Hibernate 配置和注解式 ，关联关系

　　　1：配置式(xml)关联关系 

    　  我们用Dept（部门），Emp（员工）两张表来做下面的例子。

　　　　字段

public class Dept {
    private  Integer deptno;
    private  String deptname;

    //员工实体 一对多
    private Set<Emp>emps=new HashSet<Emp>();

    public Set<Emp> getEmps() {
        return emps;
    }

    public void setEmps(Set<Emp> emps) {
        this.emps = emps;
    }
    public Integer getDeptno() {
        return deptno;
    }

    public void setDeptno(Integer deptno) {
        this.deptno = deptno;
    }

    public String getDeptname() {
        return deptname;
    }

    public void setDeptname(String deptname) {
        this.deptname = deptname;
    }
}

public class Emp {
    private Integer empno;
    private String empname;
    private Integer deptno;
    //植入部门实体
    private Dept dept=new Dept();


    public Integer getDeptno() {
        return deptno;
    }

    public void setDeptno(Integer deptno) {
        this.deptno = deptno;
    }
    public Dept getDept() {
        return dept;
    }
    public void setDept(Dept dept) {
        this.dept = dept;
    }
    public Integer getEmpno() {
        return empno;
    }

    public void setEmpno(Integer empno) {
        this.empno = empno;
    }

    public String getEmpname() {
        return empname;
    }

    public void setEmpname(String empname) {
        this.empname = empname;
    }


}

　　　　

　　　　1， 一对多 one-to-many

　　　　  重点1 ：在少的一方（Dept）植入多的一方的 Set 集合

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="cn.happy.de">
    <!--dynamic-update="true"  动态更新先检索再修改-->
    <class name="cn.happy.de.Dept" table="Dept" dynamic-update="true" >
        <id name="deptno" column="deptno">
           <generator class="native"></generator>
        </id>
            <property name="deptname" column="deptname"></property>
        <!--一对多双向关联   //员工实体 一对多private Set<Emp>emps;-->
        <!--  cascade="save-update"级联   -->
        <!--  inverse="true"放弃维护关系：不干预顶层集合数据 -->
        <!--  order-by="empno desc"排序 -->
        <set name="emps" cascade="save-update,delete" inverse="true" order-by="empno desc">
            <key column="deptno"></key>
            <one-to-many class="Emp"></one-to-many>
        </set>
    </class>

</hibernate-mapping>

　　　 重点2 ：在多的一方（Emp）植入少的一方的对象　　　　　　

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="cn.happy.de">
    <!--dynamic-update="true"  动态更新先检索再修改-->
    <class name="cn.happy.de.Emp" table="Emp" dynamic-update="true" >
        <id name="empno" column="empno">
           <generator class="native"></generator>
        </id>
        <property name="empname" column="empname"></property>
        <!--
        name:在多的一方植入对方的对象名
        class：再多的一方植入对方的类型名
        column：在当前分析的对象对应底层表的外列的值
        -->
        <many-to-one name="Dept" class="Dept" column="deptno" cascade="save-update"></many-to-one>
    </class>

</hibernate-mapping>

　　测试：修改

  @Test
    public void s2(){
        Dept dept=new Dept();
        dept.setDeptno(1);
        Emp emp=HQLutil.getSession().load(Emp.class,2);
        emp.setDept(dept);
        HQLutil.getSession().saveOrUpdate(emp);
        Transaction transaction = HQLutil.getSession().beginTransaction();
        transaction.commit();
    }

　　2， 多对多  many-to-many

　　　　Employee（员工）， Project（项目）表

public class Employee {
    private  Integer empid;
    private  String empname;
    private Set<Project>projects=new HashSet<Project>();

    public Integer getEmpid() {
        return empid;
    }

    public void setEmpid(Integer empid) {
        this.empid = empid;
    }

    public String getEmpname() {
        return empname;
    }

    public void setEmpname(String empname) {
        this.empname = empname;
    }

    public Set<Project> getProjects() {
        return projects;
    }

    public void setProjects(Set<Project> projects) {
        this.projects = projects;
    }
}

public class Project {
    private Integer proid;
    private String proname;

    public Set<Employee> getEmployees() {
        return employees;
    }

    public void setEmployees(Set<Employee> employees) {
        this.employees = employees;
    }

    private Set<Employee>employees=new HashSet<Employee>();
    public Integer getProid() {
        return proid;
    }

    public void setProid(Integer proid) {
        this.proid = proid;
    }

    public String getProname() {
        return proname;
    }

    public void setProname(String proname) {
        this.proname = proname;
    }


}

　　　　重点1 ：Employee每方都植入  Set  集合 

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="cn.happy.er">
    <!--dynamic-update="true"  动态更新先检索再修改-->
    <class name="cn.happy.er.Employee" table="Employee" dynamic-update="true">
        <id name="empid" column="empid">
           <generator class="native"></generator>
        </id>
            <property name="empname" column="empname"></property>
        <!--table:中间表-->
        <set name="projects"  table="PROEMP" cascade="save-update" lazy="extra">
            <!-- column：植入当前我们依赖的id列 -->
            <key column="REMPID"></key>
            <!-- column：植入对方我们依赖的id列 -->
            <many-to-many class="Project" column="RPROID"></many-to-many>
        </set>
    </class>

</hibernate-mapping>

　　 重点2 ：Project每方都植入  Set  集合  

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="cn.happy.er">
    <!--dynamic-update="true"  动态更新先检索再修改-->
    <class name="cn.happy.er.Project" table="Project" dynamic-update="true" >
        <id name="proid" column="proid">
           <generator class="native"></generator>
        </id>
        <property name="proname" column="proname"></property>
        <set name="employees"  table="PROEMP" cascade="save-update" >
            <key column="RPROID"></key>
            <many-to-many class="Employee" column="REMPID"></many-to-many>
        </set>

    </class>

</hibernate-mapping>

 　　　　　　　　　　2：注解式关联关系 

    注解： 

@Entity   ：持久化类

@Table    ：数据库表名

@Id　      ：主键

@GeneratedValue  ：主键生成策略

@JoinColumn(name = "dids")    ：主表在字表中的外键

@OneToOne(mappedBy = "dept",cascade = CascadeType.ALL)    mapperBy哪个类拥有这个属性就维护表关系

@ManyToMany(cascade = CascadeType.ALL)
@JoinTable(name = "PROEMP",joinColumns = {@JoinColumn(name = "REMPID")}    ：生成中间表
        ,inverseJoinColumns = {@JoinColumn(name = "RPROID")}
)