public class DBCPTest {
	
	private static DataSource dataSource = null;
	
	public static void DbcpTest() {
		try {
			// 讀取文件配置
			InputStream config = DBCPTest.class.getClassLoader().getResourceAsStream("resources/config.properties");
			Properties prop = new Properties();
			prop.load(config);
			
			// 創(chuàng)建數據源 工廠模式
			dataSource = BasicDataSourceFactory.createDataSource(prop);
			
			// 從數據源中獲取連接
			Connection connection = dataSource.getConnection();
		
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}

driverClassName=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://localhost:3306/school?useUnicode=true&characterEncoding=utf8&useSSL=true
username=root
password=19981104

public static void main(String[] args) throws PropertyVetoException, SQLException {
		// 實例化C3P0提供的連接池
		ComboPooledDataSource cpds = new ComboPooledDataSource();
		// 加載當前使用的數據庫
		cpds.setDriverClass("com.mysql.cj.jdbc.Driver");
		cpds.setJdbcUrl("jdbc:mysql://localhost:3306/school?useUnicode=true&characterEncoding=utf8&useSSL=true");
		cpds.setUser("root");
		cpds.setPassword("19981104");
		// 通過Datasource數據源獲得連接對象
		Connection connection = cpds.getConnection();
		
		// 設置初始化連接池中的連接對象
		cpds.setInitialPoolSize(2);
		
		
  
    // 也可以通過加載配置文件使用數據庫
		// 在實例化時，去加載配置文件
  	// 這里的配置文件名是xml中的named-config的name
		ComboPooledDataSource cpds2 = new ComboPooledDataSource("intergalactoApp");
		Connection connection2 = cpds2.getConnection();
		System.out.println(connection2);
	}

<?xml version="1.0" encoding="UTF-8"?>
<c3p0-config>
  <!-- 在這下面配置數據庫信息 -->
  <named-config name="intergalactoApp"> 
  	<!-- 配置驅動，url，user和password -->
  	<property name="driverClass">com.mysql.cj.jdbc.Driver</property>
    <property name="jdbcUrl">jdbc:mysql://localhost:3306/school?useSSL=true</property>
    <property name="user">root</property>
    <property name="password">password</property>
  
    <property name="acquireIncrement">50</property>
    <property name="initialPoolSize">100</property>
    <property name="minPoolSize">50</property>
    <property name="maxPoolSize">1000</property>

    <!-- intergalactoApp adopts a different approach to configuring statement caching -->
    <property name="maxStatements">0</property> 
    <property name="maxStatementsPerConnection">5</property>

  </named-config>

</c3p0-config>

public static void main(String[] agrs) throws Exception {
		
		DruidDataSource dataSource = new DruidDataSource();
		// 不管是誰想要連接數據庫服務器，都需要用戶名，密碼，url，driver
		// dataSource.setDriverClassName(driverClass);
		// dataSource.setUrl(jdbcUrl);
		
		// 讀取配置文件
		InputStream config = DruidTest.class.getClassLoader().getResourceAsStream("resources/config.properties");
		Properties prop = new Properties();
		prop.load(config);
		
		// 使用工廠模式 -- 提供了生產數據源對象的工廠
		// 讀取Druid讀取配置文件
		DataSource dataSource2 = DruidDataSourceFactory.createDataSource(prop);
		// 獲得連接對象
		Connection connection = dataSource2.getConnection();
				
	}