演示图：

如图，使用输入框形式将信息保存为JSON格式数据文件，打开文件

上面工具栏分别为：新建、打开和保存按钮

准备工作：

导入json.jar，用于操作JSON数据格式，资源链接：json.jar

导入Af开头的工具包（这步骤可以省略，主要用于方便布局和对JSON数据进行操作，如果没有请自行解决）

导入Image图片资源，用于上方工具栏

上代码：

import java.awt.BorderLayout;
import java.io.File;
import java.net.URL;

import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.JToolBar;
import javax.swing.filechooser.FileNameExtensionFilter;

import org.json.JSONObject;

import af.common.json.AfJSON;
import af.swing.AfPanel;
import af.swing.layout.AfColumnLayout;
import af.swing.layout.AfRowLayout;

public class MyFrame extends JFrame
{
	JTextField nameField = new JTextField(20);
	JTextField idField = new JTextField(20);
	JComboBox<String> sexField = new JComboBox<>();
	JTextField phoneField = new JTextField(20);
	
	public MyFrame(String title)
	{
		super(title);
		
		JPanel root = new JPanel();
		this.setContentPane(root);
		root.setLayout(new BorderLayout());
		
		//添加中间组件
		initMainPanle();
		
		//添加工具栏
		initToolBar();
	}
	
	public void initMainPanle()
	{
		//创建布局器
		AfPanel main = new AfPanel();
		this.getContentPane().add(main, BorderLayout.CENTER);
		main.padding(20);
		//纵向布局
		main.setLayout(new AfColumnLayout(10));
		
		AfPanel row1 = new AfPanel();
		row1.setLayout(new AfRowLayout(10));
		row1.add(new JLabel("姓名"), "50px");
		row1.add(nameField, "1w");
		
		AfPanel row2 = new AfPanel();
		row2.setLayout(new AfRowLayout(10));
		row2.add(new JLabel("学号"), "50px");
		row2.add(idField, "1w");
		
		AfPanel row3 = new AfPanel();
		row3.setLayout(new AfRowLayout(10));
		row3.add(new JLabel("性别"), "50px");
		row3.add(sexField, "1w");
		sexField.addItem("男");
		sexField.addItem("女");
		
		AfPanel row4 = new AfPanel();
		row4.setLayout(new AfRowLayout(10));
		row4.add(new JLabel("电话"), "50px");
		row4.add(phoneField, "1w");
		
		main.add(row1);
		main.add(row2);
		main.add(row3);
		main.add(row4);
	}
	
	private void initToolBar()
	{
		JToolBar toolBar = new JToolBar();
		this.getContentPane().add(toolBar, BorderLayout.PAGE_START);
		
		JButton newButton = createButton("image_new.png", "新建");
		JButton openButton = createButton("image_open.png", "打开");
		JButton saveButton = createButton("image_save.png", "保存");
		toolBar.add(newButton);
		toolBar.add(openButton);
		toolBar.add(saveButton);
		
		//添加按钮点击事件
		newButton.addActionListener(e->{
			doNew();
		});
		openButton.addActionListener(e->{
			doOpen();
		});
		saveButton.addActionListener(e->{
			doSave();
		});
	}
	
	//创建图标按钮
	private JButton createButton(String filePath, String toolText)
	{
		JButton button = new JButton();
		button.setToolTipText(toolText);
		button.setFocusable(false);
		
		String file = "/images/" + filePath;
		URL url = getClass().getResource(file);
		//加载图片资源
		button.setIcon(new ImageIcon(url));
		
		return button;
	}
	
	//新建（清空文本）
	private void doNew()
	{
		nameField.setText("");
		idField.setText("");
		phoneField.setText("");
		sexField.setSelectedIndex(0);
	}
	
	//打开（读取JSON文件）
	private void doOpen()
	{
		//创建文件选择器（对话框）
		JFileChooser chooser = new JFileChooser();
		//创建文件过滤器
		FileNameExtensionFilter filter = new FileNameExtensionFilter("JSON", "json", "stu");
		//过滤文件
		chooser.setFileFilter(filter);
		
		//打开对话框
		int reg = chooser.showOpenDialog(this);
		if(reg == JFileChooser.APPROVE_OPTION)
		{
			File file = chooser.getSelectedFile();
			try
			{
				//使用AFJSON工具类读取文件
				String message = AfJSON.fromFile(file, "utf-8").toString();
				//解析JSON格式文件
				JSONObject j = new JSONObject(message);
				String name = j.getString("name");
				String id = j.getString("id");
				boolean sex = j.getBoolean("sex");
				String phone = j.getString("phone");
				
				//给每一个控件赋值
				nameField.setText(name);
				idField.setText(id);
				if(sex)
					sexField.setSelectedIndex(0);
				else
					sexField.setSelectedIndex(1);
				phoneField.setText(phone);
				
				JOptionPane.showMessageDialog(this, "打开成功");
			} catch (Exception e)
			{
				// TODO Auto-generated catch block
				e.printStackTrace();
				JOptionPane.showMessageDialog(this, "出错");
			}
		}
		
		
	}
	
	//保存（写入JSON文件）
	private void doSave()
	{
		String name = nameField.getText().trim();	//trim()方法去除字符串两边的空白
		String id = idField.getText().trim();
		String phone = phoneField.getText().trim();
		boolean sex = (sexField.getSelectedIndex() == 0);
		
		//判断是否有空值
		if(name.isEmpty() || id.isEmpty() || phone.isEmpty())
		{
			JOptionPane.showMessageDialog(this, "输入不得为空！");
			return;
		}
		
		//创建JSON对象
		//转成JSON格式
		JSONObject j = new JSONObject();
		j.put("name", name);
		j.put("id", id);
		j.put("phone", phone);
		j.put("sex", sex);
		
		//打开文件选择对话框
		JFileChooser chooser = new JFileChooser();
		FileNameExtensionFilter filter = new FileNameExtensionFilter("JSON", "json");
		chooser.setFileFilter(filter);
		
		int reg = chooser.showSaveDialog(this);
		if(reg == JFileChooser.APPROVE_OPTION)
		{
			File file = chooser.getSelectedFile();
			//判断文件后缀
			if(!file.getName().endsWith("stu"))
			{
				//将文件后缀改为.stu
				String filePath = file.getAbsolutePath() + ".stu";
				file = new File(filePath);
			}
			
			try
			{
				AfJSON.toFile(j, file, "UTF-8");
				JOptionPane.showMessageDialog(this, "保存成功");
				//清空显示
				doNew();
			} catch (Exception e)
			{
				// TODO Auto-generated catch block
				e.printStackTrace();
				JOptionPane.showMessageDialog(this, "出错");
			}
		}
		
		
	}
}

在这里，我要感谢@邵发老师，里面Af打头的工具类都是他写的，我也是参考他的教程做出来的。