c3p0连接池快速入门

为什么要使用连接池，这些基本也不用说那么多

以下为快速入门案例

包目录结构

配置文件c3p0-config.xml

<c3p0-config>
    <!-- 默认配置，如果没有指定自己的，则使用这个配置 -->
    <default-config>
        <property name="checkoutTimeout">30000</property>
        <property name="idleConnectionTestPeriod">30</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>
        <user-overrides user="test-user">
            <property name="maxPoolSize">10</property>
            <property name="minPoolSize">1</property>
            <property name="maxStatements">0</property>
        </user-overrides>
    </default-config>
    <!-- 命名的配置 -->
    <named-config name="mytest">
        <property name="driverClass">com.mysql.jdbc.Driver</property>
        <property name="jdbcUrl">jdbc:mysql://localhost:3306/kafka2hive?useUnicode=true&amp;characterEncoding=UTF-8</property>
        <property name="user">root</property>
        <property name="password">123456</property>
    <!-- 如果池中数据连接不够时一次增长多少个 -->
        <property name="acquireIncrement">5</property>
        <property name="initialPoolSize">20</property>
        <property name="minPoolSize">10</property>
        <property name="maxPoolSize">40</property>
        <property name="maxStatements">0</property>
        <property name="maxStatementsPerConnection">5</property>
    </named-config>
</c3p0-config> 

JdbcC3p0Util

public class JdbcC3p0Util {
    private static ComboPooledDataSource dataSource;
    static{
        try {
            dataSource = new ComboPooledDataSource();
            dataSource.setDriverClass("com.mysql.jdbc.Driver");
            dataSource.setJdbcUrl("jdbc:mysql://localhost:3306/kafka2hive");
            dataSource.setUser("root");
            dataSource.setPassword("123456");
            // * 最大连接数
            dataSource.setMaxPoolSize(50);
            // * 最小连接数
            dataSource.setMinPoolSize(10);
            // * 每次增长的个数
            dataSource.setAcquireIncrement(5);
        } catch (PropertyVetoException e) {
            e.printStackTrace();
        }
    }
    public static Connection getConnection() throws SQLException{
        return dataSource.getConnection();
    }

    public static void main(String[] args) throws Exception {
        System.out.println(getConnection());
    }

}

JdbcC3p0Util2

public class JdbcC3p0Util2 {
    private static ComboPooledDataSource dataSource;
    static{
        dataSource = new ComboPooledDataSource("mytest");  //c3p0-config.xml <named-config name="mytest"> 配置名称
    }
    public static Connection getConnection() throws SQLException{
        return dataSource.getConnection();
    }
    public static void main(String[] args) throws Exception {
        System.out.println(getConnection());
    }

}

根据自己业务场景使用，推荐使用第二种!!