如下代码所示,我从数据库中获取行的 x 和 y 值。然后将它们存储在一个数组x
中。之后我试图在框架上画这条线,但它没有被画出来。如何在 Frame 上画线?
public class TestFrame{
static JFrame test;
public static void main(String ar[]){
test=new JFrame("Test");
JButton openLine=new JButton(new AbstractAction("Open Line"){
public void actionPerformed(ActionEvent e) {
String lineId=JOptionPane.showInputDialog("Enter Line id");
ImageComponent image=new ImageComponent();
image.openLine(lineId);
}
});
test.add(openLine, BorderLayout.NORTH);
test.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
test.setSize(600,600);
test.setVisible(true);
}
static class ImageComponent extends JComponent{
static int[] x=new int[100];
static ArrayList al=new ArrayList();
public void openLine(String line_id){
try {
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
Connection con=DriverManager.getConnection("jdbc:odbc:image");
Statement pstm=con.createStatement();
ResultSet rs=pstm.executeQuery("select * from Line where ID= '"+line_id+"'");
while(rs.next()){
x[0]=rs.getInt(3);
x[1]=rs.getInt(4);
x[2]=rs.getInt(5);
x[3]=rs.getInt(6);
al.add(x);
}
repaint();
} catch (Exception ex) {
System.out.println("Exception : "+ex);
}
}
public Graphics2D gd;
Line2D[] line=new Line2D[100];
protected void paintComponent(Graphics g) {
super.paintComponent(g);
gd=(Graphics2D)g;
gd.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
for(int i=0;i<al.size();i++){
line[i]=new Line2D.Double(x[0], x[1],x[2],x[3]);
gd.draw(line[i]);
}
}
}
}