mybatis集成dbcp2连接池（在不使用spring的情况下）

1. 通过官方文档发现 ， mybatis使用内置连接池是这样配置的

<dataSource type="POOLED">
  <property name="driver" value="${driver}"/>
  <property name="url" value="${url}"/>
  <property name="username" value="${username}"/>
  <property name="password" value="${password}"/>
</dataSource>

2. 查看 PooledDataSourceFactory 源码发现 是继承 UnpooledDataSourceFactory 类，UnpooledDataSourceFactory类是实现 DataSourceFactory接口的

public class PooledDataSourceFactory extends UnpooledDataSourceFactory {

  public PooledDataSourceFactory() {
    this.dataSource = new PooledDataSource();
  }

}

3. 所以mybatis如果需要使用外部的连接池，需要继承 UnpooledDataSourceFactory 或者实现 DataSourceFactory

public class DBCP2DataSourceFactory extends UnpooledDataSourceFactory {

    public DataSource getDataSource() {
        return new BasicDataSource();
    }

}

然后在mybatis-config.xml中type需要配置自定类的路径

<dataSource type="com.applications.memobook.db.DBCP2DataSourceFactory">
    <property name="driver" value="${driverClassName}" />
    <property name="url" value="${url}" />
    <property name="username" value="${username}" />
    <property name="password" value="${password}" />
</dataSource>