今天遇到一個(gè)問題如下：

Paste_Image.png

Paste_Image.png

把上圖的數(shù)據(jù)結(jié)構(gòu)，轉(zhuǎn)換成下圖的數(shù)據(jù)結(jié)構(gòu)。結(jié)果今天腦袋瓦特了，想了有2個(gè)小時(shí)沒用想出思路。后來在網(wǎng)友的幫助下得到解決。
回到正題:

這是原始的數(shù)據(jù)結(jié)構(gòu)：
Arera

@Data
public class Area implements Serializable {

    private String prvoince;
    private String city;
    private String district;
    private String address;

    public Area(String prvoince, String city, String district, String address) {
        this.prvoince = prvoince;
        this.city = city;
        this.district = district;
        this.address = address;
    }
}

下面是需要的輔助類

City:

@Data
public class City implements Serializable {
    private String cityName;
    private List<District> districtList;

    public void addDistrict(List<District> district) {
        for (District d : district) {
            districtList.add(d);
        }
    }

    public City(String cityName, List<District> districtList) {
        this.cityName = cityName;
        this.districtList = districtList;
    }
}

Distract:

@Data
public class District implements Serializable{
    private String districtName;
    private List<Detail> detailList;

    public void addDetail(List<Detail> detail) {
        for (Detail d : detail) {
            detailList.add(d);
        }
    }

    public District(String districtName, List<Detail> detailList) {
        this.districtName = districtName;
        this.detailList = detailList;
    }
}

Detail:

@Data
public class Detail implements Serializable {
    private String address;

    public Detail(String address) {
        this.address = address;
    }
}

下面就是開始轉(zhuǎn)換數(shù)據(jù)結(jié)構(gòu)的代碼了，其實(shí)很簡單。

public static void main(String[] args) {
        List<Area> areaList = new ArrayList<Area>();
        areaList.add(new Area("江蘇省", "南京市", "玄武區(qū)", "新模范馬路1001號"));
        areaList.add(new Area("江蘇省", "南京市", "秦淮區(qū)", "雨花臺路30號"));
        areaList.add(new Area("江蘇省", "南京市", "鼓樓區(qū)", "中山1路1號"));
        areaList.add(new Area("湖南省", "長沙市", "芙蓉區(qū)", "橘子洲"));
        areaList.add(new Area("湖南省", "長沙市", "下沙區(qū)", "寶昌路32號"));
        areaList.add(new Area("江蘇省", "徐州市", "云龍區(qū)", "云龍大道22號"));
        areaList.add(new Area("江蘇省", "徐州市", "銅山區(qū)", "上海路45號"));

        covertData(areaList);
    }
    private static void covertData(List<Area> areaList) {
        Map<String, City> cityMap = new HashMap<>(); //最終需要的數(shù)據(jù)結(jié)構(gòu)
        Map<String, District> districtMap = new HashMap<>(); //區(qū)名稱的數(shù)據(jù)結(jié)構(gòu)， 輔助作用
        areaList.stream().forEach(item -> {
            Detail detail = new Detail(item.getAddress());
            List<Detail> details = new ArrayList<>();
            details.add(detail);
            if (districtMap.containsKey(item.getDistrict())) {
                //如果區(qū)名稱已經(jīng)存在，更新區(qū)下面的詳細(xì)地址
                districtMap.get(item.getDistrict()).addDetail(details);
            } else {
                //如果區(qū)名稱不存在，就創(chuàng)建這個(gè)區(qū)并且加入map
                District district = new District(item.getDistrict(), details);
                List<District> districtList = new ArrayList<>();
                districtList.add(district);
                districtMap.put(item.getDistrict(), district);

                if (cityMap.containsKey(item.getCity())) {
                    //如果city存在，更新city下面的區(qū)
                    cityMap.get(item.getCity()).addDistrict(districtList);
                } else {
                    //如果city名稱不存在，就創(chuàng)建這個(gè)city并加入map
                    City city = new City(item.getCity(), districtList);
                    cityMap.put(item.getCity(), city);
                }
            }
        });
        System.out.println(JSONObject.toJSONString(cityMap)); //這個(gè)就是我最終需要的結(jié)果
    }

特此記一下，說不定哪天腦子又突然瓦特了。