String转数组再转String

Question

[
    {"id":"34","itemName":"1","user_id":"100001","pic":"http://localhost:8080/img/fanqie.jpg","price":"700","count":"15","buy_no":"20201014150857","szk":"aaa"},
    {"id":"3","itemName":"2","user_id":"100001","pic":"http://localhost:8080/img/xigua.jpg","price":"600","count":"10","buy_no":"20201014150857","szk":"aaa"},
    {"id":"9","itemName":"3","user_id":"100001","pic":"http://localhost:8080/img/qiezi.jpg","price":"700","count":"30","buy_no":"20201014150857","szk":"aaa"},
    {"id":"13","itemName":"4","user_id":"100001","pic":"http://localhost:8080/img/juzi.jpg","price":"700","count":"14","buy_no":"20201014150857","szk":"aaa"},
    {"id":"3","itemName":"5","user_id":"100001","pic":"http://localhost:8080/img/xigua.jpg","price":"600","count":"12","buy_no":"20201014152727","szk":"aaa"},
    {"id":"15","itemName":"6","user_id":"100001","pic":"http://localhost:8080/img/fanqie.jpg","price":"700","count":"30","buy_no":"20201014152727","szk":"aaa"},
    {"id":"84","itemName":"7","user_id":"100001","pic":"http://localhost:8080/img/taozi.jpg","price":"700","count":"18","buy_no":"20201014152727","szk":"aaa"},
    {"id":"54","itemName":"8","user_id":"100001","pic":"http://localhost:8080/img/huanggua.jpg","price":"600","count":"109","buy_no":"20201014152727","szk":"aaa"},
    {"id":"22","itemName":"9","user_id":"100001","pic":"http://localhost:8080/img/xigua.jpg","price":"600","count":"33","buy_no":"20201014183740","szk":"aaa"},
    {"id":"3","itemName":"10","user_id":"100001","pic":"http://localhost:8080/img/xigua.jpg","price":"600","count":"3","buy_no":"20201014183740","szk":"aaa"},
    {"id":"1","itemName":"11","user_id":"100001","pic":"http://localhost:8080/img/pinguo.jpg","price":"600","count":"30","buy_no":"20201015144738","szk":"aaa"},
    {"id":"76","itemName":"12","user_id":"100001","pic":"http://localhost:8080/img/qiezi.jpg","price":"700","count":"30","buy_no":"20201015144738","szk":"aaa"},
    {"id":"72","itemName":"13","user_id":"100001","pic":"http://localhost:8080/img/fanqie.jpg","price":"700","count":"3","buy_no":"20201015190607","szk":"aaa"},
    {"id":"88","itemName":"14","user_id":"100001","pic":"http://localhost:8080/img/xigua.jpg","price":"600","count":"10","buy_no":"20201015190607","szk":"aaa"},
    {"id":"2","itemName":"15","user_id":"100001","pic":"http://localhost:8080/img/xiangjiao.jpg","price":"700","count":"1","buy_no":"20201015190607","szk":"aaa"},
    {"id":"15","itemName":"16","user_id":"100001","pic":"http://localhost:8080/img/fanqie.jpg","price":"700","count":"10","buy_no":"20201014113653","szk":"aaa"},
    {"id":"3","itemName":"17","user_id":"100001","pic":"http://localhost:8080/img/xigua.jpg","price":"600","count":"3","buy_no":"20201014113653","szk":"aaa"},
    {"id":"36","itemName":"18","user_id":"100001","pic":"http://localhost:8080/img/taozi.jpg","price":"700","count":"10","buy_no":"20201014113653","szk":"aaa"}
]

上面的String是搜索数据库返回的String结果，
我想根据buyno这个字段对它进行分组，最后想给前端返回下面这样结构的
String字符串

[
    { "buy_no":"20201014150857","arr":
        [
            {"id":"1","itemName":"トマト","user_id":"100001","pic":"http://localhost:8080/img/fanqie.jpg","price":"700","count":"15","szk":"aaa"}, 
            {"id":"2","itemName":"スイカ","user_id":"100001","pic":"http://localhost:8080/img/xigua.jpg","price":"600","count":"10","szk":"aaa"},
            {"id":"3","itemName":"ナス","user_id":"100001","pic":"http://localhost:8080/img/qiezi.jpg","price":"700","count":"30","szk":"aaa"},
            {"id":"4","itemName":"ミカン","user_id":"100001","pic":"http://localhost:8080/img/juzi.jpg","price":"700","count":"14","szk":"aaa"}
        ]
    },
    { "buy_no":"20201014152727","arr":
        [
            {"id":"5","itemName":"スイカ","user_id":"100001","pic":"http://localhost:8080/img/xigua.jpg","price":"600","count":"12","szk":"aaa"}, 
            {"id":"6","itemName":"トマト","user_id":"100001","pic":"http://localhost:8080/img/fanqie.jpg","price":"700","count":"30","szk":"aaa"}, 
            {"id":"7","itemName":"モモ","user_id":"100001","pic":"http://localhost:8080/img/taozi.jpg","price":"700","count":"18","szk":"aaa"}, 
            {"id":"8","itemName":"キュウリ","user_id":"100001","pic":"http://localhost:8080/img/huanggua.jpg","price":"600","count":"109","szk":"aaa"}
        ]
    },
    { "buy_no":"20201014183740","arr":
        [
            {"id":"9","itemName":"スイカ","user_id":"100001","pic":"http://localhost:8080/img/xigua.jpg","price":"600","count":"33","szk":"aaa"}, 
            {"id":"10","itemName":"スイカ","user_id":"100001","pic":"http://localhost:8080/img/xigua.jpg","price":"600","count":"3","szk":"aaa"}
        ]
    },
    { "buy_no":"20201015144738","arr":
        [
            {"id":"11","itemName":"リンゴ","user_id":"100001","pic":"http://localhost:8080/img/pinguo.jpg","price":"600","count":"30","szk":"aaa"}, 
            {"id":"12","itemName":"イチゴ","user_id":"100001","pic":"http://localhost:8080/img/qiezi.jpg","price":"700","count":"30","szk":"aaa"}
        ]
    },
    { "buy_no":"20201015190607","arr":
        [
            {"id":"13","itemName":"トマト","user_id":"100001","pic":"http://localhost:8080/img/fanqie.jpg","price":"700","count":"3","szk":"aaa"}, 
            {"id":"14","itemName":"スイカ","user_id":"100001","pic":"http://localhost:8080/img/xigua.jpg","price":"600","count":"10","szk":"aaa"},
            {"id":"15","itemName":"バナナ","user_id":"100001","pic":"http://localhost:8080/img/xiangjiao.jpg","price":"700","count":"1","szk":"aaa"}
        ]
    },
    { "buy_no":"20201014113653","arr":
        [
            {"id":"16","itemName":"トマト","user_id":"100001","pic":"http://localhost:8080/img/fanqie.jpg","price":"700","count":"10","szk":"aaa"}, 
            {"id":"17","itemName":"スイカ","user_id":"100001","pic":"http://localhost:8080/img/xigua.jpg","price":"600","count":"3","szk":"aaa"},
            {"id":"18","itemName":"モモ","user_id":"100001","pic":"http://localhost:8080/img/taozi.jpg","price":"700","count":"10","szk":"aaa"}
        ]
    }
]

Answer 1

实体类

/**
 * @author YuLF
 * @version 1.0
 * @date 2020/10/20 13:00
 * 存储数据的实体类，为了方便我全都String
 */
public class TestBean {
    private String  id;
    private String itemName;
    private String user_id;
    private String pic;
    private String price;
    private String count;
    private String buy_no;
    private String szk;

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getItemName() {
        return itemName;
    }

    public void setItemName(String itemName) {
        this.itemName = itemName;
    }

    public String getUser_id() {
        return user_id;
    }

    public void setUser_id(String user_id) {
        this.user_id = user_id;
    }

    public String getPic() {
        return pic;
    }

    public void setPic(String pic) {
        this.pic = pic;
    }

    public String getPrice() {
        return price;
    }

    public void setPrice(String price) {
        this.price = price;
    }

    public String getCount() {
        return count;
    }

    public void setCount(String count) {
        this.count = count;
    }

    public String getBuy_no() {
        return buy_no;
    }

    public void setBuy_no(String buy_no) {
        this.buy_no = buy_no;
    }

    public String getSzk() {
        return szk;
    }

    public void setSzk(String szk) {
        this.szk = szk;
    }

    @Override
    public String toString() {
        return "TestBean{" +
                "id='" + id + '\'' +
                ", itemName='" + itemName + '\'' +
                ", user_id='" + user_id + '\'' +
                ", pic='" + pic + '\'' +
                ", price='" + price + '\'' +
                ", count='" + count + '\'' +
                ", buy_no='" + buy_no + '\'' +
                ", szk='" + szk + '\'' +
                '}';
    }
}

数据库字符串文件：

[{
  "id": "34",
  "itemName": "1",
  "user_id": "100001",
  "pic": "http://localhost:8080/img/fanqie.jpg",
  "price": "700",
  "count": "15",
  "buy_no": "20201014150857",
  "szk": "aaa"
},
  {
    "id": "3",
    "itemName": "2",
    "user_id": "100001",
    "pic": "http://localhost:8080/img/xigua.jpg",
    "price": "600",
    "count": "10",
    "buy_no": "20201014150857",
    "szk": "aaa"
  },
  {
    "id": "9",
    "itemName": "3",
    "user_id": "100001",
    "pic": "http://localhost:8080/img/qiezi.jpg",
    "price": "700",
    "count": "30",
    "buy_no": "20201014150857",
    "szk": "aaa"
  },
  {
    "id": "13",
    "itemName": "4",
    "user_id": "100001",
    "pic": "http://localhost:8080/img/juzi.jpg",
    "price": "700",
    "count": "14",
    "buy_no": "20201014150857",
    "szk": "aaa"
  },
  {
    "id": "3",
    "itemName": "5",
    "user_id": "100001",
    "pic": "http://localhost:8080/img/xigua.jpg",
    "price": "600",
    "count": "12",
    "buy_no": "20201014152727",
    "szk": "aaa"
  },
  {
    "id": "15",
    "itemName": "6",
    "user_id": "100001",
    "pic": "http://localhost:8080/img/fanqie.jpg",
    "price": "700",
    "count": "30",
    "buy_no": "20201014152727",
    "szk": "aaa"
  },
  {
    "id": "84",
    "itemName": "7",
    "user_id": "100001",
    "pic": "http://localhost:8080/img/taozi.jpg",
    "price": "700",
    "count": "18",
    "buy_no": "20201014152727",
    "szk": "aaa"
  },
  {
    "id": "54",
    "itemName": "8",
    "user_id": "100001",
    "pic": "http://localhost:8080/img/huanggua.jpg",
    "price": "600",
    "count": "109",
    "buy_no": "20201014152727",
    "szk": "aaa"
  },
  {
    "id": "22",
    "itemName": "9",
    "user_id": "100001",
    "pic": "http://localhost:8080/img/xigua.jpg",
    "price": "600",
    "count": "33",
    "buy_no": "20201014183740",
    "szk": "aaa"
  },
  {
    "id": "3",
    "itemName": "10",
    "user_id": "100001",
    "pic": "http://localhost:8080/img/xigua.jpg",
    "price": "600",
    "count": "3",
    "buy_no": "20201014183740",
    "szk": "aaa"
  },
  {
    "id": "1",
    "itemName": "11",
    "user_id": "100001",
    "pic": "http://localhost:8080/img/pinguo.jpg",
    "price": "600",
    "count": "30",
    "buy_no": "20201015144738",
    "szk": "aaa"
  },
  {
    "id": "76",
    "itemName": "12",
    "user_id": "100001",
    "pic": "http://localhost:8080/img/qiezi.jpg",
    "price": "700",
    "count": "30",
    "buy_no": "20201015144738",
    "szk": "aaa"
  },
  {
    "id": "72",
    "itemName": "13",
    "user_id": "100001",
    "pic": "http://localhost:8080/img/fanqie.jpg",
    "price": "700",
    "count": "3",
    "buy_no": "20201015190607",
    "szk": "aaa"
  },
  {
    "id": "88",
    "itemName": "14",
    "user_id": "100001",
    "pic": "http://localhost:8080/img/xigua.jpg",
    "price": "600",
    "count": "10",
    "buy_no": "20201015190607",
    "szk": "aaa"
  },
  {
    "id": "2",
    "itemName": "15",
    "user_id": "100001",
    "pic": "http://localhost:8080/img/xiangjiao.jpg",
    "price": "700",
    "count": "1",
    "buy_no": "20201015190607",
    "szk": "aaa"
  },
  {
    "id": "15",
    "itemName": "16",
    "user_id": "100001",
    "pic": "http://localhost:8080/img/fanqie.jpg",
    "price": "700",
    "count": "10",
    "buy_no": "20201014113653",
    "szk": "aaa"
  },
  {
    "id": "3",
    "itemName": "17",
    "user_id": "100001",
    "pic": "http://localhost:8080/img/xigua.jpg",
    "price": "600",
    "count": "3",
    "buy_no": "20201014113653",
    "szk": "aaa"
  },
  {
    "id": "36",
    "itemName": "18",
    "user_id": "100001",
    "pic": "http://localhost:8080/img/taozi.jpg",
    "price": "700",
    "count": "10",
    "buy_no": "20201014113653",
    "szk": "aaa"
  }
]

转换类：

/**
 * @author YuLF
 * @version 1.0
 * @date 2020/10/20 12:54
 */
public class TestMain1 {
    public static void main(String[] args) throws IOException {
        //databasesJsonStr是搜索数据库返回的String结果，
        String databasesJsonStr = getJson();
        String newJson = regroupJson(databasesJsonStr);
        System.out.println(newJson);
    }

    /**
     * 传入你数据库的json串，返回你想要的json串
     * @param oldJson
     * @return
     */
    public static String regroupJson(String oldJson){
        //1.转换为json数组，把每一个json串单独取出来存储，方便后面的重新分组
        JSONArray jsonArray = JSON.parseArray(oldJson);
        List<TestBean> list = new ArrayList<>(jsonArray.size());
        //存储所有的buy_no 并去重
        Set<String> buy_noSet = new HashSet<>();
        for(int i =0;i<jsonArray.size();i++){
            TestBean bean = new TestBean();
            bean.setBuy_no(jsonArray.getJSONObject(i).getString("buy_no"));
            buy_noSet.add(bean.getBuy_no());
            bean.setCount(jsonArray.getJSONObject(i).getString("count"));
            bean.setId(jsonArray.getJSONObject(i).getString("id"));
            bean.setItemName(jsonArray.getJSONObject(i).getString("itemName"));
            bean.setPic(jsonArray.getJSONObject(i).getString("pic"));
            bean.setPrice(jsonArray.getJSONObject(i).getString("price"));
            bean.setSzk(jsonArray.getJSONObject(i).getString("szk"));
            bean.setUser_id(jsonArray.getJSONObject(i).getString("user_id"));
            list.add(bean);
        }
        //组装新json
        //新json串
        JSONArray newJson = new JSONArray();
        for(String buy_no : buy_noSet){
            //第二层json
            JSONObject jsonObject = new JSONObject();
            jsonObject.put("buy_no",buy_no);
            //每一个数组
            JSONArray arr = new JSONArray();
            for(TestBean testBean : list){
                if(testBean.getBuy_no().equals(buy_no)){
                    //每一个数组中的每一个值
                    JSONObject arrIndex = new JSONObject();
                    arrIndex.put("id",testBean.getId());
                    arrIndex.put("itemName",testBean.getItemName());
                    arrIndex.put("user_id",testBean.getUser_id());
                    arrIndex.put("pic",testBean.getPic());
                    arrIndex.put("price",testBean.getPrice());
                    arrIndex.put("count",testBean.getCount());
                    arrIndex.put("szk",testBean.getSzk());
                    arr.add(arrIndex);
                }
            }
            jsonObject.put("arr",arr.toString());
            //每次组装一个 就添加进去一个
            newJson.add(jsonObject);
        }
        return newJson.toJSONString();
    }

    //模拟搜索数据库返回的String结果
    public static String getJson() throws IOException {
        FileInputStream in = new FileInputStream("D:/databases.json");
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(in));
        StringBuilder builder = new StringBuilder();
        String line = "";
        while((line = bufferedReader.readLine())!=null){
            builder.append(line);
        }
        bufferedReader.close();
        in.close();
        return builder.toString();
    }
}

输出

[{
    "arr": "[{\"itemName\":\"16\",\"user_id\":\"100001\",\"szk\":\"aaa\",\"price\":\"700\",\"count\":\"10\",\"id\":\"15\",\"pic\":\"http://localhost:8080/img/fanqie.jpg\"},{\"itemName\":\"17\",\"user_id\":\"100001\",\"szk\":\"aaa\",\"price\":\"600\",\"count\":\"3\",\"id\":\"3\",\"pic\":\"http://localhost:8080/img/xigua.jpg\"},{\"itemName\":\"18\",\"user_id\":\"100001\",\"szk\":\"aaa\",\"price\":\"700\",\"count\":\"10\",\"id\":\"36\",\"pic\":\"http://localhost:8080/img/taozi.jpg\"}]",
    "buy_no": "20201014113653"
}, {
    "arr": "[{\"itemName\":\"13\",\"user_id\":\"100001\",\"szk\":\"aaa\",\"price\":\"700\",\"count\":\"3\",\"id\":\"72\",\"pic\":\"http://localhost:8080/img/fanqie.jpg\"},{\"itemName\":\"14\",\"user_id\":\"100001\",\"szk\":\"aaa\",\"price\":\"600\",\"count\":\"10\",\"id\":\"88\",\"pic\":\"http://localhost:8080/img/xigua.jpg\"},{\"itemName\":\"15\",\"user_id\":\"100001\",\"szk\":\"aaa\",\"price\":\"700\",\"count\":\"1\",\"id\":\"2\",\"pic\":\"http://localhost:8080/img/xiangjiao.jpg\"}]",
    "buy_no": "20201015190607"
}, {
    "arr": "[{\"itemName\":\"9\",\"user_id\":\"100001\",\"szk\":\"aaa\",\"price\":\"600\",\"count\":\"33\",\"id\":\"22\",\"pic\":\"http://localhost:8080/img/xigua.jpg\"},{\"itemName\":\"10\",\"user_id\":\"100001\",\"szk\":\"aaa\",\"price\":\"600\",\"count\":\"3\",\"id\":\"3\",\"pic\":\"http://localhost:8080/img/xigua.jpg\"}]",
    "buy_no": "20201014183740"
}, {
    "arr": "[{\"itemName\":\"1\",\"user_id\":\"100001\",\"szk\":\"aaa\",\"price\":\"700\",\"count\":\"15\",\"id\":\"34\",\"pic\":\"http://localhost:8080/img/fanqie.jpg\"},{\"itemName\":\"2\",\"user_id\":\"100001\",\"szk\":\"aaa\",\"price\":\"600\",\"count\":\"10\",\"id\":\"3\",\"pic\":\"http://localhost:8080/img/xigua.jpg\"},{\"itemName\":\"3\",\"user_id\":\"100001\",\"szk\":\"aaa\",\"price\":\"700\",\"count\":\"30\",\"id\":\"9\",\"pic\":\"http://localhost:8080/img/qiezi.jpg\"},{\"itemName\":\"4\",\"user_id\":\"100001\",\"szk\":\"aaa\",\"price\":\"700\",\"count\":\"14\",\"id\":\"13\",\"pic\":\"http://localhost:8080/img/juzi.jpg\"}]",
    "buy_no": "20201014150857"
}, {
    "arr": "[{\"itemName\":\"11\",\"user_id\":\"100001\",\"szk\":\"aaa\",\"price\":\"600\",\"count\":\"30\",\"id\":\"1\",\"pic\":\"http://localhost:8080/img/pinguo.jpg\"},{\"itemName\":\"12\",\"user_id\":\"100001\",\"szk\":\"aaa\",\"price\":\"700\",\"count\":\"30\",\"id\":\"76\",\"pic\":\"http://localhost:8080/img/qiezi.jpg\"}]",
    "buy_no": "20201015144738"
}, {
    "arr": "[{\"itemName\":\"5\",\"user_id\":\"100001\",\"szk\":\"aaa\",\"price\":\"600\",\"count\":\"12\",\"id\":\"3\",\"pic\":\"http://localhost:8080/img/xigua.jpg\"},{\"itemName\":\"6\",\"user_id\":\"100001\",\"szk\":\"aaa\",\"price\":\"700\",\"count\":\"30\",\"id\":\"15\",\"pic\":\"http://localhost:8080/img/fanqie.jpg\"},{\"itemName\":\"7\",\"user_id\":\"100001\",\"szk\":\"aaa\",\"price\":\"700\",\"count\":\"18\",\"id\":\"84\",\"pic\":\"http://localhost:8080/img/taozi.jpg\"},{\"itemName\":\"8\",\"user_id\":\"100001\",\"szk\":\"aaa\",\"price\":\"600\",\"count\":\"109\",\"id\":\"54\",\"pic\":\"http://localhost:8080/img/huanggua.jpg\"}]",
    "buy_no": "20201014152727"
}]

我用的是：

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;

阿里巴巴的fastjson做json转换