Java中如何將json字符串轉換成map/list

更新時間：2022年07月06日 10:56:14 作者：專注_每天進步一點點

這篇文章主要介紹了Java中如何將json字符串轉換成map/list，具有很好的參考價值，希望對大家有所幫助。如有錯誤或未考慮完全的地方，望不吝賜教

將json字符串轉換成map/list

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import org.codehaus.jettison.json.JSONArray;
import org.codehaus.jettison.json.JSONObject;
 
public class JsonStr2MapOrList {
 
    /**
     * 以"{"開頭的jsonStr轉map,map里面有l(wèi)ist,list里面還裝有map
     */
    @SuppressWarnings("rawtypes")
    public static Map<String, Object> jsonStr2Map(String jsonStr) throws Exception {
        Map<String, Object> map = new HashMap<String, Object>();
        if (!jsonStr.isEmpty()) {
            JSONObject json = new JSONObject(jsonStr);
            Iterator i = json.keys();
            while (i.hasNext()) {
                String key = (String) i.next();
                String value = json.getString(key);
                if (value.indexOf("{") == 0) {
                    map.put(key.trim(), jsonStr2Map(value));
                } else if (value.indexOf("[") == 0) {
                    map.put(key.trim(), jsonStr2List(value));
                } else {
                    map.put(key.trim(), value.trim());
                }
            }
        }
        return map;
    }
 
    /**
     * 以"["開頭的String轉list,list里裝有map
     */
    public static List<Map<String, Object>> jsonStr2List(String jsonStr) throws Exception {
        List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
        JSONArray ja = new JSONArray(jsonStr);
        for (int j = 0; j < ja.length(); j++) {
            String jm = ja.getString(j);
            if (jm.indexOf("{") == 0) {
                Map<String, Object> m = jsonStr2Map(jm);
                list.add(m);
            }
        }
        return list;
    }
 
    /**
     * jsonStr和Map之間的轉換, jsonStr和List之間的轉換
     * 
     * @param args
     * @throws Exception
     */
    public static void main(String[] args) throws Exception {
        // 1.jsonStr和Map之間的轉換
        Map<String, Object> map = new HashMap<String, Object>();
        map.put("key1", "val1");
        map.put("key2", "val2");
 
        List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
        Map<String, Object> map1 = new HashMap<String, Object>();
        Map<String, Object> map2 = new HashMap<String, Object>();
        map1.put("key11", "val11");
        map1.put("key21", "val21");
        map2.put("key111", "val111");
        map2.put("key211", "val211");
        list.add(map1);
        list.add(map2);
        map.put("keyList", list);
 
        System.out.println("原始的map:" + map);
        String map2JsonStr = map.toString();
        System.out.println("map2JsonStr:" + map2JsonStr);
        Map<String, Object> jsonStr2Map = jsonStr2Map(map2JsonStr);
        System.out.println("jsonStr2Map:" + jsonStr2Map);
 
        // 2.jsonStr和List之間的轉換
        List<Object> list_ = new ArrayList<Object>();
        list_.add(map);
        String list_Str = list_.toString();
        System.out.println("list_Str:" + list_Str);
        List<Map<String, Object>> listM = jsonStr2List(list_Str);
        System.out.println("listM:" + listM);
    }
}

輸出結果：

原始的map:{key2=val2, key1=val1, keyList=[{key11=val11, key21=val21}, {key211=val211, key111=val111}]}
map2JsonStr:{key2=val2, key1=val1, keyList=[{key11=val11, key21=val21}, {key211=val211, key111=val111}]}
jsonStr2Map:{key2=val2, key1=val1, keyList=[{key11=val11, key21=val21}, {key211=val211, key111=val111}]}
list_Str:[{key2=val2, key1=val1, keyList=[{key11=val11, key21=val21}, {key211=val211, key111=val111}]}]
listM:[{key2=val2, key1=val1, keyList=[{key11=val11, key21=val21}, {key211=val211, key111=val111}]}]

字符串,json,Map互相轉換(各種轉換都有)

前提：使用jar包為fastjson

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

程序如下

? ? ? ? Map map = new HashMap();
?? ??? ?map.put("AAA", "1");
?? ??? ?map.put("BBB", "2");
?? ??? ?map.put("CCC", "3");
?? ??? ?System.out.println("map=>"+map);
?? ??? ?
?? ??? ?//1.map轉string
?? ??? ?String jsonString = JSON.toJSONString(map);
?? ??? ?System.out.println("mapToString=>"+jsonString);
?? ??? ?//2.map轉jsonObject?
?? ??? ?JSONObject JSONObj = JSONObject.parseObject(JSON.toJSONString(map));
?? ??? ?System.out.println("mapToJSON=>"+JSONObj);
?? ??? ?
?? ??? ?//3.String轉jsonObject
?? ??? ?String jsonString2 = "{\"AAA\":\"1\",\"CCC\":\"3\",\"BBB\":\"2\"}";
?? ??? ?JSONObject parseObject = JSONObject.parseObject(jsonString2);
?? ??? ?System.out.println("StringToJson=>"+parseObject);
?? ??? ?//4.String轉map
?? ??? ?Map stringToMap = ?JSONObject.parseObject(jsonString2);?
?? ??? ?System.out.println("StringToMap=>"+stringToMap);
?? ??? ?
?? ??? ?String str = "{\"age\":\"24\",\"name\":\"summer\"}";
?? ??? ?JSONObject ?jsonObject = JSONObject.parseObject(str);
?? ??? ?//5.jsonObject轉map
?? ??? ?Map jsonToMap = ?JSONObject.parseObject(jsonObject.toJSONString());?
?? ??? ?System.out.println("jsonToMap=>"+jsonToMap);
?? ??? ?//6.jsonObject轉String
?? ? ? ?String jsonString3 = jsonObject.toJSONString();
?? ? ? ?System.out.println("jsonToString=>"+jsonString3);

結果如下

map=>{AAA=1, CCC=3, BBB=2}
mapToString=>{"AAA":"1","CCC":"3","BBB":"2"}
mapToJSON=>{"AAA":"1","CCC":"3","BBB":"2"}
StringToJson=>{"AAA":"1","CCC":"3","BBB":"2"}
StringToMap=>{"AAA":"1","CCC":"3","BBB":"2"}
jsonToMap=>{"name":"summer","age":"24"}
jsonToString=>{"name":"summer","age":"24"}