hibernate3學習筆記(十一)｜復合主鍵

新建數據庫User：

1.CREATE TABLE user (
2.    name VARCHAR(100) NOT NULL,
3.    phone VARCHAR(50) NOT NULL,
4.    age INT,
5.    PRIMARY KEY(name, phone)
6.);

現將name和phone定義成復合主鍵。分別使用2種方法如下：

方法1.復合主鍵字段直接包含在PO類中。

User.java（需要實現Serializable接口，並定義equals()和hashCode()方法）

1.package com.hb3.pack_03.model;
2.
3.import java.io.Serializable;
4.import org.apache.commons.lang.builder.EqualsBuilder;
5.import org.apache.commons.lang.builder.HashCodeBuilder;
6.
7.public class User implements Serializable {
8.
9.    private static final long serialVersionUID = -8377583111386512407L;
10.
11.    private String name;
12.    private String phone;
13.    private Integer age;
14.
15.    public User() {
16.    }
17.
18.    public Integer getAge() {
19.        return age;
20.    }
21.
22.    public void setAge(Integer age) {
23.        this.age = age;
24.    }
25.
26.    public String getName() {
27.        return name;
28.    }
29.
30.    public void setName(String name) {
31.        this.name = name;
32.    }
33.
34.    public String getPhone() {
35.        return phone;
36.    }
37.
38.    public void setPhone(String phone) {
39.        this.phone = phone;
40.    }
41.
42.    public boolean equals(Object obj) {
43.        if(obj == this) {
44.            return true;
45.        }
46.
47.        if(!(obj instanceof User)) {
48.            return false;
49.        }
50.
51.        User user = (User) obj;
52.        return new EqualsBuilder()
53.                 .append(this.name, user.getName())
54.                 .append(this.phone, user.getPhone())
55.                 .isEquals();
56.    }
57.
58.    public int hashCode() {
59.        return new HashCodeBuilder()
60.                 .append(this.name)
61.                 .append(this.phone)
62.                 .toHashCode();
63.    }
64.}

在定義equals和hashCode方法時使用了apache的common-lang包。

User.hbm.xml文件：

1.<?xml version="1.0" encoding="UTF-8"?>
2.
3.<!DOCTYPE hibernate-mapping PUBLIC
4.    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
5.    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
6.
7.<hibernate-mapping>
8.
9.    <class name="com.hb3.pack_03.model.User" table="user">
10.
11.        <composite-id>
12.
13.            <key-property name="name"
14.                          column="name"
15.                          type="java.lang.String"/>
16.            <key-property name="phone"
17.                          column="phone"
18.                          type="java.lang.String"/>
19.        </composite-id>
20.
21.        <property name="age" column="age" type="java.lang.Integer"/>
22.
23.    </class>
24.
25.</hibernate-mapping>

hibernate.cfg.xml中修改：

......
<mapping resource="com/hb3/pack_03/model/User.hbm.xml" />
......

測試代碼如下：

1.package com.hb3.pack_03;
2.
3.import org.hibernate.Session;
4.import org.hibernate.SessionFactory;
5.import org.hibernate.Transaction;
6.import org.hibernate.cfg.Configuration;
7.
8.import com.hb3.pack_03.model.User;
9.
10.public class BusinessService {
11.
12.    public static void main(String[] args) {
13.
14.        Configuration config = new Configuration().configure();
15.        SessionFactory sessionFactory = config.buildSessionFactory();
16.        Session session = sessionFactory.openSession();
17.
18.        User user = new User();
19.        user.setName("shenbin");
20.        user.setPhone("0970123456");
21.        user.setAge(28);
22.        Transaction tx = session.beginTransaction();
23.        session.save(user);
24.        tx.commit();
25.
26.        user = (User) session.load(User.class, user);
27.
28.        System.out.println(user.getAge() + "\t" +  user.getName() + "\t" + user.getPhone());
29.
30.        session.close();
31.        sessionFactory.close();
32.    }
33.}

請注意：在實際測試過程中，如果數據庫已經有數據存在，則不需要上面的黑題部分向數據庫追加數據。

另外還請留意的是，光有session.save(user);而沒有tx.commit();的話,數據不會被持久到數據庫中的。

方法2.復合主鍵字段獨立到另一個類中。

UserPK.java(需要實現Serializable接口，並定義equals()和hashCode()方法)

1.package com.hb3.pack_04.model;
2.
3.import java.io.Serializable;
4.
5.import org.apache.commons.lang.builder.EqualsBuilder;
6.import org.apache.commons.lang.builder.HashCodeBuilder;
7.
8.public class UserPK implements Serializable {
9.
10.    private static final long serialVersionUID = -2457999265373664790L;
11.
12.    private String name;
13.    private String phone;
14.
15.    public String getName() {
16.        return name;
17.    }
18.    public void setName(String name) {
19.        this.name = name;
20.    }
21.    public String getPhone() {
22.        return phone;
23.    }
24.    public void setPhone(String phone) {
25.        this.phone = phone;
26.    }
27.    public boolean equals(Object obj) {
28.        if(obj == this) {
29.            return true;
30.        }
31.
32.        if(!(obj instanceof User)) {
33.            return false;
34.        }
35.
36.        UserPK pk = (UserPK) obj;
37.        return new EqualsBuilder()
38.                 .append(this.name, pk.getName())
39.                 .append(this.phone, pk.getPhone())
40.                 .isEquals();
41.    }
42.
43.    public int hashCode() {
44.        return new HashCodeBuilder()
45.                 .append(this.name)
46.                 .append(this.phone)
47.                 .toHashCode();
48.    }
49.}

User.java

1.package com.hb3.pack_04.model;
2.
3.import java.io.Serializable;
4.
5.public class User implements Serializable {
6.
7.    private static final long serialVersionUID = -8630481462628539996L;
8.
9.    private UserPK userPK;
10.    private Integer age;
11.
12.    public User() {
13.    }
14.
15.    public UserPK getUserPK() {
16.        return userPK;
17.    }
18.    public void setUserPK(UserPK userPK) {
19.        this.userPK = userPK;
20.    }
21.    public Integer getAge() {
22.        return age;
23.    }
24.    public void setAge(Integer age) {
25.        this.age = age;
26.    }
27.}

User.hbm.xml文件：

1.<?xml version="1.0" encoding="UTF-8"?>
2.
3.<!DOCTYPE hibernate-mapping PUBLIC
4.    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
5.    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
6.
7.<hibernate-mapping>
8.
9.    <class name="com.hb3.pack_04.model.User" table="user">
10.
11.        <composite-id name="userPK"
12.                      class="com.hb3.pack_04.model.UserPK"
13.                      unsaved-value="any">
14.            <key-property name="name"
15.                          column="name"
16.                          type="java.lang.String"/>
17.            <key-property name="phone"
18.                          column="phone"
19.                          type="java.lang.String"/>
20.        </composite-id>
21.
22.        <property name="age" column="age" type="java.lang.Integer"/>
23.
24.    </class>
25.
26.</hibernate-mapping>

hibernate.cfg.xml中修改：

......
<mapping resource="com/hb3/pack_04/model/User.hbm.xml" />
......

測試代碼如下：

1.package com.hb3.pack_04;
2.
3.import org.hibernate.Session;
4.import org.hibernate.SessionFactory;
5.import org.hibernate.cfg.Configuration;
6.
7.import com.hb3.pack_04.model.User;
8.import com.hb3.pack_04.model.UserPK;
9.
10.public class BusinessService {
11.
12.    public static void main(String[] args) {
13.
14.        Configuration config = new Configuration().configure();
15.        SessionFactory sessionFactory = config.buildSessionFactory();
16.        Session session = sessionFactory.openSession();
17.
18.        UserPK pk = new UserPK();
19.        pk.setName("shenbin");
20.        pk.setPhone("0970123456");
21.
22.        User user = (User) session.load(User.class, pk);
23.
24.        System.out.println(user.getAge() +
25.                    "\t" + user.getUserPK().getName() +
26.                    "\t" + user.getUserPK().getPhone());
27.
28.        session.close();
29.        sessionFactory.close();
30.    }
31.}