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
<?xml version="1.0" encoding="UTF-8"?>
<ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="http://ehcache.org/ehcache.xsd">
<!-- 磁盘缓存位置 -->
<diskStore path="java.io.tmpdir" />
<cache name="userCache"
maxElementsInMemory="0"
eternal="true"
overflowToDisk="true"
diskPersistent="true"
memoryStoreEvictionPolicy="LRU">
</cache>
</ehcache>
UserDetailsCacheConfig.java
@Slf4j
@Configuration
public 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<CachingUserDetailsService> 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
@Autowired private UserDetailsService userDetailsService;
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