本文，我们将基于 Spring Boot 技术来实现一个微服务天气预报服务接口——micro-weather-basic。micro-weather-basic 的作用是实现简单的天气预报功能，可以根据不同的城市，查询该城市的实时天气情况。

开发环境

• Gradle 4.0
• Spring Boot 1.5.6
• Apache HttpClient 1.5.3

数据来源

理论上，天气的数据是天气预报的实现基础。本应用与实际的天气数据无关，理论上，可以兼容多种数据来源。但为求简单，我们在网上找了一个免费、可用的天气数据接口。

• 天气数据来源为中华万年历。例如：
  • 通过城市名字获得天气数据 ：<http://wthrcdn.etouch.cn/weather_mini?city=深圳>
  • 通过城市id获得天气数据：<http://wthrcdn.etouch.cn/weather_mini?citykey=101280601>
• 城市ID列表。每个城市都有一个唯一的ID作为标识。见 <http://cj.weather.com.cn/support/Detail.aspx?id=51837fba1b35fe0f8411b6df> 或者 <http://mobile.weather.com.cn/js/citylist.xml>。

调用天气服务接口示例，我们以“深圳”城市为例，可用看到如下天气数据返回。

{     "data": {         "yesterday": {             "date": "1日星期五",             "high": "高温 33℃",             "fx": "无持续风向",             "low": "低温 26℃",             "fl": "<![CDATA[<3级]]>",             "type": "多云"         },         "city": "深圳",         "aqi": "72",         "forecast": [             {                 "date": "2日星期六",                 "high": "高温 32℃",                 "fengli": "<![CDATA[<3级]]>",                 "low": "低温 26℃",                 "fengxiang": "无持续风向",                 "type": "阵雨"             },             {                 "date": "3日星期天",                 "high": "高温 29℃",                 "fengli": "<![CDATA[5-6级]]>",                 "low": "低温 26℃",                 "fengxiang": "无持续风向",                 "type": "大雨"             },             {                 "date": "4日星期一",                 "high": "高温 29℃",                 "fengli": "<![CDATA[3-4级]]>",                 "low": "低温 26℃",                 "fengxiang": "西南风",                 "type": "暴雨"             },             {                 "date": "5日星期二",                 "high": "高温 31℃",                 "fengli": "<![CDATA[<3级]]>",                 "low": "低温 27℃",                 "fengxiang": "无持续风向",                 "type": "阵雨"             },             {                 "date": "6日星期三",                 "high": "高温 32℃",                 "fengli": "<![CDATA[<3级]]>",                 "low": "低温 27℃",                 "fengxiang": "无持续风向",                 "type": "阵雨"             }         ],         "ganmao": "风较大，阴冷潮湿，较易发生感冒，体质较弱的朋友请注意适当防护。",         "wendu": "29"     },     "status": 1000,     "desc": "OK" } 

我们通过观察数据，来了解每个返回字段的含义。

• "city": 城市名称
• "aqi": 空气指数,
• "wendu": 实时温度
• "date": 日期，包含未来5天
• "high":最高温度
• "low": 最低温度
• "fengli": 风力
• "fengxiang": 风向
• "type": 天气类型

以上数据，是我们需要的天气数据的核心数据，但是，同时也要关注下面两个字段：

• "status": 接口调用的返回状态，返回值“1000”,意味着数据是接口正常
• "desc": 接口状态的描述，“OK”代表接口正常

重点关注返回值不是“1000”的情况,说明，这个接口调用异常了。

初始化一个 Spring Boot 项目

初始化一个 Spring Boot 项目 micro-weather-basic，该项目可以直接在我们之前章节课程中的 basic-gradle 项目基础进行修改。同时，为了优化项目的构建速度，我们对Maven中央仓库地址和 Gradle Wrapper 地址做了调整。其中细节暂且不表，读者可以自行参阅源码，或者学习笔者所著的《Spring Boot 教程》（<https://github.com/waylau/spring-boot-tutorial>）。其原理，我也整理到我的博客中了：

• https://waylau.com/change-gradle-wrapper-distribution-url-to-local-file/
• https://waylau.com/use-maven-mirrors/

项目配置

添加 Apache HttpClient 的依赖，来作为我们Web请求的客户端。

// 依赖关系 dependencies { 	//...   	// 添加  Apache HttpClient 依赖 	compile('org.apache.httpcomponents:httpclient:4.5.3')   	//... } 

创建天气信息相关的值对象

创建com.waylau.spring.cloud.vo包，用于相关值对象。创建天气信息类 Weather

public class Weather implements Serializable { 	  	private static final long serialVersionUID = 1L; 		 	private String city; 	private String aqi; 	private String wendu; 	private String ganmao; 	private Yesterday yesterday; 	private List<Forecast> forecast;   	public String getCity() { 		return city; 	} 	public void setCity(String city) { 		this.city = city; 	} 	public String getAqi() { 		return aqi; 	} 	public void setAqi(String aqi) { 		this.aqi = aqi; 	} 	public String getWendu() { 		return wendu; 	} 	public void setWendu(String wendu) { 		this.wendu = wendu; 	} 	public String getGanmao() { 		return ganmao; 	} 	public void setGanmao(String ganmao) { 		this.ganmao = ganmao; 	} 	public Yesterday getYesterday() { 		return yesterday; 	} 	public void setYesterday(Yesterday yesterday) { 		this.yesterday = yesterday; 	} 	public List<Forecast> getForecast() { 		return forecast; 	} 	public void setForecast(List<Forecast> forecast) { 		this.forecast = forecast; 	} } 

昨日天气信息：

public class Yesterday implements Serializable {   	private static final long serialVersionUID = 1L; 	 	private String date; 	private String high; 	private String fx; 	private String low; 	private String fl; 	private String type;  	public Yesterday() {  	} 	     public String getDate() { 		return date; 	}  	public void setDate(String date) { 		this.date = date; 	}  	public String getHigh() { 		return high; 	}  	public void setHigh(String high) { 		this.high = high; 	}  	public String getFx() { 		return fx; 	}  	public void setFx(String fx) { 		this.fx = fx; 	}  	public String getLow() { 		return low; 	}  	public void setLow(String low) { 		this.low = low; 	}  	public String getFl() { 		return fl; 	}  	public void setFl(String fl) { 		this.fl = fl; 	}  	public String getType() { 		return type; 	}  	public void setType(String type) { 		this.type = type; 	}  } 

未来天气信息：

public class Forecast implements Serializable { 	 	private static final long serialVersionUID = 1L; 	 	private String date;     private String high;     private String fengxiang;     private String low;     private String fengli;     private String type;  	public String getDate() { 		return date; 	}  	public void setDate(String date) { 		this.date = date; 	}  	public String getHigh() { 		return high; 	}  	public void setHigh(String high) { 		this.high = high; 	}  	public String getFengxiang() { 		return fengxiang; 	}  	public void setFengxiang(String fengxiang) { 		this.fengxiang = fengxiang; 	}  	public String getLow() { 		return low; 	}  	public void setLow(String low) { 		this.low = low; 	}  	public String getFengli() { 		return fengli; 	}  	public void setFengli(String fengli) { 		this.fengli = fengli; 	}  	public String getType() { 		return type; 	}  	public void setType(String type) { 		this.type = type; 	}  	public Forecast() {  	}   } 

WeatherResponse 作为整个消息的返回对象

public class WeatherResponse implements Serializable {  	private static final long serialVersionUID = 1L;  	private Weather data; // 消息数据 	private String status; // 消息状态 	private String desc; // 消息描述  	public Weather getData() { 		return data; 	}  	public void setData(Weather data) { 		this.data = data; 	}  	public String getStatus() { 		return status; 	}  	public void setStatus(String status) { 		this.status = status; 	}  	public String getDesc() { 		return desc; 	}  	public void setDesc(String desc) { 		this.desc = desc; 	}  } 

服务接口及实现

定义了获取服务的两个接口方法

public interface WeatherDataService {  	/** 	 * 根据城市ID查询天气数据 	 * @param cityId 	 * @return 	 */ 	WeatherResponse getDataByCityId(String cityId); 	 	/** 	 * 根据城市名称查询天气数据 	 * @param cityId 	 * @return 	 */ 	WeatherResponse getDataByCityName(String cityName); } 

其实现为:

@Service public class WeatherDataServiceImpl implements WeatherDataService {  	@Autowired 	private RestTemplate restTemplate;  	private final String WEATHER_API = "http://wthrcdn.etouch.cn/weather_mini";  	@Override 	public WeatherResponse getDataByCityId(String cityId) { 		String uri = WEATHER_API + "?citykey=" + cityId; 		return this.doGetWeatherData(uri); 	}  	@Override 	public WeatherResponse getDataByCityName(String cityName) { 		String uri = WEATHER_API + "?city=" + cityName; 		return this.doGetWeatherData(uri); 	}  	private WeatherResponse doGetWeatherData(String uri) { 		ResponseEntity<String> response = restTemplate.getForEntity(uri, String.class); 		String strBody = null;  		if (response.getStatusCodeValue() == 200) { 			strBody = response.getBody(); 		}  		ObjectMapper mapper = new ObjectMapper(); 		WeatherResponse weather = null;  		try { 			weather = mapper.readValue(strBody, WeatherResponse.class); 		} catch (IOException e) { 			e.printStackTrace(); 		}  		return weather; 	}  } 

返回的天气信息采用了 Jackson 来进行反序列化成为 WeatherResponse 对象。

控制器层

控制器层暴露了RESTful API 地址。

@RestController @RequestMapping("/weather")	 public class WeatherController {  	@Autowired 	private WeatherDataService weatherDataService; 	 	@GetMapping("/cityId/{cityId}") 	public WeatherResponse getReportByCityId(@PathVariable("cityId") String cityId) { 		return weatherDataService.getDataByCityId(cityId); 	} 	 	@GetMapping("/cityName/{cityName}") 	public WeatherResponse getReportByCityName(@PathVariable("cityName") String cityName) { 		return weatherDataService.getDataByCityName(cityName); 	}  } 

@RestController自动会将返回的数据，序列化成 JSON数据格式。

配置类

RestConfiguration 是 RestTemplate 的配置类。

@Configuration public class RestConfiguration {  	@Autowired       private RestTemplateBuilder builder;        @Bean       public RestTemplate restTemplate() {           return builder.build();       }  } 

访问API

运行项目之后，访问项目的 API ：

• <http://localhost:8080/weather/cityId/101280601>
• <http://localhost:8080/weather/cityName/惠州>

能看到如下的数据返回

源码

本章节的源码，见 <https://github.com/waylau/spring-cloud-tutorial/> samples目录下的micro-weather-basic。

参考引用

• https://waylau.com/spring-boot-weather-report/
• https://github.com/waylau/spring-boot-tutorial