一、准备工作
1.db.properties文件（记得修改自己的数据库和用户名、密码）
|
1
2
3
4
|
dataSource.driver=com.mysql.jdbc.DriverdataSource.url=jdbc:mysql://localhost:3306/mybatis?useUnicode=true&characterEncoding=utf8dataSource.username=blogdataSource.password=blog |
2.主配置文件
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
|
<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd"><configuration><!-- 引入外部配置文件--> <properties resource="db.properties"></properties> <!-- 别名设置，不设置时引用要使用全包名，设置后可以使用自定义别名，更加简洁 --> <typeAliases> <!-- 别名设置有两种，一种是一个一个设置，另外一种是设置某个包，默认别名为类名（大小写都可以，建议小写） --> <!-- 第一种设置 <typeAlias type="com.mybatis_demo.domain.User" alias="user"/>--> <!-- 第二种设置，整个包下面的类都进行别名设置，推荐第二种 --> <package name="com.mybatis_demo.domain"/> </typeAliases><!-- 环境模式：development开发模式 work工作模式 --> <environments default="development"> <!-- 环境变量 --> <environment id="development"> <!-- 使用jdbc的事务管理 --> <transactionManager type="JDBC"/> <!-- 使用连接池 --> <dataSource type="POOLED"> <property name="driver" value="${dataSource.driver}"/> <property name="url" value="${dataSource.url}"/> <property name="username" value="${dataSource.username}"/> <property name="password" value="${dataSource.password}"/> </dataSource> </environment> </environments> <!-- 引入mapper映射文件 --> <mappers> <!-- 1.相对路径引入--> <!-- <mapper resource="mapper/UserMapper.xml"/> --> <!-- 2.绝对路径引入 --> <!-- <mapper url="file:\\\D:\sts-bundle\workplace\mybatis_demo\src\main\resources\mapper\UserMapper.xml"/> --> <!-- 3.对应mapper接口全包名引入，需要对应的mapper.xml与接口mapper处于同一包下才可以，且xml文件名与接口名要相同，xml文件中的namespace必须是对应接口的全包名 --> <!-- <mapper class="com.mybatis_demo.mapper.UserMapper"/> --> <!-- 4.包引入，要求跟接口引入一样 --> <!-- <mapper resource="mapper/UserMapper2.xml"/> --> <package name="com.mybatis_demo.mapper"/> </mappers></configuration> |
3.创建User类和包装类UserVo
User.java
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
|
package com.mybatis_demo.domain;public class User { private Integer uid; private String uname; private Integer age; private String address; public Integer getUid() { return uid; } public void setUid(Integer uid) { this.uid = uid; } public String getUname() { return uname; } public void setUname(String uname) { this.uname = uname; } public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } public String getAddress() { return address; } public void setAddress(String address) { this.address = address; } @Override public String toString() { return "User [uid=" + uid + ", uname=" + uname + ", age=" + age + ", address=" + address + "]"; }} |
UserVo.java
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
|
package com.mybatis_demo.domain;import java.util.List;public class UserVo extends User { private Integer[] ids; private List<Integer> idList; public Integer[] getIds() { return ids; } public void setIds(Integer[] ids) { this.ids = ids; } public List<Integer> getIdList() { return idList; } public void setIdList(List<Integer> idList) { this.idList = idList; } } |
二、遍历数组和集合的映射文件和对应的接口
1.mapper映射文件
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
|
<?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="com.mybatis_demo.mapper.UserMapper"><!-- 遍历list集合，collection="list"，如果你传参的时候是直接传递list集合，那么这里只能填list,不能填参数名 --><select id="selectByList" resultType="User"> select * from t_user where uid in <foreach collection="list" item="item" open="(" separator="," close=")"> #{item} </foreach></select><!-- 遍历数组 ，collection="array"，如果你传参的时候是直接传递数组，那么这里只能填array,不能填参数名--><select id="selectByArray" resultType="User"> select * from t_user where uid in <foreach collection="array" item="item" open="(" separator="," close=")"> #{item} </foreach></select><!-- 遍历包装类中的数组，collection="ids"，这里不再是array,而是包装类中对应的变量名，因为你传递的参数是一个包装类，mybatis是通过get方法获取包装类中的数组 --><select id="selectUserVoByArray" parameterType="UserVo" resultType="User"> select * from t_user where uid in <foreach collection="ids" item="item" open="(" separator="," close=")"> #{item} </foreach></select><!-- 遍历包装类中的list集合，collection="idList"，这里不再是list,而是包装类中对应的变量名，因为你传递的参数是一个包装类，mybatis是通过get方法获取包装类中的list集合 --><select id="selectUserVoByList" parameterType="UserVo" resultType="User"> select * from t_user where uid in <foreach collection="idList" item="item" open="(" separator="," close=")"> #{item} </foreach></select></mapper> |
2.mapper接口
UserMapper.interface
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
|
package com.mybatis_demo.mapper;import java.util.List;import java.util.Map;import com.mybatis_demo.domain.User;import com.mybatis_demo.domain.UserVo;public interface UserMapper { //mybatis使用mapper动态代理 //4大原则，一个注意 //1.接口中的方法名需要与对应mapper.xml的id一致 //2.接口中的返回值需要与对应mapper.xml的返回值类型保持一致 //3.接口中的参数需要与对应mapper.xml的参数类型、个数、参数名保持一致 //4.对应mapper.xml的名字空间需要修改成对应接口的全包名 //注意：mapper动态代理根据返回值类型,mybatis会自动选择调用selectone还是selectlist.... //用list封装条件 public List<User> selectByList(List<Integer> testlist); //用数组封装条件 public List<User> selectByArray(Integer[] ids); //用包装类中的数组封装条件 public List<User> selectUserVoByArray(UserVo userVo); //用包装类中的list封装条件 public List<User> selectUserVoByList(UserVo userVo); } |
三、测试代码
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
|
package com.mybatis_demo.test;import java.io.IOException;import java.io.InputStream;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import org.apache.ibatis.io.Resources;import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory;import org.apache.ibatis.session.SqlSessionFactoryBuilder;import org.junit.Test;import com.mybatis_demo.domain.User;import com.mybatis_demo.domain.UserVo;import com.mybatis_demo.mapper.UserMapper;public class TestMapper { //用包装类中的list封装条件，传递参数是一个包装类 @Test public void test_selectUserVoByList() { try { //读取配置文件 InputStream in = Resources.getResourceAsStream("sqlMapConfig.xml"); //创建SqlSessionFactoryBuilder对象，用来获取SqlSessionFactory对象 SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder(); //利用SqlSessionFactoryBuilder对象build一个SqlSessionFactory对象 SqlSessionFactory build = builder.build(in); //利用sqlSessionFactory获取session对象 SqlSession session = build.openSession(); //通过session对象获取对应mapper接口 UserMapper mapper = session.getMapper(UserMapper.class); List<Integer> idList = new ArrayList<Integer>(); idList.add(5); idList.add(3); idList.add(123); idList.add(19); UserVo userVo = new UserVo(); userVo.setIdList(idList); List<User> users = mapper.selectUserVoByList(userVo); for (User user : users) { System.out.println(user); } } catch (IOException e) { e.printStackTrace(); } } //用包装类中的array封装条件，传递参数是一个包装类 @Test public void test_selectUserVoByArray() { try { //读取配置文件 InputStream in = Resources.getResourceAsStream("sqlMapConfig.xml"); //创建SqlSessionFactoryBuilder对象，用来获取SqlSessionFactory对象 SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder(); //利用SqlSessionFactoryBuilder对象build一个SqlSessionFactory对象 SqlSessionFactory build = builder.build(in); //利用sqlSessionFactory获取session对象 SqlSession session = build.openSession(); //通过session对象获取对应mapper接口 UserMapper mapper = session.getMapper(UserMapper.class); Integer[] ids = new Integer[]{5,9,30}; UserVo userVo = new UserVo(); userVo.setIds(ids); List<User> users = mapper.selectUserVoByArray(userVo); for (User user : users) { System.out.println(user); } } catch (IOException e) { e.printStackTrace(); } } //用数组封装条件，传递参数是一个数组 @Test public void test_selectByArray() { try { //读取配置文件 InputStream in = Resources.getResourceAsStream("sqlMapConfig.xml"); //创建SqlSessionFactoryBuilder对象，用来获取SqlSessionFactory对象 SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder(); //利用SqlSessionFactoryBuilder对象build一个SqlSessionFactory对象 SqlSessionFactory build = builder.build(in); //利用sqlSessionFactory获取session对象 SqlSession session = build.openSession(); //通过session对象获取对应mapper接口 UserMapper mapper = session.getMapper(UserMapper.class); Integer[] ids = new Integer[]{5,9,30}; List<User> users = mapper.selectByArray(ids); for (User user : users) { System.out.println(user); } } catch (IOException e) { e.printStackTrace(); } } //用list封装条件，传递参数是一个list集合 @Test public void test_selectByList() { try { //读取配置文件 InputStream in = Resources.getResourceAsStream("sqlMapConfig.xml"); //创建SqlSessionFactoryBuilder对象，用来获取SqlSessionFactory对象 SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder(); //利用SqlSessionFactoryBuilder对象build一个SqlSessionFactory对象 SqlSessionFactory build = builder.build(in); //利用sqlSessionFactory获取session对象 SqlSession session = build.openSession(); //通过session对象获取对应mapper接口 UserMapper mapper = session.getMapper(UserMapper.class); List<Integer> list = new ArrayList<Integer>(); list.add(5); list.add(3); list.add(123); list.add(19); List<User> users = mapper.selectByList(list); for (User user : users) { System.out.println(user); } } catch (IOException e) { e.printStackTrace(); } }} |
四、总结
1.如果你传参的时候直接传一个数组，那么使用foreach遍历时collection=“array”,这里是固定写法，即这里的array与你的实参名无关
2.如果你传参的时候直接传一list集合，那么使用foreach遍历时collection=“list”,这里是固定写法，即这里的list与你的实参名无关
3.如果你传参的时候直接传一个含有数组成员变量的类，那么使用foreach遍历时collection=“你的变量名”,这里不再是固定写法，即这里的命名取决于成员变量的变量名，例如：成员变量名是test,那么就是collection=“test”
4.如果你传参的时候直接传一个含有list集合成员变量的类，跟3的情况一样
以上为个人经验，希望能给大家一个参考，也希望大家多多支持服务器之家。
原文链接：https://blog.csdn.net/ChOLg/article/details/100162800
