再结合网上各路神人及之前写的博客Swing编程方面步骤，如下：

package calPack;

import javax.swing.*;

import java.awt.*;

import java.awt.event.*;

public class Calculator extends JFrame{//自定义类文件，必须继承JFrame框架

//定义组件

JMenuBar jmb;

JMenu[] jm;

JMenuItem[] jmi;

JTextField jtf;

JButton[] jb;

public static void main(String[] args)// 添加主函数，并调用类的构造函数

{

new Calculator();

}

public Calculator()//添加构造函数

{

//创建组件

jmb = new JMenuBar();

jm = new JMenu[3];

jm[0] = new JMenu("查看(V)");

jm[1] = new JMenu("编辑(E)");

jm[2] = new JMenu("帮助(H)");

jmi = new JMenuItem[4];

jmi[0] = new JMenuItem("标准型(T)");

jmi[1] = new JMenuItem("复制(C)");

jmi[2] = new JMenuItem("粘贴(P)");

jmi[3] = new JMenuItem("关于(A)");

jtf = new JTextField("0");

jb = new JButton[28];

jb[0] = new JButton("MC");

jb[1] = new JButton("MR");

jb[2] = new JButton("MS");

jb[3] = new JButton("M+");

jb[4] = new JButton("M-");

jb[5] = new JButton("Backspace");

jb[6] = new JButton("CE");

jb[7] = new JButton("C");

jb[8] = new JButton("+/-");

jb[9] = new JButton("sqrt");

jb[10] = new JButton("7");

jb[11] = new JButton("8");

jb[12] = new JButton("9");

jb[13] = new JButton("/");

jb[14] = new JButton("%");

jb[15] = new JButton("4");

jb[16] = new JButton("5");

jb[17] = new JButton("6");

jb[18] = new JButton("*");

jb[19] = new JButton("1/x");

jb[20] = new JButton("1");

jb[21] = new JButton("2");

jb[22] = new JButton("3");

jb[23] = new JButton("-");

jb[24] = new JButton("=");

jb[25] = new JButton("0");

jb[26] = new JButton(".");

jb[27] = new JButton("+");

initGUI();//设置布局，添加组件

//设置窗口属性

this.setTitle("使用java制作的简易计算器By毛二");//基础属性

this.setIconImage(new ImageIcon("熊猫.jpg").getImage());//设置窗口标题

this.setSize(400,250);//设置大小，按像素

this.setLocation(200,200);//设置初始位置，默认是屏幕最左上角

this.setVisible(true);//让它显示，位置可变

this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);//设置默认到关闭操作，不然java虚拟机还没也关闭

}

//设置布局。

private void initGUI() {

this.setJMenuBar(jmb);

jmb.add(jm[0]);

jmb.add(jm[1]);

jmb.add(jm[2]);

jm[0].add(jmi[0]);

jm[1].add(jmi[1]);

jm[1].add(jmi[2]);

jm[2].add(jmi[3]);

jtf.setEditable(false);//文本框不可编辑

GridBagLayout gridbag = new GridBagLayout();

GridBagConstraints c = new GridBagConstraints();

setLayout(gridbag);

c.weightx = 0.01;//容器上的计算器各个部件成一个布局，这个参数，可以把容器和窗体合二为一，不会出现窗体过大而容器还留有空隙

c.weighty = 0.01;

c.fill = GridBagConstraints.BOTH;

//文本框

c.gridx = 0;

c.gridy = 0;

c.gridwidth = 5;

c.gridheight = 2;

add(jtf,c);

//MC

c.gridx = 0;

c.gridy = 2;

c.gridwidth = 1; // 横占一个单元格

c.gridheight = 1; // 列占一个单元格

addButton(jb[0],gridbag,c);//添加按钮到面板布局

//MR

c.gridx = 1; //换行，放置组件，只需要修改行的参数就行，其他参数暂时不变。

addButton(jb[1],gridbag,c);

//MS

c.gridx = 2;

addButton(jb[2],gridbag,c);

//M+

c.gridx = 3;

addButton(jb[3],gridbag,c);

//M-

c.gridx = 4;

addButton(jb[4],gridbag,c);

//Backspace

c.gridx = 0;

c.gridy = 3;

addButton(jb[5],gridbag,c);

//CE

c.gridx = 1;

addButton(jb[6],gridbag,c);

//C

c.gridx = 2;

addButton(jb[7],gridbag,c);

//+/-

c.gridx = 3;

addButton(jb[8],gridbag,c);

//Sqrt

c.gridx = 4;

addButton(jb[9],gridbag,c);

//7

c.gridx = 0;

c.gridy = 4;

addButton(jb[10],gridbag,c);

//8

c.gridx = 1;

addButton(jb[11],gridbag,c);

//9

c.gridx = 2;

addButton(jb[12],gridbag,c);

///

c.gridx = 3;

addButton(jb[13],gridbag,c);

//%

c.gridx = 4;

addButton(jb[14],gridbag,c);

//4

c.gridx = 0;

c.gridy = 5;

addButton(jb[15],gridbag,c);

//5

c.gridx = 1;

addButton(jb[16],gridbag,c);

//6

c.gridx = 2;

addButton(jb[17],gridbag,c);

//*

c.gridx = 3;

addButton(jb[18],gridbag,c);

//1/x

c.gridx = 4;

addButton(jb[19],gridbag,c);

//1

c.gridx = 0;

c.gridy = 6;

addButton(jb[20],gridbag,c);

//2

c.gridx = 1;

addButton(jb[21],gridbag,c);

//3

c.gridx = 2;

addButton(jb[22],gridbag,c);

//-

c.gridx = 3;

addButton(jb[23],gridbag,c);

//=

c.gridx = 4;

c.gridy = 6;

c.gridheight = 2; //重新设置列，列占二个单元格

addButton(jb[24],gridbag,c);

//0

c.gridx = 0;

c.gridy = 7;

c.gridwidth = 2; // 重新设置横，横占二个单元格

c.gridheight = 1; // 恢复列，列占一个单元格

addButton(jb[25],gridbag,c);

//.

c.gridx = 2;

c.gridwidth = 1; // 恢复横，横占一个单元格

addButton(jb[26],gridbag,c);

//+

c.gridx = 3;

addButton(jb[27],gridbag,c);

}

//添加按钮到面板布局

private void addButton(JButton jButton, GridBagLayout gridbag,

GridBagConstraints c) {

gridbag.setConstraints(jButton, c);

add(jButton);

}

}

效果如下：