ScheduledExecutorService只循環一次

Question

我想實現一個ScheduledExecutorService線程循環每秒，但現在它只有一次循環。

我的問題是我如何設置它，使它週期性地循環而不是一次迭代？

另外，如何將連接池傳遞到線程，以便每次迭代都可以查詢數據庫？任何幫助深表感謝。

public static void main(String[] args) throws InterruptedException { 
     EventQueue.invokeLater(new Runnable() { 
      @Override 
      public void run() { 
       try { 
        AdminManager frame = new AdminManager(); 
        frame.setVisible(true); 
       } catch (Exception e) { 
        e.printStackTrace(); 
       } 

      } 
     }); 

     BoneCP connectionPool = null; 
     Connection connection = null; 

     try { 
      // load the database driver (make sure this is in your classpath!) 
      Class.forName("com.mysql.jdbc.Driver"); 
     } catch (Exception e) { 
      e.printStackTrace(); 
      return; 
     } 

     try { 
      // setup the connection pool 
      BoneCPConfig config = new BoneCPConfig(); 
      config.setJdbcUrl("jdbc:mysql://192.0.0.1:3306/database"); // jdbc url specific to your database, eg jdbc:mysql://127.0.0.1/yourdb 
      config.setUsername("root"); 
      config.setPassword(""); 
      connectionPool = new BoneCP(config); // setup the connection pool 

      connection = connectionPool.getConnection(); // fetch a connection 

      if (connection != null){ 
       System.out.println("Connection successful!"); 
      } 

     } catch (SQLException e) { 
      e.printStackTrace(); 
     } finally { 
      if (connection != null) { 
       try { 
        connection.close(); 
       } catch (SQLException e) { 
        e.printStackTrace(); 
       } 
      } 
     } 

     ScheduledExecutorService exec = Executors.newSingleThreadScheduledExecutor(); 
     exec.schedule(new Runnable(){ 
      @Override 
      public void run(){ 
       System.out.println("Working ... "); 

      } 
     }, 1, TimeUnit.SECONDS); 

     //connectionPool.shutdown(); // shutdown connection pool. 
} 

Answer 1

http://docs.oracle.com/javase/1.5.0/docs/api/java/util/concurrent/ScheduledExecutorService.html

有一個scheduleAtFixedRate方法。 要將某些內容傳遞給匿名類，它需要聲明爲final。 它需要在相同的範圍內。

此外，你現在的代碼正在關閉連接，如果你打算把它傳遞給另一個線程，你需要保持它打開。

！編輯一些示例代碼

public class Whatever { 
    public static void main(String[] args) throws Exception { 
     // ... do your frame thing 

     loadDataBaseDriver(); 
     BoneCP connectionPool = createConnectionPool(); 

     try { 
      final Connection connection = connectionPool.getConnection(); 
      ScheduledExecutorService exec = Executors.newSingleThreadScheduledExecutor(); 

      exec.scheduleAtFixedRate(new Runnable(){ 
       @Override 
       public void run(){ 
        System.out.println("Working ... "); 

        // use connection 
       } 
      }, 0, 1, TimeUnit.SECONDS); 
     } catch (SQLException e) { 
      // do whatever 
     } 
    } 

    public static BoneCP createConnectionPool() throws SQLException { 
     BoneCPConfig config = new BoneCPConfig(); 
     config.setJdbcUrl("jdbc:mysql://192.0.0.1:3306/database"); // jdbc url specific to your database, eg jdbc:mysql://127.0.0.1/yourdb 
     config.setUsername("root"); 
     config.setPassword(""); 
     connectionPool = new BoneCP(config); 
     return connectionPool; 
    } 

    public static void loadDataBaseDriver() { 
     try { 
      // load the database driver (make sure this is in your classpath!) 
      Class.forName("com.mysql.jdbc.Driver"); 
     } catch (Exception e) { 
      e.printStackTrace(); 
      return; 
     } 
    } 

} 

我不知道你在呼喚這樣方法的簽名中的錯誤可能 是錯誤的