spring-data-redis连接操作redis

骑猪看日落 2022-09-24 15:15 193阅读 0赞

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>
 
 		
 		<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：

<bean id="jedisPoolConfig" class="redis.clients.jedis.JedisPoolConfig">
 		 <property name="maxTotal" value="500"/>  
 		 <property name="maxIdle" value="100"/>
 		 <property name="maxWaitMillis" value="1000"/> 
 		 <property name="timeBetweenEvictionRunsMillis" value="30000"/>
 		 <property name="minEvictableIdleTimeMillis" value="30000"/>
 		 <property name="testOnBorrow" value="true"/>	
 		 <property name="testOnReturn" value="true"/>	
 		 <property name="testWhileIdle" value="true"/>
 	</bean>
 	 
 	
 	<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}" />
 		
 	</bean> 
 
 	<bean id="redisTemplate" class="org.springframework.data.redis.core.StringRedisTemplate" > 
 		<property name="connectionFactory" ref="jedisConnectionFactory" /> 
 	</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=127.0.0.1
    redis.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" />
 	</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 RedisConnection
    2016-08-02 20:43:16,609 DEBUG RedisConnectionUtils:205 - Closing Redis Connection
    2016-08-02 20:43:16,610  INFO RedisServiceTest:54 - lpop value is 0
    2016-08-02 20:43:16,610 DEBUG RedisConnectionUtils:125 - Opening RedisConnection
    2016-08-02 20:43:16,611 DEBUG RedisConnectionUtils:205 - Closing Redis Connection
    2016-08-02 20:43:16,611  INFO RedisServiceTest:54 - lpop value is 1
    2016-08-02 20:43:16,611 DEBUG RedisConnectionUtils:125 - Opening RedisConnection
    2016-08-02 20:43:16,611 DEBUG RedisConnectionUtils:205 - Closing Redis Connection
    2016-08-02 20:43:16,612  INFO RedisServiceTest:54 - lpop value is 2
    2016-08-02 20:43:16,612 DEBUG RedisConnectionUtils:125 - Opening RedisConnection
    2016-08-02 20:43:16,612 DEBUG RedisConnectionUtils:205 - Closing Redis Connection
    2016-08-02 20:43:16,612  INFO RedisServiceTest:54 - lpop value is 3
    2016-08-02 20:43:16,612 DEBUG RedisConnectionUtils:125 - Opening RedisConnection
    2016-08-02 20:43:16,613 DEBUG RedisConnectionUtils:205 - Closing Redis Connection
    2016-08-02 20:43:16,613  INFO RedisServiceTest:54 - lpop value is 4
    2016-08-02 20:43:16,613 DEBUG RedisConnectionUtils:125 - Opening RedisConnection
    2016-08-02 20:43:16,613 DEBUG RedisConnectionUtils:205 - Closing Redis Connection
    2016-08-02 20:43:16,613  INFO RedisServiceTest:54 - lpop value is 5
    2016-08-02 20:43:16,613 DEBUG RedisConnectionUtils:125 - Opening RedisConnection
    2016-08-02 20:43:16,614 DEBUG RedisConnectionUtils:205 - Closing Redis Connection
    2016-08-02 20:43:16,614  INFO RedisServiceTest:54 - lpop value is 6
    2016-08-02 20:43:16,614 DEBUG RedisConnectionUtils:125 - Opening RedisConnection
    2016-08-02 20:43:16,614 DEBUG RedisConnectionUtils:205 - Closing Redis Connection
    2016-08-02 20:43:16,618  INFO RedisServiceTest:54 - lpop value is 7
    2016-08-02 20:43:16,618 DEBUG RedisConnectionUtils:125 - Opening RedisConnection
    2016-08-02 20:43:16,618 DEBUG RedisConnectionUtils:205 - Closing Redis Connection
    2016-08-02 20:43:16,618  INFO RedisServiceTest:54 - lpop value is 8
    2016-08-02 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][api]，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][]

[redis client]: http://www.redis.cn/clients.html
[api]: http://docs.spring.io/spring-data/redis/docs/1.7.2.RELEASE/api/
[redis-test]: https://github.com/xueshui/redis-test