DBUtil.java:连接数据库工具类(Oracle，MySQL，SQLServer)

1.JDBC连接Oracle数据库
这个只要安装了Oracle数据库，就有Oracle自带jar包

package xinlong.utli;

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

public class DBUtil {

    /**
     * 连接Oracle数据库
     * @return
     */
    public static Connection getConn(){
        Connection conn = null;
        try {
            //加载驱动
            Class.forName("oracle.jdbc.OracleDriver");
            //加载数据库的url,user,password
            conn = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:ORCL","XinLong","123");
        } catch (Exception e) {
            e.printStackTrace();
        }
        return conn;
    }

    /**
     * 关闭连接，释放资源
     * @param conn
     */
    public static void close(Connection conn){
        if(conn!=null){
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * 测试连接
     * @param args
     */
    public static void main(String[] args) {
        System.out.println(DBUtil.getConn());
    }
}

2.连接MySql数据库
这个去百度找自己对应版本的jar包

package com.util;

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

public class DBUtil {

	/**
	 * 获取连接
	 * @return
	 */
	public static Connection getConn(){
		Connection conn = null;
		String driver = "com.mysql.cj.jdbc.Driver";
		String url = "jdbc:mysql://localhost:3306/sushe?&useSSL=false&serverTimezone=UTC";//sushe为数据库名
		String user = "root";//用户名
		String password = "123456";//密码
		try {
			//加载驱动
			Class.forName(driver);
			conn = DriverManager.getConnection(url, user, password);
		} catch (Exception e) {
		}
		return conn; 
	}
	//关闭连接，释放资源
	public static void close(Connection conn){
		if(conn != null){
			try {
				conn.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
	}
}

3.连接SQL Server数据库
这个去百度找自己对应版本的jar包

java
package com.chaz.util;

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

public class DBUtil {

	public static Connection getConn() {

		String url = "jdbc:sqlserver://localhost:1433;databaseName=MyBook";
		String user = "sa";//数据库用户名
		String pwd = "1";//密码
		String className = "com.microsoft.sqlserver.jdbc.SQLServerDriver";
		Connection conn = null;

		try {
			Class.forName(className);
			conn = DriverManager.getConnection(url, user, pwd);
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return conn;
	}

	public static void close(Connection conn, PreparedStatement ps, ResultSet rs) {
		if (conn != null) {
			try {
				conn.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		if (ps != null) {
			try {
				ps.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		if (rs != null) {
			try {
				rs.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
	}
}