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>${junit.version}</version>
<scope>test</scope>
</dependency>
</dependencies>
</project>
主要用到的jia包是spring-context、spring-data-redis、jedis以及日志打印相关的三个jar包
配置spring-data-redis如下application-context-redis.xml：
<!-- 配置方法见 //www.jb51.net/database/201311/254449.html -->
<bean id="jedisPoolConfig" class="redis.clients.jedis.JedisPoolConfig">
<property name="maxTotal" value="500"/> <!-- 控制一个pool可分配多少个jedis实例 -->
<property name="maxIdle" value="100"/><!-- 最大能够保持idel状态的对象数 -->
<property name="maxWaitMillis" value="1000"/><!-- 表示当borrow一个jedis实例时，最大的等待时间，如果超过等待时间，则直接抛出JedisConnectionException -->
<property name="timeBetweenEvictionRunsMillis" value="30000"/><!-- 多长时间检查一次连接池中空闲的连接 -->
<property name="minEvictableIdleTimeMillis" value="30000"/><!-- 空闲连接多长时间后会被收回, 单位是毫秒 -->
<property name="testOnBorrow" value="true"/> <!-- 当调用borrow Object方法时，是否进行有效性检查 -->
<property name="testOnReturn" value="true"/> <!-- 当调用return Object方法时，是否进行有效性检查 -->
<property name="testWhileIdle" value="true"/>
</bean>
<span style="white-space:pre"> </span><!-- 直连master -->
<bean id="jedisConnectionFactory"
class="org.springframework.data.redis.connection.jedis.JedisConnectionFactory">
<constructor-arg ref="jedisPoolConfig" />
<property name="hostName" value="${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=127.0.0.1
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" /><!-- 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 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，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
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