mybatis与spring的整合

Posted 2020-09-25

spring 框架

Spring是一个轻量级的控制反转(IoC)和面向切面(AOP)的容器框架。

两个重要模块：Spring 面向方面编程（AOP）和控制反转 （IOC） 容器。

控制反转模式（也称作依赖性介入）的基本概念是：不创建对象，但是描述创建它们的方式。在代码中不直接与对象和服务连接，但在配置文件中描述哪一个组件需要哪一项服务。

容器 （在 Spring 框架中是 IOC 容器） 负责将这些联系在一起。在典型的 IOC 场景中，容器创建了所有对象，并设置必要的属性将它们连接在一起，决定什么时间调用方法

mybatis框架

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结果集的检索。

MyBatis 使用简单的 XML或注解用于配置和原始映射，将接口和 Java 的POJOs（Plain Old Java Objects，普通的 Java对象）映射成数据库中的记录。

1.项目结构

POJO-----User.java

package com.it.ms.pojo;

import java.io.Serializable;
import java.util.Date;

public class User implements Serializable {
    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    private Integer id;
    private String username;// 用户姓名
    private String sex;// 性别
    private Date birthday;// 生日
    private String address;// 地址


    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getSex() {
        return sex;
    }
    public void setSex(String sex) {
        this.sex = sex;
    }
    public Date getBirthday() {
        return birthday;
    }
    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }
    public String getAddress() {
        return address;
    }
    public void setAddress(String address) {
        this.address = address;
    }
    @Override
    public String toString() {
        return "User [id=" + id + ", username=" + username + ", sex=" + sex
                + ", birthday=" + birthday + ", address=" + address + "]";
    }

    
    

}

pojo----Order

package com.it.ms.pojo;

import java.io.Serializable;
import java.util.Date;

public class Orders  implements Serializable{
    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    private Integer id;

    private Integer userId;

    private String number;

    private Date createtime;

    private String note;
    
    private User user;
    
    public User getUser() {
        return user;
    }

    public void setUser(User user) {
        this.user = user;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public Integer getUserId() {
        return userId;
    }

    public void setUserId(Integer userId) {
        this.userId = userId;
    }

    public String getNumber() {
        return number;
    }

    public void setNumber(String number) {
        this.number = number == null ? null : number.trim();
    }

    public Date getCreatetime() {
        return createtime;
    }

    public void setCreatetime(Date createtime) {
        this.createtime = createtime;
    }

    public String getNote() {
        return note;
    }

    public void setNote(String note) {
        this.note = note == null ? null : note.trim();
    }

    @Override
    public String toString() {
        return "Orders [id=" + id + ", userId=" + userId + ", number=" + number
                + ", createtime=" + createtime + ", note=" + note + "]";
    }

    
    
}

DA0---UserMapper

package com.it.ms.mapper;

import com.it.ms.pojo.User;

public interface UserMapper {

    //根据ID查用户
    public User findById(Integer id);
}

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.it.ms.mapper.UserMapper">
    <select id="findById" parameterType="Integer" resultType="com.it.ms.pojo.User">
        select * from user where id = #{id};
    </select>
</mapper>

DAO---OrderMapper.java

package com.it.ms.mapper;

public interface OrderMapper {

}

OrderMapper.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.it.ms.mapper.OrderMapper">
    
</mapper>

 

记载文件db.properties

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/matbatis?characterEncoding=utf-8
jdbc.username=root
jdbc.password=0821

Spring配置文件 applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:context="http://www.springframework.org/schema/context" 
    xmlns:p="http://www.springframework.org/schema/p"
    xmlns:aop="http://www.springframework.org/schema/aop" 
    xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans 
    http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
    http://www.springframework.org/schema/context 
    http://www.springframework.org/schema/context/spring-context-4.0.xsd
    http://www.springframework.org/schema/aop 
    http://www.springframework.org/schema/aop/spring-aop-4.0.xsd 
    http://www.springframework.org/schema/tx 
    http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
    http://www.springframework.org/schema/util 
    http://www.springframework.org/schema/util/spring-util-4.0.xsd">
    
    <!-- 加载配置文件 -->
    <context:property-placeholder location="classpath:db.properties"/>
    
    
    <!-- 数据库连接池 -->
    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
        <property name="driverClassName" value="${jdbc.driver}"/>
        <property name="url" value="${jdbc.url}"/>
        <property name="username" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>
        <property name="maxActive" value="10"/>
        <property name="maxIdle" value="5"/>
    </bean>
    <!-- 配置sqlSessionFactory -->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <!-- 配置mybatis核心文件 -->
        <property name="configLocation" value="classpath:sqlMapConfig.xml"/>
        <!-- 配置数据源 -->
        <property name="dataSource" ref="dataSource"/>
    </bean>
    <!-- 配置MapperScannerConfigurer  -->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer"> 
        <property name="basePackage" value="com.it.ms.mapper"></property>
    </bean>
</beans>

mybatis配置文件  sqlMapConfig.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>
    <mappers>
        <mapper resource="com/it/ms/mapper/UserMapper.xml"/>
        <mapper resource="com/it/ms/mapper/OrderMapper.xml"/>
    </mappers>
</configuration>

注意：因为在spring配置文件中使用的是扫描包的方式来寻找mapper映射文件，所以在mybatis中需要配置两个映射文件，即使在这里没有用到OrderMapper。当然，在spring配置文件中扫描基本包了。在这里的mapper配置是可以一起去掉的，但是不能只写一个，会报错。

 

Test

package com.it.ms.test;

import org.junit.Before;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.it.ms.mapper.UserMapper;
import com.it.ms.pojo.User;

public class UserMapperTest {
    
    private ApplicationContext context;
    
    @Before
    public void setUp() throws Exception{
        context = new ClassPathXmlApplicationContext("classpath:applicationContext.xml");
    }
    
    @Test
    public void testFindById(){
        //获取Mapper
        UserMapper userMapper = (UserMapper) context.getBean("userMapper");
        User user = userMapper.findById(1);
        System.out.println(user);
    }
    
}