JDBC数据库的连接

迷南。 2024-03-31 10:58 110阅读 0赞

## JDBC数据库的连接 ##

**简介**：本文以简洁的篇幅带领大家快速入门java连接数据库，以查询为演示方案。  
**推荐学习路线**：[JDBC数据库的连接][JDBC]\->[Connection（数据库连接对象）][Connection]\->[Driud数据库连接池的使用][Driud]\->[ResultSet][]\->[通过PreparedStatement预防SQL注入][PreparedStatement_SQL]\->[JDBC增删改查案例讲解][JDBC 1] 大家跟着敲完基本就可以JDBC基础毕业了。

### 编写代码步骤 ###

*  创建工程，导入驱动jar包

**下载官网**：https://downloads.mysql.com/archives/c-j/  
![在这里插入图片描述][ff53d8578bc141538a9c062696e2d491.png]

*  注册驱动
    
        # mysql5的注册驱动的办法。
        Class.forName("com.mysql.jdbc.Driver");
    
        # mysql8的注册驱动的办法。
        Class.forName("com.mysql.cj.jdbc.Driver");
 *  获取连接
    
        Connection conn = DriverManager.getConnection(url, username, password);
    
    Java代码需要发送SQL给MySQL服务端，就需要先建立连接
 *  定义SQL语句
    
        String sql =  “update…” ;
 *  获取执行SQL对象
    
    执行SQL语句需要SQL执行对象，而这个执行对象就是Statement对象
    
        Statement stmt = conn.createStatement();
 *  执行SQL
    
        stmt.executeUpdate(sql);
 *  处理返回结果
 *  释放资源

### 具体操作 ###

*  创建新的空的项目,定义项目的名称，并指定位置  
    ![在这里插入图片描述][806faca7f15a48a0b117e393482aa612.png]  
    ![在这里插入图片描述][02332a205071404aab4550cd02a6b365.png]
 *  对项目进行设置，JDK版本、编译版本  
    ![在这里插入图片描述][f2843094c9a74a769256bcf8ceeb5261.png]  
    ![在这里插入图片描述][047d1b20b43941fc8aa958b575802d18.png]

### 创建lib ###

![在这里插入图片描述][3af8183ea3ce46e492d67234e0f70735.png]  
![在这里插入图片描述][d9bdd2c18f824bcf8e92c2e530465b13.png]

### 导入驱动包 ###

将mysql的驱动包放在模块下的lib目录（随意命名）下，并将该jar包添加为库文件  
![在这里插入图片描述][aa7b95e1bc154e97911264fff2775e35.png]

*  在添加为库文件的时候，有如下三个选项
    
     *  Global Library ： 全局有效
     *  Project Library : 项目有效
     *  Module Library ： 模块有效  
        ![在这里插入图片描述][eec7dc0bff9448d3957144b58b763fd0.png]

### 创建src与创建类 ###

![在这里插入图片描述][24bbbe6f50d54699955263085a8f23a8.png]  
![在这里插入图片描述][7ff7f86069b4460c91958f1f3dd7fcbd.png]  
![在这里插入图片描述][360f3c5c2caf4345b1eea44551780abe.png]  
![在这里插入图片描述][44949e0d0b154fb792981fa856fdc8cd.png]  
![在这里插入图片描述][3d574d7af0084f89bd1010b50bc479e0.png]

### 快速入门代码 ###

建表语句

/*
     Navicat MySQL Data Transfer
    
     Source Server         : 本机
     Source Server Type    : MySQL
     Source Server Version : 80024
     Source Host           : localhost:3306
     Source Schema         : books
    
     Target Server Type    : MySQL
     Target Server Version : 80024
     File Encoding         : 65001
    
     Date: 01/12/2022 12:53:02
    */
    
    SET NAMES utf8mb4;
    SET FOREIGN_KEY_CHECKS = 0;
    
    -- ----------------------------
    -- Table structure for book
    -- ----------------------------
    DROP TABLE IF EXISTS `book`;
    CREATE TABLE `book`  (
      `reclD` varchar(6) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NULL DEFAULT NULL,
      `title` varchar(40) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NULL DEFAULT NULL,
      `type` varchar(20) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NULL DEFAULT NULL,
      `price` varchar(10) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NULL DEFAULT NULL
    ) ENGINE = InnoDB CHARACTER SET = utf8mb4 COLLATE = utf8mb4_0900_ai_ci ROW_FORMAT = Dynamic;
    
    SET FOREIGN_KEY_CHECKS = 1;
    insert into book values("1",	"Java Programming",	"Computer",	"20"),
    					   ("2",	"Java EE Technology",	"Computer",	"41"),
    					   ("3",	"Information System",	"Computer",	"37");

![在这里插入图片描述][7b515ecf34844226915f27f90b7d2ef1.png]

package com.study.jdbc;
    
    
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.ResultSet;
    import java.sql.Statement;
    
    
    /**
     * JDBC快速入门
     */
    public class JDBCDemo {
        
    
        public static void main(String[] args) throws Exception {
        
            //1. 注册驱动
            Class.forName("com.mysql.cj.jdbc.Driver");
            //2. 获取连接
            // String url = "jdbc:mysql://127.0.0.1:3306/books"; // 如果是mysql5这样写
            String url = "jdbc:mysql://localhost:3306/books?serverTimezone=GMT%2B8&useOldAliasMetadataBehavior=true"; // 如果是mysql8这样写
            String username = "root";
            String password = "1234";
    
            Connection conn = DriverManager.getConnection(url, username, password);
            //3. 定义sql
            String sql = "select * from book";
            //4. 获取执行sql的对象 Statement
            Statement stmt =  conn.createStatement();
            //5. 执行sql
            ResultSet rs = stmt.executeQuery(sql);
    //        //6. 处理结果
            while(rs.next()){
        
                // 获取数据
                String recId = rs.getString(1);
                String title = rs.getString(2);
                String type = rs.getString(3);
                double price = rs.getDouble(4);
                System.out.print(recId + " ");
                System.out.print(title + " ");
                System.out.print(type + " ");
                System.out.println(price);
                System.out.println();
                System.out.println("--------------");
            }
            //7. 释放资源
            stmt.close();
            conn.close();
        }
    }

**运行结果**：  
![在这里插入图片描述][2bdefeeef06145a38b6776486063dfaa.png]

[JDBC]: https://blog.csdn.net/qq_51447496/article/details/128018451
[Connection]: https://blog.csdn.net/qq_51447496/article/details/128026554
[Driud]: https://blog.csdn.net/qq_51447496/article/details/128027478
[ResultSet]: https://blog.csdn.net/qq_51447496/article/details/128027846
[PreparedStatement_SQL]: https://blog.csdn.net/qq_51447496/article/details/128032906
[JDBC 1]: https://blog.csdn.net/qq_51447496/article/details/128036297
[ff53d8578bc141538a9c062696e2d491.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/08074b9d27dd40668da5e4f196510d57.png
[806faca7f15a48a0b117e393482aa612.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/2d12a18b89df47358bc0ed14fe9d26f8.png
[02332a205071404aab4550cd02a6b365.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/9e17b4667eb34cc2b40e0eb14956d024.png
[f2843094c9a74a769256bcf8ceeb5261.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/e41e58a08f434e05a4d5032f3d9145d5.png
[047d1b20b43941fc8aa958b575802d18.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/bf2a4fc6f5ae40e2b85985bed251b84d.png
[3af8183ea3ce46e492d67234e0f70735.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/0c3efcd11afb497fbaa26b92765b9b14.png
[d9bdd2c18f824bcf8e92c2e530465b13.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/897ec7ff487146b988d85c86f1865514.png
[aa7b95e1bc154e97911264fff2775e35.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/4b93c542a981433d934b3e9e9031f984.png
[eec7dc0bff9448d3957144b58b763fd0.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/baa598548bd94fd68b72f26a856b5242.png
[24bbbe6f50d54699955263085a8f23a8.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/3866b41bb9614a348a9f3ffc8a929531.png
[7ff7f86069b4460c91958f1f3dd7fcbd.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/9fc8219f034f415090881652934ca5cb.png
[360f3c5c2caf4345b1eea44551780abe.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/e990668c22ef470cb5633452baca5571.png
[44949e0d0b154fb792981fa856fdc8cd.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/21650a97cc8343a38e76c1d041123db7.png
[3d574d7af0084f89bd1010b50bc479e0.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/455c28ed2c6a4d139709ac00e7e86a1d.png
[7b515ecf34844226915f27f90b7d2ef1.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/21be4b917f6344f5a389b2995332c1bc.png
[2bdefeeef06145a38b6776486063dfaa.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/cc9f7fb3db924d67a1cff25d4b62a631.png