SSM之整合Redis

Redis安装与使用

第一步当然是安装Redis，这里以Windows上的安装为例。

• 首先下载Redis,可以选择msi或zip包安装方式
• zip方式需打开cmd窗口，在解压后的目录下运行redis-server redis.windows.conf启动Redis
• 采用msi方式安装后Redis默认启动，不需要进行任何配置
• 可以在redis.windows.conf文件中修改Redis端口号、密码等配置，修改完成后使用redis-server redis.windows.conf命令重新启动
• 在Redis安装目录下执行redis-cli -h 127.0.0.1 -p 6379 -a 密码打开Redis操作界面
• 如果报错(error) ERR operation not permitted，使用auth 密码进行验证

SSM整合Redis

这里直接在上一篇SSM之框架整合的基础上进行Redis整合，这里需要注意，存入Redis的pojo类必须实现Serializable接口。

配置pom.xml引入Redis依赖

<!--redis-->
<dependency>
    <groupId>org.springframework.data</groupId>
    <artifactId>spring-data-redis</artifactId>
    <version>1.6.1.RELEASE</version>
</dependency>
<dependency>
    <groupId>redis.clients</groupId>
    <artifactId>jedis</artifactId>
    <version>2.7.3</version>
</dependency>

redis.properties

redis.host=127.0.0.1
redis.port=6379
redis.password=redis
redis.maxIdle=100
redis.maxWait=1000
redis.testOnBorrow=true
redis.timeout=100000
defaultCacheExpireTime=3600

applicationContext-redis.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop.xsd
        http://www.springframework.org/schema/tx
        http://www.springframework.org/schema/tx/spring-tx.xsd">

    <!--引入Redis配置文件-->
    <bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="locations">
            <list>
                <value>classpath:redis.properties</value>
            </list>
        </property>
    </bean>

    <!-- jedis 连接池配置 -->
    <bean id="poolConfig" class="redis.clients.jedis.JedisPoolConfig">
        <property name="maxIdle" value="${redis.maxIdle}"/>
        <property name="maxWaitMillis" value="${redis.maxWait}"/>
        <property name="testOnBorrow" value="${redis.testOnBorrow}"/>
    </bean>
    <!-- redis连接工厂 -->
    <bean id="connectionFactory" class="org.springframework.data.redis.connection.jedis.JedisConnectionFactory">
        <property name="poolConfig" ref="poolConfig"/>
        <property name="port" value="${redis.port}"/>
        <property name="hostName" value="${redis.host}"/>
        <property name="password" value="${redis.password}"/>
        <property name="timeout" value="${redis.timeout}"></property>
    </bean>
    <bean id="redisTemplate" class="org.springframework.data.redis.core.RedisTemplate">
        <property name="connectionFactory" ref="connectionFactory"/>
        <property name="keySerializer">
            <bean class="org.springframework.data.redis.serializer.StringRedisSerializer"/>
        </property>
        <property name="valueSerializer">
            <bean class="org.springframework.data.redis.serializer.JdkSerializationRedisSerializer"/>
        </property>
    </bean>
    <!-- 缓存拦截器配置 -->
    <bean id="methodCacheInterceptor" class="com.zkh.interceptor.MethodCacheInterceptor">
        <property name="redisUtil" ref="redisUtil"/>
        <property name="defaultCacheExpireTime" value="${defaultCacheExpireTime}"/>
        <!-- 禁用缓存的类名列表 -->
        <property name="targetNamesList">
            <list>
                <value></value>
            </list>
        </property>
        <!-- 禁用缓存的方法名列表 -->
        <property name="methodNamesList">
            <list>
                <value></value>
            </list>
        </property>
    </bean>
    <bean id="redisUtil" class="com.zkh.util.RedisUtil">
        <property name="redisTemplate" ref="redisTemplate"/>
    </bean>
    <!--配置切面拦截方法 -->
    <aop:config proxy-target-class="true">
        <aop:pointcut id="controllerMethodPointcut" expression="
        execution(* com.zkh.service.impl.*.select*(..))"/>
        <aop:advisor advice-ref="methodCacheInterceptor" pointcut-ref="controllerMethodPointcut"/>
    </aop:config>
</beans>

MethodCacheInterceptor.java

package com.zkh.interceptor;

import com.zkh.util.RedisUtil;
import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;

import java.util.List;

/**
 * Redis缓存过滤器
 */
public class MethodCacheInterceptor implements MethodInterceptor {
    private RedisUtil redisUtil;
    private List<String> targetNamesList; // 禁用缓存的类名列表
    private List<String> methodNamesList; // 禁用缓存的方法列表
    private String defaultCacheExpireTime; // 缓存默认的过期时间

    @Override
    public Object invoke(MethodInvocation invocation) throws Throwable {
        Object value = null;

        String targetName = invocation.getThis().getClass().getName();
        String methodName = invocation.getMethod().getName();
        if (!isAddCache(targetName, methodName)) {
            // 跳过缓存返回结果
            return invocation.proceed();
        }
        Object[] arguments = invocation.getArguments();
        String key = getCacheKey(targetName, methodName, arguments);
        try {
            // 判断是否有缓存
            if (redisUtil.exists(key)) {
                return redisUtil.get(key);
            }
            // 写入缓存
            value = invocation.proceed();
            if (value != null) {
                final String tkey = key;
                final Object tvalue = value;
                new Thread(new Runnable() {
                    @Override
                    public void run() {
                        redisUtil.set(tkey, tvalue, Long.parseLong(defaultCacheExpireTime));
                    }
                }).start();
            }
        } catch (Exception e) {
            e.printStackTrace();
            if (value == null) {
                return invocation.proceed();
            }
        }
        return value;
    }

    /**
     * 是否加入缓存
     *
     * @return
     */
    private boolean isAddCache(String targetName, String methodName) {
        boolean flag = true;
        if (targetNamesList.contains(targetName)
                || methodNamesList.contains(methodName) || targetName.contains("$$EnhancerBySpringCGLIB$$")) {
            flag = false;
        }
        return flag;
    }

    /**
     * 创建缓存key
     *
     * @param targetName
     * @param methodName
     * @param arguments
     */
    private String getCacheKey(String targetName, String methodName,
                               Object[] arguments) {
        StringBuffer sbu = new StringBuffer();
        sbu.append(targetName).append("_").append(methodName);
        if ((arguments != null) && (arguments.length != 0)) {
            for (int i = 0; i < arguments.length; i++) {
                sbu.append("_").append(arguments[i]);
            }
        }
        return sbu.toString();
    }

    public void setRedisUtil(RedisUtil redisUtil) {
        this.redisUtil = redisUtil;
    }

    public void setTargetNamesList(List<String> targetNamesList) {
        this.targetNamesList = targetNamesList;
    }

    public void setMethodNamesList(List<String> methodNamesList) {
        this.methodNamesList = methodNamesList;
    }

    public void setDefaultCacheExpireTime(String defaultCacheExpireTime) {
        this.defaultCacheExpireTime = defaultCacheExpireTime;
    }
}

RedisUtil.java 工具类

package com.zkh.util;

import org.apache.log4j.Logger;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.ValueOperations;

import java.io.Serializable;
import java.util.Set;
import java.util.concurrent.TimeUnit;

/**
 * Redis工具类
 */
public class RedisUtil {
    private RedisTemplate<Serializable, Object> redisTemplate;

    /**
     * 批量删除对应的value
     *
     * @param keys
     */
    public void remove(final String... keys) {
        for (String key : keys) {
            remove(key);
        }
    }

    /**
     * 批量删除key
     *
     * @param pattern
     */
    public void removePattern(final String pattern) {
        Set<Serializable> keys = redisTemplate.keys(pattern);
        if (keys.size() > 0)
            redisTemplate.delete(keys);
    }

    /**
     * 删除对应的value
     *
     * @param key
     */
    public void remove(final String key) {
        if (exists(key)) {
            redisTemplate.delete(key);
        }
    }

    /**
     * 判断缓存中是否有对应的value
     *
     * @param key
     * @return
     */
    public boolean exists(final String key) {
        return redisTemplate.hasKey(key);
    }

    /**
     * 读取缓存
     *
     * @param key
     * @return
     */
    public Object get(final String key) {
        Object result = null;
        ValueOperations<Serializable, Object> operations = redisTemplate
                .opsForValue();
        result = operations.get(key);
        return result;
    }

    /**
     * 写入缓存
     *
     * @param key
     * @param value
     * @return
     */
    public boolean set(final String key, Object value) {
        boolean result = false;
        try {
            ValueOperations<Serializable, Object> operations = redisTemplate
                    .opsForValue();
            operations.set(key, value);
            result = true;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return result;
    }

    /**
     * 写入缓存
     *
     * @param key
     * @param value
     * @return
     */
    public boolean set(final String key, Object value, Long expireTime) {
        boolean result = false;
        try {
            ValueOperations<Serializable, Object> operations = redisTemplate
                    .opsForValue();
            operations.set(key, value);
            redisTemplate.expire(key, expireTime, TimeUnit.SECONDS);
            result = true;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return result;
    }

    public void setRedisTemplate(
            RedisTemplate<Serializable, Object> redisTemplate) {
        this.redisTemplate = redisTemplate;
    }
}

效果展示

刚开始Redis中没有任何记录，接下来访问一下第一页记录

再查看缓存，记录已经存如Redis，并且第一次访问会从Mysql中读取数据

按F5刷新页面，从Tomcat控制台可以看到没有进行SQL查询，而是直接从Redis中读取缓存数据，减轻了数据库的负担

具体代码已发布在Github上，地址：SSM

本文为作者kMacro原创，转载请注明来源：https://zkhdev.github.io/2017/03/22/java-ssm-redis/