GUI之进度条JProgressBar 的使用

package com.example;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.FlowLayout;
import java.awt.GridBagLayout;
import java.awt.HeadlessException;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JProgressBar;

/**
* Created by jiawei on 2018/8/4.
*/

public class JProgressBarDemo extends JFrame{
MyPanel panel = new MyPanel();

public JProgressBarDemo() throws HeadlessException {

    panel.setLayout(new FlowLayout(1,5,15));
    JButton start = new JButton("start");
    start.setForeground(Color.RED);
    JProgressBar bar = new JProgressBar();
    bar.setOrientation(JProgressBar.HORIZONTAL);
    bar.setPreferredSize(new Dimension(300,20));
    bar.setMinimum(0);
    bar.setMaximum(100);
    bar.setValue(0);
    bar.setStringPainted(true);
    bar.setBackground(Color.blue);
    bar.setBorderPainted(true);
    panel.add(start);
    panel.add(bar);
    add(panel,BorderLayout.CENTER);
    pack();

    start.addActionListener(new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent actionEvent) {
            new Thread(new Runnable() {
                @Override
                public void run() {
                       for(int i=0; i<=100;i++){
                           bar.setValue(i);
                           try {
                               Thread.sleep(100);
                           } catch (InterruptedException e) {
                               e.printStackTrace();
                           }
                       }
                       bar.setString("下载完成！");
                }
            }).start();
        }
    });
}

public static void main(String[] args){
    EventQueue.invokeLater(new Runnable() {
        @Override
        public void run() {
            JProgressBarDemo demo = new JProgressBarDemo();
            demo.setTitle("myProgressBar");
            demo.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            demo.setLocationByPlatform(true);
            demo.setSize(new Dimension(400,100));
            //让窗体居中显示
            demo.setLocationRelativeTo(null);
            demo.setVisible(true);
        }
    });
}

}

class MyPanel extends JPanel{

@Override
public void setPreferredSize(Dimension dimension) {
    super.setPreferredSize(new Dimension(400,400));
}

}