Mybatis(五)

一、目录结构

二、代码

1、AccountDao

 1 package cn.bijian.dao;
 2 
 3 
 4 import cn.bijian.model.Account;
 5 
 6 import java.util.List;
 7 
 8 public interface AccountDao {
 9     /*
10     查询所有账户及其用户信息（使用assocation实现延迟加载）
11      */
12     List<Account> findAll();
13     /*
14     （使用collection实现延迟加载）
15      */
16     List<Account> findByUid(Integer id);
17 
18 }

2、UserDao

 1 package cn.bijian.dao;
 2 
 3 import cn.bijian.model.User;
 4 
 5 import java.util.List;
 6 
 7 public interface UserDao {
 8     /*
 9     根据id查询（使用assocation实现延迟加载）
10      */
11     User findById(Integer id);
12     /*
13     查询所有用户及其账户信息（使用collection实现延迟加载）
14      */
15     List<User> findAll();
16 }

3、Account

 1 package cn.bijian.model;
 2 
 3 import java.io.Serializable;
 4 
 5 public class Account implements Serializable {
 6     private Integer id;
 7     private Integer uid;
 8     private Double money;
 9     private User user;
10 
11     public Integer getId() {
12         return id;
13     }
14 
15     public void setId(Integer id) {
16         this.id = id;
17     }
18 
19     public Integer getUid() {
20         return uid;
21     }
22 
23     public void setUid(Integer uid) {
24         this.uid = uid;
25     }
26 
27     public Double getMoney() {
28         return money;
29     }
30 
31     public void setMoney(Double money) {
32         this.money = money;
33     }
34 
35     public User getUser() {
36         return user;
37     }
38 
39     public void setUser(User user) {
40         this.user = user;
41     }
42 
43     @Override
44     public String toString() {
45         return "Account{" +
46                 "id=" + id +
47                 ", uid=" + uid +
48                 ", money=" + money +
49                 ", user=" + user +
50                 '}';
51     }
52 }

4、User

 1 package cn.bijian.model;
 2 
 3 import java.io.Serializable;
 4 import java.util.Date;
 5 import java.util.List;
 6 
 7 public class User implements Serializable {
 8     private Integer id;
 9     private String username;
10     private Date birthday;
11     private String sex;
12     private String address;
13     private List<Account> accounts;
14 
15     public Integer getId() {
16         return id;
17     }
18 
19     public void setId(Integer id) {
20         this.id = id;
21     }
22 
23     public String getUsername() {
24         return username;
25     }
26 
27     public void setUsername(String username) {
28         this.username = username;
29     }
30 
31     public Date getBirthday() {
32         return birthday;
33     }
34 
35     public void setBirthday(Date birthday) {
36         this.birthday = birthday;
37     }
38 
39     public String getSex() {
40         return sex;
41     }
42 
43     public void setSex(String sex) {
44         this.sex = sex;
45     }
46 
47     public String getAddress() {
48         return address;
49     }
50 
51     public void setAddress(String address) {
52         this.address = address;
53     }
54 
55     public List<Account> getAccounts() {
56         return accounts;
57     }
58 
59     public void setAccounts(List<Account> accounts) {
60         this.accounts = accounts;
61     }
62 
63     @Override
64     public String toString() {
65         return "User{" +
66                 "id=" + id +
67                 ", username='" + username + '\'' +
68                 ", birthday=" + birthday +
69                 ", sex='" + sex + '\'' +
70                 ", address='" + address + '\'' +
71                 ", accounts=" + accounts +
72                 '}';
73     }
74 }

5、AccountDao.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="cn.bijian.dao.AccountDao">
    <!--（使用assocation实现延迟加载）-->
    <resultMap id="accountMap" type="cn.bijian.model.Account">
        <id column="id" property="id"/>
        <result column="uid" property="uid"/>
        <result column="money" property="money"/>
        <association property="user" javaType="cn.bijian.model.User"
                     select="cn.bijian.dao.UserDao.findById" column="uid">
        </association>
    </resultMap>
    <select id="findAll" resultMap="accountMap">
        select * from account
    </select>
    <!--（使用collection实现延迟加载）-->
    <select id="findByUid" parameterType="int" resultType="cn.bijian.model.Account">
        select * from account where uid = #{uid}
    </select>

</mapper>

6、UserDao.xml

 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <!DOCTYPE mapper
 3         PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
 4         "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
 5 
 6 <mapper namespace="cn.bijian.dao.UserDao">
 7     <cache></cache>  <!-- 开启二级缓存（2）   -->
 8     <!--（使用assocation实现延迟加载）-->
 9     <select id="findById" parameterType="int" resultType="cn.bijian.model.User" useCache="true">
10         <!--
11             开启二级缓存（3） useCache="true"
12             针对每次查询如果需要最新的数据，则需设置useCache="false"，禁用二级缓存
13         -->
14         select * from user where id = #{uid}
15     </select>
16     <!--（使用collection实现延迟加载）-->
17     <resultMap id="userMap" type="cn.bijian.model.User">
18         <id column="id" property="id"></id>
19         <result column="username" property="username"></result>
20         <result column="sex" property="sex"></result>
21         <result column="address" property="address"></result>
22         <result column="birthday" property="birthday"></result>
23         <collection property="accounts" ofType="cn.bijian.model.Account"
24                     select="cn.bijian.dao.AccountDao.findByUid" column="id">
25                     <!--column="id"用于指定select属性的sql语句参数来源,参数来自于user的id列-->
26         </collection>
27     </resultMap>
28     <select id="findAll" resultMap="userMap">
29         select * from user
30     </select>
31 
32 </mapper>

7、SqlMapConfig.xml

 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <!DOCTYPE configuration
 3         PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
 4         "http://mybatis.org/dtd/mybatis-3-config.dtd">
 5 <configuration>
 6     <settings>
 7         <setting name="lazyLoadingEnabled" value="true"/>
 8         <setting name="aggressiveLazyLoading" value="false"/>
 9         <setting name="cacheEnabled" value="true"/><!--开启二级缓存（1）-->
10     </settings>
11 
12     <environments default="mysql">
13         <environment id="mysql">
14             <transactionManager type="JDBC"></transactionManager>
15             <dataSource type="POOLED">  <!--连接池-->
16                 <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
17                 <property name="url" value="jdbc:mysql://localhost:3306/mybatis?serverTimezone=UTC"/>
18                 <property name="username" value="root"/>
19                 <property name="password" value="123456"/>
20             </dataSource>
21         </environment>
22     </environments>
23 
24     <mappers>
25         <mapper resource="cn/bijian/dao/UserDao.xml"></mapper>
26         <mapper resource="cn/bijian/dao/AccountDao.xml"></mapper>
27     </mappers>
28 
29 </configuration>

8、MybatisTest

 1 package cn.bijian;
 2 
 3 import cn.bijian.dao.AccountDao;
 4 import cn.bijian.model.Account;
 5 import org.apache.ibatis.io.Resources;
 6 import org.apache.ibatis.session.SqlSession;
 7 import org.apache.ibatis.session.SqlSessionFactory;
 8 import org.apache.ibatis.session.SqlSessionFactoryBuilder;
 9 import org.junit.After;
10 import org.junit.Before;
11 import org.junit.Test;
12 
13 
14 import java.io.IOException;
15 import java.io.InputStream;
16 import java.util.List;
17 
18 
19 public class MybatisTest {
20     private InputStream in;
21     private SqlSessionFactory sessionFactory;
22     private SqlSession session;
23     private AccountDao accountDao;
24 
25     @Before
26     public void init() throws IOException {
27         in = Resources.getResourceAsStream("SqlMapConfig.xml");
28         SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
29         sessionFactory = builder.build(in);
30         session = sessionFactory.openSession();
31         accountDao = session.getMapper(AccountDao.class);
32     }
33 
34     @After
35     public void destroy() throws IOException {
36 //        session.commit();
37         session.close();
38         in.close();
39     }
40     /*
41         只查账户信息不查用户信息（使用assocation实现延迟加载）
42      */
43     @Test
44     public void testFindAll(){
45         List<Account> accounts = accountDao.findAll();
46     }
47 
48 }

9、MybatisTest2

 1 package cn.bijian;
 2 
 3 import cn.bijian.dao.UserDao;
 4 import cn.bijian.model.User;
 5 import org.apache.ibatis.io.Resources;
 6 import org.apache.ibatis.session.SqlSession;
 7 import org.apache.ibatis.session.SqlSessionFactory;
 8 import org.apache.ibatis.session.SqlSessionFactoryBuilder;
 9 import org.junit.After;
10 import org.junit.Before;
11 import org.junit.Test;
12 
13 import java.io.IOException;
14 import java.io.InputStream;
15 import java.util.List;
16 
17 
18 public class MybatisTest2 {
19     private InputStream in;
20     private SqlSessionFactory sessionFactory;
21     private SqlSession session;
22     private UserDao userDao;
23 
24     @Before
25     public void init() throws IOException {
26         in = Resources.getResourceAsStream("SqlMapConfig.xml");
27         SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
28         sessionFactory = builder.build(in);
29         session = sessionFactory.openSession();
30         userDao = session.getMapper(UserDao.class);
31     }
32 
33     @After
34     public void destroy() throws IOException {
35 //        session.commit();
36         session.close();
37         in.close();
38     }
39     /*
40         （使用collection实现延迟加载）
41      */
42     @Test
43     public void testFindAll(){
44         List<User> users = userDao.findAll();
45     }
46 
47 }

10、MybatisTest3

 1 package cn.bijian;
 2 
 3 import cn.bijian.dao.UserDao;
 4 import cn.bijian.model.User;
 5 import org.apache.ibatis.io.Resources;
 6 import org.apache.ibatis.session.SqlSession;
 7 import org.apache.ibatis.session.SqlSessionFactory;
 8 import org.apache.ibatis.session.SqlSessionFactoryBuilder;
 9 import org.junit.After;
10 import org.junit.Before;
11 import org.junit.Test;
12 
13 import java.io.IOException;
14 import java.io.InputStream;
15 import java.util.List;
16 
17 
18 public class MybatisTest3 {
19     private InputStream in;
20     private SqlSessionFactory sessionFactory;
21     private SqlSession session;
22     private UserDao userDao;
23 
24     @Before
25     public void init() throws IOException {
26         in = Resources.getResourceAsStream("SqlMapConfig.xml");
27         SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
28         sessionFactory = builder.build(in);
29         session = sessionFactory.openSession();
30         userDao = session.getMapper(UserDao.class);
31     }
32 
33     @After
34     public void destroy() throws IOException {
35 //        session.commit();
36         session.close();
37         in.close();
38     }
39     /*
40         （测试一级缓存，session范围的缓存） Total: 1
41      */
42     @Test
43     public void testFindById(){
44         User user = userDao.findById(41);
45         System.out.println("第一次查询:"+user);
46         //清空缓存
47 //        session.clearCache();
48 //        userDao = session.getMapper(UserDao.class);
49 
50         User user2 = userDao.findById(41);
51         System.out.println("第二次查询:"+user2);
52         System.out.println(user==user2);
53     }
54     /*
55     一级缓存的同步功能：（以update举例，判断user==user2）
56         当执行session.close()后，再次获取session并查询id=？的User对象时又重新执行了sql语句，从数据库查询。
57      */
58 }

11、MybatisTest4

 1 package cn.bijian;
 2 
 3 import cn.bijian.dao.UserDao;
 4 import cn.bijian.model.User;
 5 import org.apache.ibatis.io.Resources;
 6 import org.apache.ibatis.session.SqlSession;
 7 import org.apache.ibatis.session.SqlSessionFactory;
 8 import org.apache.ibatis.session.SqlSessionFactoryBuilder;
 9 import org.junit.After;
10 import org.junit.Before;
11 import org.junit.Test;
12 
13 import java.io.IOException;
14 import java.io.InputStream;
15 
16 /*
17     测试二级缓存，mapper范围的缓存
18  */
19 public class MybatisTest4 {
20     private InputStream in;
21     private SqlSessionFactory sessionFactory;
22 
23     @Before
24     public void init() throws IOException {
25         in = Resources.getResourceAsStream("SqlMapConfig.xml");
26         SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
27         sessionFactory = builder.build(in);
28     }
29 
30     @After
31     public void destroy() throws IOException {
32         in.close();
33     }
34     /*
35         （测试一级缓存，session范围的缓存）
36         第一次查询后关闭一级缓存，再次执行二次查询的时候，并没有对数据库发出sql语句，此时数据来自二级缓存。
37      */
38     @Test
39     public void testFirst(){
40         SqlSession session1 = sessionFactory.openSession();
41         UserDao dao1 = session1.getMapper(UserDao.class);
42         User user1 = dao1.findById(41);
43         System.out.println(user1);
44         session1.close();//一级缓存消失
45 
46         SqlSession session2 = sessionFactory.openSession();
47         UserDao dao2 = session2.getMapper(UserDao.class);
48         User user2 = dao2.findById(41);
49         System.out.println(user2);
50         session1.close();//一级缓存消失
51 
52         System.out.println(user1==user2);
53     }
54 }

 

posted on 2021-10-29 15:28  晨曦生辉耀匕尖  阅读(30)  评论(0)  编辑  收藏  举报