GSON是Google提供的用来在Java对象和JSON数据之间进行映射的Java类库。可以将一个Json字符转成一个Java对象，或者将一个Java转化为Json字符串。
特点:
a、快速、高效
b、代码量少、简洁
c、面向对象
d、数据传递和解析方便
Gon介绍
<dependency>
<groupId>com.google.code.gson</groupId>
<artifactId>gson</artifactId>
<version>2.8.0</version>
</dependency>
Gson的创建方式
- Gson gson = new gson();
- 通过GsonBuilder()，可以配置多种配置。
Gson gson = new GsonBuilder()
.setLenient()// json宽松
.enableComplexMapKeySerialization()//支持Map的key为复杂对象的形式
.serializeNulls() //智能null
.setPrettyPrinting()// 调教格式
.disableHtmlEscaping() //默认是GSON把HTML 转义的
.create();
Gson的基本用法
之前写过一个获取天气参数的API,就需要去解析返回的json数据，就以此为例。
获取天气参数
String url = "http://t.weather.sojson.com/api/weather/city/101010100";
String resultStr = HttpClientUtil.sendGetRequest(url, "UTF-8");
返回结果(就不格式化了)
{shidu=15%, pm25=15.0, pm10=35.0, quality=优, wendu=3, ganmao=各类人群可自由活动,
yesterday={date=06, sunrise=07:36, high=高温 3.0℃, low=低温 -7.0℃, sunset=17:03,
aqi=58.0, ymd=2019-01-06, week=星期日, fx=西南风, fl=<3级, type=晴,
notice=愿你拥有比阳光明媚的心情}, forecast=[{date=07, sunrise=07:36, high=高温 2.0℃,
low=低温 -7.0℃, sunset=17:04, aqi=48.0, ymd=2019-01-07, week=星期一, fx=北风,
fl=3-4级, type=多云, notice=阴晴之间，谨防紫外线侵扰}, {date=08, sunrise=07:36,
high=高温 1.0℃, low=低温 -9.0℃, sunset=17:05, aqi=28.0, ymd=2019-01-08, week=星期二,
fx=北风, fl=3-4级, type=晴, notice=愿你拥有比阳光明媚的心情}, {date=09, sunrise=07:36,
high=高温 2.0℃, low=低温 -8.0℃, sunset=17:06, aqi=83.0, ymd=2019-01-09, week=星期三,
fx=西南风, fl=<3级, type=多云, notice=阴晴之间，谨防紫外线侵扰}, {date=10, sunrise=07:36,
high=高温 4.0℃, low=低温 -7.0℃, sunset=17:07, aqi=128.0, ymd=2019-01-10, week=星期四,
fx=西南风, fl=<3级, type=晴, notice=愿你拥有比阳光明媚的心情}, {date=11, sunrise=07:36,
high=高温 5.0℃, low=低温 -6.0℃, sunset=17:08, aqi=238.0, ymd=2019-01-11, week=星期五,
fx=西南风, fl=<3级, type=多云, notice=阴晴之间，谨防紫外线侵扰}]}
可以新建一个天气的Bean，将返回的json数据转换成对象
//GSON直接解析成对象
ResultBean resultBean = new Gson().fromJson(resultStr,ResultBean.class);
解析简单的json
data:{
shidu = 15 % ,
pm25 = 15.0,
pm10 = 35.0,
quality = 优,
wendu = 3,
ganmao = 各类人群可自由活动,
}
JsonObject jsonObject =(JsonObject) new JsonParser().parse(resultStr);
Int wendu = jsonObject.get("data").getAsJsonObject().get("wendu").getAsInt();
String quality= jsonObject.get("data").getAsJsonObject().get("quality").getAsString();
解析多层对象
data:{
shidu = 15 % ,
pm25 = 15.0,
pm10 = 35.0,
quality = 优,
wendu = 3,
ganmao = 各类人群可自由活动,
yesterday :{
date = 06,
sunrise = 07: 36,
high = 高温 3.0℃,
low = 低温 - 7.0℃,
sunset = 17: 03,
aqi = 58.0,
ymd = 2019 - 01 - 06,
week = 星期日,
fx = 西南风,
fl = < 3 级,
type = 晴,
notice = 愿你拥有比阳光明媚的心情
}
}
JsonObject jsonObject = (JsonObject) new JsonParser().parse(resultStr);
JsonObject yesterday = jsonObject.get("data").getAsJsonObject().get("yesterday ").getAsJsonObject();
String type = yesterday.get("type").getAsString();
解析带数组的json
{
shidu = 15 % , pm25 = 15.0, pm10 = 35.0, quality = 优, wendu = 3, ganmao = 各类人群可自由活动,
yesterday = {
date = 06,
sunrise = 07: 36,
high = 高温 3.0℃,
low = 低温 - 7.0℃,
sunset = 17: 03,
aqi = 58.0,
ymd = 2019 - 01 - 06,
week = 星期日,
fx = 西南风,
fl = < 3 级,
type = 晴,
notice = 愿你拥有比阳光明媚的心情
},
forecast = [{
date = 07,
sunrise = 07: 36,
high = 高温 2.0℃,
low = 低温 - 7.0℃,
sunset = 17: 04,
aqi = 48.0,
ymd = 2019 - 01 - 07,
week = 星期一,
fx = 北风,
fl = 3 - 4 级,
type = 多云,
notice = 阴晴之间， 谨防紫外线侵扰
}, {
date = 08,
sunrise = 07: 36,
high = 高温 1.0℃,
low = 低温 - 9.0℃,
sunset = 17: 05,
aqi = 28.0,
ymd = 2019 - 01 - 08,
week = 星期二,
fx = 北风,
fl = 3 - 4 级,
type = 晴,
notice = 愿你拥有比阳光明媚的心情
}, {
date = 09,
sunrise = 07: 36,
high = 高温 2.0℃,
low = 低温 - 8.0℃,
sunset = 17: 06,
aqi = 83.0,
ymd = 2019 - 01 - 09,
week = 星期三,
fx = 西南风,
fl = < 3 级,
type = 多云,
notice = 阴晴之间， 谨防紫外线侵扰
}, {
date = 10,
sunrise = 07: 36,
high = 高温 4.0℃,
low = 低温 - 7.0℃,
sunset = 17: 07,
aqi = 128.0,
ymd = 2019 - 01 - 10,
week = 星期四,
fx = 西南风,
fl = < 3 级,
type = 晴,
notice = 愿你拥有比阳光明媚的心情
}, {
date = 11,
sunrise = 07: 36,
high = 高温 5.0℃,
low = 低温 - 6.0℃,
sunset = 17: 08,
aqi = 238.0,
ymd = 2019 - 01 - 11,
week = 星期五,
fx = 西南风,
fl = < 3 级,
type = 多云,
notice = 阴晴之间， 谨防紫外线侵扰
}]
}
JsonObject jsonObject =(JsonObject) new JsonParser().parse(resultStr);
//获取data
JsonObject data = jsonObject.get("data").getAsJsonObject();
//获取数组
JsonArray forecast = data.getAsJsonObject().get("forecast").getAsJsonArray();
String type = forecast.get(0).getAsJsonObject().get("type").getAsString();
