        emp.setEname("熊");

        Idcard idcard=new Idcard();

        idcard.setInum("232325199009092020");

        idcard.setEmp(emp);

        emp.setIdcard(idcard);

        session.save(idcard);

    }

}

　　然后我们看运行结果

接下来我们再看一对多双向关联的配置

我们重新写一个例子，这次我们用员工和部门的列子来说；

首先还是先看实体类，注意看配置，看注解的书写，看每个属性的配置。

这个部门的实体类

package cn.curry.entity3;

import javax.persistence.*;

import java.util.HashSet;

import java.util.Set;

/**

 * Created by Curry on 2017/2/16.

 */

@Entity

@Table(name="Dept02")

public class Dept {

    @Id

    @GeneratedValue

    private Integer did;

    @Column

    private String dname;

    @OneToMany(mappedBy = "dept",cascade = CascadeType.ALL,fetch = FetchType.LAZY)

    private Set<Emp> emps=new HashSet<Emp>();

    public Integer getDid() {

        return did;

    }

    public void setDid(Integer did) {

        this.did = did;

    }

    public String getDname() {

        return dname;

    }

    public void setDname(String dname) {

        this.dname = dname;

    }

    public Set<Emp> getEmps() {

        return emps;

    }

    public void setEmps(Set<Emp> emps) {

        this.emps = emps;

    }

}

这个是员工的实体类

package cn.curry.entity3;

import javax.persistence.*;

/**

 * Created by Curry on 2017/2/16.

 */

@Entity

@Table(name = "Emp02")

public class Emp {

    @Id

    @GeneratedValue

    private Integer eid;

    @Column

    private String ename;

    @ManyToOne

    @JoinColumn(name="did")

    private Dept dept;

    public Integer getEid() {

        return eid;

    }

    public void setEid(Integer eid) {

        this.eid = eid;

    }

    public String getEname() {

        return ename;

    }

    public void setEname(String ename) {

        this.ename = ename;

    }

    public Dept getDept() {

        return dept;

    }

    public void setDept(Dept dept) {

        this.dept = dept;

    }

}

因为我的hibernate.cfg.xml文件已经写好了，可以回看下。

接下来我们看测试类。

package cn.curry.test;

import cn.curry.entity3.Dept;

import cn.curry.entity3.Emp;

import org.hibernate.Session;

import org.hibernate.Transaction;

import org.junit.After;

import org.junit.Before;

import org.junit.Test;

/**

 * Created by Curry on 2017/2/16.

 */

public class MyTest3 {

    Session session=null;

    Transaction tx;

    @Before

    public void before(){

        session = HibernateUtil.currentSession();

        tx=session.beginTransaction();

    }

    @After

    public void after(){

        tx.commit();

        HibernateUtil.closeSession();

    }

    @Test

    public void testOneToOne(){

        Dept dept=new Dept();

        dept.setDname("财务部");

        Emp emp=new Emp();

        emp.setEname("熊");

        dept.getEmps().add(emp);

        emp.setDept(dept);

        session.save(dept);

    }

    @Test

    public void select(){

        Dept dept =session.get(Dept.class,);

        System.out.println(dept.getDname());

        System.out.println(dept.getEmps().iterator().next().getEname());

    }

}

然后我们看运行结果

就是这样接下来我们看最后一个例子多对多双向关联。最后一个例子我们拿游戏和玩家来进行举例。

还是先看下实体类。

先看游戏的实体类

package cn.curry.entity4;

import javax.persistence.*;

import javax.swing.text.PlainDocument;

import java.util.HashSet;

import java.util.Set;

/**

 * Created by Curry on 2017/2/16.

 */

@Entity

@Table(name = "Game")

public class Game {

    @Id

    @GeneratedValue(strategy = GenerationType.SEQUENCE,generator = "sql_Game")

    @SequenceGenerator(name="sql_Game",sequenceName = "sql_Game",allocationSize = ,initialValue = )

    private Integer gid;

    @Column

    private String gname;

    @ManyToMany(cascade = CascadeType.ALL)

    @JoinTable(name = "PG",joinColumns = {@JoinColumn(name="gid")},inverseJoinColumns = {@JoinColumn(name="pid")})

    private Set<Palyer> palyerSet=new HashSet<Palyer>();

    public Integer getGid() {

        return gid;

    }

    public void setGid(Integer gid) {

        this.gid = gid;

    }

    public String getGname() {

        return gname;

    }

    public void setGname(String gname) {

        this.gname = gname;

    }

    public Set<Palyer> getPalyerSet() {

        return palyerSet;

    }

    public void setPalyerSet(Set<Palyer> palyerSet) {

        this.palyerSet = palyerSet;

    }

}

再看玩家的实体类

package cn.curry.entity4;

import javax.persistence.*;

import java.util.HashSet;

import java.util.Set;

/**

 * Created by Curry on 2017/2/16.

 */

@Entity

@Table(name = "Player")

public class Palyer {

    @Id

    @GeneratedValue(strategy = GenerationType.SEQUENCE,generator = "sql_Player")

    @SequenceGenerator(name="sql_Player",sequenceName = "sql_Palyer",allocationSize = ,initialValue = )

    private Integer pid;

    @Column

    private String pname;

    @ManyToMany(cascade = CascadeType.ALL,mappedBy = "palyerSet")

    private Set<Game> gameSet=new HashSet<Game>();

    public Integer getPid() {

        return pid;

    }

    public void setPid(Integer pid) {

        this.pid = pid;

    }

    public String getPname() {

        return pname;

    }

    public void setPname(String pname) {

        this.pname = pname;

    }

    public Set<Game> getGameSet() {

        return gameSet;

    }

    public void setGameSet(Set<Game> gameSet) {

        this.gameSet = gameSet;

    }

}

最后看一下测试吧

package cn.curry.test;

import cn.curry.entity4.Game;

import cn.curry.entity4.Palyer;

import org.hibernate.Session;

import org.hibernate.Transaction;

import org.junit.After;

import org.junit.Before;

import org.junit.Test;

/**

 * Created by Curry on 2017/2/16.

 */

public class MyTets4 {

    Session session=null;

    Transaction tx;

    @Before

    public void before(){

        session = HibernateUtil.currentSession();

        tx=session.beginTransaction();

    }

    @After

    public void after(){

        tx.commit();

        HibernateUtil.closeSession();

    }

    @Test

    public void testManyToMany(){

        Game game1=new Game();

        game1.setGname("NBA2K17");

        Game game2=new Game();

        game2.setGname("DNF");

        Palyer palyer1=new Palyer();

        palyer1.setPname("熊大");

        Palyer palyer2=new Palyer();

        palyer2.setPname("熊二");

        game1.getPalyerSet().add(palyer1);

        game1.getPalyerSet().add(palyer2);

        game2.getPalyerSet().add(palyer1);

        game2.getPalyerSet().add(palyer2);

        palyer1.getGameSet().add(game1);

        palyer1.getGameSet().add(game2);

        palyer2.getGameSet().add(game1);

        palyer2.getGameSet().add(game2);

        session.save(game1);

        session.save(game2);

    }

}

我们看运行结果

到这里所有例子就写完了。如果有不明白我写的东西，或者觉得那里有问题可以留言交流。

还有idea16的使用也可留言交流下。

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