JScrollPane 滚动条不起作用的问题

fei得更高 2020-06-30 03:52:04



import java.awt.Color;

import java.awt.Container;

import java.util.HashMap;

import java.util.Map;



import javax.swing.BorderFactory;

import javax.swing.JFrame;

import javax.swing.JLabel;

import javax.swing.JPanel;

import javax.swing.JScrollPane;



public class MainFrame extends JFrame

{



	/**

	 * 

	 */

	private static final long serialVersionUID = 1L;

	

	private final int ROW_HEIGHT = 30;

	private final int NUM_WIDTH = 50;

	private final int OP_WIDTH = 150;

	

	private JScrollPane scroll = new JScrollPane();

	private JPanel panel = new JPanel();

	private Container container;

	private Map<Integer, JPanel> rowMap = new HashMap<Integer, JPanel>();

	

	public MainFrame()

	{

		this.setSize(800, 600);

		this.setTitle("测试一下滚动");

		container = this.getContentPane();

		container.setLayout(null);		

		scroll.setBounds(10, 10, 400, 300);

		scroll.setBorder(BorderFactory.createLineBorder(Color.black));

		panel.setLayout(null);	

		panel.setBounds(0, 0, 400, 600);

		scroll.setViewportView(panel);

		addRow();

		for (int i = 0; i < 20; i++)

		{

			addRow();

		}

		scroll.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);

		scroll.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);

		container.add(scroll);		

		this.setVisible(true);

	}

	

	private void addRow()

	{

		int targetRowIndex = rowMap.size();

		JPanel rowPanel = new JPanel();

		rowPanel.setLayout(null);

		int beginY = ROW_HEIGHT * targetRowIndex;

		rowPanel.setBounds(0, beginY, 300, ROW_HEIGHT);

		JLabel label = new JLabel();

		label.setText(targetRowIndex + "");

		label.setBounds(0, 0, NUM_WIDTH, ROW_HEIGHT);

		rowPanel.add(label);

		label = new JLabel();

		label.setText("添加");

		label.setForeground(Color.BLUE);

		label.setBounds(NUM_WIDTH, 0, OP_WIDTH, ROW_HEIGHT);

		rowPanel.add(label);

		rowMap.put(targetRowIndex, rowPanel);

		panel.add(rowPanel);

	}

}