Blog background is Java development. JSON-related conversions, values, etc. are often used in daily development, but sometimes we still forget or encounter some strange problems. Use this record to remind yourself~updated from time to time~
Article directory
1. JSONObject related
Conversion between entity class and JSONObject
//实体类转为JSONObject
JSONObject jsonObject = JSON.toJSON(entity);
JSONObject jsonObject = JSONObject.parseObject(JSON.toJSONString(entity));
//JSONObject转为实体类
Entity entity = JSONObject.toJavaObject(jsonObject, Entity.class);
Map and JSONObject conversion
//Map转为JSONObject
JSONObject jsonObject = JSON.toJSON(map);
JSONObject jsonObject = JSONObject.parseObject(JSON.toJSONString(map));
//JSONObject转为Map
Map<String, Object> map = JSONObject.toJavaObject(jsonObject, Map.class);
String to JSONObject
JSONObject jsonObject = JSONObject.fromObject(stringText);
NULL values are not filtered when converting entity classes to JSON strings
String jsonStr = JSONObject.toJSONString(VO,SerializerFeature.WriteMapNullValue);
Get the key value in JSONObject
JSONObject baseInfo = jsonObject.getJSONObject("detail");
// 遍历基本信息
for (Map.Entry<String, Object> entry : baseInfo.entrySet()) {
System.out.println(entry.getKey() + " : " + entry.getValue());
}
2. JSONArray related
List and JSONArray conversion
//List转为JSONArray
JSONArray jsonArray = JSON.toJSON(list);
JSONArray jsonArray = JSONArray.parseArray(JSON.toJSONString(list));
//JSONArray转为List
List<Entity> list = JSONObject.parseArray(jsonArray.toJSONString(), Entity.class);
List<Map<>> and JSONArray conversion
//List<Map<>>转为JSONArray
JSONArray jsonArray = JSON.toJSON(maps);
JSONArray jsonArray = JSONArray.parseArray(JSON.toJSONString(maps));
//JSONArray转List<hashmap>
JSONArray array = jsonObject.getJSONArray("array");
List<HashMap> objects = JSONObject.parseArray(JSONObject.toJSONString(array),HashMap.class);
//JSONArray转为List<Map<>>
List<Map<>> maps = JSONObject.parseArray(jsonArray.toJSONString(), Map.class);
//JSONArray转为List<Map<>>方法2
List<Map<String, String>> list=new ArrayList<Map<String, String>>();
JSONArray jsonArr=JSONObject.fromObject(jsonStr).getJSONArray("data");
if(jsonArr!=null && jsonArr.size()>0){
for(int i=0;i<jsonArr.size();i++){
JSONObject jsonObj=(JSONObject) jsonArr.get(i);
Map<String, String> map = new HashMap<String, String>();
for (Iterator<?> iter = jsonObj.keys(); iter.hasNext(); ) {
String key = (String) iter.next();
String value = jsonObj.get(key).toString();
map.put(key, value);
}
list.add(map);
}
JASONArray to JSONObject
JSONArray result_type = new JSONArray();
StringBuffer selectType = new StringBuffer();
selectType.append(" select id from table");
result_type = jdbcTemp.queryForJSONArray(selectType.toString());
JSONObject jsonObject = new JSONObject();
for (int i = 0; i < result_type.size(); i++) {
JSONObject jsonObject = (JSONObject) result_type.get(i);
}
return jsonObject;
Solve the problem: Converting JASONArray to JSONObject only returns the last JSONObject
StringBuilder builder = new StringBuilder();
//业务代码
//转换
for (int i = 0; i < jsonArray.size(); i++) {
jsonObject = (JSONObject) jsonArray.get(i);
builder.append(jsonObject).append("\n");
}
//业务代码
return builder.toString();
String to JSONArray
JSONArray jsonArray = JSONArray.fromObject(stringText);
3. Object related
Object转JSONObject
JSONObject json = (JSONObject) JSONObject.toJSON(list.get(0));
Object to List
//Object转List<String>
public static List<String> objToList1(Object obj) throw CoreException{
List<String> result = new ArrayList<String>();
if (obj instanceof ArrayList<?>) {
for (Object o : (List<?>) obj) {
result.add(String.class.cast(o));
}
}
return result;
}
//通用工具类
public static <T> List<T> objToList(Object obj, Class<T> cla) throw CoreException{
List<T> list = new ArrayList<T>();
if (obj instanceof ArrayList<?>) {
for (Object o : (List<?>) obj) {
list.add(cla.cast(o));
}
return list;
}
return null;
}
//调用
List<String> list = objToList(obj,String.class);
//注意：int.class = Integer.TYPE !=Integer.class