jar包自己準備，此處不羅嗦，直接看程式碼，簡單通俗易懂

package com.util;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

/**
 * 
 * @ClassName DBUtil
 * @Description 資料庫工具類
 * @author 程軍強
 * @Date 2017年10月25日 下午9:40:14
 * @version 1.0.0
 */
public class DBUtil {

	private static final String MYSQL = "jdbc:mysql://";

	private static final String ORACLE = "jdbc:oracle:thin:@";

	private static final String SQLSERVER = "jdbc:microsoft:sqlserver://";
	private DBUtil() {
	}

	public static Connection getConnection(String DBType, String url,
			String user, String password) throws SQLException {
		if ("mysql".equalsIgnoreCase(DBType))
			return getMySqlConn(url, user, password);
		if ("oracle".equalsIgnoreCase(DBType))
			return getOracleConn(url, user, password);
		if ("sqlserver".equals(DBType)){
			return getSqlServerConn(url, user, password);
		}
		return null;
	}

	public static void closeConn(Connection conn) {
		if (conn != null) {
			try {
				conn.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		}
	}

	private static Connection getMySqlConn(String url, String user,
			String password) throws SQLException {
		Connection conn = null;
		try {
			Class.forName("com.mysql.jdbc.Driver");//載入驅動
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}
		conn = DriverManager.getConnection(MYSQL + url, "root", "root");

		return conn;
	}

	private static Connection getOracleConn(String url, String user,
			String password) throws SQLException {
		Connection conn = null;
		try {
			Class.forName("oracle.jdbc.driver.OracleDriver");//載入驅動
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}
		conn = DriverManager.getConnection(ORACLE + url, "scott", "tiger");

		return conn;
	}
	
	private static Connection getSqlServerConn(String url, String user,
			String password) throws SQLException {
		Connection conn = null;
		try {
			Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver");//載入驅動
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}
		conn = DriverManager.getConnection(SQLSERVER + url, "root", "root");

		return conn;
	}
	
	//測試
	public static void main(String[] args) {
		try {
			Connection conn = getConnection("MySQL", "127.0.0.1", "root",
					"root");
			if (conn == null) {
				System.out.println("Connection the database is failled !");
			} else {
				System.out.println(conn.toString());
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}

	}

}