异常：

org.springframework.data.redis.RedisConnectionFailureException: Cannot get Jedis connection;
nested exception is redis.clients.jedis.exceptions.JedisConnectionException: Could not get a resource from the pool

at org.springframework.data.redis.connection.jedis.JedisConnectionFactory.fetchJedisConnector(JedisConnectionFactory.java:162) ~[spring-data-redis-1.5.0.RELEASE.jar:1.5.0.RELEASE]

at org.springframework.data.redis.connection.jedis.JedisConnectionFactory.getConnection(JedisConnectionFactory.java:251) ~[spring-data-redis-1.5.0.RELEASE.jar:1.5.0.RELEASE]

at org.springframework.data.redis.connection.jedis.JedisConnectionFactory.getConnection(JedisConnectionFactory.java:58) ~[spring-data-redis-1.5.0.RELEASE.jar:1.5.0.RELEASE]

at org.springframework.data.redis.core.RedisConnectionUtils.doGetConnection(RedisConnectionUtils.java:128) ~[spring-data-redis-1.5.0.RELEASE.jar:1.5.0.RELEASE]

at org.springframework.data.redis.core.RedisConnectionUtils.getConnection(RedisConnectionUtils.java:91) ~[spring-data-redis-1.5.0.RELEASE.jar:1.5.0.RELEASE]

at org.springframework.data.redis.core.RedisConnectionUtils.getConnection(RedisConnectionUtils.java:78) ~[spring-data-redis-1.5.0.RELEASE.jar:1.5.0.RELEASE]

at org.springframework.data.redis.core.RedisTemplate.execute(RedisTemplate.java:178) ~[spring-data-redis-1.5.0.RELEASE.jar:1.5.0.RELEASE]

at org.springframework.data.redis.core.RedisTemplate.execute(RedisTemplate.java:153) ~[spring-data-redis-1.5.0.RELEASE.jar:1.5.0.RELEASE]

at org.springframework.data.redis.core.AbstractOperations.execute(AbstractOperations.java:86) ~[spring-data-redis-1.5.0.RELEASE.jar:1.5.0.RELEASE]

at org.springframework.data.redis.core.DefaultValueOperations.get(DefaultValueOperations.java:43) ~[spring-data-redis-1.5.0.RELEASE.jar:1.5.0.RELEASE]

at com.enci.isms.web.common.redis.RedisServiceImpl.get(RedisServiceImpl.java:36) ~[RedisServiceImpl.class:na]



at com.enci.isms.web.web.common.CoreController.core(CoreController.java:122) ~[CoreController.class:na]

at com.enci.isms.web.web.common.CoreController$$FastClassBySpringCGLIB$$3d05e0de.invoke(<generated>) ~[CoreController.class:na]

at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204) ~[spring-core-4.3.2.RELEASE.jar:4.3.2.RELEASE]



at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:720) ~[spring-aop-4.3.2.RELEASE.jar:4.3.2.RELEASE]

at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157) ~[spring-aop-4.3.2.RELEASE.jar:4.3.2.RELEASE]

at org.springframework.aop.framework.adapter.MethodBeforeAdviceInterceptor.invoke(MethodBeforeAdviceInterceptor.java:52) ~[spring-aop-4.3.2.RELEASE.jar:4.3.2.RELEASE]

at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) ~[spring-aop-4.3.2.RELEASE.jar:4.3.2.RELEASE]

at org.springframework.aop.framework.adapter.AfterReturningAdviceInterceptor.invoke(AfterReturningAdviceInterceptor.java:52) ~[spring-aop-4.3.2.RELEASE.jar:4.3.2.RELEASE]

at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) ~[spring-aop-4.3.2.RELEASE.jar:4.3.2.RELEASE]

at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92) ~[spring-aop-4.3.2.RELEASE.jar:4.3.2.RELEASE]

at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) ~[spring-aop-4.3.2.RELEASE.jar:4.3.2.RELEASE]

at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:655) ~[spring-aop-4.3.2.RELEASE.jar:4.3.2.RELEASE]

at com.enci.isms.web.web.common.CoreController$$EnhancerBySpringCGLIB$$ad51e650.core(<generated>) ~[CoreController.class:na]



at sun.reflect.GeneratedMethodAccessor130.invoke(Unknown Source) ~[na:na]

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.7.0_79]
at java.lang.reflect.Method.invoke(Method.java:606) ~[na:1.7.0_79]

at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:221) ~[spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]

at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136) ~[spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]

at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:114) ~[spring-webmvc-4.3.2.RELEASE.jar:4.3.2.RELEASE]

at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827) ~[spring-webmvc-4.3.2.RELEASE.jar:4.3.2.RELEASE]

at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738) ~[spring-webmvc-4.3.2.RELEASE.jar:4.3.2.RELEASE]

at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) ~[spring-webmvc-4.3.2.RELEASE.jar:4.3.2.RELEASE]

at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:963) ~[spring-webmvc-4.3.2.RELEASE.jar:4.3.2.RELEASE]

at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897) ~[spring-webmvc-4.3.2.RELEASE.jar:4.3.2.RELEASE]

at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970) ~[spring-webmvc-4.3.2.RELEASE.jar:4.3.2.RELEASE]

at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:872) ~[spring-webmvc-4.3.2.RELEASE.jar:4.3.2.RELEASE]

at javax.servlet.http.HttpServlet.service(HttpServlet.java:646) [servlet-api.jar:na]

at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846) ~[spring-webmvc-4.3.2.RELEASE.jar:4.3.2.RELEASE]

at javax.servlet.http.HttpServlet.service(HttpServlet.java:727) [servlet-api.jar:na]

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303) [catalina.jar:7.0.57]

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) [catalina.jar:7.0.57]

at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) [tomcat7-websocket.jar:7.0.57]

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) [catalina.jar:7.0.57]

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) [catalina.jar:7.0.57]

at org.apache.shiro.web.servlet.ProxiedFilterChain.doFilter(ProxiedFilterChain.java:61) [shiro-all-1.3.2.jar:1.3.2]

at org.apache.shiro.web.servlet.AdviceFilter.executeChain(AdviceFilter.java:108) [shiro-all-1.3.2.jar:1.3.2]

at org.apache.shiro.web.servlet.AdviceFilter.doFilterInternal(AdviceFilter.java:137) [shiro-all-1.3.2.jar:1.3.2]

at org.apache.shiro.web.servlet.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:125) [shiro-all-1.3.2.jar:1.3.2]

at org.apache.shiro.web.servlet.ProxiedFilterChain.doFilter(ProxiedFilterChain.java:66) [shiro-all-1.3.2.jar:1.3.2]

at org.apache.shiro.web.servlet.AbstractShiroFilter.executeChain(AbstractShiroFilter.java:449) [shiro-all-1.3.2.jar:1.3.2]

at org.apache.shiro.web.servlet.AbstractShiroFilter$1.call(AbstractShiroFilter.java:365) [shiro-all-1.3.2.jar:1.3.2]

at org.apache.shiro.subject.support.SubjectCallable.doCall(SubjectCallable.java:90) [shiro-all-1.3.2.jar:1.3.2]

at org.apache.shiro.subject.support.SubjectCallable.call(SubjectCallable.java:83) [shiro-all-1.3.2.jar:1.3.2]

at org.apache.shiro.subject.support.DelegatingSubject.execute(DelegatingSubject.java:383) [shiro-all-1.3.2.jar:1.3.2]

at org.apache.shiro.web.servlet.AbstractShiroFilter.doFilterInternal(AbstractShiroFilter.java:362) [shiro-all-1.3.2.jar:1.3.2]

at org.apache.shiro.web.servlet.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:125) [shiro-all-1.3.2.jar:1.3.2]

at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346) [spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]

at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:262) [spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) [catalina.jar:7.0.57]

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) [catalina.jar:7.0.57]

at com.enci.isms.web.filter.DomainFilter.doFilter(DomainFilter.java:34) [DomainFilter.class:na]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) [catalina.jar:7.0.57]

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) [catalina.jar:7.0.57]

at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:101) [spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]

at eap.web.filter.LogMDCFilter.doFilterCleaned(LogMDCFilter.java:41) [isms-common-1.0.0-SNAPSHOT.jar:na]

at eap.web.filter.EnhanceFilter.doFilterInternal(EnhanceFilter.java:47) [isms-common-1.0.0-SNAPSHOT.jar:na]

at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) [catalina.jar:7.0.57]

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) [catalina.jar:7.0.57]

at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197) [spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]

at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) [catalina.jar:7.0.57]

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) [catalina.jar:7.0.57]

at eap.web.filter.XssFilter.doFilter(XssFilter.java:21) [isms-common-1.0.0-SNAPSHOT.jar:na]

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) [catalina.jar:7.0.57]

at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) [catalina.jar:7.0.57]

at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220) [catalina.jar:7.0.57]

at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122) [catalina.jar:7.0.57]

at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:503) [catalina.jar:7.0.57]

at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170) [catalina.jar:7.0.57]

at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103) [catalina.jar:7.0.57]

at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950) [catalina.jar:7.0.57]

at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116) [catalina.jar:7.0.57]

at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:421) [catalina.jar:7.0.57]

at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1070) [tomcat-coyote.jar:7.0.57]

at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:611) [tomcat-coyote.jar:7.0.57]

at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:314) [tomcat-coyote.jar:7.0.57]

at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) [na:1.7.0_79]

at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) [na:1.7.0_79]

at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-coyote.jar:7.0.57]

at java.lang.Thread.run(Thread.java:745) [na:1.7.0_79]
Caused by: redis.clients.jedis.exceptions.JedisConnectionException: Could not get a resource from the pool

at redis.clients.util.Pool.getResource(Pool.java:42) ~[jedis-2.4.2.jar:na]

at org.springframework.data.redis.connection.jedis.JedisConnectionFactory.fetchJedisConnector(JedisConnectionFactory.java:155) ~[spring-data-redis-1.5.0.RELEASE.jar:1.5.0.RELEASE]

... 91 common frames omitted
Caused by: redis.clients.jedis.exceptions.JedisConnectionException: java.net.ConnectException: Connection refused

产生此错误的原因通常是：

 一、Redis没有启动；

我自己遇到一次这样的问题。汗！

二、由于防火墙原因无法连接到Redis;

1、服务器防火墙入站规则。

2、访问Redis的应用程序所在主机的出站规则。

三、IP地址或端口错误

四、Jedis 对象用完以后，要释放掉,不让会一直占用，所以会出现无法获取新的资源。

五、Spring Boot项目，缺少依赖

如果使用Redis与Spring Boot，也会抛出此异常。
如果你使用的是Spring Boot，那么Redis的依赖是不够的，
您还需要从redis.io手动下载并安装Redis，然后将其从终端运行

1. me@my_pc:/path/to/redis/dir$ ./src/redis-server ./redis.conf  

运行服务器后，您需要在使用Redis的所有应用程序中添加相关行：
application.properties:

spring.redis.host: <yourhost> // usually localhost, but can also be on a LAN  
spring.redis.port: <yourport> // usually 6379, but settable in redis.conf 

application.yml:​​​​​​​

spring:  
  redis:  
    host: <yourhost> // usually localhost, but can also be on a LAN  
    port: <yourport> // usually 6379, but settable in redis.conf  

六、vm.overcommit_memory = 0，fork失败

1. 使用redis-cli，执行ping命令，异常信息出来了：  
2. (error)MISCONF Redis is configured to save RDB snapshots, but is currently  
3. not able to persist on disk. Commands that may modify the data set  
4. are disabled. Please check Redis logs for details about the error.    
5. 然后查看redis日志，出现了  
6. WARNING overcommit_memory is set to 0! Background save may fail under low memory condition. To fix this issue add 'vm.overcommit_memory = 1' to /etc/sysctl.conf and then reboot or run the command 'sysctl vm.overcommit_memory=1' for this to take effect.  
7. 问题已经很清晰了，bgsave会fork一个子进程，因为vm.overcommit_memory = 0，所以申请的内存大小和父进程的一样，由于redis已经使用了60%的内存空间，所以fork失败  
8. 解决办法：    
9. /etc/sysctl.conf 添加 vm.overcommit_memory=1  
10. sysctl  vm.overcommit_memory=1  

七、当jedispool中的jedis被取完 等待超过你设置的 MaxWaitMillis 就会抛出Could not get a resource from the pool 

       注意：RedisTemplate要求所有的key为非空，而值可以为空，但需要跟底层的序列化转换器要求一致，针对每个序列化转换器的要求可以查看Java文档来得到更多信息。
　    redis是以key-value的形式将数据存在内存中，key就是简单的string，key似乎没有长度限制，不过原则上应该尽可能的短小且可读性强，无论是否基于持久存储，
key在服务的整个生命周期中都会在内存中，因此减小key的尺寸可以有效的节约内存，同时也能优化key检索的效率。

八、连接池中空闲的连接过一阵子就会自动断开，但是连接池还以为连接正常

参考配置文件：

JedisPoolConfig config = new JedisPoolConfig();  
config.setMaxTotal(200);  
config.setMaxIdle(50);  
config.setMinIdle(8);//设置最小空闲数  
config.setMaxWaitMillis(10000);  
config.setTestOnBorrow(true);  
config.setTestOnReturn(true);  
//Idle时进行连接扫描  
config.setTestWhileIdle(true);  
//表示idle object evitor两次扫描之间要sleep的毫秒数  
config.setTimeBetweenEvictionRunsMillis(30000);  
//表示idle object evitor每次扫描的最多的对象数  
config.setNumTestsPerEvictionRun(10);  
//表示一个对象至少停留在idle状态的最短时间，然后才能被idle object evitor扫描并驱逐；这一项只有在timeBetweenEvictionRunsMillis大于0时才有意义  
config.setMinEvictableIdleTimeMillis(60000);  
JedisPool pool = new JedisPool(config, ip, port, 10000, "密码", 0); 

​​​​​​​ 如有披露或问题欢迎留言或者入群探讨