我已经编写了代码来驱动差分驱动机器人通过我选择的固定路径。我试图从命令行运行代码： java StartRobot 或者能够在浏览器中运行应用程序的Applet。我的代码如下：
import java.awt.*;
import javax.swing.*;
import java.util.ArrayList;
import java.util.List;
class DifferentialDriveRobot {
public static void main(String[] args) {
new DifferentialDriveRobot();
}
public DifferentialDriveRobot() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
createAndShowGUI();
}
});
}
public void createAndShowGUI() {
JFrame frame = new JFrame("Differential Drive Robot");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
Robots robots = new Robots();
frame.add(robots);
frame.setSize(400,400);
frame.setVisible(true);
new Thread(new Drive(robots)).start();
}
public static int random(int maxRange) {
return (int) Math.round((Math.random() * maxRange));
}
public class Robots extends JPanel {
private List<Bot> robots;
public Robots() {
robots = new ArrayList<Bot>(1);
robots.add(new Bot(Color.red));
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
for(Bot robot : robots) {
robot.paint(g2d);
}
g2d.dispose();
}
public List<Bot> getRobots() {
return robots;
}
}
public class Drive implements Runnable {
private Robots parent;
public Drive(Robots parent) {
this.parent = parent;
}
@Override
public void run() {
int width = getParent().getWidth();
int height = getParent().getHeight();
for(Bot robot : getParent().getRobots()) {
int x = 5;
int y = 5;
int diameter = robot.getDiameter();
if(x + diameter > width) {
x = width - diameter;
}
if(y + diameter > height) {
y = height - diameter;
}
robot.setX(x);
robot.setY(y);
}
while(getParent().isVisible()) {
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
getParent().repaint();
}
});
for(Bot robot : getParent().getRobots()) {
move(robot);
}
try {
Thread.sleep(100);
} catch(InterruptedException ex) {}
}
}
public Robots getParent() {
return parent;
}
public void move(Bot robot) {
int diameter = robot.getDiameter();
double v1 = robot.getV1();
double v2 = robot.getV2();
double x = robot.getX();
double y = robot.getY();
double theta = robot.getTheta();
double dx, dy, dtheta;
int time = robot.getTime();
dx = 0.5*(Math.cos(Math.toRadians(theta)))*(v1+v2);
dy = 0.5*(Math.sin(Math.toRadians(theta)))*(v1+v2);
dtheta = (-1)*(0.5*(v2-v1));
if((x + dx < 0 || x + diameter + dx > getParent().getWidth()) || (y + dy < 0 || y + diameter + dy > getParent().getHeight())) {
v1 = 0;
v2 = 0;
} else {
if(time == 50) {
v2 = 0;
} else if(time > 50 && time < 300 && theta == 89.5) {
v1 = v2 = 1;
} else if(time > 300 && time < 450) {
v1 = 1;
v2 = 3;
}
if(time > 400 && theta == -89.0 && time < 500) {
v1 = 5;
v2 = 5;
}
if(time > 500 && time < 550) {
v1 = v2 = 0;
} else if(time > 550 && time < 600) {
v1 = v2 = -2;
} else if(time > 600) {
v1 = v2 = 0;
}
}
x = x + dx;
y = y + dy;
theta = theta + dtheta;
time = time + 1;
robot.setTheta(theta);
robot.setV1(v1);
robot.setV2(v2);
robot.setX(x);
robot.setY(y);
robot.setTime(time);
}
}
public class Bot {
private Color color;
private double x, y;
private int diameter;
private double v1, v2;
private double theta;
private int time;
public Bot(Color color) {
setColor(color);
v1 = 1;
v2 = 1;
diameter = 30;
theta = 0;
time = 0;
}
public int getTime() {
return time;
}
public void setTime(int time) {
this.time = time;
}
public int getDiameter() {
return diameter;
}
public void setColor(Color color) {
this.color = color;
}
public void setX(double x) {
this.x = x;
}
public void setY(double y) {
this.y = y;
}
public void setTheta(double theta) {
this.theta = theta;
}
public Color getColor() {
return color;
}
public double getX() {
return x;
}
public double getY() {
return y;
}
public double getV1() {
return v1;
}
public double getV2() {
return v2;
}
public double getTheta() {
return theta;
}
public void setV1(double v1) {
this.v1 = v1;
}
public void setV2(double v2) {
this.v2 = v2;
}
protected void paint(Graphics2D g2d) {
double x = getX();
double y = getY();
double v1 = getV1();
double v2 = getV2();
g2d.rotate(Math.toRadians(theta),x,y);
g2d.setColor(getColor());
g2d.fillRect((int)x, (int)y, getDiameter(), getDiameter());
g2d.setColor(Color.black);
g2d.fillOval((int)x+9,(int)y-5,15,15);
g2d.fillOval((int)x+9,(int)y+20,15,15);
}
}
}
过去我可以通过在我的.java文件中添加以下内容来完成此任务：
public class StartRobot extends JApplet {
public void init() {
EventQueue.invokeLater(new Runnable() {
public void run() {
DifferentialDriveRobot panel = new DifferentialDriveRobot();
getContentPane.add(panel);
}
});
}
public static void main(String[] args) {
//Schedule a job for the event-dispatching thread:
//creating and showing this application's GUI.
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
DifferentialDriveRobot panel = new DifferentialDriveRobot();
panel.createAndShowGUI();
}
});
}
}
但是，这会在编译时抛出错误。我认为这是因为我的主类DifferentialDriveRobot没有扩展JPanel，而是我完成此操作的子类。有没有快速解决这个问题？
答案 0 :(得分：5)
类DifferentialDriveRobot是一个无法添加到applet的非组件类。这个类会导致创建JFrame并添加您的Robot面板类。如果您在浏览器中运行applet，这将导致出现JFrame，这通常是不可取的。
您可以将班级Robot定义为您的小程序：
public class Robot extends JApplet {
public void init() {
...
}
然后将小程序添加到您的main方法：
public static void main(String[] args) {
JFrame frame = new JFrame("Applet Demo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(500, 400);
JApplet applet = new Robot();
applet.init();
applet.start();
frame.add(applet);
frame.setVisible(true);
}
如果您希望applet作为应用程序运行，一个很好的选择是将其完全转换为基于JFrame的应用程序，并使用Java Web Start进行部署。