### 歡迎訪問我的GitHub
> 這裡分類和彙總了欣宸的全部原創(含配套原始碼)：[https://github.com/zq2599/blog_demos](https://github.com/zq2599/blog_demos)

### 本篇概覽
- 本文的實戰是開發一個springboot應用，透過RestTemplate獲取公共的遠端api服務，將查詢到的指定城市的天氣資訊返回給前端；

### 建立springboot應用
- 基於maven建立一個springboot應用，pom資訊如下，注意新增了**httpclient**：

```xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemalocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelversion>4.0.0</modelversion>
    <parent>
        <groupid>org.springframework.boot</groupid>
        <artifactid>spring-boot-starter-parent</artifactid>
        <version>2.1.2.RELEASE</version>
        <relativepath></relativepath> 
    </parent>
    <groupid>com.bolingcavalry</groupid>
    <artifactid>weatherservice</artifactid>
    <version>0.0.1-SNAPSHOT</version>
    <name>weatherservice</name>
    <description>Demo project for Spring Boot</description>

<dependencies>
        <dependency>
            <groupid>org.springframework.boot</groupid>
            <artifactid>spring-boot-starter-web</artifactid>
        </dependency>

<dependency>
            <groupid>org.apache.httpcomponents</groupid>
            <artifactid>httpclient</artifactid>
            <version>4.5.7</version>
        </dependency>

<dependency>
            <groupid>org.springframework.boot</groupid>
            <artifactid>spring-boot-starter-test</artifactid>
            <scope>test</scope>
        </dependency>
    </dependencies>

<build>
        <plugins>
            <plugin>
                <groupid>org.springframework.boot</groupid>
                <artifactid>spring-boot-maven-plugin</artifactid>
            </plugin>
        </plugins>
    </build>
</project>
```

- 啟動類如下：

```java
package com.bolingcavalry.weatherservice;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class WeatherserviceApplication {
    public static void main(String[] args) {
        SpringApplication.run(WeatherserviceApplication.class, args);
    }
}
```

### 建立配置類
- 建立一個配置類，這裡注意要使用HttpComponentsClientHttpRequestFactory作為RestTemplate構造方法的入參，這樣才能支援gzip壓縮的response，否則得到的就是亂碼：

```java
package com.bolingcavalry.weatherservice;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.client.HttpComponentsClientHttpRequestFactory;
import org.springframework.http.converter.StringHttpMessageConverter;
import org.springframework.web.client.RestTemplate;
import java.nio.charset.StandardCharsets;

@Configuration
public class WeatherConfig {
    @Bean
    public RestTemplate restTemplate(){
        RestTemplate restTemplate = new RestTemplate(new HttpComponentsClientHttpRequestFactory());
        restTemplate.getMessageConverters().set(1, new StringHttpMessageConverter(StandardCharsets.UTF_8));
        return restTemplate;
    }
}
```

### 建立controller

- 建立一個controller來接收web請求，然後發起氣象服務網站發起天氣查詢：

```java
package com.bolingcavalry.weatherservice.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.*;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

@RestController
public class QueryWeather {

@Autowired
    RestTemplate restTemplate;

@RequestMapping(value = "/get/{city}", method = RequestMethod.GET)
    public String extern(@PathVariable("city") String city){
        String apiURL = "http://wthrcdn.etouch.cn/weather_mini?city=" + city;
        ResponseEntity<string> responseEntity = restTemplate.getForEntity(apiURL, String.class);

if(200==responseEntity.getStatusCodeValue()){
            return responseEntity.getBody();
        }else{
            return "error with code : " + responseEntity.getStatusCodeValue();
        }
    }
}
```

### 驗證
- 啟動應用WeatherserviceApplication，假如伺服器IP地址是172.30.192.1，瀏覽器響應如下圖，地址是：http://172.30.192.1:8080/get/深圳

![在這裡插入圖片描述](https://img-blog.csdnimg.cn/20190206233606329.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2JvbGluZ19jYXZhbHJ5,size_16,color_FFFFFF,t_70)

### 原始碼下載
- 接下來的實戰是編寫Flink應用的原始碼，您可以選擇直接從GitHub下載這個工程的原始碼，地址和連結資訊如下表所示：

| 名稱      |   連結 |   備註|
| :-------- | :----| :----|
| 專案主頁| https://github.com/zq2599/blog_demos | 該專案在GitHub上的主頁 |
| git倉庫地址(https)| https://github.com/zq2599/blog_demos.git | 該專案原始碼的倉庫地址，https協議 |
| git倉庫地址(ssh)| git@github.com:zq2599/blog_demos.git | 該專案原始碼的倉庫地址，ssh協議 |

- 這個git專案中有多個資料夾，本章原始碼在flinkkafkademo這個資料夾下，如下圖紅框所示：
![在這裡插入圖片描述](https://img-blog.csdnimg.cn/20190207144200102.jpg?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2JvbGluZ19jYXZhbHJ5,size_16,color_FFFFFF,t_70)

### 歡迎關注ITpub：程式設計師欣宸
> [學習路上，你不孤單，欣宸原創一路相伴...](http://blog.itpub.net/70017844/)</string>

springboot應用查詢城市天氣

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