Java的Swing布局

一、流布局FlowLayout

默认地，自左向右逐个排列

当一行排满时，自动排到下一行

setPreferredSize()：控制每个控件的显示高度和宽度

案例效果

MyFrame.java

package swing布局;

import javax.swing.*;
import java.awt.*;

public class MyFrame extends JFrame {
    public MyFrame(String title){
        super(title);

        Container contentPane=getContentPane();
        //这里的参数设置的是对齐方式FlowLayout.LEFT左对齐
        LayoutManager layout=new FlowLayout(FlowLayout.LEFT);
        contentPane.setLayout(layout);

        JLabel a1=new ColorfulLabel("1",Color.YELLOW);

        JLabel a2=new ColorfulLabel("2",Color.GREEN);

        JLabel a3=new ColorfulLabel("3",Color.LIGHT_GRAY);

        JLabel a4=new ColorfulLabel("4",Color.CYAN);

        JLabel a5=new ColorfulLabel("5",Color.WHITE);

        contentPane.add(a1);
        contentPane.add(a2);
        contentPane.add(a3);
        contentPane.add(a4);
        contentPane.add(a5);

        //设置宽和高
        a4.setPreferredSize(new Dimension(150,30));

    }

    private static class ColorfulLabel extends JLabel{
        public ColorfulLabel(String text,Color bgColor){
            super(text);
            setOpaque(true);
            setBackground(bgColor);
            setPreferredSize(new Dimension(60,30));
            setHorizontalAlignment(SwingConstants.CENTER);
        }
    }
}

SwingDemo.java

package swing布局;

import javax.swing.*;

public class SwingDemo {
    private static void CreateGUI(){
        JFrame frame=new MyFrame("流布局");
        frame.setSize(400,300);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                CreateGUI();
            }
        });
    }
}

二、边界布局BorderLayout

把容器分为上、下、左、右、中五个区域

setPreferredSize（）

对于上下边界，可以调整高度

对于左右边界，可以调整宽度

运行结果

 MyFrame2.java

package swing布局;

import javax.swing.*;
import java.awt.*;

public class MyFrame2 extends JFrame {
    public MyFrame2(String title){
        super(title);

        Container contentPane=getContentPane();

        contentPane.setLayout(new BorderLayout());

        JLabel a1=new ColorfulLabel("1",Color.YELLOW);

        JLabel a2=new ColorfulLabel("2",Color.GREEN);

        JLabel a3=new ColorfulLabel("3",Color.LIGHT_GRAY);

        JLabel a4=new ColorfulLabel("4",Color.CYAN);

        JLabel a5=new ColorfulLabel("5",Color.WHITE);
        //五个区域
        contentPane.add(a1,BorderLayout.PAGE_START);
        contentPane.add(a2,BorderLayout.PAGE_END);
        contentPane.add(a3,BorderLayout.LINE_START);
        contentPane.add(a4,BorderLayout.LINE_END);
        contentPane.add(a5,BorderLayout.CENTER);

        //设置宽和高
        a1.setPreferredSize(new Dimension(0,80));
        a3.setPreferredSize(new Dimension(100,0));
    }

    private static class ColorfulLabel extends JLabel{
        public ColorfulLabel(String text,Color bgColor){
            super(text);
            setOpaque(true);
            setBackground(bgColor);
            setPreferredSize(new Dimension(60,30));
            setHorizontalAlignment(SwingConstants.CENTER);
        }
    }
}

SwingDemo02.java

package swing布局;

import javax.swing.*;

public class SwingDemo02 {
    private static void CreateGUI(){
        JFrame frame=new MyFrame2("边界布局");
        frame.setSize(400,300);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                CreateGUI();
            }
        });
    }
}

三、卡片布局CardLayout

运行结果

 

 

 通过切换下拉框的内容切换卡片

MyFrame3.java

package swing布局;

import javax.swing.*;
import java.awt.*;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;

public class MyFrame3 extends JFrame {
    JPanel cards=new JPanel();
    JComboBox<String> options=new JComboBox<>();
    public MyFrame3(String title){
        super(title);
        //内容面板
        Container contentPane=getContentPane();
        contentPane.setLayout(new BorderLayout());
        //向下拉框列表添加内容
        options.addItem("第一个面板");
        options.addItem("第二个面板");
        //将下拉框添加至边界布局的顶部
        contentPane.add(options,BorderLayout.PAGE_START);
        //将卡片布局添加至边界布局的center
        contentPane.add(cards,BorderLayout.CENTER);

        //创建第一个面板
        JPanel p1=new JPanel();
        p1.add(new JButton("红"));
        p1.add(new JButton("绿"));
        p1.add(new JButton("蓝"));
        //创建第二个面板
        JPanel p2=new JPanel();
        p2.add(new JLabel("输入"));
        p2.add(new JTextField(20));


        //将这两个面板添加到卡片布局中,其中的第二个参数为布局的名称，方便调用
        cards.setLayout(new CardLayout());
        cards.add(p1,"buttons");
        cards.add(p2,"text");

        //添加事件响应
        options.addItemListener(new ItemListener() {
            @Override
            public void itemStateChanged(ItemEvent e) {
                ItemChange();
            }
        });
    }

    private void ItemChange() {
        CardLayout cardLayout=(CardLayout)cards.getLayout();
        int index=options.getSelectedIndex();
        System.out.println(index);
        if (index==0){
            cardLayout.show(cards,"buttons");
        }else if(index==1){
            cardLayout.show(cards,"text");
        }
    }

}

SwingDemo03.java

package swing布局;

import javax.swing.*;

public class SwingDemo03 {
    private static void CreateGUI(){
        JFrame frame=new MyFrame3("卡片布局");
        frame.setSize(400,300);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                CreateGUI();
            }
        });
    }
}