Redis客户端简单封装（spring）

    Jedis客户端已经比较易用了，不过在spring环境下，可能还需要简单的封装一下。

一、单节点Redis服务使用

    即只有一个Redis server，或者在M-S模式下，只有Master提供读写服务时使用，配置中指定Master的IP和Port即可。此处使用了Spring FactoryBean方式来创建JedisPool实例。

    1、SingletonClientFactoryBean.java

public class SingletonClientFactoryBean implements FactoryBean<JedisPool>,InitializingBean {

    private JedisPool jedisPool;

    private int maxTotal = 128;

    //最大空闲连接数
    private int maxIdle = 2;

    //最小空闲连接数
    private int minIdle = 1;
    //如果连接池耗尽，最大阻塞的时间，默认为6秒
    private long maxWait = 6000;//单位毫秒
    private String host;
    private int port;
    private int database = 0;//选择数据库，默认为0
    private int timeout = 3000;//connectionTimeout，soTimeout，默认为30秒

    private boolean testOnBorrow = true;
    private boolean testOnReturn = true;

    private String password;

    public void setMaxTotal(int maxTotal) {
        this.maxTotal = maxTotal;
    }

    public void setMaxIdle(int maxIdle) {
        this.maxIdle = maxIdle;
    }

    public void setMinIdle(int minIdle) {
        this.minIdle = minIdle;
    }

    public void setMaxWait(long maxWait) {
        this.maxWait = maxWait;
    }

    public void setHost(String host) {
        this.host = host;
    }

    public void setPort(int port) {
        this.port = port;
    }

    public void setDatabase(int database) {
        this.database = database;
    }

    public void setTimeout(int timeout) {
        this.timeout = timeout;
    }

    public void setTestOnBorrow(boolean testOnBorrow) {
        this.testOnBorrow = testOnBorrow;
    }

    public void setTestOnReturn(boolean testOnReturn) {
        this.testOnReturn = testOnReturn;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    protected JedisPoolConfig buildConfig() {
        JedisPoolConfig config = new JedisPoolConfig();
        config.setMinIdle(minIdle);
        config.setMaxIdle(maxIdle);
        config.setMaxTotal(maxTotal);
        config.setTestOnBorrow(testOnBorrow);
        config.setTestOnReturn(testOnReturn);
        config.setBlockWhenExhausted(true);
        config.setMaxWaitMillis(maxWait);
        config.setFairness(false);

        return config;
    }

    @Override
    public void afterPropertiesSet() throws Exception {
        JedisPoolConfig config = buildConfig();
        jedisPool = new JedisPool(config,host,port,timeout, password, database,null);
    }

    @Override
    public JedisPool getObject() throws Exception {
        return jedisPool;
    }

    @Override
    public Class<?> getObjectType() {
        return JedisPool.class;
    }

    @Override
    public boolean isSingleton() {
        return true;
    }
}

    2、Spring.xml配置

    <bean id="redisClient" class="com.demo.redis.spring.SingletonClientFactoryBean">
        <property name="host" value="127.0.0.1"/>
        <property name="port" value="6379" />
        <property name="maxTotal" value="256"/>
        <property name="maxIdle" value="8" />
        <property name="maxWait" value="3000" />
        <property name="timeout" value="3000" />
        <property name="minIdle" value="2" />
    </bean>

    3、客户端使用

        Jedis jedis = redisClient.getResource();
        String cacheContent = null;
        try {
            cacheContent = jedis.get("hello_world");
        }finally {
            redisClient.close();
        }
        //获取redis数据之后，立即释放连接，然后开始进行业务处理
        if(cacheContent == null) {
            //DB operation
        }
        //..

 二、基于M-S模式下读写分离

    通常情况下，Slave只是作为数据备份，不提供read操作，这种考虑是为了避免slave提供stale数据而导致一些问题。不过在很多场景下，即使slave数据有一定的延迟，我们仍然可以兼容或者正常处理，此时我们可以将slave提供read服务，并在M-S集群中将read操作分流，此时我们的Redis集群将可以支撑更高的QPS。

    本文实例中，仅仅提供了“读写分离”的样板，尚未对所有的redis方法进行重写和封装，请开发者后续继续补充即可。此外，slave节点如果异常，我们应该支持failover，这一部分特性后续在扩展。

    1、ReadWriteRedisClient.java

public class ReadWriteRedisClient implements InitializingBean {

    //master:port,slave:port,slave:port...
    //master first
    private String hosts;
    private JedisPool master;
    private List<JedisPool> slaves = new ArrayList<>();

    private int maxTotal = 128;

    //最大空闲连接数
    private int maxIdle = 2;

    //最小空闲连接数
    private int minIdle = 1;
    //如果连接池耗尽，最大阻塞的时间，默认为6秒
    private long maxWait = 6000;//单位毫秒
    private int database = 0;//选择数据库，默认为0
    private int timeout = 3000;//connectionTimeout，soTimeout，默认为30秒

    private boolean testOnBorrow = true;
    private boolean testOnReturn = true;

    private String password;

    private Random random = new Random();

    public void setMaxTotal(int maxTotal) {
        this.maxTotal = maxTotal;
    }

    public void setMaxIdle(int maxIdle) {
        this.maxIdle = maxIdle;
    }

    public void setMinIdle(int minIdle) {
        this.minIdle = minIdle;
    }

    public void setMaxWait(long maxWait) {
        this.maxWait = maxWait;
    }

    public void setDatabase(int database) {
        this.database = database;
    }

    public void setTimeout(int timeout) {
        this.timeout = timeout;
    }

    public void setTestOnBorrow(boolean testOnBorrow) {
        this.testOnBorrow = testOnBorrow;
    }

    public void setTestOnReturn(boolean testOnReturn) {
        this.testOnReturn = testOnReturn;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public void setHosts(String hosts) {
        this.hosts = hosts;
    }

    protected JedisPoolConfig buildConfig() {
        JedisPoolConfig config = new JedisPoolConfig();
        config.setMinIdle(minIdle);
        config.setMaxIdle(maxIdle);
        config.setMaxTotal(maxTotal);
        config.setTestOnBorrow(testOnBorrow);
        config.setTestOnReturn(testOnReturn);
        config.setBlockWhenExhausted(true);
        config.setMaxWaitMillis(maxWait);
        config.setFairness(false);

        return config;
    }

    @Override
    public void afterPropertiesSet() throws Exception {
        JedisPoolConfig config = buildConfig();
        String[] hostAndPorts = hosts.split(",");
        String masterHP = hostAndPorts[0];
        String[] ms = masterHP.split(":");
        master = new JedisPool(config,ms[0],Integer.valueOf(ms[1]),timeout, password, database,null);
        if(hostAndPorts.length > 1) {
            for(int i = 1; i < hostAndPorts.length; i++) {
                String[] ss = hostAndPorts[i].split(":");
                JedisPool slave = new JedisPool(config,ss[0],Integer.valueOf(ss[1]),timeout, password, database,null);
                slaves.add(slave);
            }
        }
        slaves.add(master);
    }

    public String get(String key) {
        Jedis jedis = fetchResource(true);
        try {
            return jedis.get(key);
        } finally {
            jedis.close();
        }
    }

    public List<String> mget(String... keys) {
        Jedis jedis = fetchResource(true);
        try {
            return jedis.mget(keys);
        } finally {
            jedis.close();
        }
    }

    public String setex(String key,int seconds,String value) {
        Jedis jedis = fetchResource(false);
        try {
            return jedis.setex(key,seconds,value);
        } finally {
            jedis.close();
        }
    }

    public Long setnx(String key,String value) {
        Jedis jedis = fetchResource(false);
        try {
            return jedis.setnx(key,value);
        } finally {
            jedis.close();
        }
    }

    public String set(String key,String value) {
        Jedis jedis = fetchResource(false);
        try {
            return jedis.set(key,value);
        } finally {
            jedis.close();
        }
    }

    public Long del(String key) {
        Jedis jedis = fetchResource(false);
        try {
            return jedis.del(key);
        } finally {
            jedis.close();
        }
    }

    public Long expire(String key,int seconds) {
        Jedis jedis = fetchResource(false);
        try {
            return jedis.expire(key,seconds);
        } finally {
            jedis.close();
        }
    }

    public Boolean exists(String key) {
        Jedis jedis = fetchResource(false);
        try {
            return jedis.exists(key);
        } finally {
            jedis.close();
        }
    }

    public Long exists(String... keys) {
        Jedis jedis = fetchResource(false);
        try {
            return jedis.exists(keys);
        } finally {
            jedis.close();
        }
    }

    private Jedis fetchResource(boolean read) {
        if(slaves.isEmpty() || !read) {
            return master.getResource();
        }
        int size = slaves.size();
        int i = random.nextInt(size);
        return slaves.get(i).getResource();
    }


    public static void main(String[] args) throws Exception {
        String prefix = "_test_";
        ReadWriteRedisClient client = new ReadWriteRedisClient();
        client.setHosts("127.0.0.1:6379,127.0.0.1:6379");

        client.afterPropertiesSet();

        client.set(prefix + "10001","test");
        System.out.println(client.get(prefix + "10001"));
    }
}

    2、Spring.xml配置

    <bean id="readWriteRedisClient" class="com.demo.redis.spring.ReadWriteRedisClient">
        <property name="hosts" value="127.0.0.1:6379,127.0.0.1:7379"/>
        <property name="maxTotal" value="256"/>
        <property name="maxIdle" value="8" />
        <property name="maxWait" value="3000" />
        <property name="timeout" value="3000" />
        <property name="minIdle" value="2" />
    </bean>

    3、客户端使用

    @Autowired
    private JedisPool redisClient;
    
    public void test() {
        Jedis jedis = redisClient.getResource();
        //..
        String cacheContent = null;
        try {
            cacheContent = readWriteRedisClient.get("hello_world");
        } catch (Exception e) {
            //如果redis网络异常， 你可以选择重新抛出，或者忽略
        }
        if(cacheContent == null) {
            //redis中不存在，或者异常
        }
    }

  

三、基于Cluster模式的客户端

    JedisCluster实例的简单封装，内部仍然基于连接池。需要注意，cluster模式下，mget等这种multi-keys操作将不再支持。其实我们无论如何封装，都无法非常合理的解决multi-keys问题，这里涉及到K-V在集群中的迁移、节点可用性、批量操作的异常处理，特别在异常处理时，如果某个key操作异常（可能对应的redis节点异常），那么其他已经操作成功的keys、或者后续尚未操作的keys该如何处理？这个答案是模糊不清的。此外，我们JAVA开发者通常会使用线程池 + Future机制来分解multi-keys操作，其实这会带来很大的性能隐患，不建议使用。

    本人最终决定，保留redis Cluster的api方式，不做特殊封装，仅仅让其在spring环境中更易于使用即可。

    1、ClusterClientFactoryBean.java

public class ClusterClientFactoryBean implements FactoryBean<JedisCluster>,InitializingBean {

    private JedisCluster jedisCluster;

    private int maxTotal = 128;

    //最大空闲连接数
    private int maxIdle = 6;

    //最小空闲连接数
    private int minIdle = 1;
    //如果连接池耗尽，最大阻塞的时间，默认为6秒
    private long maxWait = 6000;//单位毫秒

    private int timeout = 3000;//connectionTimeout，soTimeout，默认为3秒

    private boolean testOnBorrow = true;
    private boolean testOnReturn = true;

    private String addresses;//ip:port;ip:port

    public void setMaxTotal(int maxTotal) {
        this.maxTotal = maxTotal;
    }

    public void setMaxIdle(int maxIdle) {
        this.maxIdle = maxIdle;
    }

    public void setMinIdle(int minIdle) {
        this.minIdle = minIdle;
    }

    public void setMaxWait(long maxWait) {
        this.maxWait = maxWait;
    }

    public void setTimeout(int timeout) {
        this.timeout = timeout;
    }

    public void setTestOnBorrow(boolean testOnBorrow) {
        this.testOnBorrow = testOnBorrow;
    }

    public void setTestOnReturn(boolean testOnReturn) {
        this.testOnReturn = testOnReturn;
    }

    public void setAddresses(String addresses) {
        this.addresses = addresses;
    }

    protected JedisPoolConfig buildConfig() {
        JedisPoolConfig config = new JedisPoolConfig();

        config.setMinIdle(minIdle);
        config.setMaxIdle(maxIdle);
        config.setMaxTotal(maxTotal);
        config.setTestOnBorrow(testOnBorrow);
        config.setTestOnReturn(testOnReturn);
        config.setBlockWhenExhausted(true);
        config.setMaxWaitMillis(maxWait);
        config.setFairness(false);

        return config;
    }

    private Set<HostAndPort> buildHostAndPorts() {
        String[] hostPorts = addresses.split(",");
        Set<HostAndPort> hostAndPorts = new HashSet<>();
        for(String item : hostPorts) {
            String[] hostPort = item.split(":");
            HostAndPort hostAndPort = new HostAndPort(hostPort[0],Integer.valueOf(hostPort[1]));
            hostAndPorts.add(hostAndPort);
        }
        return hostAndPorts;
    }

    @Override
    public void afterPropertiesSet() throws Exception {
        JedisPoolConfig config = buildConfig();
        Set<HostAndPort> hostAndPorts = buildHostAndPorts();
        jedisCluster = new JedisCluster(hostAndPorts,timeout,config);
    }

    @Override
    public JedisCluster getObject() throws Exception {
        return jedisCluster;
    }

    @Override
    public Class<?> getObjectType() {
        return JedisCluster.class;
    }

    @Override
    public boolean isSingleton() {
        return true;
    }
}

    2、Spring.xml配置

    <bean id="clusterRedisClient" class="com.demo.redis.spring.ClusterClientFactoryBean">
        <property name="addresses" value="127.0.0.1:6379,127.0.01:7379,127.0.0.1:8379"/>
        <property name="maxTotal" value="256"/>
        <property name="maxIdle" value="8" />
        <property name="maxWait" value="3000" />
        <property name="timeout" value="3000" />
        <property name="minIdle" value="2" />
    </bean>

    3、客户端使用

    @Autowired
    private JedisCluster clusterRedisClient;
    public void test() {
        String cacheContent = null;
        try {
            cacheContent = clusterRedisClient.get("hello_world");
        } catch (Exception e) {
            //如果异常，你可以决定是否忽略
        }
        if(cacheContent == null) {
            //如果cache中不存在，或者redis异常
        }
    }