mybatis-config.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">
<!--配置项，所有配置放在这里面-->
<configuration>


    <settings>
<!--        如果实现类的属性名称和表的字段名称不一样就无法正确获取数据，就需要配置配置驼峰命名法-->
        <setting name="mapUnderscoreToCamelCase" value="true"/>
    </settings>

    <plugins>
        <plugin interceptor="com.github.pagehelper.PageInterceptor">
            <property name="helperDialect" value="mysql"/>
            <property name="reasonable" value="true"/>
        </plugin>
    </plugins>

    <!--环境配置标签 default代表默认使用哪个标识下的配置信息 environment可以多个-->
   <environments default="dev">
<!--       id=唯一标识-->
       <environment id="dev">
<!--           用什么方式管理数据库事务commit/rollback-->
           <transactionManager type="JDBC"></transactionManager>
<!--           数据源type表示以什么样的方式对数据源进行管理 POOLED基于连接池的形式进行管理-->
<!--           <dataSource type="POOLED">-->
           <dataSource type="com.imooc.mybatis.datasource.C3P0DatasourceFactory">
               <property name="driverClass" value="com.mysql.jdbc.Driver"/>
<!--               useUnicode=true代表使用Unicode编码解决中文乱码问题-->
               <property name="jdbcUrl" value="jdbc:mysql://localhost:3306/babytun?useUnicode=true&amp;charactEncoding=UTF-8"/>
               <property name="username" value="root"/>
               <property name="password" value="q123"/>
<!--               initialPoolSize表示连接池初始连接数量-->
               <property name="initialPoolSize" value="5"/>
<!--               最大连接池连接数量-->
               <property name="maxPoolSize" value="20"/>
<!--               最小连接池连接数量-->
               <property name="minPoolSize" value="5"/>
           </dataSource>
       </environment>
   </environments>

    <mappers>
        <mapper resource="goods.xml"/>
        <mapper resource="goodsDetail.xml"/>
    </mappers>

</configuration>

C3P0DatasourceFactory:

package com.imooc.mybatis.datasource;

import com.mchange.v2.c3p0.ComboPooledDataSource;
import org.apache.ibatis.datasource.unpooled.UnpooledDataSourceFactory;

/**
 * C3P0与Mybatis兼容使用的数据源工厂类
 */

public class C3P0DatasourceFactory extends UnpooledDataSourceFactory {
    public C3P0DatasourceFactory() {
//        ComboPooledDataSource()是由c3p0提供的符合连接池的数据源，this.dataSource由UnpooledDataSourceFactory提供
        this.dataSource=new ComboPooledDataSource();
    }
}

目录：

pom.xml

<?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.imooc</groupId>
    <artifactId>MyBatis</artifactId>
    <version>1.0-SNAPSHOT</version>
    <repositories>
        <repository>
            <id>aliyun</id>
            <name>aliyun></name>
            <url>https://maven.aliyun.com/repository/public</url>
        </repository>
    </repositories>
    <dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.1</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-classic</artifactId>
            <version>1.2.3</version>
        </dependency>
        <dependency>
            <groupId>com.github.pagehelper</groupId>
            <artifactId>pagehelper</artifactId>
            <version>5.2.0</version>
        </dependency>
        <dependency>
            <groupId>com.github.jsqlparser</groupId>
            <artifactId>jsqlparser</artifactId>
            <version>3.2</version>
        </dependency>
        <dependency>
            <groupId>com.mchange</groupId>
            <artifactId>c3p0</artifactId>
            <version>0.9.5.4</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/com.mchange/mchange-commons-java -->
        <dependency>
            <groupId>com.mchange</groupId>
            <artifactId>mchange-commons-java</artifactId>
            <version>0.2.15</version>
        </dependency>
    </dependencies>

</project>

错误信息：

java.lang.NoClassDefFoundError: Could not initialize class com.imooc.mybatis.utils.MyBatisUtils

at com.imooc.mybatis.MyBatisTestor.testSelectTgoods(MyBatisTestor.java:79)

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

at java.lang.reflect.Method.invoke(Method.java:498)

at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)

at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)

at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)

at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)

at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)

at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)

at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)

at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)

at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)

at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)

at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)

at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)

at org.junit.runners.ParentRunner.run(ParentRunner.java:363)

at org.junit.runner.JUnitCore.run(JUnitCore.java:137)

at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)

at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)

at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:230)

at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:58)