Spring整合MybatisPlus，以及遇到的一些问题

╰+攻爆jí腚メ 2023-07-13 10:43 2阅读 0赞

## 一、前言 ##

1.本次只是简单的整合了 Spring和MybatisPlus，并做了最简单的测试  
2.想要整合Spring和MybatisPlus，首先要熟悉Spring框架  
3.使用maven项目构建工具

## 二、步骤 ##

1.创建工程就省略了，简单展示一下目录结构。。。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQ0NzE5NTI3_size_16_color_FFFFFF_t_70]  
2.首先在pom文件添加依赖

<dependencies>
    		 <dependency> <groupId>com.baomidou</groupId> <artifactId>mybatis-plus</artifactId> <version>2.3</version> </dependency>  <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.9</version> </dependency>  <dependency> <groupId>log4j</groupId> <artifactId>log4j</artifactId> <version>1.2.17</version> </dependency> 
            <dependency>
                <groupId>com.mchange</groupId>
                <artifactId>c3p0</artifactId>
                <version>0.9.5.2</version>
            </dependency>
    		 <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.6</version> </dependency>  <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>4.2.4.RELEASE</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-orm</artifactId> <version>4.2.4.RELEASE</version> </dependency>
    	</dependencies>

3.学过mybatis的都应该知道，mybatis有一个全局配置文件，但是与Spring整合后里面不需要添加内容，但是我们一般都要保留。在resource目录下建一个`mybatis-config.xml`这个xml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>
    </configuration>

4.resource目录下建一个Spring的核心文件`applicationContext.xml`这个xml文件。

<?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xmlns:context="http://www.springframework.org/schema/context"
           xmlns:aop="http://www.springframework.org/schema/aop" xmlns:mvc="http://www.springframework.org/schema/mvc"
           xmlns:tx="http://www.springframework.org/schema/tx" xmlns:util="http://www.springframework.org/schema/util"
           xmlns="http://www.springframework.org/schema/beans" xmlns:dubbo="http://code.alibabatech.com/schema/dubbo"
           xmlns:mybatis-spring="http://mybatis.org/schema/mybatis-spring"
           xsi:schemaLocation="http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.2.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.2.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.2.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.2.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-4.2.xsd http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.2.xsd http://code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd http://mybatis.org/schema/mybatis-spring http://mybatis.org/schema/mybatis-spring-1.2.xsd">
         <context:property-placeholder location="classpath:db.properties" />  <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"> <property name="driverClass" value="${jdbc.driver}"></property> <property name="jdbcUrl" value="${jdbc.url}"></property> <property name="user" value="${jdbc.username}"></property> <property name="password" value="${jdbc.password}"></property> </bean>  <bean id="dataSourceTransactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager"> <property name="dataSource" ref="dataSource"></property> </bean>  <tx:annotation-driven transaction-manager="dataSourceTransactionManager"/>    <bean id="sqlSessionFactory" class="com.baomidou.mybatisplus.spring.MybatisSqlSessionFactoryBean"> <property name="dataSource" ref="dataSource"></property>  <property name="configLocation" value="classpath:mybatis-config.xml"></property> </bean>

5.resource目录下建一个`db.proerties`这个properties文件

jdbc.driver=com.mysql.jdbc.Driver
    jdbc.url=jdbc:mysql://localhost:3306/db_mybatis_plus?characterEncoding=utf-8
    jdbc.username=root
    jdbc.password=自己数据的密码

6.为了我们测试方便，添加一个日志文件。resource目录下建一个`log4j.xml`这个xml文件

<?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">
    		<param name="Encoding" value="UTF-8" />
    		<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="info" />
    	</logger>
    	<root>
    		<level value="debug" />
    		<appender-ref ref="STDOUT" />
    	</root>
    </log4j:configuration>

7.既然要测试，我们就要准备数据库表和实体类  
（1）数据库表，使用的是mysql数据库，创建一个新的数据库和表，并添加了几条数据。

CREATE DATABASE db_mybatis_plus;
    USE db_mybatis_plus;
    CREATE TABLE tbl_employee(
    id INT(11) PRIMARY KEY AUTO_INCREMENT,
    last_name VARCHAR(50), email VARCHAR(50),
    gender INT(1), age INT
    );
    INSERT INTO tbl_employee(last_name,email,gender,age) VALUES('Tom','tom@123.com',1,22); 
    INSERT INTO tbl_employee(last_name,email,gender,age) VALUES('Jerry','jerry@123.com',0,25); 
    INSERT INTO tbl_employee(last_name,email,gender,age) VALUES('rose','rose@123.com',1,30); 
    INSERT INTO tbl_employee(last_name,email,gender,age) VALUES('jack','jack@123.com',0,35);

（2）Java实体类，对应数据库表字段。

private Integer id;
    
    	private String lastName;
    
    	private String email;
    	
    	private Integer gender;
    
    	private Integer age;
    	//无参构造
    	//有参构造
    	//getter和setter方法
    	//toString 方法
    	//太占地了，我就省略l，但是你不要省略，特别的setter和getter方法。

（3）创建个mapper接口，继承MybatisPlus提提供的BaseMapper接口，泛型是实体类对象  
EmployeeMapper

public interface EmployeeMapper extends BaseMapper<Employee>{ 
    
    }

不放心，来张图  
![在这里插入图片描述][20200311163522399.png]

## 三、测试 ##

1.首先测试一下连接数据库成功没有

//获取Spring容器
    private ApplicationContext ioc = new ClassPathXmlApplicationContext("applicationContext.xml");
    	private EmployeeMapper employeeMapper = ioc.getBean("employeeMapper",EmployeeMapper.class);

写个测试方法

@Test
    	public void testMp() throws SQLException { 
    		DataSource dataSource = ioc.getBean("dataSource",DataSource.class);
    		System.out.println(dataSource);
    		Connection connection = dataSource.getConnection();
    		System.out.println(connection);
    		connection.close();
    
    	}

来张图，没有报错，八成就是配置没有问题  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQ0NzE5NTI3_size_16_color_FFFFFF_t_70 1]  
日志效果  
![在这里插入图片描述][20200311164204131.png]  
2.测试个insert插入方法的使用把，当然这么直接测试八成会报错  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQ0NzE5NTI3_size_16_color_FFFFFF_t_70 2]  
3.报错信息

org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.reflection.ReflectionException: Could not set property 'id' of 'class com.atguigu.mp.beans.Employee' with value '1237661424084324353' Cause: java.lang.IllegalArgumentException: argument type mismatch

4.解决办法，在实体类的id属性上加注解，声明主键是自增长策略

@TableId(type = IdType.AUTO)

![在这里插入图片描述][20200311164724709.png]  
5.再次运行还会抛出一个异常

com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Table 'mp.employee' doesn't exist

解决办法，在实体类类名哪加注解，声明实体类对应数据库表（因为实体类名和表名不一致，如果一直不会抛出这个异常）

@TableName(value = "tbl_employee")

这两个异常，当然还有更简单的解决方法，这里就先不提了  
![在这里插入图片描述][20200311164910543.png]  
6.在运行，这次会成功，返回结果为1，并且打印出SQL语句  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQ0NzE5NTI3_size_16_color_FFFFFF_t_70 3]大功告成

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[20200311163522399.png]: https://img-blog.csdnimg.cn/20200311163522399.png
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[20200311164204131.png]: https://img-blog.csdnimg.cn/20200311164204131.png
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[20200311164724709.png]: https://img-blog.csdnimg.cn/20200311164724709.png
[20200311164910543.png]: https://img-blog.csdnimg.cn/20200311164910543.png
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