java JDBC串連mysql

標籤：多個   print   while   查詢   uid   對象   return   exe   指定   

1. 下載驅動包：http://dev.mysql.com/downloads/connector/j/，解壓得到jar檔案，例如mysql-connector-java-8.0.11.jar
2. 在項目下建立檔案夾，將jar包放進去，點擊項目右鍵，【構建路徑】——【配置構建路徑】，添加jar檔案
3. 串連資料庫
4. 加粗部分為新特性

•  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";//指定要訪問的資料庫store11         12         //已載入完驅動13         try14         {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      * 關閉 添加功能 資源 5      * @param pstmt,rs,conn 6      */ 7         public static void addClose(PreparedStatement pstmt, Connection conn) 8         { 9             /*10              * 多個 try-catch 出發點：安全11              */12             try13             {14                 if (pstmt != null)15                 {16                     pstmt.close();17                 }18             } catch (SQLException e1)19             {20                 e1.printStackTrace();21             }22             try23             {24                 if (conn != null)25                 {26                     conn.close();27                 }28             } catch (SQLException e)29             {30                 e.printStackTrace();31             }32         }33         34         /**35          * 關閉資源36          * @param pstmt,rs,conn37          */38         public static void queryClose(PreparedStatement pstmt, ResultSet rs, Connection conn)39         {40             try41             {42                 if (pstmt != null)43                 {44                     pstmt.close();45                 }46             } catch (SQLException e1)47             {48                 e1.printStackTrace();49             }50             try51             {52                 if (rs != null )53                 {54                     rs.close();55                 }56             } catch (SQLException e1)57             {58                 e1.printStackTrace();59             }60             try61             {62                 if (conn != null)63                 {64                     conn.close();65                 }66             } catch (SQLException e)67             {68                 e.printStackTrace();69             }70         }71         72 }

  測試代碼。測試是否串連成功：

•  1 public class Show { 2  3     public static void main(String[] args) { 4         //聲明Connection對象 5         Connection con; 6         //驅動程式名 7         String driver = "com.mysql.cj.jdbc.Driver"; 8         //URL指向要訪問的資料庫名mydata 9         String url = "jdbc:mysql://localhost:3306/store?useSSL=false&serverTimezone=UTC";10         //MySQL配置時的使用者名稱11         String user = "root";12         //MySQL配置時的密碼13         String password = "root";14         //遍曆查詢結果集15         try {16             //載入驅動程式17             Class.forName(driver);18             //1.getConnection()方法，串連MySQL資料庫！！19             con = DriverManager.getConnection(url,user,password);20             if(!con.isClosed())21                 System.out.println("Succeeded connecting to the Database!");22             //2.建立statement類對象，用來執行SQL語句！！23             Statement statement = con.createStatement();24             //要執行的SQL語句25             String sql = "select * from goods where Gid=‘g231‘";26             //3.ResultSet類，用來存放擷取的結果集！！27             ResultSet rs = statement.executeQuery(sql);28             System.out.println("-----------------");29             System.out.println("執行結果如下所示:");  30             System.out.println("-----------------");  31             System.out.println("名稱" + "\t" + "數量");  32             System.out.println("-----------------");  33              34             String Gname = null;35             String Gnum = null;36             while(rs.next()){37                 //擷取stuname這列資料38                 Gname = rs.getString("Gname");39                 //擷取stuid這列資料40                 Gnum = rs.getString("Gnum");41 42                 //輸出結果43                 System.out.println(Gname + "\t" + Gnum);44             }45             rs.close();46             con.close();47         } catch(ClassNotFoundException e) {   48             //資料庫驅動類異常處理49             System.out.println("Sorry,can`t find the Driver!");   50             e.printStackTrace();   51             } catch(SQLException e) {52             //資料庫連接失敗異常處理53             e.printStackTrace();  54             }catch (Exception e) {55             // TODO: handle exception56             e.printStackTrace();57         }finally{58             System.out.println("資料庫資料成功擷取！！");59         }60     }61 62 }

   

java JDBC串連mysql