spring-data-redis连接操作redis

Java连接redis的客户端有很多，其中比较常用的是Jedis. (参考：redis client)

spring-data-redis则是对Jedis进行了高度封装，使用起来非常方便。下面就以代码为例说明spring-data-redis的使用。

整个项目使用maven管理jar包，pom文件如下：

<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><groupId>com.snow</groupId><artifactId>redis-test</artifactId><version>0.0.1</version><packaging>jar</packaging><name>redis-test</name><url>http://maven.apache.org</url><properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><spring.version>4.3.2.RELEASE</spring.version><slf4j.version>1.7.12</slf4j.version><log4j.version>1.2.17</log4j.version><junit.version>4.12</junit.version><spring-data-redis.version>1.7.2.RELEASE</spring-data-redis.version></properties><dependencies><dependency><groupId>org.springframework</groupId><artifactId>spring-context</artifactId><version>${spring.version}</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-test</artifactId><version>${spring.version}</version><scope>test</scope></dependency><dependency><groupId>redis.clients</groupId><artifactId>jedis</artifactId><version>2.5.0</version><type>jar</type></dependency><dependency><groupId>org.springframework.data</groupId><artifactId>spring-data-redis</artifactId><version>${spring-data-redis.version}</version><type>jar</type></dependency><!-- log --><dependency><groupId>log4j</groupId><artifactId>log4j</artifactId><version>${log4j.version}</version></dependency><dependency><groupId>org.slf4j</groupId><artifactId>slf4j-log4j12</artifactId><version>${slf4j.version}</version></dependency><dependency><groupId>org.slf4j</groupId><artifactId>slf4j-api</artifactId><version>${slf4j.version}</version></dependency><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>${junit.version}</version><scope>test</scope></dependency></dependencies></project>

主要用到的jia包是spring-context、spring-data-redis、jedis以及日志打印相关的三个jar包

配置spring-data-redis如下application-context-redis.xml：

    <!-- 配置方法见 http://www.2cto.com/database/201311/254449.html --><bean id="jedisPoolConfig" class="redis.clients.jedis.JedisPoolConfig"> <property name="maxTotal" value="500"/> <!-- 控制一个pool可分配多少个jedis实例 -->  <property name="maxIdle" value="100"/><!-- 最大能够保持idel状态的对象数 --> <property name="maxWaitMillis" value="1000"/><!-- 表示当borrow一个jedis实例时，最大的等待时间，如果超过等待时间，则直接抛出JedisConnectionException -->  <property name="timeBetweenEvictionRunsMillis" value="30000"/><!-- 多长时间检查一次连接池中空闲的连接 --> <property name="minEvictableIdleTimeMillis" value="30000"/><!-- 空闲连接多长时间后会被收回, 单位是毫秒 --> <property name="testOnBorrow" value="true"/><!-- 当调用borrow Object方法时，是否进行有效性检查 --> <property name="testOnReturn" value="true"/><!-- 当调用return Object方法时，是否进行有效性检查 --> <property name="testWhileIdle" value="true"/></bean>        <span style="white-space:pre"></span><!-- 直连master --><bean id="jedisConnectionFactory"class="org.springframework.data.redis.connection.jedis.JedisConnectionFactory"><constructor-arg ref="jedisPoolConfig" /><property name="hostName" value="${redis.hostName}" /><property name="port" value="${redis.port}" /><!-- <property name="password" value ="${redis.password}" /> --></bean>         <span style="white-space:pre"></span><bean id="redisTemplate" class="org.springframework.data.redis.core.StringRedisTemplate" >     <span style="white-space:pre"></span><property name="connectionFactory" ref="jedisConnectionFactory" />      <span style="white-space:pre"></span></bean>

在配置文件中先配置一个连接池，然后配置一个connection工厂，最后配置bean redisTemplate，我们使用的class是StringRedisTemplate，从而决定我们后面的操作key及value都必须是String类型的。而通常我们希望将一个对象存入到redis中，这个时候可以将对象转为json字符串之后再存储，取出来的时候再将json字符串转换为对象。这种操作还是比较方便的，都有线程的jar包。除了StringRedisTemplate之外，我们还可以使用RedisTemplate类，这里暂不介绍。

在application-context-redis.xml这个配置文件中还需要用到redis的host和port信息，我们可以配置一个文件properties文件如下：redis.properties

redis.hostName=127.0.0.1redis.port=6379

这个配置文件需要在application-contex.xml中加载，同时application-context.xml还需要加载application-context-redis.xml配置文件

<bean id="dbPropertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"><property name="ignoreUnresolvablePlaceholders" value="true" /><property name="locations"><list><value>classpath:redis.properties</value></list></property><property name="fileEncoding" value="UTF-8" /><!-- 资源文件的编码 --></bean><import resource="classpath:application-context-redis.xml" />  

接下来可以写个redis操作的接口

public interface RedisService {    public void setStr(String key, String value);        public String getStr(String key);        public void rPushList(String key, String value);    public String lPopList(String key);    public void delKey(String key);}

接口实现如下：

@Service(value = "redisService")public class RedisServiceImpl extends AbstractRedisDao<String, String> implements RedisService {    @Override    public void setStr(String key, String value) {        getRedisTemplate().opsForValue().set(key, value);    }    @Override    public String getStr(String key) {        return getRedisTemplate().opsForValue().get(key);    }    @Override    public void rPushList(String key, String value) {        getRedisTemplate().opsForList().rightPush(key, value);    }    @Override    public String lPopList(String key) {        return getRedisTemplate().opsForList().leftPop(key);    }        @Override    public void delKey(String key) {        getRedisTemplate().delete(key);    }}

在该实现中继承了一个AbstractRedisDao，这个主要是提供getRedisTemplate()函数，使我们能够调用在application-context-redis.xml中配置的redisTemplate bean实例

public abstract class AbstractRedisDao<K, V> {    @Autowired    protected RedisTemplate<K, V> redisTemplate;    // 设置redisTemplate    public void setRedisTemplate(RedisTemplate<K, V> redisTemplate) {        this.redisTemplate = redisTemplate;    }    public RedisTemplate<K, V> getRedisTemplate() {        return redisTemplate;    }}

主要的程序都已经写完了，接下来可以用Junit写个单元测试对接口测试下。

public class RedisServiceTest extends AbstractUnitTest {    private static final Logger logger = LoggerFactory.getLogger(RedisServiceTest.class);    @Resource    private RedisService redisService;    @Test    public void testSetStr() {        String key = "test";        String value = "valuetest";        redisService.setStr(key, value);    }    @Test    public void testGetStr() {        String key = "test";        String value = redisService.getStr(key);        logger.info("The value is {}", value);    }    @Test    public void testRPushList() {        String key = "list";        for (int i = 0; i < 10; i++) {            redisService.rPushList(key, String.valueOf(i));        }    }            @Test    public void testLPopList() {        String key = "list";                for(int i = 0; i < 9; i++) {            String value = redisService.lPopList(key);            logger.info("lpop value is {}", value);        }    }        @Test    public void testDelKey() {        String key = "list";        redisService.delKey(key);    }    }

在这个测试类中，为了能够运行这些测试函数，需要对所有的bean进行实例化，这个过程是在 AbstractUnitTest中实现的，代码如下：

@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration(locations = {"classpath:application-context.xml"})public abstract class AbstractUnitTest {    private static final Logger logger = LoggerFactory.getLogger(AbstractUnitTest.class);//    @Test//    public void stub() {//        logger.info("msg from abstract unit test, just ignore this.");//    }    @After    public void teardown() throws InterruptedException {        logger.info("unit test complete.");        TimeUnit.MILLISECONDS.sleep(500);// 因为有些测试是需要异步插入操作记录的，sleep一下等待线程结束    }}

AbstractUnitTest类可以作为测试spring的一个通用类。

主要的代码就这些了，运行下可以看到结果是没有问题的。下面我摘抄一段打印输出说明一个问题：

016-08-02 20:43:16,608 DEBUG RedisConnectionUtils:125 - Opening RedisConnection2016-08-02 20:43:16,609 DEBUG RedisConnectionUtils:205 - Closing Redis Connection2016-08-02 20:43:16,610  INFO RedisServiceTest:54 - lpop value is 02016-08-02 20:43:16,610 DEBUG RedisConnectionUtils:125 - Opening RedisConnection2016-08-02 20:43:16,611 DEBUG RedisConnectionUtils:205 - Closing Redis Connection2016-08-02 20:43:16,611  INFO RedisServiceTest:54 - lpop value is 12016-08-02 20:43:16,611 DEBUG RedisConnectionUtils:125 - Opening RedisConnection2016-08-02 20:43:16,611 DEBUG RedisConnectionUtils:205 - Closing Redis Connection2016-08-02 20:43:16,612  INFO RedisServiceTest:54 - lpop value is 22016-08-02 20:43:16,612 DEBUG RedisConnectionUtils:125 - Opening RedisConnection2016-08-02 20:43:16,612 DEBUG RedisConnectionUtils:205 - Closing Redis Connection2016-08-02 20:43:16,612  INFO RedisServiceTest:54 - lpop value is 32016-08-02 20:43:16,612 DEBUG RedisConnectionUtils:125 - Opening RedisConnection2016-08-02 20:43:16,613 DEBUG RedisConnectionUtils:205 - Closing Redis Connection2016-08-02 20:43:16,613  INFO RedisServiceTest:54 - lpop value is 42016-08-02 20:43:16,613 DEBUG RedisConnectionUtils:125 - Opening RedisConnection2016-08-02 20:43:16,613 DEBUG RedisConnectionUtils:205 - Closing Redis Connection2016-08-02 20:43:16,613  INFO RedisServiceTest:54 - lpop value is 52016-08-02 20:43:16,613 DEBUG RedisConnectionUtils:125 - Opening RedisConnection2016-08-02 20:43:16,614 DEBUG RedisConnectionUtils:205 - Closing Redis Connection2016-08-02 20:43:16,614  INFO RedisServiceTest:54 - lpop value is 62016-08-02 20:43:16,614 DEBUG RedisConnectionUtils:125 - Opening RedisConnection2016-08-02 20:43:16,614 DEBUG RedisConnectionUtils:205 - Closing Redis Connection2016-08-02 20:43:16,618  INFO RedisServiceTest:54 - lpop value is 72016-08-02 20:43:16,618 DEBUG RedisConnectionUtils:125 - Opening RedisConnection2016-08-02 20:43:16,618 DEBUG RedisConnectionUtils:205 - Closing Redis Connection2016-08-02 20:43:16,618  INFO RedisServiceTest:54 - lpop value is 82016-08-02 20:43:16,618  INFO AbstractUnitTest:34 - unit test complete.

这段输出是运行testLPopList得到的，这里面opening RedisConnection进行了9次，然后又Closing Redis Connection 9次，这是不是说每次执行redis操作都需要创建一个连接，操作完然后又关闭连接呢？实际上不是这样的，阅读源代码我们可以发现我们对redis的所有操作都是通过回调execute函数执行的，其代码如下：

public <T> T execute(RedisCallback<T> action, boolean exposeConnection) {    return execute(action, exposeConnection, false);}// execute实现如下：// org.springframework.data.redis.core.RedisTemplate<K, V> --- 最终实现public <T> T execute(RedisCallback<T> action, boolean exposeConnection, boolean pipeline) {    Assert.isTrue(initialized, "template not initialized; call afterPropertiesSet() before using it");    Assert.notNull(action, "Callback object must not be null");    RedisConnectionFactory factory = getConnectionFactory();    RedisConnection conn = null;    try {        if (enableTransactionSupport) {            // only bind resources in case of potential transaction synchronization            conn = RedisConnectionUtils.bindConnection(factory, enableTransactionSupport);        } else {            conn = RedisConnectionUtils.getConnection(factory);        }        boolean existingConnection = TransactionSynchronizationManager.hasResource(factory);        RedisConnection connToUse = preProcessConnection(conn, existingConnection);        boolean pipelineStatus = connToUse.isPipelined();        if (pipeline && !pipelineStatus) {            connToUse.openPipeline();        }        RedisConnection connToExpose = (exposeConnection ? connToUse : createRedisConnectionProxy(connToUse));        T result = action.doInRedis(connToExpose);        // close pipeline        if (pipeline && !pipelineStatus) {            connToUse.closePipeline();        }        // TODO: any other connection processing?        return postProcessResult(result, connToUse, existingConnection);    } finally {        if (!enableTransactionSupport) {            RedisConnectionUtils.releaseConnection(conn, factory);        }    }}

这里面每次执行action.doInRedis(connToExpose)前都要调用RedisConnectionUtils.getConnection(factory);获得一个连接，进入RedisConnnectionUtils类中，getConnection(factory)最终调用的是doGetConnection(factory, true, false, enableTranactionSupport)这个函数。这个函数我们可以看下api文档，发现实际上并不是真的创建一个新的redis连接，它只是在connectFactory中获取一个连接，也就是从连接池中取出一个连接。当然如果connectFactory没有连接可用，此时如果allowCreate=true便会创建出一个新的连接，并且加入到connectFactory中。

基本上可以确定真实的情况是spring-data-redis已经帮我们封装了连接池管理，我们只需要调用一系列操作函数即可，这给操作redis带来了极大的方便。

最后附上本文源代码：redis-test