package cn.com.entity;

import java.awt.*;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import java.awt.event.KeyAdapter;

import java.awt.event.KeyEvent;

import java.awt.image.MemoryImageSource;

import java.util.Random;

import javax.swing.JDialog;

import javax.swing.JPanel;

import javax.swing.Timer;

public class Rain extends JDialog implements ActionListener {

private Random random = new Random();

private Dimension screenSize;

private JPanel graphicsPanel;

//行高,列宽

private final static int gap = 20;

//存放雨点顶部的位置信息(marginTop)

private int[] posArr;

//行数

private int lines;

//列数

private int columns;

public Rain() {

initComponents();

}

private void initComponents() {

setLayout(new BorderLayout());

graphicsPanel = new GraphicsPanel();

add(graphicsPanel, BorderLayout.CENTER);

//设置光标不可见

Toolkit defaultToolkit = Toolkit.getDefaultToolkit();

Image image = defaultToolkit.createImage(new MemoryImageSource(0, 0, null, 0, 0));

Cursor invisibleCursor = defaultToolkit.createCustomCursor(image, new Point(0, 0), “cursor”);

setCursor(invisibleCursor);

//ESC键退出

KeyPressListener keyPressListener = new KeyPressListener();

this.addKeyListener(keyPressListener);

//this.setAlwaysOnTop(true);

//去标题栏

this.setUndecorated(true);

//全屏

this.getGraphicsConfiguration().getDevice().setFullScreenWindow(this);

this.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);

setVisible(true);

screenSize = Toolkit.getDefaultToolkit().getScreenSize();

lines = screenSize.height / gap;

columns = screenSize.width / gap;

posArr = new int[columns + 1];

random = new Random();

for (int i = 0; i < posArr.length; i++) {

posArr[i] = random.nextInt(lines);

}

//每秒10帧

new Timer(100, this).start();

}

/**

* @return 随机字符

*/

private char getChr() {

return (char) (random.nextInt(94) + 33);

}

public void actionPerformed(ActionEvent e) {

graphicsPanel.repaint();

}

private class GraphicsPanel extends JPanel {

public void paint(Graphics g) {

Graphics2D g2d = (Graphics2D) g;

g2d.setFont(getFont().deriveFont(Font.BOLD));

g2d.setColor(Color. BLACK );

g2d.fillRect(0, 0, screenSize.width, screenSize.height);

//当前列

int currentColumn = 0;

for (int x = 0; x < screenSize.width; x += gap) {

int endPos = posArr[currentColumn];

g2d.setColor(Color.CYAN);

g2d.drawString(String.valueOf(getChr()), x, endPos * gap);

}

//每放完一帧，当前列上雨点的位置随机下移1~5行

posArr[currentColumn] += random.nextInt(5);

//当雨点位置超过屏幕高度时，重新产生一个随机位置

if (posArr[currentColumn] * gap > getHeight()) {

posArr[currentColumn] = random.nextInt(lines);

}

currentColumn++;

}

}

}

private class KeyPressListener extends KeyAdapter {

public void keyPressed(KeyEvent e) {

if (e.getKeyCode() == KeyEvent.VK_ESCAPE) {

System.exit(0);

}

}

}

public static void main(String[] args) {

new Rain();

}

}