功能 --獲取json響應數據的值
示例片段：
{
"message":"ok",
"nu":"350757819118",
"ischeck":"1",
"condition":"F00",
"com":"huitongkuaidi",
"status":"200",
"state":"3",
"data":
[
{
"time":"2017-12-21 15:42:29",
"ftime":"2017-12-21 15:42:29",
"context":"廣州市|廣州市【廣州新永和站】，周祥代 已簽收",
"location":""
},
{
"time":"2017-12-17 21:29:25",
"ftime":"2017-12-17 21:29:25",
"context":"西安市|西安市【西安西郊五站】，【趙永剛/02962255063】已攬收",
"location":""
}
]
}
1）Destination Variable Name：取值成功後，保存的變量名，後面引用時就是用此處設置的變量名
2）JSONPath Expression：表達式，即時取值的表達式【$.variableName】
①所取的字段只有一個值時：$.variableName --$.message、$.status
②所取字段有多個值時（例如data）：
--> 如果依然使用$.variableName（$.data），則會取出所有值，如下所示
vardata=
[
{
"time":"2017-12-21 15:42:29",
"ftime":"2017-12-21 15:42:29",
"context":"廣州市|廣州市【廣州新永和站】，周祥代 已簽收",
"location":""
},
{
"time":"2017-12-17 21:29:25",
"ftime":"2017-12-17 21:29:25",
"context":"西安市|西安市【西安西郊五站】，【趙永剛\/02962255063】已攬收",
"location":""
}
]
-------------------------------------------------------------------------------
vardata_1=
{
"ftime":"2017-12-21 15:42:29",
"context":"廣州市|廣州市【廣州新永和站】，周祥代 已簽收",
"location":"",
"time":"2017-12-21 15:42:29"
}
vardata_2=
{
"ftime":"2017-12-17 21:29:25",
"context":"西安市|西安市【西安西郊五站】，【趙永剛\/02962255063】已攬收",
"location":"",
"time":"2017-12-17 21:29:25"
}
vardata_matchNr=2
--> 但在實際使用過程，只需要取其中的一個值來使用，表達式爲：$.data[0]、$.data[0].context
3）Default Value：缺省值，即取值失敗時顯示變量名
