Mybatis使用c3p0

Mybatis支持第三方连接池
在Mybatis官方有提到第三方连接池的实现:

你可以通过实现接口 org.apache.ibatis.datasource.DataSourceFactory 来使用第三方数据源实现：

public interface DataSourceFactory { void setProperties(Properties
props); DataSource getDataSource(); }
org.apache.ibatis.datasource.unpooled.UnpooledDataSourceFactory
可被用作父类来构建新的数据源适配器，比如下面这段插入 C3P0 数据源所必需的代码：

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

public class C3P0DataSourceFactory extends UnpooledDataSourceFactory {

public C3P0DataSourceFactory() {
this.dataSource = new ComboPooledDataSource(); } }

也可以查看官网: Mybatis官网
可以看输出需要实现

org.apache.ibatis.datasource.DataSourceFactory

这个接口 或者继承 这个类

org.apache.ibatis.datasource.unpooled.UnpooledDataSourceFactory

查看源码可以看出UnpooledDataSourceFactory已经实现了DataSourceFactory接口,我们只需要继承UnpooledDataSourceFactory并在构造器中添加c3p0的连接对象即可

• 1 使用maven导包

        <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.23</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/com.mchange/c3p0 -->
        <dependency>
            <groupId>com.mchange</groupId>
            <artifactId>c3p0</artifactId>
            <version>0.9.5.2</version>
        </dependency>
<!--        Mybaatis-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.5</version>
        </dependency>

• 2 写入Mybatis-config.xml配置信息
  这里注意c3p0和mybatis使用的数据源名称不一致 Mybatis配置信息时需要使用c3p0的数据源名称

<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<!--这里可以选择引用properties文件 -->
<!--    <properties resource="jdbc.properties"></properties>-->
    <settings>
<!--        开启驼峰命名法-->
        <setting name="mapUnderscoreToCamelCase" value="true"/>
    </settings>
<environments default="development">
    <environment id="development">
        <transactionManager type="JDBC"></transactionManager>
<!--        <dataSource type="POOLED">-->
        <dataSource type="sun.cn.C3p0DataSource">
<!--            <property name="driver" value="${driver}"/>-->
            <property name="driverClass" value="com.mysql.cj.jdbc.Driver"/>
<!--            <property name="url" value="${url}"/>-->
            <property name="jdbcUrl" value="jdbc:mysql:///mybatis_test?serverTimezone=UTC"/>
<!--            <property name="username" value="${username}"/>-->
            <property name="user" value="root"/>
<!--            <property name="password" value="${password}"/>-->
            <property name="password" value="123456"/>
        </dataSource>
    </environment>

</environments>
<mappers >
<!--    <mapper class="sun.cn.CatDao"></mapper>-->
<mapper class="sun.cn.CatDao"></mapper>
</mappers>

</configuration>

• 3 编写dao和bean

package sun.cn;

public class Cat {
    Integer cid;
    String cage;
    String cname;
    public Integer getId() {
        return cid;
    }

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

    public String getAge() {
        return cage;
    }

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

    public String getName() {
        return cname;
    }

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

    @Override
    public String toString() {
        return "Cat{" +
                "id=" + cid +
                ", age='" + cage + '\'' +
                ", name='" + cname + '\'' +
                ", catkind=" +
                '}';
    }
}

dao对象简化操作就不在配置映射器直接使用注解实现

package sun.cn;

import org.apache.ibatis.annotations.Select;

import java.util.List;

public interface CatDao{
    @Select(" select * from cat")
    List<Cat> getAllByList();
}

添加数据源配置器

package sun.cn;

import com.mchange.v2.c3p0.ComboPooledDataSource;
import org.apache.ibatis.datasource.unpooled.UnpooledDataSourceFactory;;
public class C3p0DataSource extends UnpooledDataSourceFactory {
    public C3p0DataSource(){
        this.dataSource = new ComboPooledDataSource();
    }
}

测试

import java.sql.SQLException;
import java.util.List;

public class test {
    public static void main(String[] args) throws IOException, SQLException {
        SqlSessionFactory sqlSessionFactory =
                new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("Mybatis-config.xml"));
        SqlSession sqlSession = sqlSessionFactory.openSession();
        CatDao c = sqlSession.getMapper(CatDao.class);
        List<Cat> list = c.getAllByList();
        System.out.println(list);

    }
}

数据库信息

create table `cat` (
	`cid` int (11),
	`cage` varchar (150),
	`cname` varchar (150),
	`kid` int (11)
); 
insert into `cat` (`cid`, `cage`, `cname`, `kid`) values('1','11','hello','1');
insert into `cat` (`cid`, `cage`, `cname`, `kid`) values('2','10','杰瑞','2');
insert into `cat` (`cid`, `cage`, `cname`, `kid`) values('3','10','tom','1');
insert into `cat` (`cid`, `cage`, `cname`, `kid`) values('4','10','tomm','1');