前面介绍了 Spring 怎样集成 C3P0，下面将通过一个简单示例演示 C3P0 和 Spring Boot 集成，然后通过 JdbcTemplate 从 MySQL 5.7.* 中获取数据库时间戳。
Spring Boot 项目的依赖如下：
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.7.13</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.hxstrive.jdbc_pool</groupId>
<artifactId>c3p0_spring_boot</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>c3p0_spring_boot</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>8</java.version>
</properties>
<dependencies>
<!-- https://mvnrepository.com/artifact/c3p0/c3p0 -->
<dependency>
<groupId>c3p0</groupId>
<artifactId>c3p0</artifactId>
<version>0.9.1.2</version>
</dependency>
<!-- MySQL 驱动依赖 -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.38</version>
</dependency>
<!-- Spring Boot JDBC依赖驱动 -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<!-- Spring Boot Web 驱动依赖 -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!-- Spring Boot 开发和测试依赖 -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<scope>runtime</scope>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<excludes>
<exclude>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
</exclude>
</excludes>
</configuration>
</plugin>
</plugins>
</build>
</project>使用 @Configuration 声明一个配置类，配置 JdbcTemplate 和 DataSource（数据源），代码如下：
package com.hxstrive.pool.c3p0_spring_boot.config;
import com.mchange.v2.c3p0.ComboPooledDataSource;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.jdbc.core.JdbcTemplate;
import javax.sql.DataSource;
/**
* C3P0配置
* @author hxstrive.com
*/
@Configuration
public class C3p0Config {
/**
* 配置 JdbcTemplate
* @param dataSource 数据源
* @return
*/
@Bean
public JdbcTemplate getJdbcTemplate(DataSource dataSource) {
return new JdbcTemplate(dataSource);
}
/**
* 配置数据源
* @return 返回 com.mchange.v2.c3p0.ComboPooledDataSource 数据源
*/
@Bean
public DataSource getDataSource() throws Exception {
ComboPooledDataSource dataSource = new ComboPooledDataSource();
dataSource.setDriverClass("com.mysql.jdbc.Driver");
dataSource.setJdbcUrl("jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf8&useSSL=false");
dataSource.setUser("root");
dataSource.setPassword("aaaaaa");
// 连接初始化时创建的连接数
dataSource.setInitialPoolSize(3);
// 连接池中拥有的最大连接数，如果获得新的连接时，连接总数已满，则不会再获取新连接，而是等待其他连接释放
dataSource.setMaxPoolSize(10);
// 连接池保持的最小连接数
dataSource.setMinPoolSize(3);
// 连接池在无空闲连接可用时一次性创建的新数据库连接数
dataSource.setAcquireIncrement(3);
return dataSource;
}
}Spring Boot 项目的启动类，代码如下：
package com.hxstrive.pool.c3p0_spring_boot;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class C3p0SpringBootApplication {
public static void main(String[] args) {
SpringApplication.run(C3p0SpringBootApplication.class, args);
}
}通过 @SpringBootTest 注解声明一个测试类，通过单元测试进行测试，代码如下：
package com.hxstrive.pool.c3p0_spring_boot;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.jdbc.core.JdbcTemplate;
import java.sql.Timestamp;
@SpringBootTest
class C3p0SpringBootApplicationTests {
@Autowired
private JdbcTemplate jdbcTemplate;
@Test
void contextLoads() {
// 获取数据库当前的时间戳
Timestamp ts = jdbcTemplate.queryForObject("select CURRENT_TIMESTAMP() as ct", Timestamp.class);
System.out.println(ts);
}
}运行测试类，输出如下：
... 省略 ...
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v2.7.13)
2023-07-04 13:25:47.075 INFO 13772 --- [ main] c.h.p.c.C3p0SpringBootApplicationTests : Starting C3p0SpringBootApplicationTests using Java 1.8.0_45 on hxstrive with PID 13772 (started by Administrator in D:\~my_workspace\jdbc_pool\c3p0_spring_boot)
2023-07-04 13:25:47.079 INFO 13772 --- [ main] c.h.p.c.C3p0SpringBootApplicationTests : No active profile set, falling back to 1 default profile: "default"
2023-07-04 13:25:49.356 INFO 13772 --- [ main] com.mchange.v2.log.MLog : MLog clients using java 1.4+ standard logging.
2023-07-04 13:25:50.223 INFO 13772 --- [ main] com.mchange.v2.c3p0.C3P0Registry : Initializing c3p0-0.9.1.2 [built 21-May-2007 15:04:56; debug? true; trace: 10]
2023-07-04 13:25:53.090 INFO 13772 --- [ main] c.h.p.c.C3p0SpringBootApplicationTests : Started C3p0SpringBootApplicationTests in 6.701 seconds (JVM running for 10.351)
2023-07-04 13:25:53.983 INFO 13772 --- [ main] c.m.v.c.i.AbstractPoolBackedDataSource : 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, dataSourceName -> 2va78sax8pac4kq046sf|3f36b447, debugUnreturnedConnectionStackTraces -> false, description -> null, driverClass -> com.mysql.jdbc.Driver, factoryClassLocation -> null, forceIgnoreUnresolvedTransactions -> false, identityToken -> 2va78sax8pac4kq046sf|3f36b447, idleConnectionTestPeriod -> 0, initialPoolSize -> 3, jdbcUrl -> jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf8&useSSL=false, maxAdministrativeTaskTime -> 0, maxConnectionAge -> 0, maxIdleTime -> 0, maxIdleTimeExcessConnections -> 0, maxPoolSize -> 10, maxStatements -> 0, maxStatementsPerConnection -> 0, minPoolSize -> 3, numHelperThreads -> 3, numThreadsAwaitingCheckoutDefaultUser -> 0, preferredTestQuery -> null, properties -> {user=******, password=******}, propertyCycle -> 0, testConnectionOnCheckin -> false, testConnectionOnCheckout -> false, unreturnedConnectionTimeout -> 0, usesTraditionalReflectiveProxies -> false ]
2023-07-04 13:25:54.0
Process finished with exit code 0
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