fastjson与各类型的转换
参考：
https://www.cnblogs.com/ceshi2016/p/7381478.html
http://www.cnblogs.com/goody9807/p/4244862.html
https://www.cnblogs.com/DreamDrive/p/5778959.html
https://www.cnblogs.com/janson071/p/9646678.html 多层嵌套
1、对象和JSON的转换
以Board对象为例：
// Board定义 public class Board implements Comparable<Board> { public String name; public String pinlei; public double gpm; public double ctr; public Board() {} public Board(String name, String pinlei, double gpm, double ctr) { this.name = name; this.pinlei = pinlei; this.gpm = gpm; this.ctr = ctr; } @Override public int compareTo(Board board) { if(this.gpm >= board.gpm) { return -1; } return 1; } @Override public String toString() { return name + String.valueOf(gpm) + "-"; } } // Board 对象转化JSON字符串 String r_str = JSON.toJSONString(board) System.out.println(r_str); // 输出结果: {"ctr":0.1,"gpm":0.5,"name":"美白防晒霜","pinlei":"防晒霜"}
2、对象List和JSONArray的转换
// Board对象的list 可以直接转化到 JSONArray JSONArray jArray=JSON.parseArray(JSON.toJSONString(boards)); // jArray转换到JSON数组字符串 System.out.println(jArray.toJSONString(); // 输出结果: [{"ctr":0.0,"pinlei":"防晒霜3","gpm":0.8,"name":"美白防晒霜3"},{"ctr":0.0,"pinlei":"防晒霜4","gpm":0.5,"name":"美白防晒霜4"}]
3、字符串和JSON相互转换
/**字符串转Json对象**/ String jsonInfo = "{"ctr":0.0,"gpm":0.8,"name":"美白防晒霜3","pinlei":"防晒霜3"}"; JSONObject jsonObject = JSONObject.parseObject(jsonInfo); /**Json对象转字符串**/ String jsonStrng = JSON.toJSONString(jsonObject);
4、字符串和JSON数组相互转换
// 将字符串jsonArrayStr转化为JSONArray.
// jsonArrayStr示例: [{"ctr":0.0,"pinlei":"防晒霜3","gpm":0.8,"name":"美白防晒霜3"},{"ctr":0.0,"pinlei":"防晒霜4","gpm":0.5,"name":"美白防晒霜4"}]
JSONArray array = JSONArray.parseArray(jsonArrayStr)); // 将JSON数组jsonArray转化字符串 String jsonArrayStr = jsonArray.toJSONString();
5、map和JSON相互转换
/**map转Json对象**/ Map<String, String> map = new HashMap<String, String>(); JSONObject jsonObject = JSONObject.parseObject(JSON.toJSONString(map)); /**Json对象转map**/ Map<String, Object> map2 = JSONObject.toJavaObject(jsonObject, Map.class);
6、map和字符串相互转换
/**map转字符串, 一般不直接Map对象使用toString()转化，而是先转换为Json对象再转字符串**/ Map<String, String> map = new HashMap<String, String>(); JSONObject jsonObject = JSONObject.parseObject(JSON.toJSONString(map));
jsonObject.toString();
// map.toString(); 不推荐
/**json字符串转map, 通过先转json再转map实现，见上**/
7、JSONArray和JSON遍历
// JsonArray遍历, 参考 https://www.jianshu.com/p/ca9b83ebac7b private static void LoopJSONArray(){ //颜色数组字符串 String colorStr = "[{'name':'刘德华','age':28,'sex':'男'}," + "{'name':'张学友','age':29,'sex':'男'}]"; //转化为数组 JSONArray jsonArr = JSONArray.fromObject(colorStr); for (int i = 0; i < jsonArr.size(); i++) { JSONObject jsonObject = jsonArr.getJSONObject(i); String name = jsonObject.getString("name"); Integer age = (Integer) jsonObject.get("age"); System.out.println("name:"+name+";age:"+age); } } // Json遍历 JSONObject jsonObject = new JSONObject(s); //然后用Iterator迭代器遍历取值 JSONObject jsonObject = new JSONObject(jsonString); Iterator iterator = jsonObject.keys(); while(iterator.hasNext()){ key = (String) iterator.next(); value = jsonObject.getString(key); }
废弃
/**字符串转Json数组并解析**/
try {
JSONArray array = JSONArray.parseArray(line));
String[] fields = {"lat", "lng", "poi_id", "poi_name", "poi_type", "roadidx"};
if (null != array) {
Iterator<Object> iter = array.iterator();
while (iter.hasNext()) {
JSONObject json = (JSONObject)iter.next();
for (int i = 0; i < fields.length; i++) {
System.out.println(json.getString(fields[i]));
}
}
}
}catch (JSONException e) {
System.err.println("json paese exception = " + jsonStr);
}
/**map转Json对象**/
Map<String, String> map = new HashMap<String, String>();
JSONObject jsonObject = JSONObject.parseObject(JSON.toJSONString(map));
/**Json对象转map**/
Map<String, Object> map2 = JSONObject.toJavaObject(jsonObject, Map.class);
/**将List转换成JSONArray**/
List<String> list = new ArrayList<String>();
JSONArray jsonArray = JSONArray.parseArray(JSON.toJSONString(list));
/**将JSONArray转换成List**/
http://www.cnblogs.com/goody9807/p/4244862.html
/**字符串转Json对象**/
String jsonInfo = "";
JSONObject jsonObject2 = JSONObject.parseObject(jsonInfo);
/**Json对象转字符串**/
String jsonStrng = JSON.toJSONString(jsonObject2);
/**对JSONObject中的指定字段重新赋值**/
JSONObject posJson = new JSONObject();
posJson.put("op", "in");
/**其它**/
public class JsonDemo { public static void main(String[] args) { //1.json字符串转换为对象 String jsonString="{'name':'42313123','id':'2345','age':12}"; JSONObject jsonObject = JSONObject.parseObject(jsonString); String id = jsonObject.getString("id"); System.out.println(id); //2. JSONObject转化成自定义类对象 PeoplePo peoplePo1 = JSONObject.parseObject(jsonString, PeoplePo.class); System.out.println(peoplePo1); //3. JSONObject转化成Map集合 Map map = JSONObject.parseObject(jsonString, Map.class); System.out.println(map); //4. 自定义对象转化成json格式的字符串 PeoplePo peoplePo = new PeoplePo(); peoplePo.setId("1"); peoplePo.setAge(11); peoplePo.setName("LH"); String peopleJson = JSON.toJSONString(peoplePo); System.out.println(peopleJson); //5. String类型转化成JSONObject; String str = "{\"result\":\"success\",\"message\":\"成功！\"}"; JSONObject jsonObject1 = JSONObject.parseObject(str); System.out.println(jsonObject1); //6. JSONObject转化成JSONArray的两种方式 String str1 = "{\"result\":\"success\",\"message\":\"成功！\",\"data\":[{\"name\":\"Tom\",\"age\":\"20\"}]}"; JSONObject jsonToArray = JSONObject.parseObject(str1); //方式一 JSONArray data = jsonToArray.getJSONArray("data"); System.out.println(data); //方式二 JSONArray jsonArray = JSONArray.parseArray(jsonToArray.getString("data")); System.out.println(jsonArray); //7. jsonArray转化成JSONObject并取出其中的元素数据 JSONObject o = (JSONObject) jsonArray.get(0); String name = o.getString("name"); System.out.println(o); System.out.println(name); System.out.println(jsonArray.toString()); } } //转自 https://blog.csdn.net/lh19960914/article/details/87861308
