Java连接数据库的步骤介绍

// MySQL 8.0 以下版本 - JDBC 驱动名及数据库 URL

     static final String JDBC_DRIVER = "com.mysql.jdbc.Driver" ; 

     static final String DB_URL = "jdbc:mysql://localhost:3306/RUNOOB" ;

     // MySQL 8.0 以上版本 - JDBC 驱动名及数据库 URL

     //static final String JDBC_DRIVER = "com.mysql.cj.jdbc.Driver"; 

     //static final String DB_URL = "jdbc:mysql://localhost:3306/RUNOOB?useSSL=false&serverTimezone=UTC";

     // 数据库的用户名与密码，需要根据自己的设置

     static final String USER = "root" ;

     static final String PASS = "123456" ;

// 注册 JDBC 驱动

       Class.forName(JDBC_DRIVER);

// 打开链接

             System.out.println( "连接数据库..." );

             conn = DriverManager.getConnection(DB_URL,USER,PASS);

// 执行查询

             System.out.println( " 实例化Statement对象..." );

             stmt = conn.createStatement();

             String sql;

             sql = "SELECT id, name, url FROM websites" ;

             ResultSet rs = stmt.executeQuery(sql);

// 展开结果集数据库

             while (rs.next()){

                 // 通过字段检索,假设如下三个字段为查询字段

                 int id  = rs.getInt( "id" );

                 String name = rs.getString( "name" );

                 String url = rs.getString( "url" );

                 // 输出数据

                 System.out.print( "ID: " + id);

                 System.out.print( ", NAME: " + name);

                 System.out.print( ", URL: " + url);

                 System.out.print( "\n" );

// 完成后关闭

             rs.close();

             stmt.close();

             conn.close();

//处理错误或者异常

try {

..............

} catch (SQLException se){

             // 处理 JDBC 错误

             se.printStackTrace();

         } catch (Exception e){

             // 处理 Class.forName 错误

             e.printStackTrace();

         } finally {

             // 关闭资源

             try {

                 if (stmt!= null ) stmt.close();

             } catch (SQLException se2){

             } // 什么都不做

             try {

                 if (conn!= null ) conn.close();

             } catch (SQLException se){

                 se.printStackTrace();

             }

         }