Java实现map转换成json的方法详解

Map<String, Object> map = new HashMap<String, Object>();

       map.put( "a" , "a" );

       map.put( "b" , "123" );

       JSONObject json = new JSONObject(map);

Map<String, Object> map = new HashMap<>();

       map.put( "a" , "b" );

       String s = JSONObject.toJSONString(map);

JSONObject json = new JSONObject();

       json.put( "c" , "v" );

       json.put( "z" , "123n);

       json.toJSONString();

JSONObject json = new JSONObject();

         json.put( "ccc" , "321" );

         json.put( "bbb" , "123" );

         Map<String, Object> map = (Map<String, Object>)json;

String str = "{" username ":" dsad "," qwewqe ":" 123 "}" ;

JSONObject json = JSONObject.parseObject(str);

<!-- https://mvnrepository测试数据/artifact/com.google.code.gson/gson -->

< dependency >

     < groupId >com.google.code.gson</ groupId >

     < artifactId >gson</ artifactId >

     < version >2.3.1</ version >

</ dependency >

Map<String,String> map = new HashMap<String,String>();

map.put( "a" , "aaa" );

map.put( "b" , "bbb" );

map.put( "c" , "ccc" );

String json=JSON.toJSONString(map);

System.out.println(json); //输出{"a":"aaa","b":"bbb","c":"ccc"}

Map map1 = JSON.parseObject(json);

System.out.println(map1.get( "a" ));

for (Object mapData : map.entrySet()) {

Map.Entry<String,String> entry = (Map.Entry<String,String>)mapData;

System.out.println(entry.getKey()+ "--->" +entry.getValue());

}

/*输出

b--->bbb

c--->ccc

a--->aaa

*/

//Map -> JSON

Map<String,Bar> map = new HashMap<String, Bar>();

map.put( "a" , new Bar());

map.put( "b" , new Bar());

map.put( "c" , new Bar());

String json = JSON.toJSONString(map, true );

System.out.println(json);

/*

输出{

     "a":{

         "barAge":383687382,

         "barDate":1494945882018,

         "barName":"name_1689176802"

     },

     "b":{

         "barAge":-100528778,

         "barDate":1494945882018,

         "barName":"name_-878176366"

     },

     "c":{

         "barAge":-344075192,

         "barDate":1494945882018,

         "barName":"name_-1710740534"

     }

}

*/

Map<String,Bar> map1 = (Map<String,Bar>)JSON.parse(json);

for (String key : map1.keySet()) {

System.out.println(key+ ":" +map1.get(key));

}

/*输出

b:{"barAge":-100528778,"barDate":1494945882018,"barName":"name_-878176366"}

c:{"barAge":-344075192,"barDate":1494945882018,"barName":"name_-1710740534"}

a:{"barAge":383687382,"barDate":1494945882018,"barName":"name_1689176802"}

*/

StringBuilder sb = new StringBuilder();

     List<String> keys = new ArrayList<String>(map.keySet());

     Collections.sort(keys); //排序。

     for (String k : keys){

         String v = params.get(k);

         if (StringUtils.isNotEmpty(v)){

             sb.append(v);

         }

     }

     //return MD5.toMD5(sb+key, "UTF-8");这个就不用看了~~~