java后台解析json字符串

json 字符数组如下
[
[ {
"trade_code": "A",
"trade_name": "%E5%86%9C%E3%80%81%E6%9E%97%E3%80%81%E7%89%A7%E3%80%81%E6%B8%94%E4%B8%9A",
"num500100": "0",
"invest500100": "0",
"num500101": "0",
"invest500101": "0",
"num500102": "0",
"invest500102": "0",
"num500103": "0",
"invest500103": "0"｝]
,
[
{
"name_county": "市辖区",
"code_county": "500100"
},
{
"name_county": "万州区",
"code_county": "500101"
},
{
"name_county": "涪陵区",
"code_county": "500102"
}]

请问在后台如何拿到对应的数据
例如 "name_county": "市辖区",
"code_county": "500100"
"num500100": "0",
"invest500100": "0",
求大神给一下思路 代码