Spring和mybatis整合笔记

念故思旧

已于 2022-04-23 21:42:38 修改

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分类专栏： SSM框架文章标签： java 后端

于 2022-04-23 21:41:05 首次发布

本文链接：https://blog.youkuaiyun.com/weixin_56612338/article/details/124370725

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1 篇文章

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Spring-mybatis整合

注:本次笔记是在b站上观看的动力节点王妈妈的视频后自己总结的笔记,如果哪里有错误,还请各位大佬指出,谢谢,互相学习呀

1.目录结构

在这里插入图片描述

2.pom文件

这里是pom文件中的所需依赖和插件

<properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>

    <dependencies>
        <!--单元测试-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
            <scope>test</scope>
        </dependency>
        <!--spring核心ioc-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.2.5.RELEASE</version>
        </dependency>
        <!--做spring事务用到的-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-tx</artifactId>
            <version>5.2.5.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>5.2.5.RELEASE</version>
        </dependency>
        <!--mybatis依赖-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.1</version>
        </dependency>
        <!--mybatis和spring集成的依赖-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>1.3.1</version>
        </dependency>
        <!--mysql驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.9</version>
        </dependency>
        <!--阿里公司的数据库连接池-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.12</version>
        </dependency>
    </dependencies>

    <build>
        <!--目的是把src/main/java目录中的xml文件包含到输出结果中。输出到classes目录中-->
        <resources>
            <resource>
                <directory>src/main/java</directory><!--所在的目录-->
                <includes><!--包括目录下的.properties,.xml 文件都会扫描到-->
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
        </resources>

        <!--指定jdk的版本-->
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.10.1</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>

3.编写dao

定义接口,实现插入数据库数据和查询数据库两个方法

package com.bjpowernode.dao;

import com.bjpowernode.domain.Student;

import java.util.List;

public interface StudentDao {
    //插入数据的方法(这里我们插入的是一个学生对象)
    int insertStudent(Student student);
    //查询数据库里面的学生信息
    List<Student> selectStudents();
}

4.编写 Dao 接口 Mapper 映射文件 StudentDao.xml

Mybatis框架抛开了Dao的实现类,直接映射到xml文件中的SQL语句,直接对数据库进行操作,这种对Dao的实现方式称为Mapper的动态代理方式

<?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.bjpowernode.dao.StudentDao">
    <insert id="insertStudent">
		insert into student values(#{id},#{name},#{email},#{age})
	</insert>
	<select id="selectStudents" resultType="com.bjpowernode.domain.Student">
		select id,name,email,age from student order by id desc
	</select>
</mapper>

5.编写domain中的实体类Student

这个Student实体类其实就是一个JavaBean,这里建议编写实体类里面的属性名时最好和数据库中字段名保持一致

package com.bjpowernode.domain;

public class Student {

    //属性名和列名一样
    private Integer id;
    private String name;
    private String email;
    private Integer age;

    public Student() {
    }

    public Student(Integer id, String name, String email, Integer age) {
        this.id = id;
        this.name = name;
        this.email = email;
        this.age = age;
    }

    public Integer getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "Student{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", email='" + email + '\'' +
                ", age=" + age +
                '}';
    }

}

6.定义Service层和接口StudentService

service层是做具体的业务的

package com.bjpowernode.service;

import com.bjpowernode.domain.Student;

import java.util.List;

public interface StudentService {

    int addStudent(Student student);
    List<Student> queryStudents();
}

7.定义接口的实现类StudentServiceImpl

因为我们把对象都交给spring了,所以这里引入的studentDao对象要有set方法,使用set注入,交给Spring的ioc容器管理

package com.bjpowernode.service.impl;

import com.bjpowernode.dao.StudentDao;
import com.bjpowernode.domain.Student;
import com.bjpowernode.service.StudentService;

import java.util.List;

public class StudentServiceImpl implements StudentService {

    //引用类型
    private StudentDao studentDao;

    //使用set注入,赋值
    public void setStudentDao(StudentDao studentDao) {
        this.studentDao = studentDao;
    }

    @Override
    public int addStudent(Student student) {
        int nums = studentDao.insertStudent(student);
        return nums;
    }

    @Override
    public List<Student> queryStudents() {

        List<Student> students = studentDao.selectStudents();
        return students;
    }
}

8.Mybatis.xml主配置文件

之前我们在写Mybatis.xml配置文件时,需要写dataSource(数据源),在这里不需要了,因为交给spring管理了,数据源写在applicationContext.xml(spring的主配置文件)里面就可以了

<?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>
    <!--控制日志的输出-->
    <settings>
        <setting name="logImpl" value="STDOUT_LOGGING"/>
    </settings>

    <!--设置别名-->
    <typeAliases>
        <!--name:实体类所在的包名-->
        <package name="com.bjpowernode.domain"/>
    </typeAliases>
</configuration>

9.编写spring的主配置文件applicationContext.xml

这个文件需要指明properties的位置,DataSource数据源,创建sqlSessionFactory和MapperScannerConfigurer对象

说明:

1.properties:文件里面是关于连接数据库的信息,如url,username,password等,可以在spring主配置文件中利用${}来获取数据库连接信息,更加灵活

2.DataSource数据源:声明数据源,这里使用阿里巴巴的druid,这个数据库连接池可以不需要数据库连接的驱动,提供强大的监控和扩展功能

3.sqlSessionFactory:这里获取sqlSessionFactory是因为要利用它里面的openSession方法获取sqlSession

4.MapperScannerConfigurer:使用SqlSession的getMapper(StudentDao.class) ,在内部调用getMapper()生成每个dao接口的代理对象.

<?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:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd">

    <!--
        把数据库的配置信息,写在一个独立的文件,便于修改数据库的配置内容
        spring知道jdbc.properties文件的位置
    -->
    <context:property-placeholder location="classpath:jdbc.properties"/>
    
    <!--声明数据源DataSource 作用是连接数据库的-->
    <bean id="MyDataSource" class="com.alibaba.druid.pool.DruidDataSource"
          init-method="init" destroy-method="close">
        <!--set注入给DruidDataSource提供连接数据库信息-->
        <!--
            使用属性配置文件中的数据,语法${key}
        -->
        <property name="url" value="${jdbc.url}"/>
        <property name="username" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>
        <property name="maxActive" value="${jdbc.maxActive}"/>
    </bean>
    
    <!--声明的是mybatis中提供的SqlSessionFactoryBean类,这个类内部创建SqlSessionFactory-->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <!--set注入,把数据库连接池付给了dataSource属性-->
        <property name="dataSource" ref="MyDataSource"/>
        <!--mybatis主配置文件的位置
            configLocation属性是Resource类型,读取配置文件
            它的赋值,使用value,指定文件的路径,使用classpath:表示文件的位置
        -->
        <property name="configLocation" value="classpath:mybatis.xml"/>
    </bean>

    <!--创建dao对象,使用SqlSession的getMapper(StudentDao.class)
        MapperScannerConfigurer:在内部调用getMapper()生成每个dao接口的代理对象.
    -->
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <!--指定SqlSessionFactory对象的id-->
        <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/>
        <!--指定包名,包名是dao接口所在的包名
            MapperScannerConfigurer会扫描到这个包中所有的接口,把每个接口都执行
            一次getMapper()方法,得到每个接口的dao对象
            创建好的dao对象放入到spring的容器中的.dao对象的默认名称是 接口名首字母小写
        -->
        <property name="basePackage" value="com.bjpowernode.dao"/>
    </bean>

    <!--声明service-->
    <bean id="studentService" class="com.bjpowernode.service.impl.StudentServiceImpl">
        <property name="studentDao" ref="studentDao"/>
    </bean>
</beans>

10.编写jdbc.properties

这样写的原因是解耦合,更加灵活,便于以后的维护

jdbc.url=jdbc:mysql://localhost:3306/数据库名称
jdbc.username=root
jdbc.password=密码
jdbc.maxActive=最大连接数

11.编写测试文件

package com.bjpowernode;

import com.bjpowernode.dao.StudentDao;
import com.bjpowernode.domain.Student;
import com.bjpowernode.service.StudentService;
import org.junit.Test;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import java.util.List;

public class MyTest {
	
    //获取ioc容器里面所有的对象
    @Test
    public void test01(){
        String config = "applicationContext.xml";
        ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext(config);
        String[] names = ctx.getBeanDefinitionNames();
        for (String na:names){
            System.out.println("容器中对象名称:"+na+"|"+ctx.getBean(na));
        }
    }
    //利用dao插入数据
    @Test
    public void testDaoInsert(){
        String config = "applicationContext.xml";
        ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext(config);
        //获取spring容器中的dao对象
        StudentDao dao = (StudentDao) ctx.getBean("studentDao");
        Student student = new Student();
        student.setId(1013);
        student.setName("周峰");
        student.setEmail("zhoufeng@qq.com");
        student.setAge(20);
        int nums = dao.insertStudent(student);
        System.out.println("nums="+nums);

    }
	
    //利用service插入数据
    @Test
    public void testServiceInsert(){
        String config = "applicationContext.xml";
        ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext(config);
        //获取spring容器中的dao对象
        StudentService service = (StudentService) ctx.getBean("studentService");
        Student student = new Student();
        student.setId(1014);
        student.setName("小明");
        student.setEmail("xiaoming@qq.com");
        student.setAge(20);
        int nums = service.addStudent(student);
        System.out.println("nums="+nums);
    }
	
    //利用service查询数据
    @Test
    public void testServiceSelect(){
        String config = "applicationContext.xml";
        ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext(config);
        //获取spring容器中的dao对象
        StudentService service = (StudentService) ctx.getBean("studentService");
        List<Student> students = service.queryStudents();
        for (Student stu:students){
            System.out.println("stu=="+stu);
        }

    }
}

在这里插入图片描述