driverClassName=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://localhost:3306/jdbc
username=root
password=root
initialSize=5
maxActive=10
maxWait=3000

package druid;
import com.alibaba.druid.pool.DruidDataSourceFactory;
import javax.sql.DataSource; 
import java.io.InputStream;
import java.sql.Connection;
import java.util.Properties;
public class DruidDemo {
    public static void main(String[] args) throws Exception {
        //加载配置文件
        Properties pro = new Properties();
        InputStream is = DruidDemo.class.getClassLoader().getResourceAsStream("druid.properties");
        pro.load(is);
        //获取连接池对象
        DataSource ds = DruidDataSourceFactory.createDataSource(pro);
        //获取连接
        Connection conn = ds.getConnection();
        System.out.println(conn);
    }
}

package druid.utils;
import com.alibaba.druid.pool.DruidDataSourceFactory;
import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;
public class  JDBCUtils {
    //定义成员变量
    private static DataSource ds;
    static {
        //加载配置文件
        Properties pro = new Properties();
        try {
            pro.load(JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties"));
            ds = DruidDataSourceFactory.createDataSource(pro);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    //获取连接
    public static Connection getConnection() throws SQLException {
        return ds.getConnection();
    }
    //释放资源
    public static void close(Statement stmt, Connection conn){
        if (stmt != null){
            try {
                stmt.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        if (conn != null){
            try {
                conn.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
    public static void close(ResultSet rs, Statement stmt, Connection conn){
        if (rs != null){
            try {
                rs.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        close(stmt, conn);
    }
    //获取连接池
    public static DataSource getDataSource(){
        return ds; 
    }
}