FSTConfiguration

Spring boot 项目集成Redisson做分布式锁的时候，抛异常 NoClassDefFoundError: Lorg/nustaq/serialization/FSTConfiguration，本文总结一下解决方案。

问题背景

Spring boot 项目集成Redisson配置分布式锁的时候，提示如下异常：

Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.redisson.api.RedissonClient]: Factory method 'redisson' threw exception; nested exception is java.lang.NoClassDefFoundError: Lorg/nustaq/serialization/FSTConfiguration;

问题分析

缺少fst依赖导致的，添加maven依赖

<dependency>
  <groupId>de.ruedigermoeller</groupId>
  <artifactId>fst</artifactId>
  <version>2.57</version>
</dependency>

问题延伸

fst是什么？FST fast-serialization 是重新实现的 Java 快速对象序列化的开发包。序列化速度更快（2-10倍）、体积更小，而且兼容 JDK 原生的序列化。要求 JDK 1.7 支持。

// ! reuse this Object, it caches metadata. Performance degrades massively
// if you create a new Configuration Object with each serialization !
static FSTConfiguration conf = FSTConfiguration.createDefaultConfiguration();
...
public MyClass myreadMethod(InputStream stream) throws IOException, ClassNotFoundException
{
    FSTObjectInput in = conf.getObjectInput(stream);
    MyClass result = in.readObject(MyClass.class);
    // DON'T: in.close(); here prevents reuse and will result in an exception      
    stream.close();
    return result;
}

public void mywriteMethod( OutputStream stream, MyClass toWrite ) throws IOException 
{
    FSTObjectOutput out = conf.getObjectOutput(stream);
    out.writeObject( toWrite, MyClass.class );
    // DON'T out.close() when using factory method;
    out.flush();
    stream.close();
}