彈簧布局管理器怎么在Java項目中使用

import java.awt.Container;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.Spring;
import javax.swing.SpringLayout;


public class SpringLayout_3 extends JFrame {

	private static final long serialVersionUID = -6045918631932051025L;

	public SpringLayout_3() {
		// TODO Auto-generated constructor stub
		Container container = getContentPane();
		SpringLayout springLayout = new SpringLayout();
		container.setLayout(springLayout);
		JLabel topicLabel = new JLabel("主題 :");
		JLabel contentLabel = new JLabel("內(nèi)容 :");
		final JTextField textField = new JTextField(30);
		JTextArea textArea = new JTextArea(3, 30);
		JScrollPane scrollPane = new JScrollPane();
		scrollPane.setViewportView(textArea);
		textArea.setLineWrap(true);
		final JButton confirmButton = new JButton("取消");
		JButton cancelButton = new JButton("確認");
		Spring st = Spring.constant(10);
		Spring st2 = Spring.constant(30);
		container.add(topicLabel);
		springLayout.putConstraint(SpringLayout.NORTH, topicLabel, st, 
				SpringLayout.NORTH, container);
		springLayout.putConstraint(SpringLayout.WEST, topicLabel, st, 
				SpringLayout.WEST, container);
		container.add(textField);
		springLayout.putConstraint(SpringLayout.WEST, textField, st2, 
				SpringLayout.EAST, topicLabel);
		springLayout.putConstraint(SpringLayout.NORTH, textField, 0, 
				SpringLayout.NORTH, topicLabel);
		springLayout.putConstraint(SpringLayout.EAST, textField, Spring.minus(st), 
				SpringLayout.EAST, container);
		container.add(contentLabel);
		springLayout.putConstraint(SpringLayout.WEST, contentLabel, 0, 
				SpringLayout.WEST, topicLabel);
		springLayout.putConstraint(SpringLayout.NORTH, contentLabel, st, 
				SpringLayout.SOUTH, topicLabel);
		container.add(scrollPane);
		springLayout.putConstraint(SpringLayout.NORTH, scrollPane, 0, 
				SpringLayout.NORTH, contentLabel);
		springLayout.putConstraint(SpringLayout.WEST, scrollPane, 0, 
				SpringLayout.WEST, textField);
		springLayout.putConstraint(SpringLayout.EAST, scrollPane, Spring.minus(st), 
				SpringLayout.EAST, container);
		container.add(confirmButton);
		springLayout.putConstraint(SpringLayout.SOUTH, scrollPane, Spring.minus(st), 
				SpringLayout.NORTH, confirmButton);
		springLayout.putConstraint(SpringLayout.EAST, confirmButton, Spring.minus(st), 
				SpringLayout.EAST, container);
		springLayout.putConstraint(SpringLayout.SOUTH, confirmButton, Spring.minus(st), 
				SpringLayout.SOUTH, container);
		container.add(cancelButton);
		springLayout.putConstraint(SpringLayout.EAST, cancelButton, Spring.minus(st), 
				SpringLayout.WEST, confirmButton);
		springLayout.putConstraint(SpringLayout.NORTH, cancelButton, 0, 
				SpringLayout.NORTH, confirmButton);	
		
		// make the text field focused every time the window is activated
		addWindowFocusListener(new WindowAdapter() {

			@Override
			public void windowGainedFocus(WindowEvent e) {
				// TODO Auto-generated method stub
				textField.requestFocus();
			}

		});
	}

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		SpringLayout_3 frame = new SpringLayout_3();
		frame.setTitle("使用彈簧布局管理器");
		frame.setVisible(true);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.setBounds(100, 100, 600, 300);
	}

}