package org.c3p0tets.datasourcec;

import com.mchange.v2.c3p0.ComboPooledDataSource;

import java.io.FileInputStream;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Properties;

public class C3P0_ {
    //    方式1.相关参数，在程序中指定user,url,password等
    public void testC3P0_01() throws Exception {
//        System.out.println(System.getProperty("user.dir"));
        //1. 创建一个数据源对象
        ComboPooledDataSource comboPooledDataSource = new ComboPooledDataSource();

        //2.通过配置文件获取mysql.properties的相关连接信息
        Properties properties = new Properties();

        properties.load(new FileInputStream("src/main/resources/mysql.properties"));
        String url = properties.getProperty("url");
        String user = properties.getProperty("user");
        String password = properties.getProperty("password");
        String driver = properties.getProperty("driver");

        //给数据源设置相关信息
        //连接管理由comboDataSource管理
        comboPooledDataSource.setDriverClass(driver);
        comboPooledDataSource.setJdbcUrl(url);
        comboPooledDataSource.setUser(user);
        comboPooledDataSource.setPassword(password);

        //设置初始化连接数
        comboPooledDataSource.setInitialPoolSize(10);
        comboPooledDataSource.setMaxPoolSize(50);

        //获取Connection
        Connection connection = comboPooledDataSource.getConnection();
        System.out.println("连接成功！");
        connection.close();

    }

    public void testC3P0_test02() throws Exception{
        //使用配置文件的模板完成操作
        ComboPooledDataSource comboPooledDataSource = new ComboPooledDataSource("meowrain");
        Connection connection = comboPooledDataSource.getConnection();
        System.out.println("连接成功");
        connection.close();
    }


}

直接封装成工具类

package org.c3p0tets.utils;

import com.mchange.v2.c3p0.ComboPooledDataSource;

import java.beans.PropertyVetoException;
import java.io.FileInputStream;
import java.io.IOException;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

public class C3P0Utils {
    private static ComboPooledDataSource dataSource;

    static {
        Properties properties = new Properties();
        try {
            properties.load(new FileInputStream("src/main/resources/mysql.properties"));
            String url = properties.getProperty("url");
            String user = properties.getProperty("user");
            String password = properties.getProperty("password");
            String driver = properties.getProperty("driver");
            dataSource = new ComboPooledDataSource();

            dataSource.setDriverClass(driver);
            dataSource.setJdbcUrl(url);
            dataSource.setUser(user);
            dataSource.setPassword(password);
            //设置初始化连接数
            dataSource.setInitialPoolSize(10);
            dataSource.setMaxPoolSize(50);
        } catch (IOException | PropertyVetoException e) {
            throw new RuntimeException();
        }

    }

    public static Connection getConnection() throws SQLException {
        return dataSource.getConnection();
    }

    public static void close(ResultSet set, Statement statement, Connection connection) {
        if (set != null) {
            try {
                set.close();
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }
        }
        if (statement != null) {
            try {
                statement.close();
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }
        }
        if (connection != null) {
            try {
                connection.close();
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }
        }
    }
}

maven

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>c3p0Test</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>17</maven.compiler.source>
        <maven.compiler.target>17</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>
<dependencies>
    <!-- https://mvnrepository.com/artifact/com.mchange/c3p0 -->
    <dependency>
        <groupId>com.mchange</groupId>
        <artifactId>c3p0</artifactId>
        <version>0.9.5.5</version>
    </dependency>

    <!-- https://mvnrepository.com/artifact/com.mysql/mysql-connector-j -->
    <dependency>
        <groupId>com.mysql</groupId>
        <artifactId>mysql-connector-j</artifactId>
        <version>8.2.0</version>
    </dependency>
    <!-- https://mvnrepository.com/artifact/org.junit.jupiter/junit-jupiter-api -->
    <dependency>
        <groupId>org.junit.jupiter</groupId>
        <artifactId>junit-jupiter-api</artifactId>
        <version>5.10.1</version>
        <scope>test</scope>
    </dependency>

</dependencies>
    <build>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
            </resource>
        </resources>
    </build>
</project>