基于Spring Boot的天气预报服务

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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：

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();  
    }

}