如何使用java中的jfreechart绘制mysql数据库表中数据的散点图。我使用过 Swing 库。 任何链接都会有帮助。我搜索了谷歌但找不到理解的解决方案。 如果您有代码，请提供给我。 实际上我确实做了条形图并使用 jfreechart 绘制了它。 我用于条形图的代码在这里。这里的display3函数显示条形图。 如何修改它以显示散点图？
public void display3() throws SQLException, ClassNotFoundException{
DefaultCategoryDataset dataset = new DefaultCategoryDataset();
String JDBC_DRIVER="com.mysql.jdbc.Driver";
String DB_URL="jdbc:mysql://localhost/data2";
Connection conn;
Statement stmt;
String USER = "root";
String PASS = "";
try{
Class.forName(JDBC_DRIVER);
conn=DriverManager.getConnection(DB_URL,USER,PASS);
System.out.println("Creating statement...");
stmt = conn.createStatement();
String sql;
sql="SELECT * FROM `production` WHERE crop_id = 1 AND location_id = 1";
ResultSet rs=stmt.executeQuery(sql);
while (rs.next()){
//String student = rs.getString("studentname");
String yeartext = rs.getString("year_of_production");
//double value = Double.parseDouble(text);
String productiontext = rs.getString("production_amount");
double production = Double.parseDouble(productiontext);
Integer year = Integer.parseInt(yeartext);
dataset.setValue(production, "production", year);
}
JFreeChart chart = ChartFactory.createBarChart("Bar Graph",// Chart Title
"Year", //horizontal axis label
"Paddy Production", // vertical axis label
dataset, //data
PlotOrientation.VERTICAL, //orientation of chart
true, //include legend
false, // tool tips
true);//urls
CategoryPlot p = chart.getCategoryPlot();
ChartPanel chartPanel = new ChartPanel(chart, false);
jPanel9.setLayout(new BorderLayout());
jPanel9.add(chartPanel, BorderLayout.EAST);
jPanel9.add(chartPanel);
SwingUtilities.updateComponentTreeUI(this);
p.setRangeGridlinePaint(blue);
System.out.println("Database created successfully...");
} catch(SQLException se) {
//Handle errors for JDBC
System.out.println("Connect failed ! ");
se.printStackTrace();
}
}
I finally solved my problem:
精炼代码如下并且有效:
public void display3() throws SQLException, ClassNotFoundException{
//DefaultCategoryDataset dataset = new DefaultCategoryDataset();
XYSeriesCollection dataset = new XYSeriesCollection();
XYSeries series = new XYSeries("production");
String JDBC_DRIVER="com.mysql.jdbc.Driver";
String DB_URL="jdbc:mysql://localhost/data2";
Connection conn;
Statement stmt;
String USER = "root";
String PASS = "";
try{
Class.forName(JDBC_DRIVER);
conn=DriverManager.getConnection(DB_URL,USER,PASS);
System.out.println("Creating statement...");
stmt = conn.createStatement();
String sql;
sql="SELECT * FROM `production` WHERE crop_id = 1 AND location_id = 1";
ResultSet rs=stmt.executeQuery(sql);
while (rs.next()){
//String student = rs.getString("studentname");
String yeartext = rs.getString("year_of_production");
//double value = Double.parseDouble(text);
String productiontext = rs.getString("production_amount");
double production = Double.parseDouble(productiontext);
double year = Double.parseDouble(yeartext);
series.add(year,production) ;
//dataset.addSeries(series);
}
dataset.addSeries(series);
JFreeChart chart = ChartFactory.createScatterPlot("Scatter Plot","Year","Paddy Production", dataset);
//CategoryPlot p = chart.getCategoryPlot();
//XYPlot xyplot = (XYPlot)jfreechart.getPlot();
//http://stackoverflow.com/questions/12417732/jfreechart-with-scroller
ChartPanel chartPanel = new ChartPanel(chart, false);
jPanel9.setLayout(new BorderLayout());
jPanel9.add(chartPanel, BorderLayout.EAST);
jPanel9.add(chartPanel);
SwingUtilities.updateComponentTreeUI(this);
// p.setRangeGridlinePaint(blue);
System.out.println("Database created successfully...");
}catch(SQLException se){
//Handle errors for JDBC
System.out.println("Connect failed ! ");
se.printStackTrace();
// JOptionPane.showMessageDialog(MajorUI.this, err.getMessage());
}
}
最佳答案
这个完整的示例在内存中创建一个合适的数据库表，将其查询到 JDBCXYDataset并以散点图显示数据集。请注意第一列如何成为域，而连续的列如何成为单独的系列。
import java.awt.EventQueue;
import java.sql.Connection;
import java.sql.Date;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Calendar;
import java.util.Random;
import javax.swing.JFrame;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.axis.DateAxis;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.chart.plot.XYPlot;
import org.jfree.data.jdbc.JDBCXYDataset;
/**
* @see http://stackoverflow.com/a/24592754/230513
*/
public class JDBCTest {
private static final int N = 30;
private static final Random r = new Random();
private void display() {
JFrame f = new JFrame("JDBCTest");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JDBCXYDataset jds = createDataset();
JFreeChart chart = ChartFactory.createScatterPlot("Inventory",
"Date", "Count", jds, PlotOrientation.VERTICAL, true, true, false);
XYPlot plot = chart.getXYPlot();
plot.setDomainAxis(new DateAxis("Date"));
f.add(new ChartPanel(chart));
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
for (int i = 0; i < jds.getItemCount(); i++) {
System.out.println(new Date(jds.getX(0, i).longValue()));
}
}
private JDBCXYDataset createDataset() {
try {
Connection conn = DriverManager.getConnection(
"jdbc:h2:mem:test", "", "");
Statement st = conn.createStatement();
st.execute("create table inventory(when date, n1 integer, n2 integer)");
PreparedStatement ps = conn.prepareStatement(
"insert into inventory values (?, ?, ?)");
Calendar c = Calendar.getInstance();
for (int i = 0; i < N; i++) {
ps.setDate(1, new Date(c.getTimeInMillis()));
ps.setInt(2, N / 3 + r.nextInt(N / 3));
ps.setInt(3, N / 2 + r.nextInt(N / 3));
ps.execute();
c.add(Calendar.MONTH, 1);
}
JDBCXYDataset jds = new JDBCXYDataset(conn);
jds.executeQuery("select when, n1, n2 from inventory");
return jds;
} catch (SQLException ex) {
ex.printStackTrace(System.err);
}
return null;
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
new JDBCTest().display();
}
});
}
}
关于java - 来自数据库的 jfreechart 散点图，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/24591898/