ITEEDU

14-1-2:为JSlider组件加入刻度.

上面这个例子中,你是否觉得好像少了什么?没错,就是刻度!接下来,我们来设置JSlider的刻度与数字,并增加一些设置项目,完 整的JSlider组件就大功告成了.

import javax.swing.*;
import javax.swing.border.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.event.*;
import java.util.*;

public class SliderDemo2 implements ChangeListener {
	JFrame f = null;
	JSlider slider1;
	JSlider slider2;
	JSlider slider3;
	JLabel label1;
	JLabel label2;
	JLabel label3;

	public SliderDemo2() {
		f = new JFrame("JSlider Example");
		Container contentPane = f.getContentPane();

		JPanel panel1 = new JPanel();
		panel1.setLayout(new GridLayout(2, 1));
		slider1 = new JSlider();
		// setPaintTicks()方法是设置是否在JSlider加上刻度，若为true则下面两行才有作用。
		slider1.setPaintTicks(true);

		/*
		 * 设置大刻度与小刻度之间的距离(setMajorTickSpacing()与setMinorTickSpacing()方法).例如若大刻度间距离为30
		 * ，小刻度间距离为10，则表示2个大刻度间会有3个小刻度.
		 */
		slider1.setMajorTickSpacing(20);
		slider1.setMinorTickSpacing(10);

		// setPaintLabels()方法为设置是否数字标记，若设为true，则JSlider刻度上就会有数值出现。
		slider1.setPaintLabels(true);

		// setPaintTrack()方法表示是否出现滑动杆的横杆。默认值为true.
		slider1.setPaintTrack(true);

		// setSnapToTicks()方法表示一次移动一个小刻度，而不再是一次移动一个单位刻度。
		slider1.setSnapToTicks(true);

		label1 = new JLabel("目前刻度：" + slider1.getValue());
		panel1.add(label1);
		panel1.add(slider1);
		panel1.setBorder(BorderFactory.createTitledBorder(BorderFactory
				.createEtchedBorder(), "Slider 1", TitledBorder.LEFT,
				TitledBorder.TOP));

		JPanel panel2 = new JPanel();
		panel2.setLayout(new GridLayout(2, 1));
		slider2 = new JSlider(JSlider.HORIZONTAL);
		slider2.setMinimum(0);
		slider2.setMaximum(100);
		slider2.setValue(30);
		slider2.setExtent(50);
		slider2.setPaintTicks(true);
		slider2.setMajorTickSpacing(10);
		slider2.setMinorTickSpacing(2);
		slider2.setPaintLabels(true);

		/*
		 * JComponent提供了一个putClientProperty()方法，可以使得JSlider中的小于滑动杆位置与大于滑动杆位置间的颜色不
		 * 一样
		 * ，这样的视觉效果会比较好，"JSlider.isFilled"值是定义在MetalSliderUI这个类的SLIDER_FILL常数中，
		 * 此类是定义在java的JSlider默认外观，你可以在javax.swing.plaf.metal.package中找到这个类。
		 */
		slider2.putClientProperty("JSlider.isFilled", Boolean.TRUE);
		label2 = new JLabel("目前刻度：" + slider2.getValue());
		panel2.add(label2);
		panel2.add(slider2);
		panel2.setBorder(BorderFactory.createTitledBorder(BorderFactory
				.createEtchedBorder(), "Slider 2", TitledBorder.LEFT,
				TitledBorder.TOP));

		JPanel panel3 = new JPanel();
		panel3.setLayout(new GridLayout(2, 1));
		slider3 = new JSlider(20, 80);
		slider3.setOrientation(JSlider.VERTICAL);
		slider3.setPaintTicks(true);
		slider3.setMajorTickSpacing(30);
		slider3.setMinorTickSpacing(10);
		slider3.setPaintLabels(true);
		slider3.putClientProperty("JSlider.isFilled", Boolean.TRUE);
		label3 = new JLabel("目前刻度：" + slider3.getValue());
		panel3.add(label3);
		panel3.add(slider3);
		panel3.setBorder(BorderFactory.createTitledBorder(BorderFactory
				.createEtchedBorder(), "Slider 3", TitledBorder.LEFT,
				TitledBorder.TOP));

		slider1.addChangeListener(this);
		slider2.addChangeListener(this);
		slider3.addChangeListener(this);

		panel1.setPreferredSize(new Dimension(300, 130));
		panel2.setPreferredSize(new Dimension(300, 130));
		panel3.setPreferredSize(new Dimension(150, 260));

		GridBagConstraints c;
		int gridx, gridy, gridwidth, gridheight, anchor, fill, ipadx, ipady;
		double weightx, weighty;
		Insets inset;

		GridBagLayout gridbag = new GridBagLayout();
		contentPane.setLayout(gridbag);

		gridx = 0; // 第0行
		gridy = 0; // 第0列
		gridwidth = 2; // 占两单位宽度
		gridheight = 1; // 占一单位高度
		weightx = 0;
		weighty = 0;
		anchor = GridBagConstraints.CENTER;
		fill = GridBagConstraints.BOTH;
		inset = new Insets(0, 0, 0, 0);
		ipadx = 0;
		ipady = 0;
		c = new GridBagConstraints(gridx, gridy, gridwidth, gridheight,
				weightx, weighty, anchor, fill, inset, ipadx, ipady);
		gridbag.setConstraints(panel1, c);
		contentPane.add(panel1);

		gridx = 0;
		gridy = 1;
		c = new GridBagConstraints(gridx, gridy, gridwidth, gridheight,
				weightx, weighty, anchor, fill, inset, ipadx, ipady);
		gridbag.setConstraints(panel2, c);
		contentPane.add(panel2);

		gridx = 2;
		gridy = 0;
		gridwidth = 1; // 占一单位宽度
		gridheight = 2; // 占两单位高度
		c = new GridBagConstraints(gridx, gridy, gridwidth, gridheight,
				weightx, weighty, anchor, fill, inset, ipadx, ipady);
		gridbag.setConstraints(panel3, c);
		contentPane.add(panel3);

		f.pack();
		f.setVisible(true);

		f.addWindowListener(new WindowAdapter() {
			public void windowClosing(WindowEvent e) {
				System.exit(0);
			}
		});
	}

	public static void main(String[] args) {
		new SliderDemo2();
	}

	public void stateChanged(ChangeEvent e) {
		if ((JSlider) e.getSource() == slider1)
			label1.setText("目前刻度：" + slider1.getValue());
		if ((JSlider) e.getSource() == slider2)
			label2.setText("目前刻度：" + slider2.getValue());
		if ((JSlider) e.getSource() == slider3)
			label3.setText("目前刻度：" + slider3.getValue());
	}
}