前些天知道了如何获取数字签名SHA1，那它用来干嘛的呢？今天就来学习一下它的用处。
比如说我们要开发一款基于位置的服务，如地图、天气预报等。我们要用到API Key。
百度API Key申请地址：
创建应用 如图：
提交后得到API Key 如图：
接口实例：？location=南昌&output=json&ak=你的API Key&mcode=你的数字签名SHA1;com.example.administrator.jsontest（包名）
接口参数说明
参数类型 参数名称 是否必须 具体描述String location true 输入城市名或经纬度，城市名如北京或者131，经纬度格式为lng，lat坐标，如：location=116.305145,39.982368;全国值为all，返回省会城市自治区，港澳台天气情况多城市天气预报中间用“|”分隔，如：location=116.305145,39.982368|123.342323,36238945|...
String output false 输出的数据格式，默认为xml格式，当output设置为json时，输出的为json数据格式
String coord_type false 请求参数坐标类型，默认为gcj02经纬度坐标。允许的值为bd09ll、bd09mc、gcj02、wgs84；
返回的JSON数据
{ "error":0, "status":"success", "date":"2016-03-05", "results":[ { "currentCity":"北京", "pm25":"144", "index":[ { "title":"穿衣", "zs":"较冷", "tipt":"穿衣指数", "des":"建议着厚外套加毛衣等服装。年老体弱者宜着大衣、呢外套加羊毛衫。"}, { "title":"洗车", "zs":"不宜", "tipt":"洗车指数", "des":"不宜洗车，未来24小时内有扬沙或浮尘，如果在此期间洗车，极易很快蒙上新的灰尘。"}, { "title":"旅游", "zs":"一般", "tipt":"旅游指数", "des":"风稍大，扬沙或浮尘天气对能见度和空气质量都会有些影响，出行请注意交通安全和采取适当的防尘措施。"}, { "title":"感冒", "zs":"易发", "tipt":"感冒指数", "des":"昼夜温差大，风力较强，易发生感冒，请注意适当增减衣服，加强自我防护避免感冒。"}, { "title":"运动", "zs":"较不宜", "tipt":"运动指数", "des":"有扬沙或浮尘，建议适当停止户外运动，选择在室内进行运动，以避免吸入更多沙尘，有损健康。"}, { "title":"紫外线强度", "zs":"最弱", "tipt":"紫外线强度指数", "des":"属弱紫外线辐射天气，无需特别防护。若长期在户外，建议涂擦SPF在8-12之间的防晒护肤品。"} ], "weather_data":[ { "date":"周六 03月05日 (实时：12℃)", "dayPictureUrl":"http://api.map.baidu.com/images/weather/day/fuchen.png", "nightPictureUrl":"http://api.map.baidu.com/images/weather/night/qing.png", "weather":"浮尘转晴", "wind":"北风4-5级", "temperature":"12 ~ -1℃"}, { "date":"周日", "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":"微风", "temperature":"10 ~ -3℃"}, { "date":"周一", "dayPictureUrl":"http://api.map.baidu.com/images/weather/day/duoyun.png", "nightPictureUrl":"http://api.map.baidu.com/images/weather/night/yin.png", "weather":"多云转阴", "wind":"微风", "temperature":"13 ~ 2℃"}, { "date":"周二", "dayPictureUrl":"http://api.map.baidu.com/images/weather/day/yin.png", "nightPictureUrl":"http://api.map.baidu.com/images/weather/night/duoyun.png", "weather":"阴转多云", "wind":"北风3-4级", "temperature":"6 ~ -1℃"} ]}]}数据解析public class WeatherData { public String date; public String error; public List<Results> results; public String status; public class Results{ public String currentCity; public List<Index> index; public String pm25; public List<Weather_data> weather_data; } public class Index{ public String des; public String tipt; public String title; public String zs; } public class Weather_data{ public String date; public String dayPictureUrl; public String nightPictureUrl; public String temperature; public String weather; public String wind; } }