执行 SQL UPDATE 语句后刷新 JTable

Question

我创建了一个 JTable 并定义了 MyTableModel 以便从 MySQL DB 填充此表。但是，问题是当我执行 UPDATE 语句时，JTable 中包含了一个额外的行（但不在 MySQL DB 中）。

我应该如何更新我的代码才能在不重新打开应用程序的情况下正确更新 JTable？ （我正在使用 fireTableChanged(null)）

 public class QueryTableModel extends AbstractTableModel {
      Vector cache;
      int colCount;
      String[] headers;

      String db;
      String dbHost;
      String dbLogin;
      String dbPassw;     
      Statement statement;

      public QueryTableModel() {
        cache = new Vector();
      }

      public String getColumnName(int i) {
        return headers[i];
      }

      public int getColumnCount() {
        return colCount;
      }

      public int getRowCount() {
        return cache.size();
      }

      public Object getValueAt(int row, int col) {
        return ((String[]) cache.elementAt(row))[col];
      }

      public Connection getConnection()
                throws Exception {
            String dbURL = "";
            try {
                Class.forName("com.mysql.jdbc.Driver");
            } catch (ClassNotFoundException e) {
                System.out.println("Cannot find the MySQL JDBC driver. ");
                throw (e);
            }
            try {
                dbURL = "jdbc:mysql://" + dbHost + "/" + db;
                // WINDOWS
                Connection con = DriverManager.getConnection(dbURL,dbLogin,dbPassw);
                // LINUX
                // Connection con = DriverManager.getConnection(url);
                return con;
            } catch (SQLException e) {
                System.out.println("No connection with " + dbURL);
                throw (e);
            }
        }

      public void setQuery(String query) {
        cache = new Vector();
        try {
          // Execute the query and store the result set and its metadata
          Connection con = getConnection();
          Statement statement = con.createStatement();
          ResultSet rs = statement.executeQuery(query);
          ResultSetMetaData meta = rs.getMetaData();
          colCount = meta.getColumnCount();

          // Rebuild the headers array with the new column names
          headers = new String[colCount];
          for (int h = 1; h <= colCount; h++) {
            headers[h - 1] = meta.getColumnName(h);
          }

          while (rs.next()) {
            String[] record = new String[colCount];
            for (int i = 0; i < colCount; i++) {
              record[i] = rs.getString(i + 1);
            }
            cache.addElement(record);
          }
          fireTableChanged(null);

          rs.close();
          if (con.getAutoCommit() != false) {
            con.close();
          }

        } catch (Exception e) {
          cache = new Vector(); // blank it out and keep going.
          e.printStackTrace();
        }
      }

      public void setQueryUpdate(String[] data, String q) {
        try {
          Connection con = getConnection();
          Statement statement = con.createStatement();
          int rs = statement.executeUpdate(q);
          String[] record = new String[data.length];
          for (int i = 0; i < data.length; i++) {
            record[i] = data[i];
          }
          cache.addElement(record);
          fireTableChanged(null);
          if (con.getAutoCommit() != false) {
            con.close();
          }
        } catch (Exception e) {
          cache = new Vector(); // blank it out and keep going.
          System.out.println(e.getMessage());
        }
      }

    }

Answer 1

现在我明白你在这里尝试了什么。您需要致电：

fireTableDataChanged();

如果你调用fireTableChange(null)，所有的监听器都会被调用，Event 等于 null。根据实现，它将 a) 抛出 NPE 或 b) 什么也不做。 fireTableDataChanged(); 告诉侦听器数据已更改并相应更新。