Java连接MySQL数据库的模板

简单连接

• 使用jdbc连接

成员类

package com.entity;

import java.util.Date;

/**
 * 此类中包换所有用户信息，包括：username:用户名;
 *                           p_headline:公开笔记的标题；
 *                           p_content:公开笔记的内容；
 *                           prasisepoints:点赞数；
 *                           pageview:页面浏览量；
 *                           time：笔记的发布时间；
 *                        以及以上类的getter()方法和setter()方法；
 *                        这是主类，包含最多；
 * @author 10593
 */
public class User {

    private String username;
    private String p_headline;
    private String p_content;
    private long prasisepoints;
    private long pageview;
    private Date time;

    public User(){

    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getP_headline() {
        return p_headline;
    }

    public void setP_headline(String p_headline) {
        this.p_headline = p_headline;
    }

    public String getP_content() {
        return p_content;
    }

    public void setP_content(String p_content) {
        this.p_content = p_content;
    }

    public long getPrasisepoints() {
        return prasisepoints;
    }

    public void setPrasisepoints(long prasisepoints) {
        this.prasisepoints = prasisepoints;
    }

    public long getPageview() {
        return pageview;
    }

    public void setPageview(long pageview) {
        this.pageview = pageview;
    }

    public Date getTime() {
        return time;
    }

    public void setTime(Date time) {
        this.time = time;
    }

    @Override
    public String toString() {
        return "User{" +
                "username='" + username + '\'' +
                ", p_headline='" + p_headline + '\'' +
                ", p_content='" + p_content + '\'' +
                ", prasisepoints=" + prasisepoints +
                ", pageview=" + pageview +
                ", time=" + time +
                '}';
    }

}

DBManager类

package com.util;

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

/**
 * @author 10593
 */
public class DBManager {

    private static final String url = "jdbc:mysql://localhost:3306/project?useSSL=false&serverTimezone=UTC";
    private static final String name = "com.mysql.cj.jdbc.Driver";
    private static final String username = "root";
    private static final String password = "4028144kzj";

     public Connection getConnection() {

         Connection conn = null;

         try {
             //加载mysql数据库驱动
             Class.forName(name);
         } catch (ClassNotFoundException e) {
             e.printStackTrace();
             System.out.println("加载数据库驱动异常");
             return null;
         }


         try {
             //连接mysql数据库
             conn = DriverManager.getConnection(url, username, password);
         }catch (SQLException e) {
            e.printStackTrace();
            System.out.println("连接数据库异常");
             return null;
         }

         System.out.println("成功连接到数据库");
         return conn;
     }

     //关闭数据库连接
    public void closeConn(Connection conn){
         if(conn != null){
             try{
                 conn.close();
                 System.out.println("成功关闭数据库连接");
             } catch (SQLException e){
                 e.printStackTrace();
             }
         }
    }


}

JdbcController类：jdbc连接层

package com.dao;

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


import com.entity.User;
import com.util.DBManager;


public class JdbcController {
    //查询所有用户的信息
    public ArrayList<User> getAllUserInfo(){

        DBManager obj = new DBManager();
        Connection conn = obj.getConnection();
        ArrayList<User> users = new ArrayList<>();

        if (conn == null){
            System.out.println("数据库连接出错");
            return null;
        }


            String sql = "SELECT * from users_publicnotes";
            try {
                //预编译处理sql语句
                PreparedStatement ptst = conn.prepareStatement(sql);
                ResultSet rs = ptst.executeQuery();

                rs.last();
                rs.beforeFirst();

                while (rs.next()){
                    User user = new User();
                    user.setUsername(rs.getString("username"));
                    user.setP_headline(rs.getString("p_headline"));
                    user.setP_content(rs.getString("p_content"));
                    user.setPrasisepoints(rs.getLong("praisepoints"));
                    user.setPageview(rs.getLong("pageview"));
                    user.setTime(rs.getTimestamp("time"));
                    users.add(user);
                }


            } catch (SQLException e) {
                e.printStackTrace();
                System.out.println("SQL语句有误，数据库报错");
                return null;
            }

        return users;
    }
}