用Memcached,對於緩存對象大小有要求,單個對象不得大於1MB,且不支持復雜的數據類型,譬如SET
等。基於這些限制,有必要考慮Redis!
相關鏈接:
Redis實戰之征服 Redis + Jedis + Spring (一)
Redis實戰之征服 Redis + Jedis + Spring (二)
Redis實戰之征服 Redis + Jedis + Spring (三)
言歸正傳,目前Redis大概有3中基於Java語言的Client:
- Jredis
- Jedis
- Redis4J
這里只說Jedis,因為它是官方提供的唯一Redis Client For Java Provider!
一、簡單使用Jedis
需要Jedis就從Maven獲取吧!
Maven Pom.xml
- <dependency>
- <groupId>redis.clients</groupId>
- <artifactId>jedis</artifactId>
- <version>2.1.0</version>
- <type>jar</type>
- <scope>compile</scope>
- </dependency>
<dependency> <groupId>redis.clients</groupId> <artifactId>jedis</artifactId> <version>2.1.0</version> <type>jar</type> <scope>compile</scope> </dependency>
如果只是簡單使用Jedis,以下這么幾行代碼足夠:
- Jedis jedis = new Jedis("10.11.20.140");
- String keys = "name";
- // 刪數據
- jedis.del(keys);
- // 存數據
- jedis.set(keys, "snowolf");
- // 取數據
- String value = jedis.get(keys);
- System.out.println(value);
Jedis jedis = new Jedis("10.11.20.140"); String keys = "name"; // 刪數據 jedis.del(keys); // 存數據 jedis.set(keys, "snowolf"); // 取數據 String value = jedis.get(keys); System.out.println(value);
二、池化使用Jedis
Jedis使用commons-pool完成池化實現。
先做個配置文件:
- #最大分配的對象數
- redis.pool.maxActive=1024
- #最大能夠保持idel狀態的對象數
- redis.pool.maxIdle=200
- #當池內沒有返回對象時,最大等待時間
- redis.pool.maxWait=1000
- #當調用borrow Object方法時,是否進行有效性檢查
- redis.pool.testOnBorrow=true
- #當調用return Object方法時,是否進行有效性檢查
- redis.pool.testOnReturn=true
- #IP
- redis.ip=10.11.20.140
- #Port
- redis.port=6379
#最大分配的對象數 redis.pool.maxActive=1024 #最大能夠保持idel狀態的對象數 redis.pool.maxIdle=200 #當池內沒有返回對象時,最大等待時間 redis.pool.maxWait=1000 #當調用borrow Object方法時,是否進行有效性檢查 redis.pool.testOnBorrow=true #當調用return Object方法時,是否進行有效性檢查 redis.pool.testOnReturn=true #IP redis.ip=10.11.20.140 #Port redis.port=6379
在靜態代碼段中完成初始化:
- private static JedisPool pool;
- static {
- ResourceBundle bundle = ResourceBundle.getBundle("redis");
- if (bundle == null) {
- throw new IllegalArgumentException(
- "[redis.properties] is not found!");
- }
- JedisPoolConfig config = new JedisPoolConfig();
- config.setMaxActive(Integer.valueOf(bundle
- .getString("redis.pool.maxActive")));
- config.setMaxIdle(Integer.valueOf(bundle
- .getString("redis.pool.maxIdle")));
- config.setMaxWait(Long.valueOf(bundle.getString("redis.pool.maxWait")));
- config.setTestOnBorrow(Boolean.valueOf(bundle
- .getString("redis.pool.testOnBorrow")));
- config.setTestOnReturn(Boolean.valueOf(bundle
- .getString("redis.pool.testOnReturn")));
- pool = new JedisPool(config, bundle.getString("redis.ip"),
- Integer.valueOf(bundle.getString("redis.port")));
- }
private static JedisPool pool; static { ResourceBundle bundle = ResourceBundle.getBundle("redis"); if (bundle == null) { throw new IllegalArgumentException( "[redis.properties] is not found!"); } JedisPoolConfig config = new JedisPoolConfig(); config.setMaxActive(Integer.valueOf(bundle .getString("redis.pool.maxActive"))); config.setMaxIdle(Integer.valueOf(bundle .getString("redis.pool.maxIdle"))); config.setMaxWait(Long.valueOf(bundle.getString("redis.pool.maxWait"))); config.setTestOnBorrow(Boolean.valueOf(bundle .getString("redis.pool.testOnBorrow"))); config.setTestOnReturn(Boolean.valueOf(bundle .getString("redis.pool.testOnReturn"))); pool = new JedisPool(config, bundle.getString("redis.ip"), Integer.valueOf(bundle.getString("redis.port"))); }
然后,修改前面那段jedis操作Redis
- // 從池中獲取一個Jedis對象
- Jedis jedis = pool.getResource();
- String keys = "name";
- // 刪數據
- jedis.del(keys);
- // 存數據
- jedis.set(keys, "snowolf");
- // 取數據
- String value = jedis.get(keys);
- System.out.println(value);
- // 釋放對象池
- pool.returnResource(jedis);
// 從池中獲取一個Jedis對象 Jedis jedis = pool.getResource(); String keys = "name"; // 刪數據 jedis.del(keys); // 存數據 jedis.set(keys, "snowolf"); // 取數據 String value = jedis.get(keys); System.out.println(value); // 釋放對象池 pool.returnResource(jedis);
改為從對象池中,獲取Jedis實例:
- // 從池中獲取一個Jedis對象
- Jedis jedis = pool.getResource();
// 從池中獲取一個Jedis對象 Jedis jedis = pool.getResource();
切記,最后使用后,釋放Jedis對象:
- // 釋放對象池
- pool.returnResource(jedis);
// 釋放對象池 pool.returnResource(jedis);
三、一致性哈希
Memcached完全基於分布式集群,而Redis是Master-Slave,如果想把Reids,做成集群模式,無外乎多做幾套Master-Slave,每套Master-Slave完成各自的容災處理,通過Client工具,完成一致性哈希。
PS:Memcached是在Server端完成Sharding,Redis只能依靠各個Client做Sharding。可能會在Redis 3.0系列支持Server端Sharding。
保留前面的JedisPoolConfig,新增兩個Redis的IP(redis1.ip,redis2.ip),完成兩個JedisShardInfo實例,並將其丟進List中:
- JedisShardInfo jedisShardInfo1 = new JedisShardInfo(
- bundle.getString("redis1.ip"), Integer.valueOf(bundle .getString("redis.port")));
- JedisShardInfo jedisShardInfo2 = new JedisShardInfo(
- bundle.getString("redis2.ip"), Integer.valueOf(bundle .getString("redis.port")));
- List<JedisShardInfo> list = new LinkedList<JedisShardInfo>();
- list.add(jedisShardInfo1);
- list.add(jedisShardInfo2);
JedisShardInfo jedisShardInfo1 = new JedisShardInfo( bundle.getString("redis1.ip"), Integer.valueOf(bundle .getString("redis.port"))); JedisShardInfo jedisShardInfo2 = new JedisShardInfo( bundle.getString("redis2.ip"), Integer.valueOf(bundle .getString("redis.port"))); List<JedisShardInfo> list = new LinkedList<JedisShardInfo>(); list.add(jedisShardInfo1); list.add(jedisShardInfo2);
初始化ShardedJedisPool代替JedisPool:
- ShardedJedisPool pool = new ShardedJedisPool(config, list);
ShardedJedisPool pool = new ShardedJedisPool(config, list);
改由ShardedJedis,獲取Jedis對象:
- // 從池中獲取一個Jedis對象
- ShardedJedis jedis = pool.getResource();
- String keys = "name";
- String value = "snowolf";
- // 刪數據
- jedis.del(keys);
- // 存數據
- jedis.set(keys, value);
- // 取數據
- String v = jedis.get(keys);
- System.out.println(v);
- // 釋放對象池
- pool.returnResource(jedis);
// 從池中獲取一個Jedis對象 ShardedJedis jedis = pool.getResource(); String keys = "name"; String value = "snowolf"; // 刪數據 jedis.del(keys); // 存數據 jedis.set(keys, value); // 取數據 String v = jedis.get(keys); System.out.println(v); // 釋放對象池 pool.returnResource(jedis);
四、Spring封裝參考
Ok,完成上述代碼足夠完成簡單任務,如果有必要,可以用Spring封裝初始化:
- <context:property-placeholder location="classpath:redis.properties" />
- <bean
- id="jedisPoolConfig"
- class="redis.clients.jedis.JedisPoolConfig"
- >
- <property
- name="maxActive"
- value="${redis.pool.maxActive}" />
- <property
- name="maxIdle"
- value="${redis.pool.maxIdle}" />
- <property
- name="maxWait"
- value="${redis.pool.maxWait}" />
- <property
- name="testOnBorrow"
- value="${redis.pool.testOnBorrow}" />
- </bean>
- <bean
- id="shardedJedisPool"
- class="redis.clients.jedis.ShardedJedisPool"
- >
- <constructor-arg
- index="0"
- ref="jedisPoolConfig" />
- <constructor-arg index="1">
- <list>
- <bean class="redis.clients.jedis.JedisShardInfo">
- <constructor-arg
- index="0"
- value="${redis1.ip}" />
- <constructor-arg
- index="1"
- value="${redis.port}"
- type="int" />
- </bean>
- <bean class="redis.clients.jedis.JedisShardInfo">
- <constructor-arg
- index="0"
- value="${redis2.ip}" />
- <constructor-arg
- index="1"
- value="${redis.port}"
- type="int" />
- </bean>
- </list>
- </constructor-arg>
- </bean>
<context:property-placeholder location="classpath:redis.properties" /> <bean id="jedisPoolConfig" class="redis.clients.jedis.JedisPoolConfig" > <property name="maxActive" value="${redis.pool.maxActive}" /> <property name="maxIdle" value="${redis.pool.maxIdle}" /> <property name="maxWait" value="${redis.pool.maxWait}" /> <property name="testOnBorrow" value="${redis.pool.testOnBorrow}" /> </bean> <bean id="shardedJedisPool" class="redis.clients.jedis.ShardedJedisPool" > <constructor-arg index="0" ref="jedisPoolConfig" /> <constructor-arg index="1"> <list> <bean class="redis.clients.jedis.JedisShardInfo"> <constructor-arg index="0" value="${redis1.ip}" /> <constructor-arg index="1" value="${redis.port}" type="int" /> </bean> <bean class="redis.clients.jedis.JedisShardInfo"> <constructor-arg index="0" value="${redis2.ip}" /> <constructor-arg index="1" value="${redis.port}" type="int" /> </bean> </list> </constructor-arg> </bean>
代碼可以更簡潔一些:
- private ApplicationContext app;
- private ShardedJedisPool pool;
- @Before
- public void before() throws Exception {
- app = new ClassPathXmlApplicationContext("applicationContext.xml");
- pool = (ShardedJedisPool) app.getBean("shardedJedisPool");
- }
- @Test
- public void test() {
- // 從池中獲取一個Jedis對象
- ShardedJedis jedis = pool.getResource();
- String keys = "name";
- String value = "snowolf";
- // 刪數據
- jedis.del(keys);
- // 存數據
- jedis.set(keys, value);
- // 取數據
- String v = jedis.get(keys);
- System.out.println(v);
- // 釋放對象池
- pool.returnResource(jedis);
- assertEquals(value, v);
- }
private ApplicationContext app; private ShardedJedisPool pool; @Before public void before() throws Exception { app = new ClassPathXmlApplicationContext("applicationContext.xml"); pool = (ShardedJedisPool) app.getBean("shardedJedisPool"); } @Test public void test() { // 從池中獲取一個Jedis對象 ShardedJedis jedis = pool.getResource(); String keys = "name"; String value = "snowolf"; // 刪數據 jedis.del(keys); // 存數據 jedis.set(keys, value); // 取數據 String v = jedis.get(keys); System.out.println(v); // 釋放對象池 pool.returnResource(jedis); assertEquals(value, v); }
當然,Spring提供了對於Redis的專門支持:spring-data-redis,以后有機會再深入研究。
相關鏈接:
Redis實戰之征服 Redis + Jedis + Spring (一)
Redis實戰之征服 Redis + Jedis + Spring (二)
Redis實戰之征服 Redis + Jedis + Spring (三)