如何使用 GroupLayout 构建表单？

Question

使用 GroupLayout 在 Java 中构建表单的最简单方法是什么？对于表单，我的意思是前面带有标签的文本字段。像这样的：

Answer 1

使用Group Layout，您可以执行以下操作：

package foo;

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

public class ChangeIpSettingsDialog extends JDialog
{
public ChangeIpSettingsDialog( Frame owner )
{
    super( owner, true );
    setContentPane( createContent() );
}

private Container createContent()
{
    JPanel result = new JPanel();
    result.setBorder( BorderFactory.createEmptyBorder( 10, 10, 10, 10 ) );

    // Create the layout
    GroupLayout layout = new GroupLayout( result );
    result.setLayout( layout );
    layout.setAutoCreateGaps( true );

    // Create the components we will put in the form
    JLabel ipAddressLabel = new JLabel( "IP Address:" );
    JTextField ipAddressTextField = new JTextField( 20 );
    JLabel subnetLabel = new JLabel( "Subnet:" );
    JTextField subnetTextField = new JTextField( 20 );
    JLabel gatewayLabel = new JLabel( "Gateway:" );
    JTextField gatewayTextField = new JTextField( 20 );

    // Horizontally, we want to align the labels and the text fields
    // along the left (LEADING) edge
    layout.setHorizontalGroup( layout.createSequentialGroup()
                                       .addGroup( layout.createParallelGroup( GroupLayout.Alignment.LEADING )
                                                          .addComponent( ipAddressLabel )
                                                          .addComponent( subnetLabel )
                                                          .addComponent( gatewayLabel ) )
                                       .addGroup( layout.createParallelGroup( GroupLayout.Alignment.LEADING )
                                                          .addComponent( ipAddressTextField )
                                                          .addComponent( subnetTextField )
                                                          .addComponent( gatewayTextField ) )
    );

    // Vertically, we want to align each label with his textfield
    // on the baseline of the components
    layout.setVerticalGroup( layout.createSequentialGroup()
                                     .addGroup( layout.createParallelGroup( GroupLayout.Alignment.BASELINE )
                                                        .addComponent( ipAddressLabel )
                                                        .addComponent( ipAddressTextField ) )
                                     .addGroup( layout.createParallelGroup( GroupLayout.Alignment.BASELINE )
                                                        .addComponent( subnetLabel )
                                                        .addComponent( subnetTextField ) )
                                     .addGroup( layout.createParallelGroup( GroupLayout.Alignment.BASELINE )
                                                        .addComponent( gatewayLabel )
                                                        .addComponent( gatewayTextField ) )
    );

    return result;
}

public static void main( String[] args )
{
    ChangeIpSettingsDialog dialog = new ChangeIpSettingsDialog( null );
    dialog.pack();
    dialog.setVisible( true );
}
}

Answer 2

或者您放弃 GroupLayout 并使用 FormLayout，它主要设计为...表单的布局:-)

Answer 3

只需使用 NetBeans 附带的 GUI 编辑器，称为 Matisse。这是我见过的最神奇的 GUI 编辑器。它工作得非常好，你设计的所有窗口都可以调整大小。

此编辑器使用 GroupLayout 生成代码。

Matisse 的克隆也可用作 Eclipse 插件，但我不认为它是免费的。看看这里（免责声明：我以前从未使用过这个插件，所以我无法判断它是否与原始 Matisse 质量相同）
http://marketplace.eclipse.org/content/swing-gui-designer

这是一个不错的截图：

Answer 4

如何使用GridBagLayout 实现演示布局的示例：

class Main extends JFrame implements Runnable {

    JLabel lblIpAddress = new JLabel();
    JLabel lblSubnet = new JLabel();
    JLabel lblGateway = new JLabel();

    JTextField txtIpAddress = new JTextField();
    JTextField txtSubnet = new JTextField();
    JTextField txtGateway = new JTextField();

    public void run() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        Container content = this.getContentPane();

        lblIpAddress.setText("IP Address");
        lblIpAddress.setLabelFor(txtIpAddress);
        lblSubnet.setText("Subnet");
        lblSubnet.setLabelFor(txtSubnet);
        lblGateway.setText("Gateway");
        lblGateway.setLabelFor(txtGateway);

        GridBagLayout layout = new GridBagLayout();
        content.setLayout(layout);

        content.add(lblIpAddress, newLabelConstraints());
        content.add(txtIpAddress, newTextFieldConstraints());
        content.add(lblSubnet, newLabelConstraints());
        content.add(txtSubnet, newTextFieldConstraints());
        content.add(lblGateway, newLabelConstraints());
        content.add(txtGateway, newTextFieldConstraints());

        // Add a spacer to push all the form rows to the top of the window.
        GridBagConstraints spacer = new GridBagConstraints();
        spacer.fill=BOTH;
        spacer.gridwidth=REMAINDER;
        content.add(new JPanel(), spacer);

        // make sure you can't "cut off" the controls when making the window smaller
        this.pack();
        this.setMinimumSize(this.getSize());

        this.setVisible(true);
    }

    private GridBagConstraints newConstraints() {
        GridBagConstraints c = new GridBagConstraints();
        // a little breathing room
        c.insets = new Insets(2, 2, 2, 2);
        return c;
    }

    private GridBagConstraints newLabelConstraints() {
        GridBagConstraints c = newConstraints();
        // right-align labels
        c.anchor = BASELINE_TRAILING;
        // do not grow labels
        c.weightx=0.0;
        return c;
    }

    private GridBagConstraints newTextFieldConstraints() {
        GridBagConstraints c = newConstraints();
        c.anchor = BASELINE;
        // grow text fields horizontally
        c.weightx=1.0;
        c.fill=HORIZONTAL;
        // text fields end a row
        c.gridwidth=REMAINDER;
        return c;
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Main());
    }
}

主要的缺点是，如果你想说，在底部添加一排右对齐的按钮（例如：“确定”和“取消”），这些按钮与其他任何东西都不对齐，你必须使用嵌套的 JPanel。 （或者做一些事情，比如让表单为每个按钮都有一个单独的列；然后让文本字段跨越所有这些列和一个额外的间隔列。这是相当违反直觉的，并且会否定可读性优势。我相信 MiGLayout，这是第三个-party 基于网格的布局管理器可以巧妙地处理这种情况，因为它允许合并/跨越网格单元格，和拆分合并的单元格。）