Java連接redis的客戶端有很多，其中比較常用的是Jedis. (參考：redis client)

spring-data-redis則是對Jedis進行了高度封裝，使用起來非常方便。下面就以代碼為例說明spring-data-redis的使用。

整個項目使用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以及日志打印相關的三個jar包

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

<!-- 配置方法見 //www.jb51.net/database/201311/254449.html --> <bean class='redis.clients.jedis.JedisPoolConfig'> <property name='maxTotal' value='500'/> <!-- 控制一個pool可分配多少個jedis實例 --> <property name='maxIdle' value='100'/><!-- 最大能夠保持idel狀態的對象數 --> <property name='maxWaitMillis' value='1000'/><!-- 表示當borrow一個jedis實例時，最大的等待時間，如果超過等待時間，則直接拋出JedisConnectionException --> <property name='timeBetweenEvictionRunsMillis' value='30000'/><!-- 多長時間檢查一次連接池中空閑的連接 --> <property name='minEvictableIdleTimeMillis' value='30000'/><!-- 空閑連接多長時間后會被收回, 單位是毫秒 --> <property name='testOnBorrow' value='true'/> <!-- 當調用borrow Object方法時，是否進行有效性檢查 --> <property name='testOnReturn' value='true'/> <!-- 當調用return Object方法時，是否進行有效性檢查 --> <property name='testWhileIdle' value='true'/> </bean> <span style='white-space:pre'> </span><!-- 直連master --> <bean 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 > <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個連接池，然后配置一個connection工廠，最后配置bean redisTemplate，我們使用的class是StringRedisTemplate，從而決定我們后面的操作key及value都必須是String類型的。而通常我們希望將一個對象存入到redis中，這個時候可以將對象轉為json字符串之后再存儲，取出來的時候再將json字符串轉換為對象。這種操作還是比較方便的，都有線程的jar包。除了StringRedisTemplate之外，我們還可以使用RedisTemplate類，這里暫不介紹。

在application-context-redis.xml這個配置文件中還需要用到redis的host和port信息，我們可以配置一個文件properties文件如下：redis.properties

redis.hostName=127.0.0.1redis.port=6379

這個配置文件需要在application-contex.xml中加載，同時application-context.xml還需要加載application-context-redis.xml配置文件

<bean 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' /><!-- 資源文件的編碼 --> </bean> <import resource='classpath:application-context-redis.xml' />

接下來可以寫個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); }

接口實現如下：

@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); }}

在該實現中繼承了一個AbstractRedisDao，這個主要是提供getRedisTemplate()函數，使我們能夠調用在application-context-redis.xml中配置的redisTemplate bean實例

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

主要的程序都已經寫完了，接下來可以用Junit寫個單元測試對接口測試下。

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); } }

在這個測試類中，為了能夠運行這些測試函數，需要對所有的bean進行實例化，這個過程是在 AbstractUnitTest中實現的，代碼如下：

@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);// 因為有些測試是需要異步插入操作記錄的，sleep一下等待線程結束 } }

AbstractUnitTest類可以作為測試spring的一個通用類。

主要的代碼就這些了，運行下可以看到結果是沒有問題的。下面我摘抄一段打印輸出說明一個問題：

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.

這段輸出是運行testLPopList得到的，這里面opening RedisConnection進行了9次，然后又Closing Redis Connection 9次，這是不是說每次執行redis操作都需要創建一個連接，操作完然后又關閉連接呢？實際上不是這樣的，閱讀源代碼我們可以發現我們對redis的所有操作都是通過回調execute函數執行的，其代碼如下：

public <T> T execute(RedisCallback<T> action, boolean exposeConnection) { return execute(action, exposeConnection, false);}// execute實現如下：// org.springframework.data.redis.core.RedisTemplate<K, V> --- 最終實現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 pipelineif (pipeline && !pipelineStatus) { connToUse.closePipeline();}// TODO: any other connection processing?return postProcessResult(result, connToUse, existingConnection); } finally {if (!enableTransactionSupport) { RedisConnectionUtils.releaseConnection(conn, factory);} }}

這里面每次執行action.doInRedis(connToExpose)前都要調用RedisConnectionUtils.getConnection(factory);獲得一個連接，進入RedisConnnectionUtils類中，getConnection(factory)最終調用的是doGetConnection(factory, true, false, enableTranactionSupport)這個函數。這個函數我們可以看下api文檔，發現實際上并不是真的創建一個新的redis連接，它只是在connectFactory中獲取一個連接，也就是從連接池中取出一個連接。當然如果connectFactory沒有連接可用，此時如果allowCreate=true便會創建出一個新的連接，并且加入到connectFactory中。基本上可以確定真實的情況是spring-data-redis已經幫我們封裝了連接池管理，我們只需要調用一系列操作函數即可，這給操作redis帶來了極大的方便。

最后附上本文源代碼：redis-test

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