我对Json的经验非常少,我要将复杂的Json解析为Java Objects。
我尝试了几种方法但没有成功......我正在以Json格式获取我的城市的天气预报,我需要将Json数据解析为Java Objects。
Json:
{"city":
{"city_code":"ATAT10678",
"name":"Wien",
"url":"oesterreich/wien/ATAT10678.html",
"credit":{"info":"In order to use the free weather data from wetter.com you HAVE TO display at least two out of three of the following possibilities: text, link, logo",
"text":"Powered by wetter.com","link":"http://www.wetter.com",
"logo":"Download at http://www.wetter.com/api/downloads/#logos"},
"forecast":{
"2014-08-24":{
"w":"1",
"tx":"20",
"pc":"30",
"06:00":{
"w":"2",
"tx":"16",
"pc":"30",
"tn":"15",
"p":"5",
"dhl":"2014-08-24 06:00",
"ws":"19",
"w_txt":"wolkig"},
"11:00":{
"w":"2",
"tx":"18",
"pc":"30",
"tn":"16",
"p":"6",
"dhl":"2014-08-24 11:00",
"ws":"20",
"w_txt":"wolkig"},
"17:00":{
"w":"1",
"tx":"20",
"pc":"20",
"tn":"16",
"p":"6",
"dhl":"2014-08-24 17:00",
"ws":"12",
"w_txt":"leicht bewölkt"},
"23:00":{
"w":"1",
"tx":"16",
"pc":"10",
"tn":"13",
"p":"6",
"dhl":"2014-08-24 23:00",
"ws":"7",
"w_txt":"leicht bewölkt"},
"tn":"15",
"p":"24",
"dhl":"2014-08-24 06:00",
"ws":"14",
"w_txt":"leicht bewölkt"},
"2014-08-25":{"w":"2","tx":"22","pc":"30","06:00":{"w":"2","tx":"17","pc":"20","tn":"12","p":"5","dhl":"2014-08-25 06:00","ws":"5","w_txt":"wolkig"},"11:00":{"w":"2","tx":"21","pc":"30","tn":"17","p":"6","dhl":"2014-08-25 11:00","ws":"10","w_txt":"wolkig"},"17:00":{"w":"2","tx":"22","pc":"30","tn":"18","p":"6","dhl":"2014-08-25 17:00","ws":"11","w_txt":"wolkig"},"23:00":{"w":"3","tx":"18","pc":"30","tn":"16","p":"6","dhl":"2014-08-25 23:00","ws":"6","w_txt":"bedeckt"},"tn":"12","p":"24","dhl":"2014-08-25 06:00","ws":"8","w_txt":"wolkig"},"2014-08-26":{"w":"3","tx":"22","pc":"75","06:00":{"w":"3","tx":"17","pc":"75","tn":"15","p":"5","dhl":"2014-08-26 06:00","ws":"6","w_txt":"bedeckt"},"11:00":{"w":"61","tx":"21","pc":"75","tn":"17","p":"6","dhl":"2014-08-26 11:00","ws":"9","w_txt":"leichter Regen"},"17:00":{"w":"61","tx":"22","pc":"75","tn":"18","p":"6","dhl":"2014-08-26 17:00","ws":"9","w_txt":"leichter Regen"},"23:00":{"w":"3","tx":"18","pc":"75","tn":"17","p":"6","dhl":"2014-08-26 23:00","ws":"9","w_txt":"bedeckt"},"tn":"15","p":"24","dhl":"2014-08-26 06:00","ws":"8","w_txt":"bedeckt"}}}}
我不知道如何将其解析为对象..
非常感谢您的建议!
这是我的第一次试验..
Gson gson = new Gson();
JsonObject jsonObj = gson.fromJson(br, JsonObject.class);
Map<String, LinkedTreeMap> map = new HashMap<String, LinkedTreeMap>();
map = (Map<String, LinkedTreeMap>) gson.fromJson(jsonObj.toString(), map.getClass());
LinkedTreeMap<String, LinkedTreeMap> tmp = new LinkedTreeMap<>();
tmp = map.get("city");
for(Map.Entry<String, LinkedTreeMap> e : tmp.entrySet()) {
System.out.println("k: " + e.getKey());
}
LinkedTreeMap<String, LinkedTreeMap> tmp1 = new LinkedTreeMap<>();
tmp1 = tmp.get("forecast");
for(Map.Entry<String, LinkedTreeMap> e : tmp1.entrySet()) {
System.out.println("k: " + e.getKey());
LinkedTreeMap<String, LinkedTreeMap> values = e.getValue();
for(Map.Entry<String, LinkedTreeMap> v : values.entrySet()) {
System.out.println("k: " + v.getKey() + " v: " + v.getValue());
}
}
和一天的输出:
k: city_code
k: name
k: url
k: credit
k: forecast
k: 2014-08-25
k: w v: 2
k: tx v: 23
k: pc v: 90
k: 06:00 v: {w=2, tx=17, pc=20, tn=13, p=5, dhl=2014-08-25 06:00, ws=5, w_txt=wolkig}
k: 11:00 v: {w=2, tx=21, pc=20, tn=17, p=6, dhl=2014-08-25 11:00, ws=9, w_txt=wolkig}
k: 17:00 v: {w=2, tx=23, pc=30, tn=17, p=6, dhl=2014-08-25 17:00, ws=11, w_txt=wolkig}
k: 23:00 v: {w=3, tx=17, pc=90, tn=16, p=6, dhl=2014-08-25 23:00, ws=6, w_txt=bedeckt}
k: tn v: 13
k: p v: 24
k: dhl v: 2014-08-25 06:00
k: ws v: 8
k: w_txt v: wolkig
到目前为止一直很好,但我如何得到06:00,11:00,17:00和23:00(通用因为时间可以改变),因为这是我需要的信息?
非常感谢BR 龙卷风
答案 0 :(得分:4)
以下是使用GSON的示例
import com.google.gson.JsonElement;
import com.google.gson.JsonParser;
public class CodeChefTest1 {
public static String json = "{\"balance\": 1000.21, \"num\":100, \"is_vip\":true, \"name\":\"foo\"}";
public static void main(String[] args) {
JsonElement ele = new JsonParser().parse(json);
for(java.util.Map.Entry<String, JsonElement> entr : ele.getAsJsonObject().entrySet()){
System.out.println(entr.getKey());
System.out.println(entr.getValue());
}
}
}
您可以使用上述内容并使用对isJSONArray(),isJSONObject(),isJSONPrimitive()
等JSONElements的检查在循环中运行它,并使用相同的策略执行适当的重新解析。
上面只是遍历json字符串并打印所有键值对。您可以对json字符串的日期部分执行相同的操作。
答案 1 :(得分:2)
我个人建议使用杰克逊。使用jackson,您可以将JSON字符串转换为POJO(java bean)。 https://github.com/FasterXML/jackson
该库免费,快速且易于使用。
由于你有日期和时间作为属性名称,我认为至少你的对象的那部分应该是一个JAVA地图,正如Amaynut建议的那样。
答案 2 :(得分:1)
除了gba的Jackson之外,您还可以使用Google GSON:https://code.google.com/p/google-gson/
另外,请查看此主题:Jackson Vs. Gson
答案 3 :(得分:1)
您可以使用Google提供的库 Gson 。这是一个转换为Map类型的Java对象的json对象的示例:
Gson gson=new Gson();
String json="{\"k1\":\"v1\",\"k2\":\"v2\"}";
Map<String,String> map=new HashMap<String,String>();
map=(Map<String,String>) gson.fromJson(json, map.getClass());
尝试使用 Gson 库的另一个解决方案如下:
Gson gson = new Gson();
String json="{\"k1\":\"v1\",\"k2\":\"v2\"}";
LinkedTreeMap result = gson.fromJson(json, LinkedTreeMap.class);
您需要导入这两个类:
import com.google.gson.Gson;
import com.google.gson.internal.LinkedTreeMap;
您可以查看有关同一主题的帖子: How can I convert JSON to a HashMap using Gson?
答案 4 :(得分:0)
这是第一个工作代码..(快速'肮脏)..
向Sumeet Sharma致敬!也许有人有更好的解决方案......
public void updateWeather() {
forecasts = new ArrayList<>();
try {
URL url = new URL(createURL());
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setDoOutput(true);
OutputStream os = conn.getOutputStream();
os.flush();
if (conn.getResponseCode() != 200) {
throw new RuntimeException("Failed : HTTP error code : "
+ conn.getResponseCode());
}
BufferedReader br = new BufferedReader(new InputStreamReader(
(conn.getInputStream())));
Gson gson = new Gson();
JsonObject jsonObj = gson.fromJson(br, JsonObject.class);
JsonElement element = jsonObj.get("city");
jsonObj = gson.fromJson(element.getAsJsonObject(), JsonObject.class);
element = jsonObj.get("forecast");
for (Map.Entry<String, JsonElement> entr : element.getAsJsonObject().entrySet()) {
JsonElement element1 = entr.getValue().getAsJsonObject();
for (Map.Entry<String, JsonElement> entr1 : element1.getAsJsonObject().entrySet()) {
if (entr1.getValue().isJsonObject()) {
JsonElement element2 = entr1.getValue().getAsJsonObject();
Forecast forecast = new Forecast();
for (Map.Entry<String, JsonElement> entr2 : element2.getAsJsonObject().entrySet()) {
switch (entr2.getKey()) {
case "w":
forecast.setW(entr2.getValue().getAsString());
break;
case "tx":
forecast.setTx(entr2.getValue().getAsString());
break;
case "pc":
forecast.setPc(entr2.getValue().getAsString());
break;
case "tn":
forecast.setTn(entr2.getValue().getAsString());
break;
case "p":
forecast.setP(entr2.getValue().getAsString());
break;
case "dhl":
forecast.setDhl(entr2.getValue().getAsString());
break;
case "ws":
forecast.setWs(entr2.getValue().getAsString());
break;
case "w_txt":
forecast.setW_txt(entr2.getValue().getAsString());
break;
}
}
forecasts.add(forecast);
}
}
}
conn.disconnect();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
for(Forecast f : forecasts)
System.out.println(f);
}