java连接MySql数据库

先给项目：

链接：https://pan.baidu.com/s/1ddbhL4TiWLVPWcr4nK4Epg 密码：alao

准备mysql，如果没有安装mysql，下面提供我写的如何安装mysql（资源在百度云，免费的）

https://blog.csdn.net/qq_36325069/article/details/79877050

在给个mysql的jdbc包 链接：https://pan.baidu.com/s/1wXotLZcgd6zFZZbNEvOCrQ 密码：aafa

环境：jdk配置好了，eclipse准备好了，eclipse配置好Tomcat了，可以去百度，都很好弄

给出几个链接

eclipse：3个版本，，win64位

链接：https://pan.baidu.com/s/1FwmoQ3wjKwKqxu8y6B-jrg 密码：z1cd

jdk：两个，1.6和1.8 win64位

链接：https://pan.baidu.com/s/1KBALvq-XuLDj-Iaj7EFpLA 密码：t1vx

Tomcat：3个

链接：https://pan.baidu.com/s/1XJbwryQUNPiq44wCChxECg 密码：80no

准备工作做好了，接下来就是今天的主题了

1. 新建javaweb项目，添加jar,并添加到path中，目录如下

JDBC.java文件

package com.quding.mysql;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
 import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
public class JDBC {
	
	//加载数据库驱动
	private static String dbdriver ="com.mysql.jdbc.Driver";
	//获取mysql链接地址,其中sh为数据库名称
	private static String dburl = "jdbc:mysql://127.0.01:3306/sh?characterEncoding=utf8&useSSL=true";
	//用户名称
	private static String username = "root";
	//密码
	private static String password = "newpassword";
	
	//数据库链接
	private  static Connection conn = null;
	/**
	 * 获取数据库链接
	 * @return
	 */
	private static void initConnction() {
		while(conn == null) {
			doConnection();
		}
	}
	private static void destoryConnection() {
		if(conn != null) {
			try {
				conn.close();
				System.out.println("链接关闭成功。。。。。。true");
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
				System.out.println("链接关闭失败。。。。。。false");
			}
		}
	}

	/**
	 * 进行数据库链接
	 */
	private static void doConnection() {
		// TODO Auto-generated method stub
		
		try {
			//通过驱动名称加载驱动
			Class.forName(dbdriver);
			System.out.println("加载数据库驱动。。。。。true");
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
			System.out.println("加载数据库驱动。。。。。false");
		}
		try {
			Connection connection =   DriverManager.getConnection(dburl, username, password);
			conn = connection;
			System.out.println("获取链接成功。。。。。。。true");
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
			System.out.println("获取链接失败。。。。。。。false");
		}
		
	}
	
	/**
	 * 查询方法，public，对外提供
	 */
	
	public static List<List<Object>> query(String sql){
		//
		initConnction();
		
		List<List<Object>> list = new ArrayList<List<Object>>();
		PreparedStatement ps = null;
		 ResultSet rs = null;
		try {
			
			ps= conn.prepareStatement(sql);
			rs = ps.executeQuery();
			ResultSetMetaData md = rs.getMetaData();
			int columnCount = md.getColumnCount();
			 while (rs.next()) {
	                List<Object> lst = new ArrayList<Object>();
	                for (int i = 1; i <= columnCount; ++i) {
	                    lst.add(rs.getObject(i) == null ? "" : rs.getObject(i));
	                }
	                list.add(lst);
	            }
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally {
			//closeAll(rs, ps);
		}
		return list;
	}
	
	/**
	 * 关闭链接
	 * @param rs2
	 * @param ps2
	 */
	public static void closeAll(ResultSet rs2, PreparedStatement ps2) {
		// TODO Auto-generated method stub
		destoryConnection();
		try {
			ps2.cancel();
			rs2.close();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
		
	}
	

} 

package com.quding.servlet;

import java.io.IOException;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.quding.mysql.JDBC;

/**
 * Servlet implementation class TestServlet
 */
@WebServlet("/TestServlet")
public class TestServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public TestServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		//f防止中文乱码
		response.setContentType("text/html;charset=UTF-8;pageEncoding=UTF-8");
		
		String sql = "select * from book where 1=1";
		
		List<List<Object>> list = JDBC.query(sql);
		
		String ss = list.get(0).toString();
		response.getWriter().append(ss);
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
	}

}

上面是TestServlet.java文件

运行

结果

我的数据库

特别提醒：这种方式写一个小的服务还是可以的，先熟悉这样的写法，然后建议用hibernate或Mybatis框架，可以去了解一下，开发会省事很多，找工作也好找一些（比如我，嘿嘿）