Java實作Map的集合二級連動方法解析

Map集合可以保存鍵值映射關係，這非常適合本實例所需的資料結構，所有省份資訊可以保存為Map集合的鍵，而每個鍵可以保存對應的城市信息，本實例就是利用Map集合實現了省市級聯選擇框，當選擇省份資訊時，將改變城市下拉選擇框對應的內容。

思路分析：

1. 創建全國（省，直轄市，自治區）映射集合，即LinkedHashMap對象，使用Map接口的put()方法向集合中添加指定的省與城市的映射關係，其中值為String型一維數組。

import java.util.LinkedHashMap;
import java.util.Map;
 
public class CityMap {
    /**
     * 全国（省，直辖市，自治区）映射集合
     */
    public static Map<String,String[]> model=new LinkedHashMap<String, String[]>();
    static{
        model.put("北京", new String[]{"北京"});
        model.put("上海", new String[]{"上海"});
        model.put("天津", new String[]{"天津"});
        model.put("重庆", new String[]{"重庆"});
        model.put("黑龙江", new String[]{"哈尔滨","齐齐哈尔","牡丹江","大庆","伊春","双鸭山","鹤岗","鸡西","佳木斯","七台河","黑河","绥化","大兴安岭"});
        model.put("吉林", new String[]{"长春","延边","吉林","白山","白城","四平","松原","辽源","大安","通化"});
        model.put("辽宁", new String[]{"沈阳","大连","葫芦岛","旅顺","本溪","抚顺","铁岭","辽阳","营口","阜新","朝阳","锦州","丹东","鞍山"});
        model.put("内蒙古", new String[]{"呼和浩特","呼伦贝尔","锡林浩特","包头","赤峰","海拉尔","乌海","鄂尔多斯","通辽"});
        model.put("河北", new String[]{"石家庄","唐山","张家口","廊坊","邢台","邯郸","沧州","衡水","承德","保定","秦皇岛"});
        model.put("河南", new String[]{"郑州","开封","洛阳","平顶山","焦作","鹤壁","新乡","安阳","濮阳","许昌","漯河","三门峡","南阳","商丘","信阳","周口","驻马店"});
        model.put("山东", new String[]{"济南","青岛","淄博","威海","曲阜","临沂","烟台","枣庄","聊城","济宁","菏泽","泰安","日照","东营","德州","滨州","莱芜","潍坊"});
        model.put("山西", new String[]{"太原","阳泉","晋城","晋中","临汾","运城","长治","朔州","忻州","大同","吕梁"});
        model.put("江苏", new String[]{"南京","苏州","昆山","南通","太仓","吴县","徐州","宜兴","镇江","淮安","常熟","盐城","泰州","无锡","连云港","扬州","常州","宿迁"});
        model.put("安徽", new String[]{"合肥","巢湖","蚌埠","安庆","六安","滁州","马鞍山","阜阳","宣城","铜陵","淮北","芜湖","毫州","宿州","淮南","池州"});
        model.put("陕西", new String[]{"西安","韩城","安康","汉中","宝鸡","咸阳","榆林","渭南","商洛","铜川","延安"});
        model.put("宁夏", new String[]{"银川","固原","中卫","石嘴山","吴忠"});
        model.put("甘肃", new String[]{"兰州","白银","庆阳","酒泉","天水","武威","张掖","甘南","临夏","平凉","定西","金昌"});
        model.put("青海", new String[]{"西宁","海北","海西","黄南","果洛","玉树","海东","海南"});
        model.put("湖北", new String[]{"武汉","宜昌","黄冈","恩施","荆州","神农架","十堰","咸宁","襄樊","孝感","随州","黄石","荆门","鄂州"});
        model.put("湖南", new String[]{"长沙","邵阳","常德","郴州","吉首","株洲","娄底","湘潭","益阳","永州","岳阳","衡阳","怀化","韶山","张家界"});
        model.put("浙江", new String[]{"杭州","湖州","金华","宁波","丽水","绍兴","雁荡山","衢州","嘉兴","台州","舟山","温州"});
        model.put("江西", new String[]{"南昌","萍乡","九江","上饶","抚州","吉安","鹰潭","宜春","新余","景德镇","赣州"});
        model.put("福建", new String[]{"福州","厦门","龙岩","南平","宁德","莆田","泉州","三明","漳州"});
        model.put("贵州", new String[]{"贵阳","安顺","赤水","遵义","铜仁","六盘水","毕节","凯里","都匀"});
        model.put("四川", new String[]{"成都","泸州","内江","凉山","阿坝","巴中","广元","乐山","绵阳","德阳","攀枝花","雅安","宜宾","自贡","甘孜州","达州","资阳","广安","遂宁","眉山","南充"});
        model.put("广东", new String[]{"广州","深圳","潮州","韶关","湛江","惠州","清远","东莞","江门","茂名","肇庆","汕尾","河源","揭阳","梅州","中山","德庆","阳江","云浮","珠海","汕头","佛山"});
        model.put("广西", new String[]{"南宁","桂林","阳朔","柳州","梧州","玉林","桂平","贺州","钦州","贵港","防城港","百色","北海","河池","来宾","崇左"});
        model.put("云南", new String[]{"昆明","保山","楚雄","德宏","红河","临沧","怒江","曲靖","思茅","文山","玉溪","昭通","丽江","大理"});
        model.put("海南", new String[]{"海口","三亚","儋州","琼山","通什","文昌"});
        model.put("新疆", new String[]{"乌鲁木齐","阿勒泰","阿克苏","昌吉","哈密","和田","喀什","克拉玛依","石河子","塔城","库尔勒","吐鲁番","伊宁"});
    }
}

2. 定義取得省份的方法，建立一個Map集合，將上一個步驟得到的映射集合賦值給它，使用Map集合的keySet()方法取得該集合中的所有鍵物件組成的Set集合，即為省分集合，建立一個Object型一維數組，使用Set介面的toArray()方法將Set集合轉換為數組，並傳回此數組作為省份選擇下拉列表的參數。

3. 使用JComboBox類別的setModel()方法為省份下拉列表添加省份信息，參數即為上一步中的獲取省份方法。

4. 定義根據省份取得市/縣的方法，建立一個Map集合，將步驟1中得到的映射集合賦值給它，使用Map集合的get()方法來取得指定鍵的值，即為市/縣集合，建立一個String[]型一維數組，將市/縣集合賦值給該數組。

5. 定義省份下拉清單的選項狀態變更事件，在該事件中透過JComboBox類別的getSelectedItem()方法取得選取的省份，預設為省份集合中的第一個值，然後使用JComboBox類的removeAllItems()方法清空市/縣列表，根據選取的省份取得市/縣數組，最後使用JComboBox的setModel()方法重新新增市/縣列表的值。

import java.awt.Graphics;
import java.awt.Image;
 
import javax.swing.JPanel;
 
/**
 * 带背景的面板组件
 *
 * @author ZhongWei Lee
 */
public class BackgroundPanel extends JPanel {
 
    /**
     *
     */
    private static final long serialVersionUID = 7758689434195492602L;
    /**
     * 背景图片
     */
    private Image image;
 
    /**
     * 构造方法
     */
    public BackgroundPanel() {
        super();
        setOpaque(false);
        setLayout(null);
    }
 
    /**
     * 设置图片的方法
     */
    public void setImage(Image image) {
        this.image = image;
    }
 
    @Override
    protected void paintComponent(Graphics g) {// 重写绘制组件外观
        if (image != null) {
            int width = getWidth();// 获取组件大小
            int height = getHeight();
            g.drawImage(image, 0, 0, width, height, this);// 绘制图片与组件大小相同
        }
        super.paintComponent(g);// 执行超类方法
    }
}

  import java.awt.Image;
import java.awt.Toolkit;
import java.io.BufferedInputStream;
import java.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.Iterator;
import javax.swing.ImageIcon;
 
/**
 * Utility class for managing resources such as colors, fonts, images, etc.
 *
 * This class may be freely distributed as part of any application or plugin.
 * <p>
 * Copyright (c) 2003 - 2004, Instantiations, Inc. <br>All Rights Reserved
 *
 * @author scheglov_ke
 */
public class SwingResourceManager {
     
    /**
     * Maps image names to images
     */
    private static HashMap<String, Image> m_ClassImageMap = new HashMap<String, Image>();
     
    /**
     * Returns an image encoded by the specified input stream
     * @param is InputStream The input stream encoding the image data
     * @return Image The image encoded by the specified input stream
     */
    private static Image getImage(InputStream is) {
        try {
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            byte buf[] = new byte[1024 * 4];
            while (true) {
                int n = is.read(buf);
                if (n == -1)
                    break;
                baos.write(buf, 0, n);
            }
            baos.close();
            return Toolkit.getDefaultToolkit().createImage(baos.toByteArray());
        } catch (Throwable e) {
            return null;
        }
    }
     
    /**
     * Returns an image stored in the file at the specified path relative to the specified class
     * @param clazz Class The class relative to which to find the image
     * @param path String The path to the image file
     * @return Image The image stored in the file at the specified path
     */
    public static Image getImage(Class<?> clazz, String path) {
        String key = clazz.getName() + '|' + path;
        Image image = m_ClassImageMap.get(key);
        if (image == null) {
            if ((path.length() > 0) && (path.charAt(0) == '/')) {
                String newPath = path.substring(1, path.length());
                image = getImage(new BufferedInputStream(clazz.getClassLoader().getResourceAsStream(newPath)));
            } else {
                image = getImage(clazz.getResourceAsStream(path));
            }
            m_ClassImageMap.put(key, image);
        }
        return image;
    }
     
    /**
     * Returns an image stored in the file at the specified path
     * @param path String The path to the image file
     * @return Image The image stored in the file at the specified path
     */
    public static Image getImage(String path) {
        return getImage("default", path); //$NON-NLS-1$
    }
     
    /**
     * Returns an image stored in the file at the specified path
     * @param section String The storage section in the cache
     * @param path String The path to the image file
     * @return Image The image stored in the file at the specified path
     */
    public static Image getImage(String section, String path) {
        String key = section + '|' + SwingResourceManager.class.getName() + '|' + path;
        Image image = m_ClassImageMap.get(key);
        if (image == null) {
            try {
                FileInputStream fis = new FileInputStream(path);
                image = getImage(fis);
                m_ClassImageMap.put(key, image);
                fis.close();
            } catch (IOException e) {
                return null;
            }
        }
        return image;
    }
     
    /**
     * Clear cached images in specified section
     * @param section the section do clear
     */
    public static void clearImages(String section) {
        for (Iterator<String> I = m_ClassImageMap.keySet().iterator(); I.hasNext();) {
            String key = I.next();
            if (!key.startsWith(section + '|'))
                continue;
            Image image = m_ClassImageMap.get(key);
            image.flush();
            I.remove();
        }
    }
     
    /**
     * Returns an icon stored in the file at the specified path relative to the specified class
     * @param clazz Class The class relative to which to find the icon
     * @param path String The path to the icon file
     * @return Icon The icon stored in the file at the specified path
     */
    public static ImageIcon getIcon(Class<?> clazz, String path) {
        return getIcon(getImage(clazz, path));
    }
     
    /**
     * Returns an icon stored in the file at the specified path
     * @param path String The path to the icon file
     * @return Icon The icon stored in the file at the specified path
     */
    public static ImageIcon getIcon(String path) {
        return getIcon("default", path); //$NON-NLS-1$
    }
     
    /**
     * Returns an icon stored in the file at the specified path
     * @param section String The storage section in the cache
     * @param path String The path to the icon file
     * @return Icon The icon stored in the file at the specified path
     */
    public static ImageIcon getIcon(String section, String path) {
        return getIcon(getImage(section, path));
    }
 
    /**
     * Returns an icon based on the specified image
     * @param image Image The original image
     * @return Icon The icon based on the image
     */
    public static ImageIcon getIcon(Image image) {
        if (image == null)
            return null;
        return new ImageIcon(image);
    }
}

  import java.awt.EventQueue;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.util.Map;
import java.util.Set;
 
import javax.swing.DefaultComboBoxModel;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingConstants;
import javax.swing.UIManager;
import javax.swing.border.TitledBorder;
 
 
public class MainFrame extends JFrame {
 
    /**
     *
     */
    private static final long serialVersionUID = -4595347311922711984L;
    private JTextField textField_3;
    private JTextField textField_1;
    private JComboBox comboBox_1;
    private JTextField textField;
    private JComboBox cityComboBox;
    private JComboBox comboBox;
 
    /**
     * Launch the application
     *
     * @param args
     */
    public static void main(String args[]) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    UIManager.setLookAndFeel("com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel");
                    MainFrame frame = new MainFrame();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }
 
    /**
     * Create the frame
     */
    public MainFrame() {
        getContentPane().setLayout(null);
        setBounds(100, 100, 518, 379);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        //获取默认的市/县
        String province=(String)getProvince()[0];
        setTitle("输入指定省/直辖市查询对应的市县");
 
        final BackgroundPanel backgroundPanel = new BackgroundPanel();
        backgroundPanel.setImage(SwingResourceManager.getImage(MainFrame.class, "/images/background.jpg"));
        backgroundPanel.setBounds(0, 0, 510, 380);
        getContentPane().add(backgroundPanel);
 
        final JPanel panel = new JPanel();
        panel.setOpaque(false);
        panel.setBounds(36, 126, 438, 70);
        backgroundPanel.add(panel);
        panel.setLayout(null);
        panel.setBorder(new TitledBorder(null, "居住地", TitledBorder.DEFAULT_JUSTIFICATION, TitledBorder.DEFAULT_POSITION, null, null));
        cityComboBox = new JComboBox();
        cityComboBox.setBounds(245, 25, 124, 27);
        panel.add(cityComboBox);
         
        cityComboBox.setModel(new DefaultComboBoxModel(getCity(province)));
 
        comboBox = new JComboBox();
        comboBox.setBounds(25, 25, 124, 27);
        panel.add(comboBox);
        comboBox.addItemListener(new ItemListener() {
            public void itemStateChanged(final ItemEvent e) { // 选项状态更改事件
                itemChange();
            }
        });
        comboBox.setModel(new DefaultComboBoxModel(getProvince())); // 添加省份信息
 
        final JLabel label = new JLabel();
        label.setText("省/直辖市");
        label.setBounds(155, 30, 66, 18);
        panel.add(label);
 
        final JLabel label_1 = new JLabel();
        label_1.setText("市/县");
        label_1.setBounds(375, 30, 37, 18);
        panel.add(label_1);
 
        final JLabel label_2 = new JLabel();
        label_2.setBounds(36, 43, 65, 18);
        backgroundPanel.add(label_2);
        label_2.setHorizontalAlignment(SwingConstants.RIGHT);
        label_2.setHorizontalTextPosition(SwingConstants.LEADING);
        label_2.setText("姓    名：");
 
        textField = new JTextField();
        textField.setBounds(113, 38, 154, 28);
        backgroundPanel.add(textField);
 
        final JLabel label_3 = new JLabel();
        label_3.setBounds(36, 84, 65, 18);
        backgroundPanel.add(label_3);
        label_3.setHorizontalAlignment(SwingConstants.RIGHT);
        label_3.setHorizontalTextPosition(SwingConstants.LEADING);
        label_3.setText("性    别：");
 
        comboBox_1 = new JComboBox();
        comboBox_1.setBounds(113, 81, 66, 25);
        backgroundPanel.add(comboBox_1);
        comboBox_1.setModel(new DefaultComboBoxModel(new String[] {"男", "女"}));
 
        final JLabel label_4 = new JLabel();
        label_4.setBounds(36, 212, 65, 18);
        backgroundPanel.add(label_4);
        label_4.setHorizontalAlignment(SwingConstants.RIGHT);
        label_4.setHorizontalTextPosition(SwingConstants.LEADING);
        label_4.setText("详细地址：");
 
        textField_1 = new JTextField();
        textField_1.setBounds(113, 208, 367, 28);
        backgroundPanel.add(textField_1);
 
        final JLabel label_4_1 = new JLabel();
        label_4_1.setBounds(36, 252, 65, 18);
        backgroundPanel.add(label_4_1);
        label_4_1.setHorizontalTextPosition(SwingConstants.LEADING);
        label_4_1.setHorizontalAlignment(SwingConstants.RIGHT);
        label_4_1.setText("E-mail：");
 
        textField_3 = new JTextField();
        textField_3.setBounds(113, 248, 367, 27);
        backgroundPanel.add(textField_3);
 
        final JButton button = new JButton();
        button.setBounds(159, 289, 75, 28);
        backgroundPanel.add(button);
        button.setText("保存");
 
        final JButton button_1 = new JButton();
        button_1.setBounds(265, 289, 75, 28);
        backgroundPanel.add(button_1);
        button_1.setText("重置");
        //
    }
 
    /**
     * 获取省、直辖市，自治区
     *
     * @return
     */
    public Object[] getProvince() {
        Map<String, String[]> map = CityMap.model;// 获取省份信息保存到Map中
        Set<String> set = map.keySet(); // 获取Map集合中的键，并以Set集合返回
        Object[] province = set.toArray(); // 转换为数组
        return province; // 返回获取的省份信息
    }
 
    /**
     * 获取指定省对应的市/县
     *
     * @param selectProvince
     * @return
     */
    public String[] getCity(String selectProvince) {
        Map<String, String[]> map = CityMap.model; // 获取省份信息保存到Map中
        String[] arrCity = map.get(selectProvince); // 获取指定键的值
        return arrCity; // 返回获取的市/县
    }
 
    private void itemChange() {
        String selectProvince = (String) comboBox.getSelectedItem();
        cityComboBox.removeAllItems(); // 清空市/县列表
        String[] arrCity = getCity(selectProvince); // 获取市/县
        cityComboBox.setModel(new DefaultComboBoxModel(arrCity)); // 重新添加市/县列表的值
    }
 
}

#效果如圖：

########### ## ###

以上是Java實作Map的集合二級連動方法解析的詳細內容。更多資訊請關注PHP中文網其他相關文章！