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>
hibernate.cfg.xml
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>();
10 private static Configuration config=null;
11 private static SessionFactory factory=null;
12 /**
13 * 读取配置文件
14 */
15 static{
16 try {
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 * @return
27 */
28 public static Session getSession(){
29 Session session =thread.get();
30 if(session==null){
31 session=factory.openSession();
32 thread.set(session);
33 }
34 return session;
35 }
36 /**
37 * 关闭session
38 */
39 public static void closeSession(){
40 Session session =thread.get();
41 thread.set(null);
42 session.close();
43
44 }
45
46 }
HibernateUtil.java
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>();
11
12 public Dept() {
13 }
14
15 public Dept(Integer deptno, String dname, String loc) {
16 this.deptno = deptno;
17 this.dname = dname;
18 this.loc = loc;
19 }
20
21 public Dept(Integer deptno, String dname, String loc, Set<Emp> emps) {
22 this.deptno = deptno;
23 this.dname = dname;
24 this.loc = loc;
25 this.emps = emps;
26 }
27 public Integer getDeptno() {
28 return deptno;
29 }
30 public void setDeptno(Integer deptno) {
31 this.deptno = deptno;
32 }
33 public String getDname() {
34 return dname;
35 }
36 public void setDname(String dname) {
37 this.dname = dname;
38 }
39 public String getLoc() {
40 return loc;
41 }
42 public void setLoc(String loc) {
43 this.loc = loc;
44 }
45 public Set<Emp> getEmps() {
46 return emps;
47 }
48 public void setEmps(Set<Emp> emps) {
49 this.emps = emps;
50 }
51
52 @Override
53 public String toString() {
54 return "Dept [deptno=" + deptno + ", dname=" + dname + ", loc=" + loc + "]";
55 }
56
57
58
59 }
Dept.java
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;
18 this.ename = ename;
19 this.job = job;
20 this.sal = sal;
21 }
22
23 public Emp(Integer empno, String ename, String job, Integer sal, Dept dept) {
24 super();
25 this.empno = empno;
26 this.ename = ename;
27 this.job = job;
28 this.sal = sal;
29 this.dept = dept;
30 }
31
32 public Integer getEmpno() {
33 return empno;
34 }
35
36 public void setEmpno(Integer empno) {
37 this.empno = empno;
38 }
39
40 public String getEname() {
41 return ename;
42 }
43
44 public void setEname(String ename) {
45 this.ename = ename;
46 }
47
48 public String getJob() {
49 return job;
50 }
51
52 public void setJob(String job) {
53 this.job = job;
54 }
55
56 public Integer getSal() {
57 return sal;
58 }
59
60 public void setSal(Integer sal) {
61 this.sal = sal;
62 }
63
64 public Dept getDept() {
65 return dept;
66 }
67
68 public void setDept(Dept dept) {
69 this.dept = dept;
70 }
71
72 @Override
73 public String toString() {
74 return "Emp [ empno=" + empno + ", ename=" + ename
75 + ", job=" + job + ", sal=" + sal + "]";
76 }
77
78
79
80 }
Emp.java
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>
Dept.hbm.xml
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>
Emp.hbm.xml
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 */
32 private static void 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");
41 for (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 */
51 private static void 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();
58 for (Dept dept : list) {
59 System.out.println(dept);
60 }
61 HibernateUtil.closeSession();
62 }
63 /**
64 * 4.左连接
65 */
66 private static void 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");
75 for (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 */
84 private static void 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();
91 for (Dept dept : list) {
92 System.out.println(dept);
93 }
94 HibernateUtil.closeSession();
95 }
96 /**
97 * 2.内连接
98 */
99 private static void 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");
108 for (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 */
120 private static void getDept() {
121 Session session=HibernateUtil.getSession();
122 String hql="from Dept";
123 Query query=session.createQuery(hql);
124 List<Dept> list=query.list();
125 for (Dept dept : list) {
126 System.out.println(dept);
127 System.out.println(dept.getEmps());
128 }
129 HibernateUtil.closeSession();
130
131 }
132
133 }
DpetDao.java
9.运行结果如下：remdeme.txt
1 1.内连接 2 Hibernate: 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------- 35 Hibernate: 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 50 51 -------5.迫切左连接------- 52 Hibernate: 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------- 70 Hibernate: 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
时间： 2024-10-28 14:42:38