JAVA高级教程-Json，Map，String之间的互转（11）

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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":, "barDate":18, "barName":"name_" }, "b":{ 
     "barAge":-, "barDate":18, "barName":"name_-" }, "c":{ 
     "barAge":-, "barDate":18, "barName":"name_-" } } */ 

//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":-,"barDate":18,"barName":"name_-"} c:{ 
    "barAge":-,"barDate":18,"barName":"name_-"} a:{ 
    "barAge":,"barDate":18,"barName":"name_"} */ 

——————-=————————-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(".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=.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=.0123}