java JDBC连接mysql

标签：多个   print   while   查询   uid   对象   return   exe   指定   

1. 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
2. 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
3. 连接数据库
4. 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 }

   

java JDBC连接mysql

标签：多个   print   while   查询   uid   对象   return   exe   指定   

原文地址：https://www.cnblogs.com/tobecool/p/9140831.html