java JDBC连接mysql
- 下载驱动包：http://dev.mysql.com/downloads/connector/j/，解压得到jar文件，例如mysql-connector-java-8.0.11.jar
- 在项目下新建文件夹，将jar包放进去，点击项目右键，【构建路径】——【配置构建路径】，添加jar文件
- 连接数据库
- 加粗部分为新特性
-
1 public final class DbConn 2 { 3 public static Connection getconn() 4 { 5 Connection conn = null; 6 7 String driver = "com.mysql.cj.jdbc.Driver"; 8 String user = "root"; 9 String passwd = "root"; 10 String url = "jdbc:mysql://localhost:3306/store?useSSL=false&serverTimezone=UTC";//指定要访问的数据库store 11 12 //已加载完驱动 13 try 14 { 15 Class.forName(driver); 16 conn = DriverManager.getConnection(url,user,passwd); 17 }catch (SQLException e) 18 { 19 e.printStackTrace(); 20 } 21 catch (ClassNotFoundException e) 22 { 23 e.printStackTrace(); 24 } 25 return conn; 26 } 27 28 }
1 public final class DbClose 2 { 3 /** 4 * 关闭 添加功能 资源 5 * @param pstmt,rs,conn 6 */ 7 public static void addClose(PreparedStatement pstmt, Connection conn) 8 { 9 /* 10 * 多个 try-catch 出发点：安全 11 */ 12 try 13 { 14 if (pstmt != null) 15 { 16 pstmt.close(); 17 } 18 } catch (SQLException e1) 19 { 20 e1.printStackTrace(); 21 } 22 try 23 { 24 if (conn != null) 25 { 26 conn.close(); 27 } 28 } catch (SQLException e) 29 { 30 e.printStackTrace(); 31 } 32 } 33 34 /** 35 * 关闭资源 36 * @param pstmt,rs,conn 37 */ 38 public static void queryClose(PreparedStatement pstmt, ResultSet rs, Connection conn) 39 { 40 try 41 { 42 if (pstmt != null) 43 { 44 pstmt.close(); 45 } 46 } catch (SQLException e1) 47 { 48 e1.printStackTrace(); 49 } 50 try 51 { 52 if (rs != null ) 53 { 54 rs.close(); 55 } 56 } catch (SQLException e1) 57 { 58 e1.printStackTrace(); 59 } 60 try 61 { 62 if (conn != null) 63 { 64 conn.close(); 65 } 66 } catch (SQLException e) 67 { 68 e.printStackTrace(); 69 } 70 } 71 72 }
测试代码。测试是否连接成功：
-
1 public class Show { 2 3 public static void main(String[] args) { 4 //声明Connection对象 5 Connection con; 6 //驱动程序名 7 String driver = "com.mysql.cj.jdbc.Driver"; 8 //URL指向要访问的数据库名mydata 9 String url = "jdbc:mysql://localhost:3306/store?useSSL=false&serverTimezone=UTC"; 10 //MySQL配置时的用户名 11 String user = "root"; 12 //MySQL配置时的密码 13 String password = "root"; 14 //遍历查询结果集 15 try { 16 //加载驱动程序 17 Class.forName(driver); 18 //1.getConnection()方法，连接MySQL数据库！！ 19 con = DriverManager.getConnection(url,user,password); 20 if(!con.isClosed()) 21 System.out.println("Succeeded connecting to the Database!"); 22 //2.创建statement类对象，用来执行SQL语句！！ 23 Statement statement = con.createStatement(); 24 //要执行的SQL语句 25 String sql = "select * from goods where Gid='g231'"; 26 //3.ResultSet类，用来存放获取的结果集！！ 27 ResultSet rs = statement.executeQuery(sql); 28 System.out.println("-----------------"); 29 System.out.println("执行结果如下所示:"); 30 System.out.println("-----------------"); 31 System.out.println("名称" + "\t" + "数量"); 32 System.out.println("-----------------"); 33 34 String Gname = null; 35 String Gnum = null; 36 while(rs.next()){ 37 //获取stuname这列数据 38 Gname = rs.getString("Gname"); 39 //获取stuid这列数据 40 Gnum = rs.getString("Gnum"); 41 42 //输出结果 43 System.out.println(Gname + "\t" + Gnum); 44 } 45 rs.close(); 46 con.close(); 47 } catch(ClassNotFoundException e) { 48 //数据库驱动类异常处理 49 System.out.println("Sorry,can`t find the Driver!"); 50 e.printStackTrace(); 51 } catch(SQLException e) { 52 //数据库连接失败异常处理 53 e.printStackTrace(); 54 }catch (Exception e) { 55 // TODO: handle exception 56 e.printStackTrace(); 57 }finally{ 58 System.out.println("数据库数据成功获取！！"); 59 } 60 } 61 62 }
