springboot 2.1启动，redis报错Failed to instantiat ... java.lang.NoClassDefFoundError: org/apache/commons/pool2/impl/GenericObjectPoolConfig

 SpringBoot 2.1.1集成redis，在启动时报错信息如下：

org.springframework.beans.factory.BeanCreationException: 
Error creating bean with name 'redisConnectionFactory' defined in class path resource 
[org/springframework/boot/autoconfigure/data/redis/LettuceConnectionConfiguration.class]: Bean instantiation via factory method failed; 
nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.data.redis.connection.lettuce.LettuceConnectionFactory]: 
Factory method 'redisConnectionFactory' threw exception; 
nested exception is java.lang.NoClassDefFoundError: org/apache/commons/pool2/impl/GenericObjectPoolConfig

解决方案：

引入连接池依赖

<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-pool2</artifactId>
    <version>2.8.0</version>
</dependency

另外：

由于从springboot2.0开始,spring-boot-starter-data-redis默认使用 lettuce 代替Jedis，因此需要把配置文件中redis配置中的jedis改为lettuce，

如下

#rediss
spring.redis.cluster.nodes=
spring.redis.timeout=
spring.redis.lettuce.pool.max-wait=
spring.redis.lettuce.pool.max-active=
spring.redis.lettuce.pool.max-idle=
spring.redis.lettuce.pool.min-idle=

如果使用jedis，需修改pom文件

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-redis</artifactId>
    <exclusions>
        <exclusion>
            <groupId>io.lettuce</groupId>
            <artifactId>lettuce-core</artifactId>
        </exclusion>
    </exclusions>
</dependency>
<dependency>
    <groupId>redis.clients</groupId>
    <artifactId>jedis</artifactId>
</dependency>

 RedisConfig.java

@Bean
public RedisConnectionFactory redisCF() {
    JedisConnectionFactory rcf = new JedisConnectionFactory();
    rcf.setHostName("127.0.0.1");
    rcf.setPort(6379);
    return rcf;
}

@Bean
public RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory factory) {
    RedisTemplate<String, Object> template = new RedisTemplate<String, Object>();
    template.setConnectionFactory(factory);
    return template;
}

 如果使用Lettuce ，则pom文件如下：

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>

RedisConfig.java

@Bean
public RedisConnectionFactory redisCF() {
// JedisConnectionFactory rcf = new JedisConnectionFactory();
    LettuceConnectionFactory rcf = new LettuceConnectionFactory();
    rcf.setHostName("127.0.0.1");
    rcf.setPort(6379);
//        rcf.setPassword();
    return rcf;
}

@Bean
public RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory factory) {
    RedisTemplate<String, Object> template = new RedisTemplate<String, Object>();
    template.setConnectionFactory(factory);
    return template;
}