在Spring中有一个类CachingUserDetailsService实现了UserDetailsService接口，该类使用静态代理模式为UserDetailsService提供缓存功能。该类源码如下：

CachingUserDetailsService.java

public class CachingUserDetailsService implements UserDetailsService {    private UserCache userCache = new NullUserCache();    private final UserDetailsService delegate;    CachingUserDetailsService(UserDetailsService delegate) {        this.delegate = delegate;    }    public UserCache getUserCache() {        return this.userCache;    }    public void setUserCache(UserCache userCache) {        this.userCache = userCache;    }    public UserDetails loadUserByUsername(String username) {        UserDetails user = this.userCache.getUserFromCache(username);        if (user == null) {            user = this.delegate.loadUserByUsername(username);        }        Assert.notNull(user, "UserDetailsService " + this.delegate + " returned null for username " + username + ". This is an interface contract violation");        this.userCache.putUserInCache(user);        return user;    }}

CachingUserDetailsService默认的userCache属性值为new NullUserCache()，该对象并未实现缓存。因为我打算使用EhCache来缓存UserDetails，所以需要使用Spring的EhCacheBasedUserCache类，该类是UserCache接口的实现类，主要是缓存操作。

缓存UserDetails到Ehcache的具体实现如下：

ehcache.xml

UserDetailsCacheConfig.java

@Slf4j@Configurationpublic class UserDetailsCacheConfig {    @Autowired    private CustomUserDetailsService customUserDetailsService;    @Bean    public UserCache userCache(){        try {            EhCacheBasedUserCache userCache = new EhCacheBasedUserCache();            val cacheManager = CacheManager.getInstance();            val cache = cacheManager.getCache("userCache");            userCache.setCache(cache);            return userCache;        } catch (Exception e) {            e.printStackTrace();            log.error(e.getMessage());        }        return null;    }    @Bean    public UserDetailsService userDetailsService(){        Constructor
    
      ctor = null;        try {            ctor = CachingUserDetailsService.class.getDeclaredConstructor(UserDetailsService.class);        } catch (NoSuchMethodException e) {            e.printStackTrace();        }        Assert.notNull(ctor, "CachingUserDetailsService constructor is null");        ctor.setAccessible(true);        CachingUserDetailsService cachingUserDetailsService = BeanUtils.instantiateClass(ctor, customUserDetailsService);        cachingUserDetailsService.setUserCache(userCache());        return cachingUserDetailsService;    }}
    

使用

@Autowiredprivate UserDetailsService userDetailsService;

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