Java使用C3P0数据源链接数据库

时间:2021-04-03 人气:0

1、相关jar包，这里需要3个jar包

2、具体链接数据库代码

ComboPooledDataSource类继承自AbstractComboPooledDataSource类，且AbstractComboPooledDataSource类实现了PooledDataSource接口

ComboPooledDataSource常用方法

（1）、通过ComboPooledDataSource类直接创建数据源对象

Example4.java

import com.mchange.v2.c3p0.ComboPooledDataSource;
import javax.sql.DataSource;
import java.sql.SQLException;
public class Example4{
  public static DataSource dataSource = null;
  //初始化C3P0数据源
  static {
    ComboPooledDataSource comboPooledDataSource = new ComboPooledDataSource();
    try{
      comboPooledDataSource.setDriverClass("com.mysql.jdbc.Driver");
      comboPooledDataSource.setJdbcUrl("jdbc:mysql://127.0.0.1:3306/chapter02");
      comboPooledDataSource.setUser("root");
      comboPooledDataSource.setPassword("1234");
      //初始化
      comboPooledDataSource.setInitialPoolSize(5);
      //设置最大的链接数
      comboPooledDataSource.setMaxPoolSize(15);
      dataSource = comboPooledDataSource;
    }catch (Exception e){
    }
  }
  public static void main(String[] args)throws SQLException {
    System.out.println(dataSource.getConnection());
  }
}

（2）、通过配置文件创建数据源对象

在项目的src目录下创建一个出c3p0-donfig.xml文件

c3p0-donfig.xml内容如下

<?xml version="1.0" encoding="utf-8" ?>
<c3p0-config>
  <default-config>
    <property name="user">root</property>
    <property name="password">1234</property>
    <property name="driverClass">com.mysql.jdbc.Driver</property>
    <property name="jdbcUrl">
      jdbc:mysql://localhost:3306/chapter02
    </property>
    <property name="checkoutTimeout">30000</property>
    <property name="initialPoolSize">10</property>
    <property name="maxIdleTime">30</property>
    <property name="maxPoolSize">100</property>
    <property name="minPoolSize">10</property>
    <property name="maxStatements">200</property>
  </default-config>
  <named-config name="dongyao">
    <property name="initialPoolSize">5</property>
    <property name="maxPoolSize">15</property>
    <property name="driverClass">com.mysql.jdbc.Driver</property>
    <property name="jdbcUrl">
      jdbc:mysql://localhost:3306/chapter02
    </property>
    <property name="user">root</property>
    <property name="password">1234</property>
  </named-config>
</c3p0-config>

其中<default-config>是默认配置，<named-config name=””>是自定义配置，一个配置文件中可以有一个或者多个自定义配置，调用ComboPoolDataSource(String configName)方法传入<named-config>节点中name属性的值即可创建C3P0数据源对象。

在项目的src目录下创建一个Example5的类

Example5.java

import com.mchange.v2.c3p0.ComboPooledDataSource;
 
import javax.sql.DataSource;
import java.sql.SQLException;
 
public class Example5 {
  public static DataSource dataSource = null;
  static {
    ComboPooledDataSource comboPooledDataSource = new ComboPooledDataSource("dongyao");
    dataSource = comboPooledDataSource;
  }
  public static void main(String[] args) throws SQLException {
    System.out.println(dataSource.getConnection());
  }
}

3、控制台显示

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