从json到java.util.Map的编码/解码库?

Does anyone knows a java library that could easily encode java Maps into json objects and the other way around?

有没有人知道可以将java映射轻松编码为json对象的java库?

UPDATE

更新

For reasons couldn't explain ( and I hate sometimes ) I can't use generics on my environment.

由于种种原因，我无法解释(有时我讨厌)我不能在我的环境中使用泛型。

What' I'm trying to do is to have something like this:

我想做的是有这样的东西:

Map a = new HashMap();
a.put( "name", "Oscar" );

Map b = new HashMap();
b.put( "name", "MyBoss"); 
a.put( "boss",  b ) ;


List list = new ArrayList();
list.add( a );
list.add( b );


 String json = toJson( list );
 // and create the json:
 /*
    [
       {
         "name":"Oscar",
         "boss":{
              "name":"MyBoss"
         }
        },
        {
            "name":"MyBoss"
        }
     ]

  */

And be able to have it again as a list of maps

并且可以把它作为一张地图的列表。

 List aList = ( List ) fromJson( jsonStirng );

6 个解决方案

#1

JSON-Simple looks relatively easy to use (examples below).

JSON-Simple看起来相对容易使用(示例如下)。

Map to JSON:

映射到JSON:

  Map map = new HashMap();
  map.put("name", "foo");
  map.put("nickname", "bar");
  String jsonText = JSONValue.toJSONString(map);

JSON to List/Map:

JSON /地图列表:

  String s = yourJsonString;
  List list = (JSONArray) JSONValue.parse(s);       
  Map map = (JSONObject) list.get(0);

#2

You can use Google Gson for that. It has excellent support for Generic types.

你可以用谷歌Gson。它对泛型类型有很好的支持。

Here's an SSCCE:

这里有一个SSCCE:

package com.*.q2496494;

import java.util.LinkedHashMap;
import java.util.Map;

import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;

public class Test {

   public static void main(String... args) {
        Map<String, String> map = new LinkedHashMap<String, String>();
        map.put("key1", "value1");
        map.put("key2", "value2");
        map.put("key3", "value3");
        Gson gson = new Gson();

        // Serialize.
        String json = gson.toJson(map);
        System.out.println(json); // {"key1":"value1","key2":"value2","key3":"value3"}

        // Deserialize.
        Map<String, String> map2 = gson.fromJson(json, new TypeToken<Map<String, String>>() {}.getType());
        System.out.println(map2); // {key1=value1, key2=value2, key3=value3}
    }

}

#3

You can view the site from Json.org for the list of good JSON libraries in Java.

您可以从Json.org查看该站点，以获得Java中优秀的JSON库列表。

JSon.org's own implementation JSONObject can do just that. From their JavaDoC

JSon.org自己的实现JSONObject可以做到这一点。从他们的JavaDoC

 /**
     * Construct a JSONObject from a Map.
     * 
     * @param map A map object that can be used to initialize the contents of
     *  the JSONObject.
     */
    public JSONObject(Map map);

you can do

你可以做

JSONObject json = new JSONObject(map);

To convert JSON String back to object....

JSON字符串转换回对象....

String jsonString = "{\"name\" : \"some name\", \"age\" : 10}";
JSONObject json = new JSONObject(jsonString);

and you can access values like:

您可以访问如下值:

int age = json.getInt("age");

Constructor JavaDoC

构造函数JavaDoC

Construct a JSONObject from a source JSON text string. This is the most commonly used JSONObject constructor.

从源JSON文本字符串构造JSONObject。这是最常用的JSONObject构造函数。

Parameters: source A string beginning with { (left brace) and ending with } (right brace).

参数:以{(左括号)和}(右括号)开头的字符串。

#4

I guess the real question would be which JSON library (from org.json's page) would NOT allow doing this. As far as I know every single library there would allow this in some form. So every library mentioned so far works.

我想真正的问题是哪个JSON库(来自org)。不允许这样做。据我所知，那里的每一个图书馆都会以某种形式允许这样做。到目前为止，所有提到的图书馆都是有效的。

And to add some information, Jackson works very well with all kinds of data including basic Maps and Lists:

为了补充一些信息，Jackson非常擅长处理各种数据，包括基本的地图和列表:

ObjectMapper mapper = new ObjectMapper();
String json = mapper.writeValue(list);
List listOfMaps = mapper.readValue(json, List.class);

which would handle this particular case. While generic type information can be used, it is optional when using "natural" binding to JDK container types.

它会处理这个特殊的情况。虽然可以使用泛型类型信息，但是在使用“自然”绑定到JDK容器类型时是可选的。

#5

We use http://json-lib.sourceforge.net/ in our project, it works just fine.

我们在项目中使用http://json-lib.sourceforge.net/，它运行良好。

#6

When using google gson.

当使用谷歌gson。

var getRowData =
[{
    "dayOfWeek": "Sun",
    "date": "11-Mar-2012",
    "los": "1",
    "specialEvent": "",
    "lrv": "0"
},
{
    "dayOfWeek": "Mon",
    "date": "",
    "los": "2",
    "specialEvent": "",
    "lrv": "0.16"
}];

    JsonElement root = new JsonParser().parse(request.getParameter("getRowData"));
     JsonArray  jsonArray = root.getAsJsonArray();
     JsonObject  jsonObject1 = jsonArray.get(0).getAsJsonObject();
     String dayOfWeek = jsonObject1.get("dayOfWeek").toString();

// when using jackson

/ /当使用杰克逊

    JsonFactory f = new JsonFactory();
              ObjectMapper mapper = new ObjectMapper();
          JsonParser jp = f.createJsonParser(getRowData);
          // advance stream to START_ARRAY first:
          jp.nextToken();
          // and then each time, advance to opening START_OBJECT
         while (jp.nextToken() == JsonToken.START_OBJECT) {
            Map<String,Object> userData = mapper.readValue(jp, Map.class);
            userData.get("dayOfWeek");
            // process
           // after binding, stream points to closing END_OBJECT
        }

#1