Java JDBC MySQL異常：使用Web頁讀取「ResultSet關閉後不允許的操作」

我正在使用MySQL連接器來獲取URL以在網頁上查找值。Java JDBC MySQL異常：使用Web頁讀取「ResultSet關閉後不允許的操作」

我收到上面的消息，我不知道爲什麼。它從rs1插入第一條記錄，但我不確定它爲什麼會關閉它。

下面是我的代碼

String strSQL = "SELECT * FROM element_info;"; 
    String sElementID = ""; 
    String sSymbol = ""; 
    URL urlChartLink; 
    URLConnection urlconn; 
    String sChartLink = ""; 
    String sCurrentPrice = ""; 
    String FindValue = "last_last"; 

    try { 

     Class.forName(driver).newInstance(); 
     Connection mysqlconn = DriverManager.getConnection(url + dbName, userName, password); 
     Statement st1 = mysqlconn.createStatement(); 
     ResultSet rs1 = st1.executeQuery(strSQL); 

     while (rs1.next()) { 
      // Get all of the elements 
      // Retrieve the ElementID 
      sElementID = rs1.getString(1); 
      // Retrieve the Symbol 
      sSymbol = rs1.getString(2); 
      // Retrieve the Chartlink 
      sChartLink = rs1.getString(3); 
      if (sChartLink == "") { 
       break; 
      } 

      try { 

       urlChartLink = new URL(sChartLink); 
       urlconn = urlChartLink.openConnection(); 
       urlconn.addRequestProperty("User-Agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0)"); 
       BufferedReader in = new BufferedReader(new InputStreamReader(urlconn.getInputStream(), "UTF-8")); 
       String currentLine; 

       while ((currentLine = in.readLine()) != null) { 
        // See if the value is on this record 
        int pos1 = currentLine.indexOf(FindValue); 
        int pos2 = currentLine.indexOf("</span>"); 
        // pos1 = 66 
        if (pos1 > 0) { 
         pos1 = pos1 + 21; 
         pos2 = pos2 - 1; 
         // System.out.print("pos1 = " + pos1 + "\n"); 
         // System.out.print("pos2 = " + pos2 + "\n"); 

         sCurrentPrice = currentLine.substring(pos1, pos2); 
         // System.out.print("sCurrentPrice = " + sCurrentPrice + "\n"); 

         // Import into the marketprices 
         strSQL = "INSERT INTO marketprices" 
           + "(ElementID,Symbol,PullDatetime,Price) VALUES (" + "'" + sElementID + "','" 
           + sSymbol + "','" + sToday + "','" + sCurrentPrice + "')"; 

         int val = st1.executeUpdate(strSQL); 

         if (val == 1) 
          System.out.print("Successfully inserted from " + sChartLink + "\n"); 
         break; 
        } 
       }     
       in.close(); 
      } catch (IOException e) { 
       System.out.print("Error getting ChartLink website: " + e.getMessage() + "\n"); 
       break; 
      } 
     }   
    } catch (Exception e) { 
     System.out.print("Error: " + e.getMessage() + "\n"); 
     e.printStackTrace(); 
    }

來源

2017-06-03 EddiRae

我猜你執行的結果集多次，使結果集的另一個目的，據我知道你不能重新執行結果集。在循環的結果集內創建新對象 –

您需要在循環內使用不同的語句對象：在語句上執行另一個查詢將關閉從該語句對象創建的所有打開的結果集。您可能還需要禁用自動提交。 –

您正在嘗試與語句對象，它是已在使用，你還在讀書從Statement對象現有的結果集寫的。您需要創建一個新的Statement對象爲你的代碼的更新部分：

strSQL = "INSERT INTO marketprices"+ "(ElementID,Symbol,PullDatetime,Price) VALUES (" + "'" + sElementID + "','"+ sSymbol + "','" + sToday + "','" + sCurrentPrice + "')"; 
Connection mysqlconn2 = DriverManager.getConnection(url + dbName, userName, password); 
Statement st2 = mysqlconn.createStatement(); 
int val = st2.executeUpdate(strSQL);

來源

2017-06-03 17:33:07 Siddharth

謝謝！就是這樣！一旦我做出改變，它就像一個魅力！ – EddiRae

Java JDBC MySQL異常：使用Web頁讀取「ResultSet關閉後不允許的操作」

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