hibernate双向多对一(一对多)及自身一对多关联

双向多对一(一对多)关联是最最常见的关联关系

javabean如下：

/**
 * 
 * 双向的一对多（多对一）
 * 少的一端,需要对多的一端进行集合的引用
 */
public class Account {

private int id;
private String accName;

//对多端对象集合的引用
private Set setOrders;

public Account(){

}

/**
 * @return the id
 */
public int getId() {
return id;
}

/**
 * @param id the id to set
 */
public void setId(int id) {
this.id = id;
}

/**
 * @return the accName
 */
public String getAccName() {
return accName;
}

/**
 * @param accName the accName to set
 */
public void setAccName(String accName) {
this.accName = accName;
}

/**
 * @return the setOrders
 */
public Set getSetOrders() {
return setOrders;
}

/**
 * @param setOrders the setOrders to set
 */
public void setSetOrders(Set setOrders) {
this.setOrders = setOrders;
}


}

/**
 * 
 * 双向的一对多（多对一）
 * 多的一端需要对少的一端进行对象的引用
 */
public class Orders {

private int id;
private String orderNum;
private Date orderTime;
private Account account;

public Orders(){

}

/**
 * @return the id
 */
public int getId() {
return id;
}

/**
 * @param id the id to set
 */
public void setId(int id) {
this.id = id;
}

/**
 * @return the orderNum
 */
public String getOrderNum() {
return orderNum;
}

/**
 * @param orderNum the orderNum to set
 */
public void setOrderNum(String orderNum) {
this.orderNum = orderNum;
}

/**
 * @return the orderTime
 */
public Date getOrderTime() {
return orderTime;
}

/**
 * @param orderTime the orderTime to set
 */
public void setOrderTime(Date orderTime) {
this.orderTime = orderTime;
}

public Account getAccount() {
return account;
}

public void setAccount(Account account) {
this.account = account;
}

}

映射文件：

"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">


    
    
        
        
            
        
        
        
        
        
        
      
        
    

"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">


    
    
        
        
            
        
        
       
       
       
       
    

生成的数据库表：

@Test
public void add(){
Transaction tx=null;
Session session=null;
try{
session=HibernateUtils.getSession();
tx=session.beginTransaction();
Account account=new Account();
account.setAccName("lm");
Orders order1=new Orders();
order1.setOrderNum("100");
order1.setOrderTime(new Date());
//session.save(order1);

Orders order2=new Orders();
order2.setOrderNum("10061");
order2.setOrderTime(new Date());
//session.save(order2);

order1.setAccount(account);
order2.setAccount(account);
Set setOrders=new HashSet();
setOrders.add(order1);
setOrders.add(order2);
account.setSetOrders(setOrders);

session.save(account);
tx.commit();
}catch(HibernateException he){
if(tx!=null){
tx.rollback();
}
he.printStackTrace();
}finally{
HibernateUtils.closeSession(session);
}
}

自身关联：

javabean如下：

/**
 * 
 * 双向一对多或多对一 自身关联
 * 
 */
public class Category {

private int id;
private String name;

//如果把Category看成是多的一端
private Category parent;

//如果把Category看成是少的一端,则需要对多的一端进行对象集合的引用
private Set clist;

public Category(){

}

/**
 * @return the id
 */
public int getId() {
return id;
}

/**
 * @param id the id to set
 */
public void setId(int id) {
this.id = id;
}

/**
 * @return the name
 */
public String getName() {
return name;
}

/**
 * @param name the name to set
 */
public void setName(String name) {
this.name = name;
}

/**
 * @return the parent
 */
public Category getParent() {
return parent;
}

/**
 * @param parent the parent to set
 */
public void setParent(Category parent) {
this.parent = parent;
}

/**
 * @return the clist
 */
public Set getClist() {
return clist;
}

/**
 * @param clist the clist to set
 */
public void setClist(Set clist) {
this.clist = clist;
}

}

映射文件

"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">


    
    
        
        
            
        
        
       
       
       
       
       
       
        
    

数据库表：

测试代码：

@Test
public void add(){
Transaction tx=null;
Session session=null;
try{
session=HibernateUtils.getSession();
tx=session.beginTransaction();
//添加一级分类
Category c1=new Category();
c1.setName("computer");

session.save(c1);

//添加二级分类
Category c2=new Category();
c2.setName("java");
c2.setParent(c1);
session.save(c2);
//添加二级分类
Category c3=new Category();
c3.setName(".net");
c3.setParent(c1);
session.save(c3);
tx.commit();
}catch(HibernateException he){
if(tx!=null){
tx.rollback();
}
he.printStackTrace();
}finally{
HibernateUtils.closeSession(session);
}
}

数据结构：