如何按比例分配 jswing gridbaglayout空间？

比如我要添加两个jpanel 一个占据1/6 一个占据5/6的空间
c.gridwidth = 1;
c.gridwidth = 5;
但是显示出来后结果却是各占一半呢？
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ComponentEvent;
import java.awt.event.ComponentListener;
import javax.swing.JFrame;
import javax.swing.JPanel;public class TestFrame extends JFrame { public TestFrame() {
// TODO Auto-generated constructor stub
super("TestFrame");
setLayout(new GridBagLayout());
setPreferredSize(new Dimension(800, 600));
pack();
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setVisible(true);
JPanel jp1 = new JPanel();
jp1.setBackground(Color.black);
JPanel jp2 = new JPanel();
jp2.setBackground(Color.GREEN);

GridBagConstraints c = new GridBagConstraints();
c.gridx = 0;
c.gridy = 0;
c.weightx = 1;
c.weighty = 1;
c.gridwidth = 1;
c.fill = GridBagConstraints.BOTH;
add(jp1,c);

c.gridx = 1;
c.gridy = 0;
c.gridwidth = 5;
add(jp2,c);
} /**
 * @param args
 */
public static void main(String[] args) {
// TODO Auto-generated method stub
new TestFrame(); }}