Redis的简单入门

      上次介绍了一些Redis的一些基本的操作，这次我们来实现一个简单的小例子，比如说我们正常登陆的时间，登陆成功后会跳转到网页的首页，首页也是访问量最大的，那么首页的数据每次都要从数据库查询吗?那当然不是，这是我们的缓存就派上了用场，这里我做了个小例子，用户登陆成功跳转到书籍列表查询

要使用Redis首先需要jar支持

<dependency>      <groupId>redis.clients</groupId>      <artifactId>jedis</artifactId>      <version>2.7.2</version></dependency>

添加jar后我们需要在applicationContext.xml配置Redis这里以单机版本为例，集群版已注释

<!-- 连接池配置 --><bean id="jedisPoolConfig" class="redis.clients.jedis.JedisPoolConfig"><!-- 最大连接数 --><property name="maxTotal" value="30" /><!-- 最大空闲连接数 --><property name="maxIdle" value="10" /><!-- 每次释放连接的最大数目 --><property name="numTestsPerEvictionRun" value="1024" /><!-- 释放连接的扫描间隔（毫秒） --><property name="timeBetweenEvictionRunsMillis" value="30000" /><!-- 连接最小空闲时间 --><property name="minEvictableIdleTimeMillis" value="1800000" /><!-- 连接空闲多久后释放, 当空闲时间>该值 且 空闲连接>最大空闲连接数 时直接释放 --><property name="softMinEvictableIdleTimeMillis" value="10000" /><!-- 获取连接时的最大等待毫秒数,小于零:阻塞不确定的时间,默认-1 --><property name="maxWaitMillis" value="1500" /><!-- 在获取连接的时候检查有效性, 默认false --><property name="testOnBorrow" value="true" /><!-- 在空闲时检查有效性, 默认false --><property name="testWhileIdle" value="true" /><!-- 连接耗尽时是否阻塞, false报异常,ture阻塞直到超时, 默认true --><property name="blockWhenExhausted" value="false" /></bean><!-- jedis客户端单机版 --> <bean id="jedisPool" class="redis.clients.jedis.JedisPool">    <!-- value为你安装Redis的服务器IP --><constructor-arg name="host" value="172.16.143.88"></constructor-arg> <!-- value为你安装Redis的端口号 --><constructor-arg name="port" value="6379"></constructor-arg><constructor-arg name="poolConfig" ref="jedisPoolConfig"></constructor-arg></bean>                              <!--  jedis的实现类的全路径 --><bean id="jedisClient" class="com.miao.redis.JedisClientPool"/> <!-- jedis集群版配置 --><!-- <bean id="redisClient" class="redis.clients.jedis.JedisCluster"><constructor-arg name="nodes"><set><bean class="redis.clients.jedis.HostAndPort"><constructor-arg name="host" value="192.168.25.153"></constructor-arg><constructor-arg name="port" value="7001"></constructor-arg></bean><bean class="redis.clients.jedis.HostAndPort"><constructor-arg name="host" value="192.168.25.153"></constructor-arg><constructor-arg name="port" value="7002"></constructor-arg></bean><bean class="redis.clients.jedis.HostAndPort"><constructor-arg name="host" value="192.168.25.153"></constructor-arg><constructor-arg name="port" value="7003"></constructor-arg></bean><bean class="redis.clients.jedis.HostAndPort"><constructor-arg name="host" value="192.168.25.153"></constructor-arg><constructor-arg name="port" value="7004"></constructor-arg></bean><bean class="redis.clients.jedis.HostAndPort"><constructor-arg name="host" value="192.168.25.153"></constructor-arg><constructor-arg name="port" value="7005"></constructor-arg></bean><bean class="redis.clients.jedis.HostAndPort"><constructor-arg name="host" value="192.168.25.153"></constructor-arg><constructor-arg name="port" value="7006"></constructor-arg></bean></set></constructor-arg><constructor-arg name="poolConfig" ref="jedisPoolConfig"></constructor-arg></bean><bean id="jedisClientCluster" class="com.taotao.sso.dao.JedisClientCluster"></bean> -->

配置完成后，我们需要Redis的操作接口和其实现类，这里给大家整理了还算是很齐的

接口：

package com.miao.redis;import java.util.List;import java.util.Map;import java.util.Set;public interface JedisClient {String set(String key, String value);String get(String key);Boolean exists(String key);Long expire(String key, int seconds);Long ttl(String key);Long incr(String key);Long hset(String key, String field, String value);String hget(String key, String field);Long hdel(String key, String... field);Long persist(final String key);Long del(final String key);Long hlen(final String key);Boolean hexists(final String key, final String field);Set<String> hkeys(final String key);List<String> hvals(final String key);Map<String, String> hgetAll(final String key);Long rpush(final String key, final String... string);Long lpush(final String key, final String... string);Long llen(final String key);List<String> lrange(final String key, final long start, final long end);String ltrim(final String key, final long start, final long end);String lindex(final String key, final long index);String lset(final String key, final long index, final String value);Long lrem(final String key, final long count, final String value);String lpop(final String key);String rpop(final String key);Long sadd(final String key, final String... member);Set<String> smembers(final String key);Boolean sismember(final String key, final String member);Long srem(final String key, final String... member);}

实现类：

package com.miao.redis;import java.util.List;import java.util.Map;import java.util.Set;import org.springframework.beans.factory.annotation.Autowired;import redis.clients.jedis.Jedis;import redis.clients.jedis.JedisPool;public class JedisClientPool implements JedisClient{/* * 单节点使用redis */@Autowiredprivate JedisPool jedisPool;public String set(String key, String value) {Jedis jedis = jedisPool.getResource();String result = jedis.set(key, value);jedis.close();return result;}public String get(String key) {Jedis jedis = jedisPool.getResource();String result = jedis.get(key);jedis.close();return result;}public Boolean exists(String key) {Jedis jedis = jedisPool.getResource();Boolean result = jedis.exists(key);jedis.close();return result;}public Long expire(String key, int seconds) {Jedis jedis = jedisPool.getResource();Long result = jedis.expire(key, seconds);jedis.close();return result;}public Long ttl(String key) {Jedis jedis = jedisPool.getResource();Long result = jedis.ttl(key);jedis.close();return result;}public Long incr(String key) {Jedis jedis = jedisPool.getResource();Long result = jedis.incr(key);jedis.close();return result;}public Long hset(String key, String field, String value) {Jedis jedis = jedisPool.getResource();Long result = jedis.hset(key, field, value);jedis.close();return result;}public String hget(String key, String field) {Jedis jedis = jedisPool.getResource();String result = jedis.hget(key, field);jedis.close();return result;}public Long hdel(String key, String... field) {Jedis jedis = jedisPool.getResource();Long result = jedis.hdel(key, field);jedis.close();return result;}public Long persist(String key) {Jedis jedis = jedisPool.getResource();Long result = jedis.persist(key);jedis.close();return result;}public Long del(String key) {Jedis jedis = jedisPool.getResource();Long result = jedis.del(key);jedis.close();return result;}public Long hlen(String key) {Jedis jedis = jedisPool.getResource();Long result = jedis.hlen(key);jedis.close();return result;}public Boolean hexists(String key, String field) {Jedis jedis = jedisPool.getResource();Boolean result = jedis.hexists(key, field);jedis.close();return result;}public Set<String> hkeys(String key) {Jedis jedis = jedisPool.getResource();Set<String> result = jedis.hkeys(key);jedis.close();return result;}public List<String> hvals(String key) {Jedis jedis = jedisPool.getResource();List<String> result = jedis.hvals(key);jedis.close();return result;}public Map<String, String> hgetAll(String key) {Jedis jedis = jedisPool.getResource();Map<String, String> result = jedis.hgetAll(key);jedis.close();return result;}public Long rpush(String key, String... string) {Jedis jedis = jedisPool.getResource();Long result = jedis.rpush(key, string);jedis.close();return result;}public Long lpush(String key, String... string) {Jedis jedis = jedisPool.getResource();Long result = jedis.lpush(key, string);jedis.close();return result;}public Long llen(String key) {Jedis jedis = jedisPool.getResource();Long result = jedis.llen(key);jedis.close();return result;}public List<String> lrange(String key, long start, long end) {Jedis jedis = jedisPool.getResource();List<String> result = jedis.lrange(key, start, end);jedis.close();return result;}public String ltrim(String key, long start, long end) {Jedis jedis = jedisPool.getResource();String result = jedis.ltrim(key, start, end);jedis.close();return result;}public String lindex(String key, long index) {Jedis jedis = jedisPool.getResource();String result = jedis.lindex(key, index);jedis.close();return result;}public String lset(String key, long index, String value) {Jedis jedis = jedisPool.getResource();String result = jedis.lset(key, index, value);jedis.close();return result;}public Long lrem(String key, long count, String value) {Jedis jedis = jedisPool.getResource();Long result = jedis.lrem(key, count, value);jedis.close();return result;}public String lpop(String key) {Jedis jedis = jedisPool.getResource();String result = jedis.lpop(key);jedis.close();return result;}public String rpop(String key) {Jedis jedis = jedisPool.getResource();String result = jedis.rpop(key);jedis.close();return result;}public Long sadd(String key, String... member) {Jedis jedis = jedisPool.getResource();Long result = jedis.sadd(key, member);jedis.close();return result;}public Set<String> smembers(String key) {Jedis jedis = jedisPool.getResource();Set<String> result = jedis.smembers(key);jedis.close();return result;}public Boolean sismember(String key, String member) {Jedis jedis = jedisPool.getResource();Boolean result = jedis.sismember(key, member);jedis.close();return result;}public Long srem(String key, String... member) {Jedis jedis = jedisPool.getResource();Long result = jedis.srem(key, member);jedis.close();return result;}}

上面的代码直接复制就可用，因为代码量太大，集群版就不贴出来了，如果需要可以私信我。有了接口实现类和配置文件，因为项目中把Book类转成了Json字符串类型进行存储，所以把JsonUtil也贴出来

JsonUtil所需jar包：

<!-- Jackson Json处理工具包 --><dependency><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-databind</artifactId><version>2.9.2</version></dependency>

JsonUtil工具类：

package com.miao.util;import java.util.List;import com.fasterxml.jackson.core.JsonProcessingException;import com.fasterxml.jackson.databind.JavaType;import com.fasterxml.jackson.databind.ObjectMapper;public class JsonUtils {    // 定义jackson对象    private static final ObjectMapper MAPPER = new ObjectMapper();    /**     * 将对象转换成json字符串。     * <p>Title: pojoToJson</p>     * <p>Description: </p>     * @param data     * @return     */    public static String objectToJson(Object data) {    try {String string = MAPPER.writeValueAsString(data);return string;} catch (JsonProcessingException e) {e.printStackTrace();}    return null;    }        /**     * 将json结果集转化为对象     *      * @param jsonData json数据     * @param clazz 对象中的object类型     * @return     */    public static <T> T jsonToPojo(String jsonData, Class<T> beanType) {        try {            T t = MAPPER.readValue(jsonData, beanType);            return t;        } catch (Exception e) {        e.printStackTrace();        }        return null;    }        /**     * 将json数据转换成pojo对象list     * <p>Title: jsonToList</p>     * <p>Description: </p>     * @param jsonData     * @param beanType     * @return     */    public static <T>List<T> jsonToList(String jsonData, Class<T> beanType) {    JavaType javaType = MAPPER.getTypeFactory().constructParametricType(List.class, beanType);    try {    List<T> list = MAPPER.readValue(jsonData, javaType);    return list;} catch (Exception e) {e.printStackTrace();}        return null;    }    }

登陆成功后访问show方法，那么show方法中我们应该先去查询缓存，如果缓存中没有数据，那么再去查找数据库，然后把信息存到缓存中，再次访问该放页面时直接从缓存中取值。缓存只是我们来缓解数据库压力的，所以当它出现异常不能影响我们项目正常运行。所以我们要加上try-catch,下面就代码实现，我们的业务逻辑写在service层。

package com.miao.service;import java.util.List;import java.util.UUID;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.beans.factory.annotation.Value;import org.springframework.stereotype.Service;import com.miao.mapper.BookMapper;import com.miao.pojo.Book;import com.miao.pojo.BookExample;import com.miao.redis.JedisClient;import com.miao.util.CookieUtils;import com.miao.util.JsonUtils;@Servicepublic class BookServiceImpl implements BookService {@Autowiredprivate BookMapper bookMapper;@Autowiredprivate JedisClient jedisClient;public List<Book> show(HttpServletRequest request, HttpServletResponse response) {// 先查询缓存starttry {// 查询缓存中的token值String token = CookieUtils.getCookieValue(request, "BOOK_INFOR");// 获取json对象String BooksJson = jedisClient.get("REDIS_BOOKS_KEY" + ":" + token);// 如果查询到的数据不为空或者nullif (BooksJson != null && BooksJson != "") {// 将json转换为book类型List<Book> books = JsonUtils.jsonToList(BooksJson, Book.class);// 将信息存到model中System.out.println("本次查询的是缓存");return books;}} catch (Exception e) {}// 查询缓存endBookExample example = new BookExample();System.out.println("本次查询的是数据库");List<Book> list = bookMapper.selectByExample(example);// 將书本信息存入到缓存starttry {// 生成一个随机字符码String token = UUID.randomUUID().toString();System.out.println(token);// 将book信息存储到redis中jedisClient.set("REDIS_BOOKS_KEY" + ":" + token, JsonUtils.objectToJson(list));// 设置缓存的过期时间为1000秒jedisClient.expire("REDIS_BOOKS_KEY" + ":" + token, 1000);// 将token信息写入到cookie中，默认关闭浏览器失效CookieUtils.setCookie(request, response, "BOOK_INFOR", token);System.out.println("本次是往缓存存值");} catch (Exception e) {// TODO: handle exception}// 將书本信息存入到缓存endreturn list;}}

到此我们的代码就结束了下面我们来试验下,登陆-然后刷新六次首页,我们会发现后面取值都是在缓存中取的，证明我们缓存起到了效果