Java实现Map集合二级联动示例

map集合可以保存键值映射关系，这非常适合本实例所需要的数据结构，所有省份信息可以保存为map集合的键，而每个键可以保存对应的城市信息，本实例就是利用map集合实现了省市级联选择框，当选择省份信息时，将改变城市下拉选择框对应的内容。

思路分析：

1. 创建全国（省，直辖市，自治区）映射集合，即linkedhashmap对象，使用map接口的put()方法向集合中添加指定的省与城市的映射关系，其中值为string型一维数组。

代码如下：

citymap.java

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","*","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("*", 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. 定义获取省份的方法，创建一个map集合，将上一步得到的映射集合赋值给它，使用map集合的keyset()方法获取该集合中的所有键对象组成的set集合，即为省分集合，创建一个object型一维数组，使用set接口的toarray()方法将set集合转换为数组，返回此数组作为省份选择下拉列表的参数。

3. 使用jcombobox类的setmodel()方法为省份下拉列表添加省份信息，参数即为上一步中的获取省份方法。

4. 定义根据省份获取市/县的方法，创建一个map集合，将步骤1中得到的映射集合赋值给它，使用map集合的get()方法获取指定键的值，即为市/县集合，创建一个string[]型一维数组，将市/县集合赋值给该数组。

5. 定义省份下拉列表的选项状态更改事件，在该事件中通过jcombobox类的getselecteditem()方法获取选中的省份，默认为省份集合中的第一个值，然后使用jcombobox类的removeallitems()方法清空市/县列表，根据选中的省份获取市/县数组，最后使用jcombobox的setmodel()方法重新添加市/县列表的值。

    代码如下：

backgroundpanel.java

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
    }
}

swingresourcemanager.java

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);
    }
}

mainframe.java

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
    }

}

效果如图：