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为什么要使用Redis

• 及时响应：Redis是一个基于内存的缓存系统，查询、响应的速度快
• 减少服务调用

开发环境

• JDK8+
• Gradle4+
• Redis 3.2.100
• Apache HttpClient 4.5.3
• Spring Boot Web Starter
• Spring Boot Data Redis Starter

新建项目

复制之前的micro-weather-basic项目，将副本改名为micro-weather-redis

修改源码

修改build.gradle配置，加入redis的依赖：

//依赖关系dependencies {
       //该依赖用于编译阶段	compile('org.springframework.boot:spring-boot-starter-web')		//HttpClient	compile('org.apache.httpcomponents:httpclient:4.5.6')    //Redis    compile('org.springframework.boot:spring-boot-starter-data-redis')    //该依赖用于测试阶段    testCompile('org.springframework.boot:spring-boot-starter-test')}

修改WeatherDataServiceImpl.java：

package com.study.spring.cloud.weather.service;import com.fasterxml.jackson.databind.ObjectMapper;import com.study.spring.cloud.weather.vo.WeatherResponse;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.data.redis.core.StringRedisTemplate;import org.springframework.data.redis.core.ValueOperations;import org.springframework.http.ResponseEntity;import org.springframework.stereotype.Service;import org.springframework.web.client.RestTemplate;import java.io.IOException;import java.util.concurrent.TimeUnit;@Servicepublic class WeatherDataServiceImpl implements WeatherDataService {
   	//在应用中添加日志	private final static Logger logger=LoggerFactory.getLogger(WeatherDataService.class);	private static final String WEATHER_URI="http://wthrcdn.etouch.cn/weather_mini?";	private static final long TIME_OUT=10L;	@Autowired	//对rest客户端的封装	private RestTemplate restTemplate;	@Autowired	//对redis api的封装	private StringRedisTemplate stringRedisTemplate;	@Override	public WeatherResponse getDataByCityId(String cityId) {
   				String uri=WEATHER_URI + "citykey=" + cityId;		return this.doGetWeather(uri);	}	@Override	public WeatherResponse getDataByCityName(String cityName) {
   				String uri=WEATHER_URI + "city=" + cityName;		return this.doGetWeather(uri);	}		private WeatherResponse doGetWeather(String uri) {
   		String key=uri;		String strBody=null;		ObjectMapper mapper=new ObjectMapper();		WeatherResponse resp=null;		//ValueOperations类可通过get()获取缓存中的数据		ValueOperations
   
     ops = stringRedisTemplate.opsForValue();		//先查缓存，缓存有的取缓存中的数据		if(stringRedisTemplate.hasKey(key)){
   			logger.info("Redis has data");			strBody = ops.get(key);		}else{
   			logger.info("Redis doesn't have data");			//缓存没有，再调用服务接口来获取			//得到json字符串			ResponseEntity
    
      respString = restTemplate.getForEntity(uri, String.class);			//判断ResponseEntity的状态码是否为200，为200时取出strBody			if(respString.getStatusCodeValue()==200) {
   				strBody=respString.getBody();			}			//数据写入缓存			ops.set(key, strBody, TIME_OUT, TimeUnit.SECONDS);		}		//用json反序列化成我们想要的数据		try {
   			/*			 * strBody：要解析的参数内容，从respString获取			 * WeatherResponse.class：要转成的对象类型			 */			resp=mapper.readValue(strBody,WeatherResponse.class);		}catch(IOException e) {
   			logger.error("Error!",e);		}				return resp;	}}
    
   

运行

运行Redis：

//在应用中添加日志	private final static Logger logger=LoggerFactory.getLogger(WeatherDataService.class);	private static final String WEATHER_URI="http://wthrcdn.etouch.cn/weather_mini?";	private static final long TIME_OUT=1800L;

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