spring-data-redis連接操作redis

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。下面就以代碼爲例說明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以及日誌打印相關的三個jar包

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

    <!-- 配置方法見 http://www.2cto.com/database/201311/254449.html -->
	<bean id="jedisPoolConfig" 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閒的連接 -->
		 <property name="minEvictableIdleTimeMillis" value="30000"/><!-- 空閒連接多長時間後會被收回, 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 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個連接池，然後配置一個connection工廠，最後配置bean redisTemplate，我們使用的class是StringRedisTemplate，從而決定我們後面的操作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爲json字符串之後再存儲，取出來的時候再將json字符串轉換爲對象。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，這裏暫不介紹。

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=127.0.0.1
redis.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 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" /><!-- 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，爲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);// 因爲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類可以作爲測試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 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.

這段輸出是運行testLPopList得到的，這裏面opening RedisConnection進行了9次，然後又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，操作完然後又關閉連接呢？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 pipeline
        if (pipeline && !pipelineStatus) {
            connToUse.closePipeline();
        }
        // TODO: any other connection processing?
        return postProcessResult(result, connToUse, existingConnection);
    } finally {
        if (!enableTransactionSupport) {
            RedisConnectionUtils.releaseConnection(conn, factory);
        }
    }
}

這裏面每次執行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，發現實際上並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，並且加入到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。

最後附上本文源代碼：redis-test

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