Redis主从复制和主从切换

  Redis的主从复制功能可以实现读写分离，一个主可以挂载多个从．从服务器只能实现读不可写．当主服务器挂掉之后，无法切换到从服务器写． 通过Redis的Sentinel可以实现主从切换：当主服务器挂掉之后，自动将其中一个从服务器升级为主服务器

1. 配置主从复制

   1. 建立从文件夹，譬如 /usr/local/slaves/下建立　6380 6381 两个文件夹（两个从服务器）

   2. 复制redis.conf到刚建立的两个文件夹中

   3. 修改redis.conf 中的

      1. port 6380

      2. slaveof 127.0.0.1 6379  ------ip表示主服务器的ｉｐ　　端口表示主服务器端口

      3. 保存退出，另一个从服务器做同样修改，如果端口不是6380，修改断开即可，此处修改为6381

   4. 启动主服务器　redis-server redis.conf

   5. 进入从服务器文件夹，启动从服务器
      

   6. 查看主服务器信息：redis-cli -p 6379 info Replication,可以看到有两个从服务器

   7. redis-cli -p 6379 进去主服务器，存储数据 set key val

   8. 进入从服务器，redis-cli -p 6380 查看数据 get key 　查看是否能取出数据

2. 配置主从切换

   1. 新建文件 sentinel.conf

   2. 编辑文件

   3. ####master  sentinel.conf
      ##sentinel实例之间的通讯端口
      port 26379
      ####sentinel需要监控的master信息：<mastername> <masterIP> <masterPort> <quorum>.
      ####<quorum>应该小于集群中slave的个数,只有当至少<quorum>个sentinel实例提交"master失效" 才会认为master为ODWON("客观"失效) .
      sentinel monitor mymaster 127.0.0.1 6381 1
      sentinel down-after-milliseconds mymaster 1000
      sentinel failover-timeout mymaster 180000
      sentinel parallel-syncs mymaster 1

   4. 其他两个文件只需要修改端口即可

   5. 启动redis-sentinel sentinel.conf &
      

3. 通过java读写主从服务器

   1. 需要添加Spring配置和其他两个ｊａｒ包

   2. < properties >
          < project.build.sourceEncoding >UTF-8</ project.build.sourceEncoding >
          < springVersion >3.2.9.RELEASE</ springVersion >
      </ properties >
      
      < dependencies >
          < dependency >
              < groupId >org.apache.commons</ groupId >
              < artifactId >commons-pool2</ artifactId >
              < version >2.4.2</ version >
          </ dependency >
      
      
          < dependency >
              < groupId >org.springframework.data</ groupId >
              < artifactId >spring-data-redis</ artifactId >
              < version >1.6.0.RELEASE</ version >
          </ dependency >
      
          < dependency >
              < groupId >org.springframework</ groupId >
              < artifactId >spring-context</ artifactId >
              < version >${springVersion}</ version >
          </ dependency >
          < dependency >
              < groupId >org.springframework</ groupId >
              < artifactId >spring-tx</ artifactId >
              < version >${springVersion}</ version >
          </ dependency >
          < dependency >
              < groupId >org.springframework</ groupId >
              < artifactId >spring-context-support</ artifactId >
              < version >${springVersion}</ version >
          </ dependency >
          < dependency >
              < groupId >cglib</ groupId >
              < artifactId >cglib-nodep</ artifactId >
              < version >3.1</ version >
          </ dependency >
      
      
          < dependency >
              < groupId >org.apache.commons</ groupId >
              < artifactId >commons-lang3</ artifactId >
              < version >3.1</ version >
          </ dependency >
          < dependency >
              < groupId >com.alibaba</ groupId >
              < artifactId >fastjson</ artifactId >
              < version >1.2.5</ version >
          </ dependency >
          < dependency >
              < groupId >org.aspectj</ groupId >
              < artifactId >aspectjweaver</ artifactId >
              < version >1.8.2</ version >
          </ dependency >
      
          < dependency >
              < groupId >junit</ groupId >
              < artifactId >junit</ artifactId >
              < version >4.8</ version >
              < scope >test</ scope >
          </ dependency >
          < dependency >
              < groupId >net.sf.ehcache</ groupId >
              < artifactId >ehcache</ artifactId >
              < version >2.7.5</ version >
          </ dependency >
          < dependency >
              < groupId >org.slf4j</ groupId >
              < artifactId >slf4j-api</ artifactId >
              < version >1.6.6</ version >
          </ dependency >
          < dependency >
              < groupId >redis.clients</ groupId >
              < artifactId >jedis</ artifactId >
              < version >2.4.2</ version >
          </ dependency >
          < dependency >
              < groupId >commons-pool</ groupId >
              < artifactId >commons-pool</ artifactId >
              < version >1.6</ version >
          </ dependency >
          < dependency >
              < groupId >commons-logging</ groupId >
              < artifactId >commons-logging</ artifactId >
              < version >1.1.1</ version >
          </ dependency >
          < dependency >
              < groupId >org.slf4j</ groupId >
              < artifactId >slf4j-log4j12</ artifactId >
              < version >1.7.10</ version >
              < scope >test</ scope >
          </ dependency >
      </ dependencies >

   3. Spring配置

      1. < bean  id = "redisSentinelConfiguration"  class = "org.springframework.data.redis.connection.RedisSentinelConfiguration" >
             < property  name = "master" >
                 < bean  class = "org.springframework.data.redis.connection.RedisNode" >
                     < property  name = "name"  value = "mymaster" />
                 </ bean >
             </ property >
             < property  name = "sentinels" >
                 < set >
                     < bean  class = "org.springframework.data.redis.connection.RedisNode" >
                         < constructor-arg  name = "host"  value = "127.0.0.1" ></ constructor-arg >
         
                         < constructor-arg  name = "port"  value = "26479" ></ constructor-arg >
                     </ bean >
                     < bean  class = "org.springframework.data.redis.connection.RedisNode" >
                         < constructor-arg  name = "host"  value = "127.0.0.1" ></ constructor-arg >
         
                         < constructor-arg  name = "port"  value = "26579" ></ constructor-arg >
                     </ bean >
                 </ set >
             </ property >
         </ bean >
         
         < bean  id = "jeidsConnectionFactory"
         
               class = "org.springframework.data.redis.connection.jedis.JedisConnectionFactory" >
         
             < constructor-arg  ref = "redisSentinelConfiguration" />
         
         </ bean >
         
         
         < bean  id = "redisTemplate"  class = "org.springframework.data.redis.core.RedisTemplate" >
             < property  name = "connectionFactory"  ref = "jeidsConnectionFactory" />
         </ bean >

   4. java测试

      1. import  org.junit.Before;
         import  org.junit.Test;
         import  org.springframework.context.ApplicationContext;
         import  org.springframework.context.support.ClassPathXmlApplicationContext;
         import  org.springframework.dao.DataAccessException;
         import  org.springframework.data.redis.connection.RedisConnection;
         import  org.springframework.data.redis.core.RedisCallback;
         import  org.springframework.data.redis.core.RedisTemplate;
         
         /**
          * Created by vincent on 15-10-13.
          */
         public  class  CommonTest {
         
             private  ApplicationContext context ;
         
             private  RedisTemplate redisTemplate;
             final  String key = "key7" ;
         
             @Before
             public  void  init(){
                 context =  new  ClassPathXmlApplicationContext( "applicationContext.xml" );
                 redisTemplate= context.getBean( "redisTemplate" ,RedisTemplate. class );
             }
         
             @Test
             public  void  test1(){
                 redisTemplate.execute( new  RedisCallback() {
                     @Override
                     public  Long doInRedis(RedisConnection redisConnection)  throws  DataAccessException {
                          redisConnection.set(key.getBytes(),(System.currentTimeMillis()+ "" ).getBytes());
                         return  1L;
                     }
                 });
             }
         
             @Test
             public  void   test2(){
                 Object execute = redisTemplate.execute( new  RedisCallback() {
                     @Override
                     public  Object doInRedis(RedisConnection redisConnection)  throws  DataAccessException {
                         return  redisConnection.get(key.getBytes());
                     }
                 });
         
                 System.out.println( new  String(( byte [])execute));
         
             }
         }

参考文档：

    http://redis.readthedocs.org/en/latest/topic/sentinel.html