Java的JTextField的不尊重给定的列宽

Here's the GUI I created using a grid bag layout.

Here are the major changes I made.

1. I used a JFrame. There's no reason to extend a Swing component unless you're going to override one of the class methods.

2. I arranged the JFrame methods in the proper order. The JFrame methods must be called in the order that I put in the code.

3. I grouped all of the JComponent methods together for each JComponent and created the JComponents in the order they appear on the JFrame. For the love of all developers, always create the JComponents in row, column order.

4. I removed all sizing, except for the prefered viewpoint size of the JTable.

5. I defined grid bag constraints for each and every JComponent. That way, you can adjust the constraints for each JComponent. Besides, I don't remember defaults.

There are two JPanels in this GUI. The main JPanel holds all the JComponents except for the JButtons. The second JPanel holds the JButtons. This is because there are 3 buttons, and I divided the grid bag layout into 4 columns.

网格包布局采用4列。JTable中占据了所有4列，以及按钮的JPanel。

下面的代码。

package com.ggl.testing;

import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.table.DefaultTableCellRenderer;
import javax.swing.table.TableCellRenderer;

public class UserForm {

    // top, left, bottom, right
    private static final Insets topInsets = new Insets(10, 10, 10, 10);
    private static final Insets topCenterInsets = new Insets(10, 0, 10, 10);
    private static final Insets middleInsets = new Insets(0, 10, 10, 10);
    private static final Insets middleCenterInsets = new Insets(0, 0, 10, 10);

    public UserForm() {

        JFrame frame = new JFrame("User Form");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        // Miscelaneous
        Font plain = new Font("Tahoma", Font.PLAIN, 12);
        Font bold11 = new Font("Tahoma", Font.BOLD, 11);
        Font bold12 = new Font("Tahoma", Font.BOLD, 12);

        JPanel mainPanel = new JPanel();
        mainPanel.setLayout(new GridBagLayout());

        int gridy = 0;

        // Data-In Form Components
        JLabel idl = new JLabel("Id:");
        idl.setFont(bold12);
        addComponent(mainPanel, idl, 0, gridy, 1, 1, topInsets, GridBagConstraints.LINE_START,
                GridBagConstraints.NONE);

        JTextField idtf = new JTextField(40);
        idtf.setFont(plain);
        addComponent(mainPanel, idtf, 1, gridy, 1, 1, topCenterInsets, GridBagConstraints.LINE_START,
                GridBagConstraints.HORIZONTAL);

        JLabel agl = new JLabel("Age:");
        agl.setFont(bold12);
        addComponent(mainPanel, agl, 2, gridy, 1, 1, topCenterInsets, GridBagConstraints.LINE_START,
                GridBagConstraints.NONE);

        JTextField agtf = new JTextField(40);
        agtf.setFont(plain);
        addComponent(mainPanel, agtf, 3, gridy++, 1, 1, topCenterInsets, GridBagConstraints.LINE_START,
                GridBagConstraints.HORIZONTAL);

        JLabel namel = new JLabel("Name:");
        namel.setFont(bold12);
        addComponent(mainPanel, namel, 0, gridy, 1, 1, middleInsets, GridBagConstraints.LINE_START,
                GridBagConstraints.NONE);

        JTextField nametf = new JTextField(40);
        nametf.setFont(plain);
        addComponent(mainPanel, nametf, 1, gridy, 1, 1, middleCenterInsets, GridBagConstraints.LINE_START,
                GridBagConstraints.HORIZONTAL);

        JLabel adl = new JLabel("Address:");
        adl.setFont(bold12);
        addComponent(mainPanel, adl, 2, gridy, 1, 1, middleCenterInsets, GridBagConstraints.LINE_START,
                GridBagConstraints.NONE);

        JTextField adtf = new JTextField(40);
        adtf.setFont(plain);
        addComponent(mainPanel, adtf, 3, gridy++, 1, 1, middleCenterInsets, GridBagConstraints.LINE_START,
                GridBagConstraints.HORIZONTAL);

        JLabel pnl = new JLabel("Phone Number:");
        pnl.setFont(bold12);
        addComponent(mainPanel, pnl, 0, gridy, 1, 1, middleInsets, GridBagConstraints.LINE_START,
                GridBagConstraints.NONE);

        JTextField pntf = new JTextField(40);
        pntf.setFont(plain);
        addComponent(mainPanel, pntf, 1, gridy, 1, 1, middleCenterInsets, GridBagConstraints.LINE_START,
                GridBagConstraints.HORIZONTAL);

        JLabel ln1l = new JLabel("First Lastname:");
        ln1l.setFont(bold12);
        addComponent(mainPanel, ln1l, 2, gridy, 1, 1, middleCenterInsets, GridBagConstraints.LINE_START,
                GridBagConstraints.NONE);

        JTextField ln1tf = new JTextField(40);
        ln1tf.setFont(plain);
        addComponent(mainPanel, ln1tf, 3, gridy++, 1, 1, middleCenterInsets, GridBagConstraints.LINE_START,
                GridBagConstraints.HORIZONTAL);

        JLabel ln2l = new JLabel("Second Lastname:");
        ln2l.setFont(bold12);
        addComponent(mainPanel, ln2l, 0, gridy, 1, 1, middleInsets, GridBagConstraints.LINE_START,
                GridBagConstraints.NONE);

        JTextField ln2tf = new JTextField(40);
        ln2tf.setFont(plain);
        addComponent(mainPanel, ln2tf, 1, gridy, 1, 1, middleCenterInsets, GridBagConstraints.LINE_START,
                GridBagConstraints.HORIZONTAL);

        JLabel eml = new JLabel("E-Mail:");
        eml.setFont(bold12);
        addComponent(mainPanel, eml, 2, gridy, 1, 1, middleCenterInsets, GridBagConstraints.LINE_START,
                GridBagConstraints.NONE);

        JTextField emtf = new JTextField(40);
        emtf.setFont(plain);
        addComponent(mainPanel, emtf, 3, gridy++, 1, 1, middleCenterInsets, GridBagConstraints.LINE_START,
                GridBagConstraints.HORIZONTAL);

        // JTable Creation
        String[] headline = { "Id", "Name", "First Lastname", "Second Lastname", "Age", "Address", "Phone Number",
                "E-Mail" };
        String[][] data = { { "", "", "", "", "", "", "", "" }, { "", "", "", "", "", "", "", "" } };
        JTable dataShow = new JTable(data, headline);
        dataShow.setPreferredScrollableViewportSize(new Dimension(900, 300));
        dataShow.setFillsViewportHeight(true);
        JScrollPane scrollPane = new JScrollPane(dataShow);
        addComponent(mainPanel, scrollPane, 0, gridy++, 4, 1, middleInsets, GridBagConstraints.LINE_START,
                GridBagConstraints.HORIZONTAL);


        // Table Personalization
        dataShow.getTableHeader().setFont(bold11);
        new HeaderRenderer(dataShow);

        // buttons Components 
        JPanel buttonPanel = new JPanel();
        buttonPanel.setLayout(new GridBagLayout());
        JButton save = new JButton("Save");
        save.setFont(bold12);
        addComponent(buttonPanel, save, 0, 0, 1, 1, topInsets, GridBagConstraints.CENTER,
                GridBagConstraints.HORIZONTAL);

        JButton del = new JButton("Delete");
        del.setFont(bold12);
        addComponent(buttonPanel, del, 1, 0, 1, 1, topInsets, GridBagConstraints.CENTER,
                GridBagConstraints.HORIZONTAL);

        JButton edit = new JButton("Edit");
        edit.setFont(bold12);
        addComponent(buttonPanel, edit, 2, 0, 1, 1, topInsets, GridBagConstraints.CENTER,
                GridBagConstraints.HORIZONTAL);

        addComponent(mainPanel, buttonPanel, 0, gridy++, 4, 1, middleInsets, GridBagConstraints.LINE_START,
                GridBagConstraints.HORIZONTAL);

        // set content pane
        frame.add(mainPanel);
        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);

        // For future table filling
        /*
         * String ids = idtf.getText(); String names = nametf.getText(); String ln1s =
         * ln1tf.getText(); String ln2s = ln2tf.getText(); String ags = agtf.getText();
         * String ads = adtf.getText(); String pns = pntf.getText(); String ems =
         * emtf.getText();
         */

    }

    private void addComponent(Container container, Component component, int gridx, int gridy, int gridwidth,
            int gridheight, Insets insets, int anchor, int fill) {
        GridBagConstraints gbc = new GridBagConstraints(gridx, gridy, gridwidth, gridheight, 1.0, 1.0, anchor, fill,
                insets, 0, 0);
        container.add(component, gbc);
    }

    public static void main(String[] args) {

        // invoke runnable for thread safety
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new UserForm();
            }
        });

    }

    // LEFT alignment renderer
    private class HeaderRenderer implements TableCellRenderer {

        DefaultTableCellRenderer renderer;

        public HeaderRenderer(JTable table) {
            renderer = (DefaultTableCellRenderer) table.getTableHeader().getDefaultRenderer();
            renderer.setHorizontalAlignment(JLabel.LEFT);
        }

        @Override
        public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus,
                int row, int col) {
            return renderer.getTableCellRendererComponent(table, value, isSelected, hasFocus, row, col);
        }

    }

}