Swing-setAlignmentX()用法-入门

先看下API：

public void setAlignmentX(float alignmentX)

设置垂直对齐方式。

参数： alignmentX - 新的垂直对齐方式

网上关于这个函数的详细情况介绍的不多，JAVA布局管理器提到说， setAlignmentX（left，right）只有在布局是BoxLayout.Y_AXIS才效，而setAlignmentY（top，button）在布局为BoxLayout.X_AXIS才效果。我基本同意这个理解，也就是说，setAlignmentX()用于使用了BoxLayout.Y_AXIS时，将控件在X轴方向设置为左对齐、右对齐或居中对齐；setAlignmentY()用于使用了BoxLayout.X_AXIS时，将控件在Y轴方向设置为顶对齐、底对齐或居中对齐。以下是测试代码：

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.LayoutManager;
import java.awt.TextArea;
import javax.swing.BorderFactory;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.OverlayLayout;
import javax.swing.border.EtchedBorder;

/*
 * 2015-06-13
 */
public class setAlignmentDemo {

    public static void main(String[] args) {
        // TODO Auto-generated method stub

        //第一个panel，垂直排列
        JPanel  jpanelY = new JPanel();
        jpanelY.setLayout(new BoxLayout(jpanelY,BoxLayout.Y_AXIS));
        jpanelY.setBorder(BorderFactory.createTitledBorder("BoxLayout.Y_AXIS"));
        JButton   buttonY1 = new JButton("LEFT_ALIGNMENT");
        JButton   buttonY2 = new JButton("RIGHT_ALIGNMENT");
        JButton   buttonY3 = new JButton("CENTER_ALIGNMENT");

        buttonY1.setAlignmentX(Component.LEFT_ALIGNMENT);
        buttonY2.setAlignmentX(Component.RIGHT_ALIGNMENT);
        buttonY3.setAlignmentX(Component.CENTER_ALIGNMENT);

        jpanelY.add(buttonY1);
        jpanelY.add(buttonY2);
        jpanelY.add(buttonY3);
      //第二个panel，水平排列
        JPanel  jpanelX=new JPanel();
        jpanelX.setLayout(new BoxLayout(jpanelX,BoxLayout.X_AXIS));
        jpanelX.setBorder(BorderFactory.createTitledBorder("BoxLayout.X_AXIS"));

        JButton buttonX1 = new JButton("TOP_ALIGNMENT");
        JButton buttonX2 = new JButton("BOTTOM_ALIGNMENT");
        JButton buttonX3 = new JButton("CENTER_ALIGNMENT");

        buttonX1.setAlignmentY(Component.TOP_ALIGNMENT);
        buttonX2.setAlignmentY(Component.BOTTOM_ALIGNMENT);
        buttonX3.setAlignmentY(Component.CENTER_ALIGNMENT);

        jpanelX.add(buttonX1);
        jpanelX.add(buttonX2);
        jpanelX.add(buttonX3);

        //添加两个panel到窗体
        JFrame frame = new JFrame("setAlignmentDemo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLayout(new FlowLayout());
        frame.add(jpanelX);
        frame.add(jpanelY);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }
}

运行效果如下：

运行效果图

那么问题来了，运行结果的对齐方式是反的？