在src下创建properties文件

package util;

import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Properties;

public class JDBCUitl {
	private static String driver;
	private static String url;
	private static String username;
	private static String password;

	static {
		// 创建properties对象获取文件
		Properties ps = new Properties();
		// 获取流对象
		InputStream is = JDBCUitl.class.getResourceAsStream("/driver.properties");
		try {
			// 加载文件
			ps.load(is);
			driver = ps.getProperty("driver");
			url = ps.getProperty("url");
			username = ps.getProperty("username");
			password = ps.getProperty("password");
			// 加载驱动
			Class.forName(driver);
		} catch (IOException e) {
			e.printStackTrace();
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	/**
	 * 获取链接对象
	 *
	 * @return conn
	 */
	public static Connection getConnection() {
		Connection conn = null;
		try {
			conn=DriverManager.getConnection(url, username, password);
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return conn;
	}

	/**
	 * 创建链接对象
	 *
	 * @param conn
	 * @param sql
	 * @return ps
	 */
	public static PreparedStatement getPreparedStatement(Connection conn, String sql) {
		PreparedStatement ps = null;
		try {
			ps = conn.prepareStatement(sql);
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return ps;

	}

	/**
	 * 增刪改通用语句
	 *
	 * @param sql
	 * @param objs
	 * @return i
	 */
	public static int executeDML(String sql, Object... objs) {
		Connection conn = getConnection();
		PreparedStatement ps = getPreparedStatement(conn, sql);
		try {
			conn.setAutoCommit(false);
			for (int i = 0; i < objs.length; i++) {
				ps.setObject(i + 1, objs[i]);
			}
			int i = ps.executeUpdate();
			conn.commit();
			return i;
		} catch (SQLException e) {
			try {
				conn.rollback();
			} catch (SQLException e1) {
				e1.printStackTrace();
			}
			e.printStackTrace();
		}
		return -1;
	}

	public void allClose(ResultSet rs, PreparedStatement ps, Connection conn) {
		try {
			if (rs != null) {
				rs.close();
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}
		try {
			if (ps != null) {
				ps.close();
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}

		try {
			if (conn != null) {
				conn.close();
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}

	}
}

package daoImp;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;

import dao.EmpDao;
import pojo.Emp;
import util.JDBCUitl;

public class EmpDaoImp implements EmpDao {
	/**
	 * 实现查询所有用户信息
	 */
	@Override
	public ArrayList<Emp> selAllEmpInfo() {
		String sql = "select * from empe";
		Connection conn = JDBCUitl.getConnection();
		PreparedStatement ps = JDBCUitl.getPreparedStatement(conn, sql);
		ArrayList<Emp> empList = new ArrayList<Emp>();
		try {
			ResultSet rs = ps.executeQuery();
			while (rs.next()) {
				Emp e = new Emp();
				e.setEmpId(rs.getInt("empid"));
				e.setName(rs.getString("ename"));
				e.setEmoney(rs.getInt("emoney"));
				e.setEqq(rs.getString("eqq"));
				empList.add(e);
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return empList;
	}

	/**
	 * 根据id查询用户信息
	 */
	@Override
	public Emp selEmpByEmpId(int empId) {
		String sql = "select * from empe where empid=?";
		Connection conn = JDBCUitl.getConnection();
		PreparedStatement ps = JDBCUitl.getPreparedStatement(conn, sql);
		Emp emp = null;
		try {
			ps.setInt(1, empId);
			ResultSet rs = ps.executeQuery();
			if (rs.next()) {
				emp = new Emp();
				emp.setEmpId(rs.getInt("empid"));
				emp.setName(rs.getString("ename"));
				emp.setEmoney(rs.getInt("emoney"));
				emp.setEqq(rs.getString("eqq"));
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return emp;
	}

	/**
	 * 添加用户信息
	 */
	@Override
	public int insEmpInfo(int empId, String ename, int emoney, String eqq) {
		String sql = "insert into empe values(?,?,?,?)";
		int i = JDBCUitl.executeDML(sql, empId, ename, emoney, eqq);
		return i;
	}

	/**
	 * 根据用户id更改姓名
	 */
	@Override
	public int upEmpByEmpId(String newName, int empId) {
		String sql = "update empe set ename=? where empid=?";
		int i = JDBCUitl.executeDML(sql, newName, empId);
		return i;
	}

	/**
	 * 根据id删除用户信息
	 */
	@Override
	public int delEmpByEmpId(int empId) {
		String sql = "delete from empe where empid=?";
		int i = JDBCUitl.executeDML(sql, empId);
		return i;
	}

}

原文地址：https://www.cnblogs.com/kilig/p/12110214.html