dbcp 系列

从零开始手写 mybatis (三)jdbc pool 如何从零手写实现数据库连接池 dbcp?

万字长文深入浅出数据库连接池 HikariCP/Commons DBCP/Tomcat/c3p0/druid 对比

Database Connection Pool 数据库连接池概览

c3p0 数据池入门使用教程

alibaba druid 入门介绍

数据库连接池 HikariCP 性能为什么这么快?

Apache Tomcat DBCP(Database Connection Pool) 数据库连接池-01-入门介绍

vibur-dbcp 并发、快速且功能完备的 JDBC 连接池,提供先进的性能监控功能-01-入门介绍

c3p0 是什么?

c3p0是一个易于使用的库,通过使用jdbc3规范和jdbc2的可选扩展定义的功能来扩展传统JDBC驱动程序,从而使其“企业就绪”。

从0.9.5版开始,c3p0完全支持jdbc4规范。

特别是c3p0提供了一些有用的服务:

一个类,它使传统的基于DriverManager的JDBC驱动程序适应最新的javax.sql.DataSource方案,以获取数据库连接。

DataSources后面的Connection和PreparedStatement的透明池可以“包装”传统驱动程序或任意非池化DataSources。

该库尽力使细节正确:

c3p0数据源既可引用也可序列化,因此适合绑定到各种基于JNDI的命名服务。

检入池中的Connections和Statements时,会仔细清理Statement和ResultSet,以防止客户端使用仅清理其Connections的惰性但常见的资源管理策略时资源耗尽。

该库采用JDBC 2和3规范定义的方法(即使这些与库作者的首选项冲突)。

数据源以JavaBean样式编写,提供了所有必需和大多数可选属性(以及一些非标准属性)以及无参数构造函数。

实现了所有JDBC定义的内部接口(ConnectionPoolDataSource,PooledConnection,生成ConnectionEvent的Connection等)。

您可以将c3p0类与兼容的第三方实现混合使用(尽管并非所有c3p0功能都可以与ConnectionPoolDataSource的外部实现一起使用)。

c3p0希望提供的数据源实现不适合大批量“ J2EE企业应用程序”使用。请提供反馈,错误修复等!

入门例子

maven 导入

<dependency>
    <groupId>com.mchange</groupId>
    <artifactId>c3p0</artifactId>
    <version>0.9.5.5</version>
</dependency>
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.29</version>
</dependency>

入门代码

通过代码显式指定配置:

ComboPooledDataSource source = new ComboPooledDataSource();
source.setDriverClass("com.mysql.jdbc.Driver");
source.setJdbcUrl("jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=utf-8");
source.setUser("root");
source.setPassword("123456");

//获取链接
Connection connection = source.getConnection();
System.out.println(connection.getCatalog());
  • 日志输出
七月 17, 2020 4:58:21 下午 com.mchange.v2.log.MLog 
信息: MLog clients using java 1.4+ standard logging.
七月 17, 2020 4:58:22 下午 com.mchange.v2.c3p0.C3P0Registry 
信息: Initializing c3p0-0.9.5.5 [built 11-December-2019 22:18:33 -0800; debug? true; trace: 10]
七月 17, 2020 4:58:22 下午 com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource 
信息: Initializing c3p0 pool... com.mchange.v2.c3p0.ComboPooledDataSource [ acquireIncrement -> 3, acquireRetryAttempts -> 30, acquireRetryDelay -> 1000, autoCommitOnClose -> false, automaticTestTable -> null, breakAfterAcquireFailure -> false, checkoutTimeout -> 0, connectionCustomizerClassName -> null, connectionTesterClassName -> com.mchange.v2.c3p0.impl.DefaultConnectionTester, contextClassLoaderSource -> caller, dataSourceName -> 1bqqx35abpix6b312lrdzj|7bfcd12c, debugUnreturnedConnectionStackTraces -> false, description -> null, driverClass -> com.mysql.jdbc.Driver, extensions -> {}, factoryClassLocation -> null, forceIgnoreUnresolvedTransactions -> false, forceSynchronousCheckins -> false, forceUseNamedDriverClass -> false, identityToken -> 1bqqx35abpix6b312lrdzj|7bfcd12c, idleConnectionTestPeriod -> 0, initialPoolSize -> 2, jdbcUrl -> jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=utf-8, maxAdministrativeTaskTime -> 0, maxConnectionAge -> 0, maxIdleTime -> 30, maxIdleTimeExcessConnections -> 0, maxPoolSize -> 10, maxStatements -> 50, maxStatementsPerConnection -> 0, minPoolSize -> 2, numHelperThreads -> 3, preferredTestQuery -> null, privilegeSpawnedThreads -> false, properties -> {user=******, password=******}, propertyCycle -> 0, statementCacheNumDeferredCloseThreads -> 0, testConnectionOnCheckin -> false, testConnectionOnCheckout -> false, unreturnedConnectionTimeout -> 0, userOverrides -> {}, usesTraditionalReflectiveProxies -> false ]
test

通过配置文件

配置

  • c3p0-config.xml

将该配置文件,置于 resources 文件夹下。

<c3p0-config>
    <!-- 默认配置,如果没有指定则使用这个配置 -->
    <default-config>
        <property name="driverClass">com.mysql.jdbc.Driver</property>
        <property name="jdbcUrl">
            <![CDATA[jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=UTF-8]]>
        </property>
        <property name="user">root</property>
        <property name="password">123456</property>
        <!-- 初始化池大小 -->
        <property name="initialPoolSize">2</property>
        <!-- 最大空闲时间 -->
        <property name="maxIdleTime">30</property>
        <!-- 最多有多少个连接 -->
        <property name="maxPoolSize">10</property>
        <!-- 最少几个连接 -->
        <property name="minPoolSize">2</property>
        <!-- 每次最多可以执行多少个批处理语句 -->
        <property name="maxStatements">50</property>
    </default-config>
</c3p0-config>

实现

ComboPooledDataSource source = new ComboPooledDataSource();

Connection connection = source.getConnection();
System.out.println(connection.getCatalog());

日志

七月 17, 2020 5:00:41 下午 com.mchange.v2.log.MLog 
信息: MLog clients using java 1.4+ standard logging.
七月 17, 2020 5:00:41 下午 com.mchange.v2.c3p0.C3P0Registry 
信息: Initializing c3p0-0.9.5.5 [built 11-December-2019 22:18:33 -0800; debug? true; trace: 10]
七月 17, 2020 5:00:42 下午 com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource 
信息: Initializing c3p0 pool... com.mchange.v2.c3p0.ComboPooledDataSource [ acquireIncrement -> 3, acquireRetryAttempts -> 30, acquireRetryDelay -> 1000, autoCommitOnClose -> false, automaticTestTable -> null, breakAfterAcquireFailure -> false, checkoutTimeout -> 0, connectionCustomizerClassName -> null, connectionTesterClassName -> com.mchange.v2.c3p0.impl.DefaultConnectionTester, contextClassLoaderSource -> caller, dataSourceName -> 1bqqx35abpj05mbhotd60|27082746, debugUnreturnedConnectionStackTraces -> false, description -> null, driverClass -> com.mysql.jdbc.Driver, extensions -> {}, factoryClassLocation -> null, forceIgnoreUnresolvedTransactions -> false, forceSynchronousCheckins -> false, forceUseNamedDriverClass -> false, identityToken -> 1bqqx35abpj05mbhotd60|27082746, idleConnectionTestPeriod -> 0, initialPoolSize -> 2, jdbcUrl -> jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=UTF-8, maxAdministrativeTaskTime -> 0, maxConnectionAge -> 0, maxIdleTime -> 30, maxIdleTimeExcessConnections -> 0, maxPoolSize -> 10, maxStatements -> 50, maxStatementsPerConnection -> 0, minPoolSize -> 2, numHelperThreads -> 3, preferredTestQuery -> null, privilegeSpawnedThreads -> false, properties -> {user=******, password=******}, propertyCycle -> 0, statementCacheNumDeferredCloseThreads -> 0, testConnectionOnCheckin -> false, testConnectionOnCheckout -> false, unreturnedConnectionTimeout -> 0, userOverrides -> {}, usesTraditionalReflectiveProxies -> false ]
test

参考资料

c3p0-quickstart

https://github.com/swaldman/c3p0