当前位置： 首页>编程语言>正文

mybatis Spring整合mybatis

编程语言2024-08-22 10:44:23
Spring整合mybatis简单代码(小白日记)

一、在使用mybatis之前我们需要做一些准备

1.我们需要编写一个实体类User，属性与数据库中该实体的属性一致

package com.jane.pojo;

import lombok.Data;

@Data
public class User {
    private int id;
    private String name;
    private String pwd;

    public User() {
    }

    public User(int id, String name, String pwd) {
        this.id = id;
        this.name = name;
        this.pwd = pwd;
    }

    public int getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

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

    public String getPwd() {
        return pwd;
    }

    public void setPwd(String pwd) {
        this.pwd = pwd;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", pwd='" + pwd + '\'' +
                '}';
    }
}


2.编写核心配置文件mybatisconfig.xml，主要连接数据和注册mapper文件

<?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.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis?serverTimezone=UTC"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="mapper/UserMapper.xml"/>
    </mappers>
</configuration>


3.编写接口UserMapper

package com.jane.mappers;

import com.jane.pojo.User;

import java.util.List;

public interface UserMapper {
    public List<User> selectUser();
}


4.编写UserMapper.xml，映射sql语句

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.jane.mappers.UserMapper">

    <select id="selectUser" resultType="com.jane.pojo.User">
        select * from renlei
    </select>
</mapper>


5.编写一个工具类,用来获取一个具有mybatisconfig.xml文件标准SqlSessionFactory对象

package com.jane.utils;

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 java.io.IOException;
import java.io.InputStream;


public class MybatisUtils {
    private static SqlSessionFactory factory=null;

    static{
        try{
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            factory = new SqlSessionFactoryBuilder().build(inputStream);
        }catch(IOException e){
            e.printStackTrace();
        }

    }

    public SqlSession getSqlSession(){
        return factory.openSession();
    }

}


6.编写一个测试类，测试

package com.jane.dao;

import com.jane.entity.User;
import com.jane.utils.MybatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.List;

public class UserDaoTest {
    @Test
    public void test(){
        //获取sqlSession，具体怎么获取，这个方法你已经封装在了MybatisUtils这个类里面，
        SqlSession sqlSession=new MybatisUtils().getSqlSession();
        //userDao类的实例化对象，通过Userdao获取这一系列的mapper映射
        //sqlSession.getMapper(UserDao.class)这里就是通过mybatis中的sqlSession的getMapper()方法，帮助你实例这个对象
        UserDao userDao=sqlSession.getMapper(UserDao.class);
        //建立一个userList向量，这个向量可以理解为无限扩容的一个数组，只不过里面存的是User对象，这个user对象是
        // 通过userDao的getlist()方法获取的，这个方法是映射着你写的UserMapper.xml文件里面写的sql查询方法。
        //给你返回了查询结果（），它是你在里面写的User类型（你也可以通过修改UserMapper.xml文件,让它返回其它类型）。
        List<User> userList = userDao.getList();
        //这里就是遍历这个userList，一个个打印里面的user
        for(User user : userList){
            System.out.println(user);
        }
        sqlSession.close();
    }
}


7.pom配置文件

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.huang</groupId>
    <artifactId>untitled</artifactId>
    <packaging>pom</packaging>
    <version>1.0-SNAPSHOT</version>
    <modules>
        <module>untitled-01</module>
    </modules>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>


    <dependencies>
        <!--mysql-->
        <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.21</version>
        </dependency>

        <!--mybatis-->
        <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.6</version>
        </dependency>

        <!--junit-->
        <!-- https://mvnrepository.com/artifact/junit/junit -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>

    </dependencies>

    <build>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>
        </resources>
    </build>

</project>


执行结果

mybatis Spring整合mybatis,mybatis Spring整合mybatis_sql,第1张

二、和Spring一起使用mybatis,需要在Spring应用上下文中定义至少两样东西：一个是SqlSessionFactory和至少一个数据映射器类

先来看看有哪些东西

1.实体类不会发生变化

package com.jane.pojo;

import lombok.Data;

@Data
public class User {
    private int id;
    private String name;
    private String pwd;

    public User() {
    }

    public User(int id, String name, String pwd) {
        this.id = id;
        this.name = name;
        this.pwd = pwd;
    }

    public int getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

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

    public String getPwd() {
        return pwd;
    }

    public void setPwd(String pwd) {
        this.pwd = pwd;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", pwd='" + pwd + '\'' +
                '}';
    }
}


2.接口类也不用发生变化

package com.jane.mappers;

import com.jane.pojo.User;

import java.util.List;

public interface UserMapper {
    public List<User> selectUser();
}


3.增加一个UserMapper接口的实现类去实现接口中的方法以及获取SqlSessionTemplate对象

使用Spring托管的话就需要使用SqlSessionTemplate类的对象来执行操作

package com.jane.mappers;

import com.jane.pojo.User;
import org.mybatis.spring.SqlSessionTemplate;

import java.util.List;

public class UserMapperImpl implements UserMapper{
    //我们的所有操作都使用SqlSessionTemplate来执行
    private SqlSessionTemplate sqlSession;

    public void setSqlSession(SqlSessionTemplate sqlSession){
        this.sqlSession=sqlSession;
    }
    @Override
    public List<User> selectUser() {
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        return mapper.selectUser();
    }
}


4.UserMapper的映射文件UserMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.jane.mappers.UserMapper">

    <select id="selectUser" resultType="com.jane.pojo.User">
        select * from renlei
    </select>
</mapper>


5.mybatisconfig.xml配置文件的编写：当事物交给Spring来处理的时候我们就不需要再里边设置环境和注册Mapper.xml文件了

<?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>

</configuration>


6.Spring-dao.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:aop="http://www.springframework.org/schema/aop"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop.xsd">

    <!--注册bean-->
    <!--DataSource:使用Spring的数据源替换Mybatis的配置 c3p0 dbcp druid-->
    <bean id="datasource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost:3306/mybatis"/>
        <property name="username" value="root"/>
        <property name="password" value="123456"/>
    </bean>

    <!--SqlSessionFactory-->
    <bean id="SqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="datasource"/>
        <!--绑定mybatis配置文件-->
        <property name="mapperLocations" value="classpath:mapper/*.xml"/>
        <property name="configLocation" value="classpath:mybatisconfig.xml"/>
    </bean>

    <!--SqlSessionTemplate就是我们使用的SqlSession-->
    <bean id="sqlSession" class="org.mybatis.spring.SqlSessionTemplate">
        <!--只能是用构造器注入,因为SqlSessionTemplate没有set方法-->
        <constructor-arg index="0" ref="SqlSessionFactory"/>
    </bean>

    <bean id="userMapper" class="com.jane.mappers.UserMapperImpl">
        <property name="sqlSession" ref="sqlSession"/>
    </bean>


</beans>


7.看一下pom.xml文件中需要导入哪些包

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.jane</groupId>
    <artifactId>springmaven</artifactId>
    <packaging>pom</packaging>
    <version>1.0-SNAPSHOT</version>
    <modules>

        <module>mybatisSpring</module>

    </modules>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>

    <dependencies>

        <!-- https://mvnrepository.com/artifact/org.springframework/spring-webmvc -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.3.8</version>
        </dependency>


        <!--AOP植入包-->
        <!-- https://mvnrepository.com/artifact/org.aspectj/aspectjweaver -->
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.9.7</version>
            <scope>runtime</scope>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.6</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.25</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/junit/junit -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13.1</version>
            <scope>test</scope>
        </dependency>

<!--Spring操作数据库的话，需要一个spring-jdbc-->
        <!-- https://mvnrepository.com/artifact/org.springframework/spring-jdbc -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>5.3.8</version>
        </dependency>

        <!--mybatis-Spring整合包-->
        <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis-spring -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>2.0.6</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.20</version>
            <scope>provided</scope>
        </dependency>



    </dependencies>
    <build>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.xml</include>
                </includes>
            </resource>
        </resources>
    </build>

</project>


Note：Error creating bean with name 'SqlSessionFactory' defined in class path resource [Spring-dao.xml]: Initialization of bean failed; nested exception is org.springframework.beans.ConversionNotSupportedException: Failed to convert property value of type 'java.lang.String' to required type 'javax.sql.DataSource' for property 'dataSource'; nested exception is java.lang.IllegalStateException: Cannot convert value of type 'java.lang.String' to required type 'javax.sql.DataSource' for property 'dataSource': no matching editors or conversion strategy found

翻译：在类路径资源 [Spring-dao.xml] 中定义名称为“SqlSessionFactory”的 bean 创建时出错：bean 初始化失败；嵌套异常是 org.springframework.beans.ConversionNotSupportedException：无法将“java.lang.String”类型的属性值转换为属性“dataSource”所需的类型“javax.sql.DataSource”；嵌套异常是 java.lang.IllegalStateException：无法将“java.lang.String”类型的值转换为属性“dataSource”所需的类型“javax.sql.DataSource”：找不到匹配的编辑器或转换策略

看到这个问题会觉得很高大上，第一时间就是到处搜答案，但是搜不到，其实就是在注册bean的时候没有注意到注入值的类型，我背的很熟：基本类型是value，引用类型是ref,但是敲代码的时候就忘了

mybatis Spring整合mybatis,mybatis Spring整合mybatis_java_02,第2张

执行结果

mybatis Spring整合mybatis,mybatis Spring整合mybatis_spring_03,第3张


https://www.xamrdz.com/lan/5h31967496.html

相关文章：