JDBCCategoryDataset – 执行多个查询
我想使用JDBCCategoryDataset类在JFrame中创建三个图表。
我怎样才能提出三个单独的查询？ 我在数据集对象中给出了三个不同的查询，但结果显示了三个相似的图表。 另外，它执行所有三个的最后一个查询。 我已经看到了使用DefaultPieDataset给出默认（静态）值的方式，但我想从数据库中动态检索数据。
我知道我可以创建几个JDBCCategoryDataset对象吗？ 有没有更好的办法？
package barchart; import Extra.OpenFile; import java.awt.Color; import java.awt.Dimension; import java.awt.GridLayout; import java.io.FileNotFoundException; import java.io.IOException; import java.sql.SQLException; import javax.swing.JFrame; import org.jfree.chart.ChartFactory; import org.jfree.chart.ChartPanel; import org.jfree.chart.JFreeChart; import org.jfree.chart.plot.CategoryPlot; import org.jfree.chart.plot.PlotOrientation; import org.jfree.chart.renderer.category.BarRenderer; import org.jfree.data.jdbc.JDBCCategoryDataset; import org.jfree.ui.RefineryUtilities; public class Chart { public static void main(String[] args) throws IOException { try { JDBCCategoryDataset dataset = new JDBCCategoryDataset( "jdbc:mysql://localhost:3306/jobfinder", "com.mysql.jdbc.Driver","giannis", "giannis"); JFrame frame = new JFrame("Charts"); frame.setLayout(new GridLayout(2,1)); String query = ""; query = OpenFile.getContent("query"); //Gets the query from a file // cause it's big.It's a custom class. dataset.executeQuery(query); JFreeChart chart = ChartFactory.createBarChart3D("Job Statistics", "Posts/Replys", "Quantity", dataset, PlotOrientation.VERTICAL, true, true, false); chart.setBackgroundPaint(Color.white); CategoryPlot plot = (CategoryPlot) chart.getPlot(); plot.setBackgroundPaint(Color.lightGray); plot.setRangeGridlinePaint(Color.white); BarRenderer renderer = (BarRenderer) plot.getRenderer(); renderer.setSeriesPaint(1, Color.CYAN); renderer.setSeriesPaint(0, Color.DARK_GRAY); renderer.setDrawBarOutline(false); renderer.setItemMargin(0.0); ChartPanel chartPanel = new ChartPanel(chart, false); chartPanel.setPreferredSize(new Dimension(700, 270)); frame.add(chartPanel); // query = "SELECT occuDscr Jobs,COUNT(pstOccuId) Quantity FROM occupation_field " + // "INNER JOIN job_post ON occuId = pstOccuId GROUP BY Jobs"; // dataset.executeQuery(query); // JFreeChart chart1 = // ChartFactory.createBarChart3D("Job Statistics", "Posts/Replys", "Quantity", // dataset, PlotOrientation.VERTICAL, true, true, false); // // ChartPanel chartPanel1 = new ChartPanel(chart1, false); // chartPanel.setPreferredSize(new Dimension(500/2, 270/2)); // // frame.add(chartPanel1); // // query = "SELECT occuDscr Jobs,COUNT(usrOccuId) Quantity FROM occupation_field " + // "INNER JOIN users ON occuId = usrOccuId GROUP BY Jobs"; // dataset.executeQuery(query); // JFreeChart chart2 = // ChartFactory.createBarChart3D("Job Statistics", "Posts/Replys", "Quantity", // dataset, PlotOrientation.VERTICAL, true, true, false); // // ChartPanel chartPanel2 = new ChartPanel(chart2, false); // chartPanel.setPreferredSize(new Dimension(500/2, 270/2)); // // frame.add(chartPanel2); frame.setVisible(true); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.pack(); RefineryUtilities.centerFrameOnScreen(frame); } catch (FileNotFoundException fe) { System.out.println("Error Occurred " + fe.getMessage()); System.exit(0); } catch (IOException ie) { System.out.println("Error Occurred " + ie.getMessage()); System.exit(0); } catch (ClassNotFoundException ce) { System.out.println("Error Occurred " + ce.getMessage()); System.exit(0); } catch (SQLException se) { System.out.println("Error Occurred " + se.getMessage()); System.exit(0); } } }
从概念上讲，最简单的方法是为每个面板提供自己的查询特定的JDBCCategoryDataset 。 在此相关示例中 ，每个ThermometerDemo面板都有自己的DefaultValueDataset 。
或者，定义一个具有单个JDBCCategoryDataset的类， JDBCCategoryDataset检索组成三个CategoryDataset实例所需的所有数据，并公开静态工厂方法，每个方法返回每个饼图所需的单个数据集。
附录：后一种方法假设有一些有用的启发式方法来区分完整结果集的子集。 例如，这是连续子集的部分实现：
/** @see https://stackoverflow.com/questions/8835974 */ public class MyCategoryDataset implements CategoryDataset{ private JDBCCategoryDataset set; private List subList; private MyCategoryDataset(JDBCCategoryDataset set, int first, int last) { this.set = set; subList = set.getRowKeys().subList(first, first); } public static CategoryDataset createSubset( JDBCCategoryDataset set, int first, int last) { return new MyCategoryDataset(set, first, first); } @Override public Comparable getRowKey(int row) { return (Comparable) subList.get(row); } @Override public int getRowIndex(Comparable key) { return subList.indexOf(key); } @Override public List getRowKeys() { return subList; } // TODO //@Override //public Comparable getColumnKey(int column) {} // //@Override //public int getColumnIndex(Comparable key) {} // //@Override //public List getColumnKeys() {} // //@Override //public Number getValue(Comparable rowKey, Comparable columnKey) {} // //@Override //public int getRowCount() {} // //@Override //public int getColumnCount() {} // //@Override //public Number getValue(int row, int column) {} // //@Override //public void addChangeListener(DatasetChangeListener listener) {} // //@Override //public void removeChangeListener(DatasetChangeListener listener) {} // //@Override //public DatasetGroup getGroup() {} // //@Override //public void setGroup(DatasetGroup group) {} }