DROP TABLE IF EXISTS `user`; CREATE TABLE `user` ( `user_id` int(32) NOT NULL COMMENT ‘用户id‘, `user_name` varchar(64) default NULL COMMENT ‘用户姓名‘, `user_age` int(3) default NULL COMMENT ‘用户年龄‘, PRIMARY KEY (`user_id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
相关配置的版本如下：
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5
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JDK:1.8maven:3.3.9mybatis:3.4.3 |
1 <?xml version="1.0" encoding="UTF-8"?> 2 <project xmlns="http://maven.apache.org/POM/4.0.0" 3 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 4 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> 5 <modelVersion>4.0.0</modelVersion> 6 7 <groupId>com.ys</groupId> 8 <artifactId>MybatisDemo</artifactId> 9 <version>1.0-SNAPSHOT</version> 10 <dependencies> 11 <dependency> 12 <groupId>org.mybatis</groupId> 13 <artifactId>mybatis</artifactId> 14 <version>3.4.3</version> 15 </dependency> 16 <dependency> 17 <groupId>junit</groupId> 18 <artifactId>junit</artifactId> 19 <version>4.12</version> 20 <scope>test</scope> 21 </dependency> 22 23 <dependency> 24 <groupId>mysql</groupId> 25 <artifactId>mysql-connector-java</artifactId> 26 <version>5.1.30</version> 27 </dependency> 28 29 </dependencies> 30 31 <build> 32 <plugins> 33 <plugin> 34 <groupId>org.apache.maven.plugins</groupId> 35 <artifactId>maven-compiler-plugin</artifactId> 36 <configuration> 37 <source>1.8</source> 38 <target>1.8</target> 39 </configuration> 40 </plugin> 41 </plugins> 42 43 <resources> 44 <resource> 45 <directory>src/main/java</directory> 46 <includes> 47 <include>**/*.properties</include> 48 <include>**/*.xml</include> 49 </includes> 50 <filtering>false</filtering> 51 </resource> 52 <resource> 53 <directory>src/main/resources</directory> 54 <includes> 55 <include>**/*.properties</include> 56 <include>**/*.xml</include> 57 </includes> 58 <filtering>false</filtering> 59 </resource> 60 </resources> 61 </build> 62 63 64 </project>
分别在pom文件中添加mybatis包，mysql数据库连接包，Junit测试包。
注意：由于我使用的编译器是 IDEA，这里必须在pom文件中配置对resource资源目录下的xml 文件的访问，否则，IEDA会读取不到resource目录下的配置文件。
①、jdbc.properties
1 jdbc.driver=com.mysql.jdbc.Driver 2 jdbc.url=jdbc:mysql://localhost:3306/mybatisTest?useUnicode=true&characterEncoding=utf-8 3 jdbc.username=root 4 jdbc.password=root
②、mybatsi-configuration.xml
View Code前面我们创建了 user 表，这里创建其实体类。
1 package com.ys.po;
2
3 import java.io.Serializable;
4
5 public class User implements Serializable{
6
7 public User() {
8 super();
9 }
10 public User(Integer id, String name, Integer age) {
11 super();
12 this.id = id;
13 this.name = name;
14 this.age = age;
15 }
16 private Integer id;
17 private String name;
18 private Integer age;
19 public Integer getId() {
20 return id;
21 }
22 public void setId(Integer id) {
23 this.id = id;
24 }
25 public String getName() {
26 return name;
27 }
28 public void setName(String name) {
29 this.name = name;
30 }
31 public Integer getAge() {
32 return age;
33 }
34 public void setAge(Integer age) {
35 this.age = age;
36 }
37 @Override
38 public String toString() {
39 return "User [id=" + id + ", name=" + name + ", age=" + age + "]";
40 }
41
42 }
注意：根据阿里巴巴的最新编码规范，实体类中的属性不要写基本数据类型，必须使用包装类型。比如 int 类型的 id，我们应该写成其包装类 Integer 类型。
原因：比如显示成交总额涨跌情况，即正负 x %， x 为基本数据类型，调用的 RPC 服务，调用不成功时，返回的是默认值，页面显示为 0%，这是不合理的，应该显示成中划线。所以包装数据类型的 null 值，能够表示额外的信息，如：远程调用失败，异常退出。
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 <mapper namespace="com.ys.po.userMapper">
6 <resultMap id="BaseResultMap" type="com.ys.po.User">
7 <id column="user_id" property="id" jdbcType="INTEGER"></id>
8 <result column="user_name" property="name" jdbcType="VARCHAR" />
9 <result column="user_age" property="age" jdbcType="INTEGER" />
10 </resultMap>
11
12 <sql id="Base_Column_List">
13 user_id, user_name, user_age
14 </sql>
15
16 <!-- 根据id查询 user 表数据 -->
17 <select id="selectUserById" resultMap="BaseResultMap" parameterType="java.lang.Integer">
18 select
19 <include refid="Base_Column_List" />
20 from user where user_id = #{id,jdbcType=INTEGER}
21 </select>
22
23
24 <!-- 查询 user 表的所有数据 -->
25 <select id="selectUserAll" resultMap="BaseResultMap">
26 select
27 <include refid="Base_Column_List" />
28 from user
29 </select>
30
31
32 <!-- 向 user 表插入一条数据 -->
33 <insert id="insertUser" parameterType="com.ys.po.User" >
34 insert into
35 user(<include refid="Base_Column_List" />)
36 value(#{id,jdbcType=INTEGER},#{name,jdbcType=VARCHAR},#{age,jdbcType=INTEGER})
37 </insert>
38
39 <!-- 根据 id 更新 user 表的数据 -->
40 <update id="updateUserById" parameterType="com.ys.po.User">
41 update user set
42 user_name=#{name,jdbcType=VARCHAR} where user_id=#{id,jdbcType=INTEGER}
43 </update>
44
45 <!-- 根据 id 删除 user 表的数据 -->
46 <delete id="deleteUserById" parameterType="java.lang.Integer">
47 delete from
48 user where user_id=#{id,jdbcType=INTEGER}
49 </delete>
50 </mapper>
1 package com.ys.test;
2
3 import java.io.InputStream;
4 import java.util.List;
5
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.Test;
10
11 import com.ys.po.User;
12
13 public class MybatisTest {
14 private static final String NAME_SPACE = "com.ys.po.userMapper";
15 private static SqlSessionFactory sqlSessionFactory;
16
17 static{
18 InputStream inputStream = MybatisTest.class.getClassLoader().getResourceAsStream("mybatis-configuration.xml");
19 sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
20 }
21 /**
22 * 查询单个记录
23 */
24 @Test
25 public void testSelectOne(){
26 SqlSession session = sqlSessionFactory.openSession();
27 User user = session.selectOne(NAME_SPACE+".selectUserById", 1);
28 System.out.println(user);
29 session.close();
30
31 }
32
33 /**
34 * 查询多个记录
35 */
36 @Test
37 public void testSelectList(){
38 SqlSession session = sqlSessionFactory.openSession();
39 List<User> listUser = session.selectList(NAME_SPACE+".selectUserAll");
40 if(listUser != null){
41 System.out.println(listUser.size());
42 }
43 session.close();
44 }
45
46 /**
47 * 插入一条记录
48 */
49 @Test
50 public void testInsert(){
51 SqlSession session = sqlSessionFactory.openSession();
52 User user = new User(2,"zhangsan",22);
53 session.insert(NAME_SPACE+".insertUser", user);
54 session.commit();
55 session.close();
56 }
57
58 /**
59 * 更新一条记录
60 */
61 @Test
62 public void testUpdate(){
63 SqlSession session = sqlSessionFactory.openSession();
64 User user = new User(2,"lisi",22);
65 session.update(NAME_SPACE+".updateUserById", user);
66 session.commit();
67 session.close();
68 }
69
70 /**
71 * 删除一条记录
72 */
73 @Test
74 public void testDelete(){
75 SqlSession session = sqlSessionFactory.openSession();
76 session.delete(NAME_SPACE+".deleteUserById", 2);
77 session.commit();
78 session.close();
79 }
80
81 }
出现5条绿色的横杆，然后去数据库查看相应的结果。
这个demo没什么好说的，不懂的看我前面的新手使用教程即可，这是最原始的mybatis开发方式。后面会通过这个例子深入源码分析。
原文：https://www.cnblogs.com/zhoanghua/p/9292222.html