如何为窗口应用程序设置 setBorder？

Question

我尝试创建一些用于监控网络的应用程序。我将创建 4 个JPanels 并插入例如面板insert_panel_0、insert_panel_2 到panel_2。我无法在insert_panel_0、insert_panel_2 之间设置边界。我有垂直间隙，但我没有水平间隙。

你能帮我解决吗？

import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.Toolkit;

import javax.swing.JFrame;
import javax.swing.JLayeredPane;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;

public class setting {

    public static void main(String[] args) {

        //get size window
        Dimension tk = Toolkit.getDefaultToolkit().getScreenSize();

        int  width = (int) tk.width;
        int  hight = (int) tk.height;



        JFrame frame = new JFrame(); 
        frame.setLayout(new GridLayout(1,4, 0, 0));
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().setBackground(Color.black);
        frame.setExtendedState(JFrame.MAXIMIZED_BOTH); 



        // set panels for window
        JPanel panel_0 = new JPanel();
        panel_0.setLayout(new FlowLayout(FlowLayout.CENTER, 0, 0));
        panel_0.setBorder(new EmptyBorder(20, 20,20, 20));
        panel_0.setBackground(Color.white);
        frame.add(panel_0);



        JPanel panel_1 = new JPanel();
        panel_1.setLayout(new FlowLayout(FlowLayout.CENTER, 0, 0));
        panel_1.setBackground(Color.yellow);
        panel_1.setBorder(new EmptyBorder(20, 20,20, 20));      
        frame.add(panel_1);

        JPanel panel_2 = new JPanel();
        panel_2.setLayout(new FlowLayout(FlowLayout.CENTER, 0, 0));
        panel_2.setBorder(new EmptyBorder(20, 20,20, 20));      
        panel_2.setBackground(Color.green);
        frame.add(panel_2);


        JPanel panel_3 = new JPanel();
        panel_3.setLayout(new FlowLayout(FlowLayout.CENTER, 0, 0));
        panel_3.setBorder(new EmptyBorder(20, 20,20, 20));      
        panel_3.setBackground(Color.blue);

        frame.add(panel_3);

        JPanel insert_panel_0 = new JPanel();
        insert_panel_0.setPreferredSize( new Dimension(width/4, (int) Math.round( hight*0.05)));
        insert_panel_0.setBackground(Color.black);
        panel_2.add(insert_panel_0);

        JPanel insert_panel_1 = new JPanel();
        insert_panel_1.setPreferredSize( new Dimension(width/4, (int) Math.round( hight*0.05)));
        insert_panel_1.setBackground(Color.black);
        panel_2.add(insert_panel_1);    

        frame.setVisible(true);
    }

}

Answer 1

insert_panel_0.setPreferredSize( new Dimension(width/4, (int) Math.round( hight*0.05)));

问题在于您的宽度计算。当您除以 4 时，每个黑色子面板的宽度就是整个父面板的宽度。这会导致两个问题：

1. 子面板无法适应具有 20 像素边框的父面板，因此在面板边缘进行绘制
2. FlowLayout 然后会自动将第二个面板换行到下一行。所以面板显示在两行。

解决方案是改进宽度计算，例如：

insert_panel_0.setPreferredSize( new Dimension(width/12, (int) Math.round( hight*0.05)));

现在两个面板将出现在同一行。

如果您想要两个黑色面板之间有间隙，那么您还需要：

//panel_2.setLayout(new FlowLayout(FlowLayout.CENTER, 0, 0));
panel_2.setLayout(new FlowLayout(FlowLayout.CENTER, 20, 0));

Answer 2

GridLayout 有设置水平和垂直间距的方法：setHgap(hgap) 和setVGap(vgap)。或者您可以在构造函数中创建布局时提供它们：new GridLayout(rows, cols, hgap, vgap)

希望对你有帮助。

Answer 3

您可以使用 GridBagLayout 并利用 Insets。然而这带来了一个新问题：

在计算 insert_panel_0 和 insert_panel_1 的 Dimension 时，您需要考虑插入的大小，因为如果总大小（insert_panel_0_size + insert_panel_1_size + Insets em>) 大于父级 (panel_2_size)，insert_panel_0 和 insert_panel_1 将无法正确调整大小。

构造函数和描述：（来自 java-docs）：

Insets(int top, int left, int bottom, int right) 使用指定的顶部、左侧、底部创建并初始化一个新的 Insets 对象， 和右插图。

与您的问题无关，但在 Java GUI 中，您应该始终从事件调度线程调用您的 GUI。当您开始在 GUI 中获取更复杂/动态更新的值时，这将帮助您避免不必要的行为。

您修改后的代码（您将不得不使用您的维度公式，我将其注释掉是因为：懒惰）：

import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.Insets;
import java.awt.Toolkit;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;

public class Test {

    public static void main(String[] args) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createGUI();
            }
        });
    }

    public static void createGUI() {

        //get size window
        Dimension tk = Toolkit.getDefaultToolkit().getScreenSize();

        int  width = (int) tk.width;
        int  hight = (int) tk.height;



        JFrame frame = new JFrame(); 
        frame.setLayout(new GridLayout(1,4, 0, 0));
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().setBackground(Color.black);
        frame.setExtendedState(JFrame.MAXIMIZED_BOTH); 



        // set panels for window
        JPanel panel_0 = new JPanel();
        panel_0.setLayout(new FlowLayout(FlowLayout.CENTER, 0, 0));
        panel_0.setBorder(new EmptyBorder(20, 20,20, 20));
        panel_0.setBackground(Color.white);
        frame.add(panel_0);



        JPanel panel_1 = new JPanel();
        panel_1.setLayout(new FlowLayout(FlowLayout.CENTER, 0, 0));
        panel_1.setBackground(Color.yellow);
        panel_1.setBorder(new EmptyBorder(20, 20,20, 20));      
        frame.add(panel_1);

        JPanel panel_2 = new JPanel();
        panel_2.setLayout(new GridBagLayout());
        panel_2.setBorder(new EmptyBorder(20, 20,20, 20));      
        panel_2.setBackground(Color.green);
        frame.add(panel_2);


        JPanel panel_3 = new JPanel();
        panel_3.setLayout(new FlowLayout(FlowLayout.CENTER, 0, 0));
        panel_3.setBorder(new EmptyBorder(20, 20,20, 20));      
        panel_3.setBackground(Color.blue);

        frame.add(panel_3);

        GridBagConstraints gbc = new GridBagConstraints();

        gbc.insets = new Insets(0,5,0,5); // Horizontal padding only

        JPanel insert_panel_0 = new JPanel();
        //insert_panel_0.setPreferredSize( new Dimension((width/4), (int) Math.round( hight*0.05)));
        insert_panel_0.setPreferredSize(new Dimension(200, 100));
        insert_panel_0.setBackground(Color.black);

        gbc.gridx = 0;
        gbc.gridy = 0;
        panel_2.add(insert_panel_0, gbc);

        JPanel insert_panel_1 = new JPanel();
        //insert_panel_1.setPreferredSize( new Dimension(width/4 - 10, (int) Math.round( hight*0.05)));
        insert_panel_1.setPreferredSize(new Dimension(200, 100));
        insert_panel_1.setBackground(Color.black);

        gbc.gridx = 1;
        gbc.gridy = 0;
        panel_2.add(insert_panel_1, gbc);    

        frame.setVisible(true);
    }
}