delphi xe5 delphi 解析 json
最简单的JSON大致像这样
{
"date":"周二(今天, 实时:12℃)",
"dayPictureUrl":"http://api.map.baidu.com/images/weather/day/duoyun.png",
"nightPictureUrl":"http://api.map.baidu.com/images/weather/night/duoyun.png",
"weather":"多云",
"wind":"北风微风",
"temperature":"15 ~ 6℃"
}
对于这种格式比较简单的json,解析是非常容易的
StrJson := RESTResponse1.Content;
JSONObject := TJSONObject.ParseJSONValue(TEncoding.UTF8.GetBytes(StrJson), 0)
as TJSONObject;
JSONObject.getValue('date'); 就可以得到date的值。如果像下面的这样结构比较复杂的json,就需要首先分析清楚这个json的格式才能获取成功。
{
"error":0,
"status":"success",
"date":"2014-03-04",
"results":
[
{
"currentCity":"成都",
"weather_data":
[
{
"date":"周二(今天, 实时:12℃)",
"dayPictureUrl":"http://api.map.baidu.com/images/weather/day/duoyun.png",
"nightPictureUrl":"http://api.map.baidu.com/images/weather/night/duoyun.png",
"weather":"多云",
"wind":"北风微风",
"temperature":"15 ~ 6℃"
}
,
{
"date":"周三",
"dayPictureUrl":"http://api.map.baidu.com/images/weather/day/yin.png",
"nightPictureUrl":"http://api.map.baidu.com/images/weather/night/xiaoyu.png",
"weather":"阴转小雨",
"wind":"北风微风",
"temperature":"14 ~ 7℃"
}
,
{
"date":"周四",
"dayPictureUrl":"http://api.map.baidu.com/images/weather/day/xiaoyu.png",
"nightPictureUrl":"http://api.map.baidu.com/images/weather/night/xiaoyu.png",
"weather":"小雨",
"wind":"北风微风",
"temperature":"12 ~ 7℃"
}
,
{
"date":"周五",
"dayPictureUrl":"http://api.map.baidu.com/images/weather/day/xiaoyu.png",
"nightPictureUrl":"http://api.map.baidu.com/images/weather/night/xiaoyu.png",
"weather":"小雨",
"wind":"南风微风",
"temperature":"9 ~ 6℃"
}
]
}
]
}
这是一个嵌套结构,最外层是一个记录,包含"error", "status", "date", "results"四个字段,前三个都是简单的键值对,而“results”是一个数组,目前只有一个元素,即一条记录,这条记录的字段是"currentCity"和"weather_data",再进一步"weather_data"又是一个组数,它有4个元素或者记录,每条记录里包含 "date", "dayPictureUrl","nightPictureUrl", "weather","wind", "temperature"字段。
要想取出里面的"weather_data",利用目前的DBXJSON里的TJSONObject是不能直接取出来的,例如这样
StrJson := RESTResponse1.Content;
JSONObject := TJSONObject.ParseJSONValue(TEncoding.UTF8.GetBytes(StrJson), 0)
as TJSONObject;
weather := JSONObject.GetValue('weather_data');
需要一步一步的走,由于最外面是一个简单的json,可以先取出results,然后再取weather_data。
var
JSONObject: TJSONObject;
LItem: TJSONValue;
LJPair: TJSONPair;
weather: TJSONArray;
StrJson: String;
result: String;
i: Integer;
begin
StrJson := 'xxxxxxx';//假定是上面那个json
JSONObject := TJSONObject.ParseJSONValue(TEncoding.UTF8.GetBytes(StrJson), 0)
as TJSONObject;
JSONObject := (JSONObject.GetValue('results') as TJSONArray).Get(0)
as TJSONObject;
weather := JSONObject.GetValue('weather_data') as TJSONArray;
for i := 0 to weather.size - 1 do //应该是4条记录
begin
LItem := (weather.Get(i) as TJSONObject).GetValue('weather'); //得到weather的值
result := result + '|' + LItem.Value;
end;
end
这段代码只是为了说明使用方法,没有做类型检查,最好在进行类型转换之前用is TJSONArray先判断是不是数组。