JDBC通用代码

曾经终败给现在 2022-02-15 11:46 373阅读 0赞

**一、在IDEA中新建一个空project工程项目**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5nMTUwMTE0_size_16_color_FFFFFF_t_70]

**二、准备工作：**

1.mysq驱动jar包：mysql-connector-java-5.1.37-bin.jar
    2.jdbc配置文件：jdbc.properties

**三、代码编写**

1、新建libs文件夹导入jar包  
2、src目录下新建jdbc.properties配置文件

# 驱动
    driver=com.mysql.jdbc.Driver
    # 数据库地址
    url=jdbc:mysql://localhost:3306/my_db
    # 用户名
    userName=root
    # 密码
    passWord=root

3、抽取JDBCUtil工具类

package com.mollen.demo01;
    
    import java.io.FileReader;
    import java.io.IOException;
    import java.net.URL;
    import java.sql.*;
    import java.util.Properties;
    
    /**
     * @ClassNmme: JDBCUtil
     * @Author: Mollen
     * @CreateDate: 2018-09-08 18:31:30
     * @Description:
     *           JDBCUtils工具类
     */
    public class JDBCUtils {
        private static String url;
        private static String userName;
        private static String passWord;
        private static String driver;
    
        /**
         * 1.读取配置文件
         */
        static {
            try {
                //获取文件路径 --> ClassLoader类加载器
                ClassLoader classLoader = JDBCUtils.class.getClassLoader();
                URL resource = classLoader.getResource("jdbc.properties");
                String path = resource.getPath();
    
                //加载文件
                Properties pro = new Properties();
                pro.load(new FileReader(path));
    
                //解析文件
                url = pro.getProperty("url");
                userName = pro.getProperty("userName");
                passWord = pro.getProperty("passWord");
                driver = pro.getProperty("driver");
    
                //注册驱动
                Class.forName(driver);
    
            } catch (IOException e) {
                e.printStackTrace();
            } catch (ClassNotFoundException e) {
                e.printStackTrace();
            }
        }
    
        /**
         * 2.获得数据库连接
         */
        public static Connection getConn() throws SQLException {
            return DriverManager.getConnection(url, userName, passWord);
        }
    
        /**
         * 3.释放资源（方法重载）
         */
        public static void close(PreparedStatement pstmt, Connection conn) {
            close(null,pstmt,conn);
        }
    
        public static void close(ResultSet rs, PreparedStatement pstmt, Connection conn) {
            if (rs != null) {
                try {
                    rs.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
            if (pstmt != null) {
                try {
                    pstmt.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
    
            }
            if (conn != null) {
                try {
                    conn.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
        }
    }

4.编写测试类

package com.mollen.demo01;
    
    import java.sql.Connection;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    
    /**
     * @ClassNmme: Test
     * @Author: Mollen
     * @CreateDate: 2018-09-08 18:31:37
     * @Description:
     *          测试类
     */
    public class Test {
        public static void main(String[] args) {
            Connection conn = null;
            PreparedStatement pstmt = null;
            ResultSet rs = null;
            //定义sql
            String sql = "SELECT * FROM student";
            try {
                //1.获取连接
                conn = JDBCUtils.getConn();
                //2.获取sql执行对象
                pstmt = conn.prepareStatement(sql);
                //3.执行sql
                rs = pstmt.executeQuery();
                //4.遍历集合
                while(rs.next()){
                    String name = rs.getString("name");
                    int age = rs.getInt("age");
                    System.out.println("name:"+name+"   age:"+age);
                }
            }catch (Exception e){
                e.printStackTrace();
            }finally {
    			//释放资源
                JDBCUtils.close(rs,pstmt,conn);
            }
        }
    }

**四、注意事项**

1.案例用的是mysql数据库驱动  
2.jdbc配置文件建议建在src目录下  
3.数据库执行对象用的是prepareStatement案例中没有做参数解析操作  
4.数据库连接使用完毕必须释放资源

摘自：[https://blog.csdn.net/mollen/article/details/82532290][https_blog.csdn.net_mollen_article_details_82532290]

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[https_blog.csdn.net_mollen_article_details_82532290]: https://blog.csdn.net/mollen/article/details/82532290