从小程序打开 JFrame [英] opening JFrame from applet

问题描述

所以我编写了一个小程序，它可以让一个球永远在圆圈中滚动，我想让用户决定圆圈应该以什么速度滚动，但是当我添加 JFrame 时失败了:

So I programmed am applet that makes a ball roll in circles for ever, and I wanted to make the user decide what speed the circle should roll in, but something failed when I added the JFrame:

小程序(停止、销毁和更新不出现，因为它们不重要，而在开始时什么都没有):

applet(the stop,destroy and update do not appear because they aren't important, and in start there is nothing):

public class Main extends Applet implements Runnable{

private Image I;
private Graphics GfU;
int ballX, ballY=249;
static int radius=20;
double Memory;
int changeY ,changeX=1;
Speed S = new Speed();

@Override
public void init() {
    setSize(750,750);
    S.setVisible(true);
}

@Override
public void run() {
    while(true){
        if(ballY>=250 || ballY<=-250){
            changeY=0-changeY;
            changeX=0-changeX;
        }
        ballY+=changeY;
        Memory=(double)ballY/250; 
        Memory=Math.asin(Memory);
        Memory=Math.cos(Memory);
        ballX=(int)(Memory*250);
        if(changeX==-1)
            ballX=0-ballX;

        repaint();
        try {
            Thread.sleep(17);            
        }
        catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }       
    }
}



@Override
public void paint(Graphics g) {
    g.setColor(Color.black);
    g.fillOval(ballX-radius+250, ballY-radius+250, radius*2, radius*2);
}


public void setChangeY(int changeY) {
    this.changeY = changeY;
}

public void Done(){
    S.setVisible(false);
    Thread BallRun = new Thread(this);
    BallRun.start();
}

}

JFrame:

public class Speed extends JFrame implements ActionListener{
private static final long serialVersionUID = 1L;

public Speed(){
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    JPanel P = new JPanel();
    JLabel L = new JLabel("please enter velosity(pixels per second)");
    final JTextField TF = new JTextField("00");
    final Main M = new Main();
    JButton B = new JButton("OK");

    B.addActionListener(new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent e) {
            M.setChangeY(Integer.parseInt(TF.getText()));
            M.Done();

        }
    });

    P.add(L,BorderLayout.NORTH);
    P.add(TF,BorderLayout.WEST);

}

@Override
public void actionPerformed(ActionEvent arg0) {


}
}

谢谢(如果没有信息让您感到困扰，请见谅)

thanks (and sorry if it's bothering you the lack of information)

推荐答案

setDefaultCloseOperation(EXIT_ON_CLOSE);

即使在完全受信任的小程序中，这也是不允许的.关闭框架将关闭运行启动它的小程序的 JVM.该 JVM 也可能正在运行其他小程序.

This is not allowed even in a fully trusted applet. Closing the frame would close the JVM that runs the applet that launched it. That JVM might also be running other applets.

这样看.承载小程序的网页就像一个客人，而网页则是一个宾馆.一个小程序结束JVM就像客人烧毁宾馆，同时砸碎所有窗户.

Look at it like this. The web page that hosts an applet is like a guest, while the web page is a guest house. For an applet to end the JVM is like the guest burning down the guest house while smashing out all the windows.

setDefaultCloseOperation(DISPOSE_ON_CLOSE);

可能会工作"(不会产生 AccessControlException)，但实际上，没有小程序应该启动框架.使用 JDialog 代替.

Might 'work' (to not produce an AccessControlException), but really, no applet should be launching frames. Use a JDialog instead.

一般提示:确保 Java 控制台配置为显示小程序和JWS 应用程序.如果默认级别没有输出，请将其提高并重试.如果没有其中包含的信息，我怀疑是否有可能成功开发小程序.

As a general tip: Ensure the Java Console is configured to show for applets & JWS apps. If there is no output at the default level, raise it and try again. Without the information contained in it, I doubt it would be possible to successfully develop an applet.

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