json2

接下来看一段复杂的json文本，要求用java代码解析当前的天气 和 未来三天的天气：

{

"count": 1,
"created": "2016-06-24T05:44:43Z",
"lang": "null",
"results":
{
"channel":
{
"units":
{
"distance": "km",
"pressure": "mb",
"speed": "km/h",
"temperature": "C"
},
"title": "Yahoo! Weather - Changsha, Hunan, CN",
"link": "http://us.rd.yahoo.com/dailynews/rss/weather/Country__Country/*https://weather.yahoo.com/country/state/city-12686154/",
"description": "Yahoo! Weather for Changsha, Hunan, CN",
"language": "en-us",
"lastBuildDate": "Fri, 24 Jun 2016 01:44 PM CST",
"ttl": "60",
"location":
{
"city": "Changsha",
"country": "China",
"region": " Hunan"
},
"wind":
{
"chill": "88",
"direction": "293",
"speed": "22.53"
},
"atmosphere":
{
"humidity": "90",
"pressure": "33796.17",
"rising": "0",
"visibility": "24.94"
},
"astronomy":
{
"sunrise": "5:33 am",
"sunset": "7:28 pm"
},
"image":
{
"title": "Yahoo! Weather",
"width": "142",
"height": "18",
"link": "http://weather.yahoo.com",
"url": "http://l.yimg.com/a/i/brand/purplelogo//uh/us/news-wea.gif"
},
"item":
{
"title": "Conditions for Changsha, Hunan, CN at 01:00 PM CST",
"lat": "28.148609",
"long": "112.996727",
"link": "http://us.rd.yahoo.com/dailynews/rss/weather/Country__Country/*https://weather.yahoo.com/country/state/city-12686154/",
"pubDate": "Fri, 24 Jun 2016 01:00 PM CST",
"condition":
{
"code": "47",
"date": "Fri, 24 Jun 2016 01:00 PM CST",
"temp": "30",
"text": "Scattered Thunderstorms"
},
"forecast":
[
{
"code": "4",
"date": "24 Jun 2016",
"day": "Fri",
"high": "31",
"low": "25",
"text": "Thunderstorms"
},
{
"code": "26",
"date": "25 Jun 2016",
"day": "Sat",
"high": "24",
"low": "22",
"text": "Cloudy"
},
{
"code": "47",
"date": "26 Jun 2016",
"day": "Sun",
"high": "28",
"low": "21",
"text": "Scattered Thunderstorms"
},
{
"code": "4",
"date": "27 Jun 2016",
"day": "Mon",
"high": "32",
"low": "23",
"text": "Thunderstorms"
},
{
"code": "4",
"date": "28 Jun 2016",
"day": "Tue",
"high": "33",
"low": "25",
"text": "Thunderstorms"
},
{
"code": "4",
"date": "29 Jun 2016",
"day": "Wed",
"high": "31",
"low": "27",
"text": "Thunderstorms"
},
{
"code": "4",
"date": "30 Jun 2016",
"day": "Thu",
"high": "29",
"low": "27",
"text": "Thunderstorms"
},
{
"code": "4",
"date": "01 Jul 2016",
"day": "Fri",
"high": "30",
"low": "27",
"text": "Thunderstorms"
},
{
"code": "4",
"date": "02 Jul 2016",
"day": "Sat",
"high": "29",
"low": "26",
"text": "Thunderstorms"
},
{
"code": "4",
"date": "03 Jul 2016",
"day": "Sun",
"high": "29",
"low": "25",
"text": "Thunderstorms"
}
],

"guid":
{
"isPermaLink": "false"
}
}
}
}

}

可以看到 ，数据比较复杂，嵌套层数很多。有两种办法，一种是一层一层地找，另外一种是用json-path，JSONpath.read(json字符串，”$.第一层.第二层…”)

代码如下：

//解析json
public static void parseJson(String json) {
//String t1="{'hi':'nihao'}";

//这样一层一层地找很麻烦
JSONObject jsonObject=new JSONObject().fromObject(json);
//System.out.println(jsonObject);
JSONObject j2=(JSONObject) jsonObject.get("results");
//System.out.println(j2);
//String count=jsonObject.getString("count");
//System.out.println(count);
JSONObject j3=(JSONObject) j2.get("channel");
//System.out.println(j3);
JSONObject j4=(JSONObject) j3.get("item");
//System.out.println(j4);
JSONObject j5=(JSONObject) j4.get("condition");
//System.out.println(j5);
System.out.println("当前长沙市温度："+j5.getInt("temp"));
System.out.println("当前长沙市天气描述："+j5.getString("text"));

JSONArray jsonArray=j4.getJSONArray("forecast");
//System.out.println(jsonArray);

System.out.println("未来三天天气情况：");

for(int i=1;i<=3;i++)
{

JSONObject j=jsonArray.getJSONObject(i);
System.out.println(j.getString("date")+":最高温度"+j.getInt("high")+",最低温度："+j.getInt("low")+",描述："+j.getString("text"));
}

//用json-path更简单
System.out.println("-------------json path-----------------");
//JSONObject jObject=JsonPath.read(json, "$.results.channel.item.condition");返回类型需为linkedhashmap
LinkedHashMap<String, Object> condition=JsonPath.read(json, "$.results.channel.item.condition");
//$：根目录
//System.out.println(condition);
System.out.println("当前长沙市温度："+condition.get("temp"));
System.out.println("当前长沙市天气描述："+condition.get("text"));
//System.out.println(jObject);
//JSONArray array=JsonPath.read(json, "$.results.channel.item.forecast");
//System.out.println(JsonPath.parse(jsonObject));
net.minidev.json.JSONArray array=JsonPath.read(json, "$.results.channel.item.forecast");
//LinkedHashMap<String, Object> myjJsonObject=(LinkedHashMap<String, Object>) array.get(0);
//System.out.println(myjJsonObject);
//System.out.println(array);
//LinkedHashMap<String, Object> item=JsonPath.read(json, "$.results.channel.item");
//System.out.println(item);
for(int i=1;i<=3;i++)
{

LinkedHashMap<String, Object> j=(LinkedHashMap<String, Object>) array.get(i);
System.out.println(j.get("date")+":最高温度"+j.get("high")+",最低温度："+j.get("low")+",描述："+j.get("text"));
}
}