11.hibernate的连接查询
内容导读
互联网集市收集整理的这篇技术教程文章主要介绍了11.hibernate的连接查询，小编现在分享给大家，供广大互联网技能从业者学习和参考。文章包含12002字，纯文字阅读大概需要18分钟。
内容图文
1.创建如下javaweb项目结构
2.在项目的src下创建hibernate.cfg.xml主配置文件
1
<?
xml version="1.0" encoding="UTF-8"
?>
2
<!
DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"
>
3
<
hibernate-configuration
>
4
<
session-factory
>
5
<
property
name
="connection.driver_class"
>oracle.jdbc.driver.OracleDriver</property> 6<property name="connection.url">jdbc:oracle:thin:@127.0.0.1:1521:orcl</property> 7<property name="connection.username">scott</property> 8<property name="connection.password">tiger</property> 9<property name="dialect">org.hibernate.dialect.Oracle10gDialect</property>10<property name="show_sql">true</property>11<property name="format_sql">true</property>12<mapping resource="com/entity/Dept.hbm.xml"/>13<mapping resource="com/entity/Emp.hbm.xml"/>14</session-factory>15</hibernate-configuration>
3.在项目的src下的com.util包下创建HibernateUtil.java
1
package
com.util;
2
3
import
org.hibernate.HibernateException;
4
import
org.hibernate.Session;
5
import
org.hibernate.SessionFactory;
6
import
org.hibernate.cfg.Configuration;
7
8
public
class
HibernateUtil {
9
private
static ThreadLocal<Session> thread=new ThreadLocal<Session>();
10privatestatic Configuration config=null;
11privatestatic SessionFactory factory=null;
12/**13 * 读取配置文件
14*/15static{
16try {
17 config=new Configuration().configure("/hibernate.cfg.xml");
18 factory=config.buildSessionFactory();
19 } catch (HibernateException e) {
20 System.out.println("读取配置文件失败或创建factory失败");
21 e.printStackTrace();
22 }
23 }
24/**25 * 打开session
26 * @return27*/28publicstatic Session getSession(){
29 Session session =thread.get();
30if(session==null){
31 session=factory.openSession();
32 thread.set(session);
33 }
34return session;
35 }
36/**37 * 关闭session
38*/39publicstaticvoid closeSession(){
40 Session session =thread.get();
41 thread.set(null);
42 session.close();
4344 }
4546 }
4.在项目的src下的com.entity包下创建Dept.java
1
package
com.entity;
2
3
import
java.util.HashSet;
4
import
java.util.Set;
5
6
public
class
Dept {
7
private
Integer deptno;
8
private
String dname;
9
private
String loc;
10
private Set<Emp> emps =new HashSet<Emp>();
1112public Dept() {
13 }
1415public Dept(Integer deptno, String dname, String loc) {
16this.deptno = deptno;
17this.dname = dname;
18this.loc = loc;
19 }
2021public Dept(Integer deptno, String dname, String loc, Set<Emp> emps) {
22this.deptno = deptno;
23this.dname = dname;
24this.loc = loc;
25this.emps = emps;
26 }
27public Integer getDeptno() {
28return deptno;
29 }
30publicvoid setDeptno(Integer deptno) {
31this.deptno = deptno;
32 }
33public String getDname() {
34return dname;
35 }
36publicvoid setDname(String dname) {
37this.dname = dname;
38 }
39public String getLoc() {
40return loc;
41 }
42publicvoid setLoc(String loc) {
43this.loc = loc;
44 }
45public Set<Emp> getEmps() {
46return emps;
47 }
48publicvoid setEmps(Set<Emp> emps) {
49this.emps = emps;
50 }
5152 @Override
53public String toString() {
54return "Dept [deptno=" + deptno + ", dname=" + dname + ", loc=" + loc + "]";
55 }
56575859 }
5.在项目的src下的com.entity包下创建Emp.java
1
package
com.entity;
2
3
4
5
public
class
Emp {
6
private
Integer empno;
7
private
String ename;
8
private
String job;
9
private
Integer sal;
10
private
Dept dept;
11
12
public
Emp() {
13
}
14
15
public
Emp(Integer empno, String ename, String job, Integer sal) {
16
super
();
17
this.empno = empno;
18this.ename = ename;
19this.job = job;
20this.sal = sal;
21 }
2223public Emp(Integer empno, String ename, String job, Integer sal, Dept dept) {
24super();
25this.empno = empno;
26this.ename = ename;
27this.job = job;
28this.sal = sal;
29this.dept = dept;
30 }
3132public Integer getEmpno() {
33return empno;
34 }
3536publicvoid setEmpno(Integer empno) {
37this.empno = empno;
38 }
3940public String getEname() {
41return ename;
42 }
4344publicvoid setEname(String ename) {
45this.ename = ename;
46 }
4748public String getJob() {
49return job;
50 }
5152publicvoid setJob(String job) {
53this.job = job;
54 }
5556public Integer getSal() {
57return sal;
58 }
5960publicvoid setSal(Integer sal) {
61this.sal = sal;
62 }
6364public Dept getDept() {
65return dept;
66 }
6768publicvoid setDept(Dept dept) {
69this.dept = dept;
70 }
7172 @Override
73public String toString() {
74return "Emp [ empno=" + empno + ", ename=" + ename
75 + ", job=" + job + ", sal=" + sal + "]";
76 }
77787980 }
6.在项目的src下的com.entity包下创建Dept.hbm.xml
1
<?
xml version="1.0" encoding="UTF-8"
?>
2
<!
DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"
>
3
<
hibernate-mapping
>
4
<
class
name
="com.entity.Dept"
table
="DEPT"
>
5
<
id
name
="deptno"
type
="java.lang.Integer"
column
="DEPTNO"
>
6
<
generator
class
="assigned"
/>
7
</
id
>
8
<
property
name
="dname"
type
="java.lang.String"
column
="DNAME"
/>
9
<
property
name
="loc"
type
="java.lang.String"
column
="LOC"
/>
10
<!--
一对多
-->
11
<
set
name
="emps"
inverse
="true"
cascade
="save-update"
>
12
<
key
column
="DEPTNO"
></
key
>
13
<
one-to-many
class
="com.entity.Emp"
/>
14
</
set
>
15
</
class
>
16
</
hibernate-mapping
>
7.在项目的src下的com.entity包下创建Emp.hbm.xml
1
<?
xml version="1.0" encoding="UTF-8"
?>
2
<!
DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"
>
3
<
hibernate-mapping
>
4
<
class
name
="com.entity.Emp"
table
="EMP"
>
5
<
id
name
="empno"
type
="java.lang.Integer"
column
="EMPNO"
>
6
<
generator
class
="assigned"
/>
7
</
id
>
8
<
property
name
="ename"
type
="java.lang.String"
column
="ENAME"
/>
9
<
property
name
="job"
type
="java.lang.String"
column
="JOB"
/>
10
<
property
name
="sal"
type
="java.lang.Integer"
column
="SAL"
/>
11
<!--
多对一
-->
12
<
many-to-one
name
="dept"
class
="com.entity.Dept"
column
="DEPTNO"
/>
13
</
class
>
14
</
hibernate-mapping
>
8.在项目的src下的com.dao包下创建DpetDao.java
1
package
com.dao;
2
3
import
java.util.List;
4
5
import
org.hibernate.Query;
6
import
org.hibernate.Session;
7
8
import
com.entity.Dept;
9
import
com.util.HibernateUtil;
10
11
public
class
DpetDao {
12
13
14
public
static
void
main(String[] args) {
15 System.out.println("-----------1.关联查询-----------");
16//getDept(); 17 System.out.println("-------2.内连接-------");
18 innerJoin();
19 System.out.println("-------3.迫切内连接-------");
20 innerJoinFetch();
21 System.out.println("-------4.左连接-------");
22 leftJoin();
23 System.out.println("-------5.迫切左连接-------");
24 leftJoinFetch();
25 System.out.println("-------6.右连接-------");
26 rightJoin();
27 28 }
29/** 30 * 6.右连接
31*/ 32privatestaticvoid rightJoin() {
33 Session session=HibernateUtil.getSession();
34 String hql="from Dept d right join d.emps ";
35 Query query=session.createQuery(hql);
36/*list集合中的每个元素都是一个Object数组,数组的第一个元素时Dept对象,
37 * 第二个元素时Emp对象,Dept对象的emps集合元素没有被初始化,
38 * 即emps集合没有存放关联的Emp对象*/ 39 List<Object[]> list=query.list();
40 System.out.println("dept对象"+"~~"+"emp对象");
41for (Object[] obj : list) {
42 System.out.println(obj[0]);
43 System.out.println(obj[1]);
44 }
45 HibernateUtil.closeSession();
46 47 }
48/** 49 * 5.迫切左连接
50*/ 51privatestaticvoid leftJoinFetch() {
52 Session session=HibernateUtil.getSession();
53/*Hibernate使用fetch关键字实现了将Emp对象读取出来后立即填充到对应的Dept对象
54 * 的集合属性中,*/ 55 String hql="select distinct d from Dept d left join fetch d.emps ";
56 Query query=session.createQuery(hql);
57 List<Dept> list=query.list();
58for (Dept dept : list) {
59 System.out.println(dept);
60 }
61 HibernateUtil.closeSession();
62 }
63/** 64 * 4.左连接
65*/ 66privatestaticvoid leftJoin() {
67 Session session=HibernateUtil.getSession();
68 String hql="from Dept d left join d.emps ";
69 Query query=session.createQuery(hql);
70/*list集合中的每个元素都是一个Object数组,数组的第一个元素时Dept对象,
71 * 第二个元素时Emp对象,Dept对象的emps集合元素没有被初始化,
72 * 即emps集合没有存放关联的Emp对象*/ 73 List<Object[]> list=query.list();
74 System.out.println("dept对象"+"~~"+"emp对象");
75for (Object[] obj : list) {
76 System.out.println(obj[0]);
77 System.out.println(obj[1]);
78 }
79 HibernateUtil.closeSession();
80 }
81/** 82 * 3.迫切内连接
83*/ 84privatestaticvoid innerJoinFetch() {
85 Session session=HibernateUtil.getSession();
86/*Hibernate使用fetch关键字实现了将Emp对象读取出来后立即填充到对应的Dept对象
87 * 的集合属性中,*/ 88 String hql="select distinct d from Dept d inner join fetch d.emps ";
89 Query query=session.createQuery(hql);
90 List<Dept> list=query.list();
91for (Dept dept : list) {
92 System.out.println(dept);
93 }
94 HibernateUtil.closeSession();
95 }
96/** 97 * 2.内连接
98*/ 99privatestaticvoid innerJoin() {
100 Session session=HibernateUtil.getSession();
101 String hql="from Dept d inner join d.emps ";
102 Query query=session.createQuery(hql);
103/*list集合中的每个元素都是一个Object数组,数组的第一个元素时Dept对象,
104 * 第二个元素时Emp对象,Dept对象的emps集合元素没有被初始化,
105 * 即emps集合没有存放关联的Emp对象*/106 List<Object[]> list=query.list();
107 System.out.println("dept对象"+"~~"+"emp对象");
108for (Object[] obj : list) {
109 System.out.println(obj[0]);
110 System.out.println(obj[1]);
111 }
112 HibernateUtil.closeSession();
113 }
114/**115 * Exception in thread "main" java.lang.StackOverflowError
116 * 内存溢出:死循环
117 * hiberante双向关联时:打印内容时不能你中有我,我中有你,查询默认是懒加载
118 *
119*/120privatestaticvoid getDept() {
121 Session session=HibernateUtil.getSession();
122 String hql="from Dept";
123 Query query=session.createQuery(hql);
124 List<Dept> list=query.list();
125for (Dept dept : list) {
126 System.out.println(dept);
127 System.out.println(dept.getEmps());
128 }
129 HibernateUtil.closeSession();
130131 }
132133 }
9.运行结果如下：remdeme.txt
1 1.内连接
2Hibernate:
3 select
4 dept0_.DEPTNO as DEPTNO0_0_,
5 emps1_.EMPNO as EMPNO1_1_,
6 dept0_.DNAME as DNAME0_0_,
7 dept0_.LOC as LOC0_0_,
8 emps1_.ENAME as ENAME1_1_,
9 emps1_.JOB as JOB1_1_,
10 emps1_.SAL as SAL1_1_,
11 emps1_.DEPTNO as DEPTNO1_1_
12 from
13 DEPT dept0_
14 inner join
15 EMP emps1_
16 on dept0_.DEPTNO=emps1_.DEPTNO
17 2.迫切内连接
18 select
19 dept0_.DEPTNO as DEPTNO0_0_,
20 emps1_.EMPNO as EMPNO1_1_,
21 dept0_.DNAME as DNAME0_0_,
22 dept0_.LOC as LOC0_0_,
23 emps1_.ENAME as ENAME1_1_,
24 emps1_.JOB as JOB1_1_,
25 emps1_.SAL as SAL1_1_,
26 emps1_.DEPTNO as DEPTNO1_1_,
27 emps1_.DEPTNO as DEPTNO0__,
28 emps1_.EMPNO as EMPNO0__
29 from
30 DEPT dept0_
31 inner join
32 EMP emps1_
33 on dept0_.DEPTNO=emps1_.DEPTNO
34 -------4.左连接-------
35Hibernate:
36 select
37 dept0_.DEPTNO as DEPTNO0_0_,
38 emps1_.EMPNO as EMPNO1_1_,
39 dept0_.DNAME as DNAME0_0_,
40 dept0_.LOC as LOC0_0_,
41 emps1_.ENAME as ENAME1_1_,
42 emps1_.JOB as JOB1_1_,
43 emps1_.SAL as SAL1_1_,
44 emps1_.DEPTNO as DEPTNO1_1_
45 from
46 DEPT dept0_
47 left outer join
48 EMP emps1_
49 on dept0_.DEPTNO=emps1_.DEPTNO
5051 -------5.迫切左连接-------
52Hibernate:
53 select
54 distinct dept0_.DEPTNO as DEPTNO0_0_,
55 emps1_.EMPNO as EMPNO1_1_,
56 dept0_.DNAME as DNAME0_0_,
57 dept0_.LOC as LOC0_0_,
58 emps1_.ENAME as ENAME1_1_,
59 emps1_.JOB as JOB1_1_,
60 emps1_.SAL as SAL1_1_,
61 emps1_.DEPTNO as DEPTNO1_1_,
62 emps1_.DEPTNO as DEPTNO0__,
63 emps1_.EMPNO as EMPNO0__
64 from
65 DEPT dept0_
66 left outer join
67 EMP emps1_
68 on dept0_.DEPTNO=emps1_.DEPTNO
69 -------6.右连接-------
70Hibernate:
71 select
72 dept0_.DEPTNO as DEPTNO0_0_,
73 emps1_.EMPNO as EMPNO1_1_,
74 dept0_.DNAME as DNAME0_0_,
75 dept0_.LOC as LOC0_0_,
76 emps1_.ENAME as ENAME1_1_,
77 emps1_.JOB as JOB1_1_,
78 emps1_.SAL as SAL1_1_,
79 emps1_.DEPTNO as DEPTNO1_1_
80 from
81 DEPT dept0_
82 right outer join
83 EMP emps1_
84 on dept0_.DEPTNO=emps1_.DEPTNO
原文：http://www.cnblogs.com/holly8/p/5778112.html
内容总结
以上是互联网集市为您收集整理的11.hibernate的连接查询全部内容，希望文章能够帮你解决11.hibernate的连接查询所遇到的程序开发问题。 如果觉得互联网集市技术教程内容还不错，欢迎将互联网集市网站推荐给程序员好友。
内容备注
版权声明：本文内容由互联网用户自发贡献，该文观点与技术仅代表作者本人。本站仅提供信息存储空间服务，不拥有所有权，不承担相关法律责任。如发现本站有涉嫌侵权/违法违规的内容， 请发送邮件至 gblab@vip.qq.com 举报，一经查实，本站将立刻删除。
内容手机端
扫描二维码推送至手机访问。
来源：【匿名】