Mybatis详细入门介绍

关注

原创最新推荐文章于 2026-04-06 09:18:45 发布 552 阅读 AI 写同款· GEO 优化 ›

Mybatis-Plus介绍及快速入门课程目标了解Mybatis-Plus 整合Mybatis-Plus 通用CRUD Mybatis-Plus的配置条件构造器 Mybatis-Plus 的Service封装代码生成器 Mybatis-Plus介绍 Mybatis-Plus介绍 MyBatis-Plus（简称 MP）是一个 MyBatis 的增强工具，在 MyBatis 的基础上只做增强不做改变，为简化开发提高效率而生。该框架由baomidou（苞米豆）组织开发并且开源的。官网：https://mybatis.plus/ 或 ht 阅读详情

1.Mybatis 介绍
MyBatis 是支持普通 SQL 查询，存储过程和高级映射的优秀持久
层框架。MyBatis 消除了几乎所有的 JDBC 代码和参数的手工设置以
及对结果集的检索封装。MyBatis 可以使用简单的 XML 或注解用于
配置和原始映射，将接口和 Java 的 POJO（Plain Old Java Objects，普
通的 Java 对象）映射成数据库中的记录.

JDBC- dbutils- MyBatis- Hibernate

2.mybatis 快速入门

编写第一个基于 mybaits  的测试例子:

2.1. 添加 jar 包

【mybatis 】   mybatis-3.1.1.jar
【MYSQL  驱动包】 mysql-connector-java-5.1.7-bin.jar

2.2. 建库+ 表

create database mybatis;
use mybatis;
CREATE TABLE users(id INT PRIMARY KEY AUTO_INCREMENT, NAME VARCHAR(20), age INT);
INSERT INTO users(NAME, age) VALUES('Tom', 12);
INSERT INTO users(NAME, age) VALUES('Jack', 11);

2.3. 添加 Mybatis 的配置文件 conf.xml

<?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>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC" />
<dataSource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver" />
<property name="url" value="jdbc:mysql://localhost:3306/mybatis" />
<property name="username" value="root" />
<property name="password" value="root" />
</dataSource>
</environment>
</environments>
</configuration>

2.4. 定义表所对应的实体类

public class User {
private int id;
private String name;
private int age;
//get,set 方法
                      }

2.5. 定义操作 users 表的 sql 映射文件 userMapper.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=" com.atguigu.mybatis_test.test1.userMapper">
<select id="getUser" parameterType="int"
resultType="com.atguigu.mybatis_test.test1.User">
select * from users where id=#{id}
</select>
</mapper>

2.6. 在在 conf.xml 文件中注册 userMapper.xml 文件

<mappers>
<mapper resource="com/atguigu/mybatis_test/test1/userMapper.xml"/>
</mappers>

2.7. 编写测试代码：执行定义的 select 语句

public class Test {
public static void main(String[] args) throws IOException {
String resource = "conf.xml";
//加载 mybatis 的配置文件（它也加载关联的映射文件）
Reader reader = Resources.getResourceAsReader(resource);
//构建 sqlSession 的工厂
SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);
//创建能执行映射文件中 sql 的 sqlSession
SqlSession session = sessionFactory.openSession();
//映射 sql 的标识字符串
String statement = "com.atguigu.mybatis.bean.userMapper"+".selectUser";
//执行查询返回一个唯一 user 对象的 sql
User user = session.selectOne(statement, 1);
System.out.println(user);
}  }

3. 操作 users 表的 CRUD
3.1. XML 的实现
1). 定义 sql 映射 xml 文件：

<insert id="insertUser" parameterType="com.atguigu.ibatis.bean.User">
insert into users(name, age) values(#{name}, #{age});
</insert>
<delete id="deleteUser" parameterType="int">
delete from users where id=#{id}
</delete>
<update id="updateUser" parameterType="com.atguigu.ibatis.bean.User">
update users set name=#{name},age=#{age} where id=#{id}
</update>
<select id="selectUser" parameterType="int" resultType="com.atguigu.ibatis.bean.User">
select * from users where id=#{id}
</select>
<select id="selectAllUsers" resultType="com.atguigu.ibatis.bean.User">
select * from users
</select>

2). 在在 config.xml 中注册这个映射文件

<mapper resource="net/lamp/java/ibatis/bean/userMapper.xml"/>

3). 在在 dao 中调用：

public User getUserById(int id) {
SqlSession session = sessionFactory.openSession();
User user = session.selectOne(URI+".selectUser", id);
return user;
}

3.2. 注解的实现
1). 定义 sql 映射的接口

public interface UserMapper {
@Insert("insert into users(name, age) values(#{name}, #{age})")
public int insertUser(User user);
@Delete("delete from users where id=#{id}")
public int deleteUserById(int id);
@Update("update users set name=#{name},age=#{age} where id=#{id}")
public int updateUser(User user);
@Select("select * from users where id=#{id}")
public User getUserById(int id);
@Select("select * from users")
public List<User> getAllUser();
}

2). 在在 config 中注册这个映射接口

<mapper class="com.atguigu.ibatis.crud.ano.UserMapper"/>

3). 在在 dao 类中调用

public User getUserById(int id) {
SqlSession session = sessionFactory.openSession();
UserMapper mapper = session.getMapper(UserMapper.class);
User user = mapper.getUserById(id);
return user;
}

4. 几个可以优化的地方
4.1. 连接数据库的配置单独放在一个 properties 文件中

db.properties

<properties resource="db.properties"/>
<property name="driver" value="${driver}" />
<property name="url" value="${url}" />
<property name="username" value="${username}" />
<property name="password" value="${password}" />

4.2. 为实体类定义别名, 简化 sql 映射 xml 文件中的引用

<typeAliases>
<typeAlias type="com.atguigu.ibatis.bean.User" alias="_User"/>
</typeAliases>

4.3. 可以在 src 下加入 log4j 的配置文件, 打印日志信息

添加jar:
log4j-1.2.16.jar
2.1. log4j.properties( 方式一)

log4j.properties，
log4j.rootLogger=DEBUG, Console
#Console
log4j.appender.Console=org.apache.log4j.ConsoleAppender
log4j.appender.Console.layout=org.apache.log4j.PatternLayout
log4j.appender.Console.layout.ConversionPattern=%d [%t] %-5p [%c] - %m%n
log4j.logger.java.sql.ResultSet=INFO
log4j.logger.org.apache=INFO
log4j.logger.java.sql.Connection=DEBUG
log4j.logger.java.sql.Statement=DEBUG
log4j.logger.java.sql.PreparedStatement=DEBUG

2.2. log4j.xml( 方式二)

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">
<appender name="STDOUT" class="org.apache.log4j.ConsoleAppender">
<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern"
value="%-5p %d{MM-dd HH:mm:ss,SSS} %m (%F:%L) \n" />
</layout>
</appender>
<logger name="java.sql">
<level value="debug" />
</logger>
<logger name="org.apache.ibatis">
<level value="debug" />
</logger>
<root>
<level value="debug" />
<appender-ref ref="STDOUT" />
</root>
</log4j:configuration>

5. 解决字段名与实体类属性名不相同的冲突
5.1. 准备表和数据：

CREATE TABLE orders(
order_id INT PRIMARY KEY AUTO_INCREMENT,
order_no VARCHAR(20),
order_price FLOAT
);
INSERT INTO orders(order_no, order_price) VALUES('aaaa', 23);
INSERT INTO orders(order_no, order_price) VALUES('bbbb', 33);
INSERT INTO orders(order_no, order_price) VALUES('cccc', 22);

5.2. 定义实体类：

public class Order {
private int id;
private String orderNo;
private float price;
}

5.3. 实现 getOrderById(id) 的查询：
方式一: 通过在 sql 语句中定义别名

<select id="selectOrder" parameterType="int" resultType="_Order">
select order_id id, order_no orderNo,order_price price from orders where order_id=#{id}
</select>

方式二: 通过

<select id="selectOrderResultMap" parameterType="int" resultMap="orderResultMap">
select * from orders where order_id=#{id}
</select>
<resultMap type="_Order" id="orderResultMap">
<id property="id" column="order_id"/>
<result property="orderNo" column="order_no"/>
<result property="price" column="order_price"/>
 </resultMap>

6. 实现关联表查询
6.1. 一对一关联
1). 提出需求
根据班级 id 查询班级信息(带老师的信息)
2). 创建表和数据

CREATE TABLE teacher(
t_id INT PRIMARY KEY AUTO_INCREMENT,
t_name VARCHAR(20)
);
CREATE TABLE class(
c_id INT PRIMARY KEY AUTO_INCREMENT,
c_name VARCHAR(20),
teacher_id INT
);
ALTER TABLE class ADD CONSTRAINT fk_teacher_id FOREIGN KEY (teacher_id) REFERENCES
teacher(t_id);
INSERT INTO teacher(t_name) VALUES('LS1');
INSERT INTO teacher(t_name) VALUES('LS2');
INSERT INTO class(c_name, teacher_id) VALUES('bj_a', 1);
INSERT INTO class(c_name, teacher_id) VALUES('bj_b', 2);

3). 定义实体类：

   public class Teacher {
    private int id;
    private String name;
    }
 
public class Classes {
private int id;
private String name;
private Teacher teacher;
}

4). 定义 sql 映射文件 ClassMapper.xml

<!--
方式一： 嵌套结果：使用嵌套结果映射来处理重复的联合结果的子集
封装联表查询的数据(去除重复的数据)
select * from class c, teacher t where c.teacher_id=t.t_id and c.c_id=1
-->
<select id="getClass" parameterType="int" resultMap="ClassResultMap">
select * from class c, teacher t where c.teacher_id=t.t_id and c.c_id=#{id}
</select>
<resultMap type="_Classes" id="ClassResultMap">
<id property="id" column="c_id"/>
<result property="name" column="c_name"/>
<association property="teacher" column="teacher_id" javaType="_Teacher">
<id property="id" column="t_id"/>
<result property="name" column="t_name"/>
</association>
</resultMap>

<!--
方式二： 嵌套查询：通过执行另外一个 SQL 映射语句来返回预期的复杂类型
SELECT * FROM class WHERE c_id=1;
SELECT * FROM teacher WHERE t_id=1 //1 是上一个查询得到的 teacher_id 的值
-->
<select id="getClass2" parameterType="int" resultMap="ClassResultMap2">
select * from class where c_id=#{id}
</select>
<resultMap type="_Classes" id="ClassResultMap2">
<id property="id" column="c_id"/>
<result property="name" column="c_name"/>
<association  property="teacher"  column="teacher_id"  javaType="_Teacher"
select="getTeacher">
</association>
 

</resultMap>
<select id="getTeacher" parameterType="int" resultType="_Teacher">
SELECT t_id id, t_name name FROM teacher WHERE t_id=#{id}
</select>

5). 测试

@Test
public void testOO() {
SqlSession sqlSession = factory.openSession();
Classes c = sqlSession.selectOne("com.atguigu.day03_mybatis.test5.OOMapper.getClass", 1);
System.out.println(c);
}
@Test
public void testOO2() {
SqlSession sqlSession = factory.openSession();
Classes c = sqlSession.selectOne("com.atguigu.day03_mybatis.test5.OOMapper.getClass2", 1);
System.out.println(c);
}

6.2. 一对多关联
1). 提出需求
根据 classId 查询对应的班级信息,包括学生,老师

2). 创建表和数据：

CREATE TABLE student(
s_id INT PRIMARY KEY AUTO_INCREMENT,
s_name VARCHAR(20),
class_id INT
);
INSERT INTO student(s_name, class_id) VALUES('xs_A', 1);
INSERT INTO student(s_name, class_id) VALUES('xs_B', 1);
INSERT INTO student(s_name, class_id) VALUES('xs_C', 1);
INSERT INTO student(s_name, class_id) VALUES('xs_D', 2);
INSERT INTO student(s_name, class_id) VALUES('xs_E', 2);
INSERT INTO student(s_name, class_id) VALUES('xs_F', 2);

3). 定义实体类：

public class Student {
private int id;
private String name;
}
public class Classes {
private int id;
private String name;
private Teacher teacher;
private List<Student> students;
}

4). 定义 sql 映射文件 ClassMapper.xml

<!--
方式一: 嵌套结果: 使用嵌套结果映射来处理重复的联合结果的子集
SELECT * FROM class c, teacher t,student s WHERE c.teacher_id=t.t_id AND c.C_id=s.class_id AND c.c_id=1
-->
<select id="getClass3" parameterType="int" resultMap="ClassResultMap3">
select * from class c, teacher t,student s where c.teacher_id=t.t_id and c.C_id=s.class_id and
c.c_id=#{id}
</select>
 
<resultMap type="_Classes" id="ClassResultMap3">
<id property="id" column="c_id"/>
<result property="name" column="c_name"/>
<association property="teacher" column="teacher_id" javaType="_Teacher">
<id property="id" column="t_id"/>
<result property="name" column="t_name"/>
</association>
<!-- ofType 指定 students 集合中的对象类型 -->
<collection property="students" ofType="_Student">
<id property="id" column="s_id"/>
<result property="name" column="s_name"/>
</collection>
</resultMap>
<!--
方式二：嵌套查询：通过执行另外一个 SQL 映射语句来返回预期的复杂类型
SELECT * FROM class WHERE c_id=1;
SELECT * FROM teacher WHERE t_id=1 //1 是上一个查询得到的 teacher_id 的值
SELECT * FROM student WHERE class_id=1 //1 是第一个查询得到的 c_id 字段的值
-->
<select id="getClass4" parameterType="int" resultMap="ClassResultMap4">
select * from class where c_id=#{id}
</select>
<resultMap type="_Classes" id="ClassResultMap4">
<id property="id" column="c_id"/>
<result property="name" column="c_name"/>
<association  property="teacher"  column="teacher_id"  javaType="_Teacher"
select="getTeacher2"></association>
<collection property="students" ofType="_Student" column="c_id" select="getStudent"></collection>
</resultMap>
<select id="getTeacher2" parameterType="int" resultType="_Teacher">
SELECT t_id id, t_name name FROM teacher WHERE t_id=#{id}
</select>
<select id="getStudent" parameterType="int" resultType="_Student">
SELECT s_id id, s_name name FROM student WHERE class_id=#{id}
</select>

5). 测试：

@Test
public void testOM() {
SqlSession sqlSession = factory.openSession();
Classes c = sqlSession.selectOne("com.atguigu.day03_mybatis.test5.OOMapper.getClass3", 1);
System.out.println(c);
}
@Test
public void testOM2() {
SqlSession sqlSession = factory.openSession();
Classes c = sqlSession.selectOne("com.atguigu.day03_mybatis.test5.OOMapper.getClass4", 1);
System.out.println(c);
}

7. 动态 SQL 与模糊查询
7.1. 提出需求:
实现多条件查询用户(姓名模糊匹配, 年龄在指定的最小值到最大值之间)
7.2. 准备数据表和数据:

create table d_user(
id int primary key auto_increment,
name varchar(10),
age int(3)
);
insert into d_user(name,age) values('Tom',12);
insert into d_user(name,age) values('Bob',13);
insert into d_user(name,age) values('Jack',18);

7.3. ConditionUser( 查询条件实体类)

private String name;
private int minAge;
private int maxAge;

7.4. User( 表实体类)

private int id;
private String name;
private int age;

7.5. userMapper.xml( 映射文件)

<?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.atguigu.day03_mybatis.test6.userMapper">
<select id="getUser" parameterType="com.atguigu.day03_mybatis.test6.ConditionUser"
resultType="com.atguigu.day03_mybatis.test6.User">
select * from d_user where age>=#{minAge} and age&lt;=#{maxAge}
<if test='name!="%null%"'>and name like #{name}</if>
</select>
</mapper>

7.6. UserTest( 测试)

public class UserTest {
public static void main(String[] args) throws IOException {
Reader reader = Resources.getResourceAsReader("conf.xml");
SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);
 
SqlSession sqlSession = sessionFactory.openSession();
String statement = "com.atguigu.day03_mybatis.test6.userMapper.getUser";
List<User> list = sqlSession.selectList(statement, new ConditionUser("%a%", 1, 12));
System.out.println(list);
}
}

MyBatis 中可用的动态 SQL 标签
8. 调用存储过程
8.1. 提出需求:
查询得到男性或女性的数量, 如果传入的是 0 就女性否则是男性
8.2. 准备数据库表和存储过程:

create table p_user(
id int primary key auto_increment,
name varchar(10),
sex char(2)
);
insert into p_user(name,sex) values('A',"男");
insert into p_user(name,sex) values('B',"女");
insert into p_user(name,sex) values('C',"男");

 #创建存储过程( 查询得到男性或女性的数量,  如果传入的是 0  就女性否则是男性)
DELIMITER $
CREATE PROCEDURE mybatis.ges_user_count(IN sex_id INT, OUT user_count INT)
BEGIN
IF sex_id=0 THEN
SELECT COUNT(*) FROM mybatis.p_user WHERE p_user.sex='女' INTO user_count;
ELSE
SELECT COUNT(*) FROM mybatis.p_user WHERE p_user.sex='男' INTO user_count;
END IF;
END
$
#调用存储过程
DELIMITER ;
SET @user_count = 0;
CALL mybatis.ges_user_count(1, @user_count);
SELECT @user_count;

8.3. 创建表的实体类

public class User {
private String id;
private String name;
private String sex;
}

8.4. userMapper.xml

<mapper namespace="com.atguigu.day03_mybatis.test7.userMapper">
<select id="getCount" resultType="java.util.Map" statementType="CALLABLE">
{call
ges_user_count(#{sex_id,mode=IN,jdbcType=INTEGER},#{result,mode=OUT,jdbcType=INTEGER})
}
</select>
</mapper>

8.5. 测试调用:

Map<String, Integer> paramMap = new HashMap<>();
paramMap.put("sex_id", 1);
Object returnValue = sqlSession.selectOne(statement, paramMap);
System.out.println("result="+paramMap.get("result"));
System.out.println("sex_id="+paramMap.get("sex_id"));
System.out.println("returnValue="+returnValue);

9. Mybatis 缓存
9.1. MyBatis 缓存理解
正如大多数持久层框架一样，MyBatis 同样提供了一级缓存和二级缓存的支持

一级缓存: 基于 PerpetualCache 的 HashMap 本地缓存，其存储作用域为 Session，当 Session
flush 或 close 之后，该 Session 中的所有 Cache 就将清空。
二级缓存与一级缓存其机制相同，默认也是采用 PerpetualCache，HashMap 存储，不同在于
其存储作用域为 Mapper(Namespace)，并且可自定义存储源，如 Ehcache。
对于缓存数据更新机制，当某一个作用域(一级缓存 Session/二级缓存 Namespaces)的进行了
C/U/D 操作后，默认该作用域下所有 select 中的缓存将被 clear。
9.2. Mybatis 一级缓存
1) 提出需求:
根据 id 查询对应的用户记录对象

2). 准备数据库表和数据

CREATE TABLE c_user(
id INT PRIMARY KEY AUTO_INCREMENT,
NAME VARCHAR(20),
age INT
);
INSERT INTO c_user(NAME, age) VALUES('Tom', 12);
INSERT INTO c_user(NAME, age) VALUES('Jack', 11);

3). 创建表的实体类

public class User implements Serializable{
private int id;
private String name;
private int age;
}

4). userMapper.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="com.atguigu.mybatis.test8.userMapper">
<select id="getUser" parameterType="int" resultType="_CUser">
select * from c_user where id=#{id}
</select>
<update id="updateUser" parameterType="_CUser">
update c_user set
name=#{name}, age=#{age} where id=#{id}
</update>
</mapper>

5). 测试:

/*
 

* 一级缓存: 也就 Session 级的缓存(默认开启)
*/
@Test
public void testCache1() {
SqlSession session = MybatisUtils.getSession();
String statement = "com.atguigu.mybatis.test8.userMapper.getUser";
User user = session.selectOne(statement, 1);
System.out.println(user);
/*
* 一级缓存默认就会被使用
*/
/*
user = session.selectOne(statement, 1);
System.out.println(user);
*/
/*
1. 必须是同一个 Session,如果 session 对象已经 close()过了就不可能用了
*/
/*
session = MybatisUtils.getSession();
user = session.selectOne(statement, 1);
System.out.println(user);
*/
/*
2. 查询条件是一样的
*/
/*
user = session.selectOne(statement, 2);
System.out.println(user);
*/
/*
3. 没有执行过 session.clearCache()清理缓存
*/
/*
session.clearCache();
user = session.selectOne(statement, 2);
System.out.println(user);
*/
 
 
/*
4. 没有执行过增删改的操作(这些操作都会清理缓存)
*/
/*
session.update("com.atguigu.mybatis.test8.userMapper.updateUser",
new User(2, "user", 23));
user = session.selectOne(statement, 2);
System.out.println(user);
*/
}

9.3. Mybatis 二级缓存
1). 添加一个在在 userMapper.xml 中

<mapper namespace="com.atguigu.mybatis.test8.userMapper">
<cache/>

2). 测试

/*
* 测试二级缓存
*/
@Test
public void testCache2() {
String statement = "com.atguigu.mybatis.test8.userMapper.getUser";
SqlSession session = MybatisUtils.getSession();
User user = session.selectOne(statement, 1);
session.commit();
System.out.println("user="+user);
SqlSession session2 = MybatisUtils.getSession();
user = session2.selectOne(statement, 1);
session.commit();
System.out.println("user2="+user);
}

3). 补充说明
映射语句文件中的所有 select 语句将会被缓存。
映射语句文件中的所有 insert，update 和 delete 语句会刷新缓存。
缓存会使用 Least Recently Used（LRU，最近最少使用的）算法来收回。
根据时间表（比如 no Flush Interval，没有刷新间隔），缓存不会以任何时间顺序来刷新。
缓存会存储列表集合或对象（无论查询方法返回什么）的 1024 个引用。
缓存会被视为是 read/write（可读/可写）的缓存，意味着对象检索不是共享的，而且可以
安全地被调用者修改，而不干扰其他调用者或线程所做的潜在修改

<cache
eviction="FIFO" //回收策略为先进先出
flushInterval="60000" //自动刷新时间 60s
size="512" //最多缓存 512 个引用对象
readOnly="true"/> //只读

10. spring 集成 mybatis

10.1. 添加 Jar 包

【mybatis 】
mybatis-3.2.0.jar
mybatis-spring-1.1.1.jar
log4j-1.2.17.jar
【spring 】
spring-aop-3.2.0.RELEASE.jar
spring-beans-3.2.0.RELEASE.jar
spring-context-3.2.0.RELEASE.jar
spring-core-3.2.0.RELEASE.jar
spring-expression-3.2.0.RELEASE.jar
spring-jdbc-3.2.0.RELEASE.jar
spring-test-3.2.4.RELEASE.jar
spring-tx-3.2.0.RELEASE.jar
aopalliance-1.0.jar
cglib-nodep-2.2.3.jar
commons-logging-1.1.1.jar
【MYSQL 驱动包】

mysql-connector-java-5.0.4-bin.jar
10.2. 数据库表

CREATE TABLE s_user(
user_id INT AUTO_INCREMENT PRIMARY KEY,
user_name VARCHAR(30),
user_birthday DATE,
user_salary DOUBLE
)

10.3. 编码:
2). 实体类: User

public class User {
private int id;
private String name;
private Date birthday;
private double salary;
//set,get 方法
}

3). DAO 接口: UserMapper (XXXMapper)

public interface UserMapper {
void save(User user);
void update(User user);
void delete(int id);
User findById(int id);
List<User> findAll();
}

4). SQL 映射文件: UserMapper.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="com.atguigu.mybatis.test9.UserMapper">
<resultMap type="User" id="userResult">
<result column="user_id" property="id"/>
<result column="user_name" property="name"/>
<result column="user_birthday" property="birthday"/>
<result column="user_salary" property="salary"/>
</resultMap>
<!-- 取得插入数据后的 id -->
<insert id="save" keyColumn="user_id" keyProperty="id" useGeneratedKeys="true">
insert into s_user(user_name,user_birthday,user_salary)
values(#{name},#{birthday},#{salary})
</insert>
<update id="update">
update s_user
set user_name = #{name},
user_birthday = #{birthday},
user_salary = #{salary}
where user_id = #{id}
</update>
<delete id="delete">
delete from s_user
where user_id = #{id}
</delete>
<select id="findById" resultMap="userResult">
select *
from s_user
where user_id = #{id}
</select>
<select id="findAll" resultMap="userResult">
select *
 
from s_user
</select>
</mapper>

5). 数据库连接文件: db.properties

jdbc.driverClassName=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/mybatis
jdbc.username=root
jdbc.password=root

6). spring 的配置文件: beans.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:p="http://www.springframework.org/schema/p"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:tx="http://www.springframework.org/schema/tx"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.2.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx-3.2.xsd">
<!--  关联 properties  文件 -->
<context:property-placeholder location="db.properties" />
<!--  数据源 -->
<bean id="dataSource"
class="org.springframework.jdbc.datasource.DriverManagerDataSource"
p:driverClassName="${jdbc.driverClassName}"
p:url="${jdbc.url}"
p:username="${jdbc.username}"
p:password="${jdbc.password}"/>
 
 
<!--
class:  指定用来创建 sqlSession  的工厂
dataSource-ref:  使用的数据源
typeAliasesPackage:  自动扫描的实体类包
-->
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean"
p:dataSource-ref="dataSource"
p:typeAliasesPackage="org.monmday.springmybatis.domian"/>
<!--
class :  指定自动扫描 xxxMapper.xml  映射文件的类
basePackage:  自动扫描的配置包
-->
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer"
p:basePackage="org.monmday.springmybatis.mappers"
p:sqlSessionFactoryBeanName="sqlSessionFactory"/>
<!--  事务管理 -->
<bean id="txManager"
class="org.springframework.jdbc.datasource.DataSourceTransactionManager"
p:dataSource-ref="dataSource"/>
<tx:annotation-driven transaction-manager="txManager" />
</beans>

7). 测试

@RunWith(SpringJUnit4ClassRunner.class) //使用Springtest框架
@ContextConfiguration("/beans.xml") //加载配置
public class SMTest {
@Autowired //注入
private UserMapper userMapper;
@Test
public void save() {
 
User user = new User();
user.setBirthday(new Date());
user.setName("marry");
user.setSalary(300);
userMapper.save(user);
System.out.println(user.getId());
}
@Test
public void update() {
User user = userMapper.findById(2);
user.setSalary(2000);
userMapper.update(user);
}
@Test
public void delete() {
userMapper.delete(3);
}
@Test
public void findById() {
User user = userMapper.findById(1);
System.out.println(user);
}
@Test
public void findAll() {
List<User> users = userMapper.findAll();
System.out.println(users);
}
}

收录于