目录

    • 1、Map转JSON
    • 2、**Map**转String
    • 3、JSON转String
    • 4、JSON转Map
    • 5、String转JSON
    • 6、将Json格式的字符串转换为对象
    • 7、将map转换为对象
  • 第二种 google
    • 总结

1、Map转JSON

  Map<String, Object> map = new HashMap<String, Object>();
        map.put("a", "a");
        map.put("b", "123");
        JSONObject json = new JSONObject(map);

2、Map转String

  Map<String, Object> map = new HashMap<>();
        map.put("a", "b");
        String s = JSONObject.toJSONString(map);

3、JSON转String

  JSONObject json = new JSONObject();
        json.put("c", "v");
        json.put("z", "123n);

        json.toJSONString();

4、JSON转Map

JSONObject json = new JSONObject();
        json.put("ccc", "321");
        json.put("bbb", "123");

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

5、String转JSON

 String str = "{"username":"dsad","qwewqe":"123"}";
JSONObject json = JSONObject.parseObject(str);

6、将Json格式的字符串转换为对象

import lombok.Data;

@Data
public class AlertRule {
    private String relation;
    private  UpperLower diffAbs;
    private  UpperLower diffPercent;
}

@Data
public class UpperLower {
    private BigDecimal upper;
    private  BigDecimal lower;
}

        AlertRule alertRule= JSON.parseObject("{\"diffAbs\":{\"upper\":2000,\"lower\":23000},\"diffPercent\":{\"upper\":2000,\"lower\":23000},\"relation\":\"OR\"}",AlertRule.class);
        System.out.println(alertRule.getDiffAbs());

7、将map转换为对象

public class Test01 {

    private static class Obj1 {
        private String School;
        private List<String> studen;

        public List<String> getStuden() {
            return studen;
        }

        public void setStuden(List<String> studen) {
            this.studen = studen;
        }

        public String getSchool() {
            return School;
        }

        public void setSchool(String school) {
            School = school;
        }

    }

    public static void main(String[] args) {
        Map<String,String> map = new HashMap<>();
        map.put("studens","{\"city\":{\"School\":\"san\",\"studen\":[1,2,3]}}");
        Map<String, Obj1> student = JSON.parseObject(map.get("studens"), new TypeReference<Map<String,Obj1>>(){});
        System.out.println(student);
        Set<Map.Entry<String,Obj1>> entries=student.entrySet();
        for(Map.Entry<String,Obj1> aa:entries){
            System.out.println(aa);
            Obj1 value=aa.getValue();
            String school=value.getSchool();
            System.out.println(school);
            List<String> studet=value.getStuden();
            System.out.println(studet);
        }
    }

}

第二种 google

maven坐标

<!-- https://mvnrepository.com/artifact/com.google.code.gson/gson -->
<dependency>
    <groupId>com.google.code.gson</groupId>
    <artifactId>gson</artifactId>
    <version>2.3.1</version>
</dependency>

//Map转换成JSON

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"}

//JSON转换成Map

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中含有对象Map -> JSON

//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"
	}
}
*/

//JSON -> Map

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"}
*/

-------------------=-------------------------附–MAP的ASCII排序-----------------------=------------------------

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~~~

总结

    public static void main(String[] args) {
        JSONObject alertRule= JSON.parseObject("{\"diffAbs\":{\"upper\":2000,\"lower\":23000},\"diffPercent\":{\"upper\":2000,\"lower\":23000},\"relation\":\"OR\"}");
        //json--string
        String a=JSONObject.toJSONString(alertRule);
        
        //string---json
        JSONObject b=JSONObject.parseObject(a);
        
        //json--map
        Map json_map=(Map<String,Object>)b;
        
        //map--string
        String c=JSONObject.toJSONString(json_map);

        //map--json
        JSONObject d=new JSONObject(json_map);

        //string--map
        Map<String,Object> e=JSONObject.parseObject(c,Map.class);

        //map-对象

    }

//1.Map转JSON
        Map<String, Object> map1 = new HashMap<String, Object>();
        map1.put("a", "a");
        map1.put("b", "123");
        JSONObject json = new JSONObject(map1);
        System.out.println("map"+map1);
        System.out.println("map->json"+json);

        //5.String转JSON
        String str = "{\n" +
                "    \"username\":\"dsad\",\n" +
                "    \"qwewqe\":\"123\"\n" +
                "}";
        JSONObject json3 = JSONObject.parseObject(str);
        System.out.println("string-json"+json3);


        //2.map转json string
        Map<String, Object> map2 = new HashMap<>();
        map2.put("a", "b");
        String s = JSONObject.toJSONString(map2);

        System.out.println("map"+map2);
        System.out.println("map-string1"+JSON.toJSONString(map2));
        System.out.println("map-string2"+s);

        //3.JSON转String
        JSONObject json1 = new JSONObject();
        json1.put("c", "v");
        json1.put("z", "123n");
        String ss=json.toJSONString(json1);
        System.out.println("json-string"+ss);

        //4.JSON转Map
        JSONObject json2 = new JSONObject();
        json2.put("ccc", "321");
        json2.put("bbb", "123");

        Map<String, Object> maps = (Map<String, Object>)json2;
        System.out.println("json->map"+maps);
        System.out.println(maps.get("ccc"));


        // string-map
        String str1 = "{\n" +
                "    \"username\":\"dsad\",\n" +
                "    \"qwewqe\":\"123\"\n" +
                "}";
        Map newmap = JSON.parseObject(s, Map.class);
        System.out.println("str->map"+newmap);
        
        @Data
        class User {
            String name;
            int age;
            BigDecimal salary;
        }

        //对象和map之间的转换
        User user = new User();
        user.setName("校长");
        user.setAge(3);
        user.setSalary(new BigDecimal("123456789.0123"));
        /*对象转map*/
        String jsonString1 = JSON.toJSONString(user);
        Map mapmap = JSON.parseObject(jsonString1, Map.class);
        System.out.println("map = " + mapmap);// map = {name=校长, salary=123456789.0123, age=3}

        String jsonString = JSON.toJSONString(mapmap);
        User user1 = JSON.parseObject(jsonString, User.class);//json转对象
        System.out.println("user1 = " + user1); //user1 = User{name='校长', age=3, salary=123456789.0123}

转载自：https://blog.csdn.net/web18296061989/article/details/123657550
如还看不懂，可参考案例：https://blog.csdn.net/u014212540/article/details/127687138

# java # json # windows
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