Question

如何使用java代码创建以下JSON文件？

{
"mode":"EXTENDED",
"vertices": [
    {
        "name": {
            "type": "string",
            "value": "loppper"
        },
        "lang": {
            "type": "string",
            "value": "java"
        },
        "_id": "3",
        "_type": "vertex"
    },
    {
        "name": {
            "type": "string",
            "value": "vadas"
        },
        "age": {
            "type": "integer",
            "value": 27
        },
        "_id": "2",
        "_type": "vertex"
    },
    {
        "name": {
            "type": "string",
            "value": "marko"
        },
        "age": {
            "type": "integer",
            "value": 29
        },
        "_id": "1",
        "_type": "vertex"
    },
     {
        "name": {
            "type": "string",
            "value": "mark12"
        },
        "age": {
            "type": "integer",
            "value": 31
        },
        "_id": "31",
        "_type": "vertex"
    },


    {
        "name": {
            "type": "string",
            "value": "peter"
        },
        "age": {
            "type": "integer",
            "value": 35
        },
        "_id": "6",
        "_type": "vertex"
    }]}

在JSONObject和JSONArray之间混淆。谁能请帮忙。我能够创建

{
"mode":"Extended",
"vertices" : [
[(1)
](2)
]
}

但我需要花括号而不是（1）（2）

中的方括号

Answer 1

在Java中，您可以使用gson库生成JSON字符串（并解析它们）。它就像创建一组对象一样简单，保存数据。之后，您拨打Gson.toJson(obj)。

Answer 2

我为我编写了一些util类，通过转换Map和List对象来生成JSON

public static String parseMapToJSONString(Map<String,Object> mapData){
    StringBuilder jsonData = new StringBuilder("{");
    int iteration = 0;
    for(String key: mapData.keySet()){
        if( mapData.get(key) instanceof List){
            jsonData.append("\"").append(key).append("\"").append(":")
                    .append(parseListToJSONString((List<Object>) mapData.get(key)));
        } else if(mapData.get(key) instanceof Map){
            jsonData.append("\"").append(key).append("\"").append(":")
                    .append(parseMapToJSONString((Map<String,Object>) mapData.get(key)));
        } else {
            jsonData.append("\"").append(key).append("\"").append(":").append("\"").append(mapData.get(key).toString()).append("\"");
        }
        if(mapData.size() > 1 && iteration < mapData.size() - 1){
            jsonData.append(",");
        }
        iteration++;
    }
    jsonData.append("}");
    return jsonData.toString();
}

public static String parseListToJSONString(List<Object> listData){
    StringBuilder jsonListData = new StringBuilder("[");
    int iteration = 0;
    for(Object value: listData){
        if(value instanceof String){
            jsonListData.append("\"").append(value.toString()).append("\"");
        } else if(value instanceof Map){
            jsonListData.append(parseMapToJSONString((Map<String,Object>) value));
        }
        if(iteration < listData.size()-1){
            jsonListData.append(",");
        }
        iteration++;
    }
    jsonListData.append("]");
    return jsonListData.toString();
}

一些示例代码

    Map<String,Object> testMap1 = new HashMap();
    testMap1.put("name", "Oscar");
    testMap1.put("email","peter@yahoo.com");

    List<String> majorList = new ArrayList();
    majorList.add("Math");
    majorList.add("Physics");
    testMap1.put("major",majorList);

    Map<String,Object> testMap2 = new HashMap();
    testMap2.put("name", "Alice");
    testMap2.put("school", "ABC");
    testMap1.put("mother",testMap2);

    List<Map<String,Object>> friendList = new ArrayList();
    Map<String,Object> testMap3 = new HashMap();
    testMap3.put("name", "Peter");
    testMap3.put("school", "ABC");
    Map<String,Object> testMap4 = new HashMap();
    testMap4.put("name", "Tom");
    testMap4.put("school", "ABC");
    friendList.add(testMap3);
    friendList.add(testMap4);

    testMap1.put("friends",friendList);
    System.out.println(JSONParserService.parseMapToJSONString(testMap1));

从java代码创建一个Json文件

2 个答案: