Java Cache类代码示例

import org.apache.ibatis.cache.Cache; //导入依赖的package包/类
/**
 * 检查是否配置过缓存
 *
 * @param ms
 * @throws Exception
 */
private void checkCache(MappedStatement ms) throws Exception {
    if (ms.getCache() == null) {
        String nameSpace = ms.getId().substring(0, ms.getId().lastIndexOf("."));
        Cache cache;
        try {
            //不存在的时候会抛出异常
            cache = ms.getConfiguration().getCache(nameSpace);
        } catch (IllegalArgumentException e) {
            return;
        }
        if (cache != null) {
            MetaObject metaObject = SystemMetaObject.forObject(ms);
            metaObject.setValue("cache", cache);
        }
    }
}
 

import org.apache.ibatis.cache.Cache; //导入依赖的package包/类
public Cache useCacheRef(String namespace) {
  if (namespace == null) {
    throw new BuilderException("cache-ref element requires a namespace attribute.");
  }
  try {
    unresolvedCacheRef = true;
    Cache cache = configuration.getCache(namespace);
    if (cache == null) {
      throw new IncompleteElementException("No cache for namespace '" + namespace + "' could be found.");
    }
    currentCache = cache;
    unresolvedCacheRef = false;
    return cache;
  } catch (IllegalArgumentException e) {
    throw new IncompleteElementException("No cache for namespace '" + namespace + "' could be found.", e);
  }
}
 

import org.apache.ibatis.cache.Cache; //导入依赖的package包/类
public Cache useNewCache(Class<? extends Cache> typeClass,
    Class<? extends Cache> evictionClass,
    Long flushInterval,
    Integer size,
    boolean readWrite,
    boolean blocking,
    Properties props) {
  Cache cache = new CacheBuilder(currentNamespace)
      .implementation(valueOrDefault(typeClass, PerpetualCache.class))
      .addDecorator(valueOrDefault(evictionClass, LruCache.class))
      .clearInterval(flushInterval)
      .size(size)
      .readWrite(readWrite)
      .blocking(blocking)
      .properties(props)
      .build();
  configuration.addCache(cache);
  currentCache = cache;
  return cache;
}
 

import org.apache.ibatis.cache.Cache; //导入依赖的package包/类
@Override
public <E> List<E> query(MappedStatement ms, Object parameterObject, RowBounds rowBounds, ResultHandler resultHandler, CacheKey key, BoundSql boundSql)
    throws SQLException {
  Cache cache = ms.getCache();
  if (cache != null) {
    flushCacheIfRequired(ms);
    if (ms.isUseCache() && resultHandler == null) {
      ensureNoOutParams(ms, parameterObject, boundSql);
      @SuppressWarnings("unchecked")
      List<E> list = (List<E>) tcm.getObject(cache, key);
      if (list == null) {
        list = delegate.<E> query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);
        tcm.putObject(cache, key, list); // issue #578 and #116
      }
      return list;
    }
  }
  return delegate.<E> query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);
}
 

import org.apache.ibatis.cache.Cache; //导入依赖的package包/类
@Test
public void testMappedStatementCache() throws Exception {
  Reader configReader = Resources
  .getResourceAsReader("org/apache/ibatis/submitted/xml_external_ref/MultipleCrossIncludeMapperConfig.xml");
  SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(configReader);
  configReader.close();

  Configuration configuration = sqlSessionFactory.getConfiguration();
  configuration.getMappedStatementNames();
  
  MappedStatement selectPetStatement = configuration.getMappedStatement("org.apache.ibatis.submitted.xml_external_ref.MultipleCrossIncludePetMapper.select");
  MappedStatement selectPersonStatement = configuration.getMappedStatement("org.apache.ibatis.submitted.xml_external_ref.MultipleCrossIncludePersonMapper.select");
  Cache cache = selectPetStatement.getCache();
  assertEquals("org.apache.ibatis.submitted.xml_external_ref.MultipleCrossIncludePetMapper", cache.getId());
  assertSame(cache, selectPersonStatement.getCache());
}
 

import org.apache.ibatis.cache.Cache; //导入依赖的package包/类
@Test
public void testMappedStatementCache() throws Exception {
  Reader configReader = Resources
  .getResourceAsReader("org/apache/ibatis/submitted/xml_external_ref/MapperConfig.xml");
  SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(configReader);
  configReader.close();

  Configuration configuration = sqlSessionFactory.getConfiguration();
  configuration.getMappedStatementNames();
  
  MappedStatement selectPetStatement = configuration.getMappedStatement("org.apache.ibatis.submitted.xml_external_ref.PetMapper.select");
  MappedStatement selectPersonStatement = configuration.getMappedStatement("org.apache.ibatis.submitted.xml_external_ref.PersonMapper.select");
  Cache cache = selectPetStatement.getCache();
  assertEquals("org.apache.ibatis.submitted.xml_external_ref.PetMapper", cache.getId());
  assertSame(cache, selectPersonStatement.getCache());
}
 

import org.apache.ibatis.cache.Cache; //导入依赖的package包/类
private void cacheElement(XNode context) throws Exception {
	if (context != null) {
		String type = context.getStringAttribute("type", "PERPETUAL");
		Class<? extends Cache> typeClass = typeAliasRegistry
				.resolveAlias(type);
		String eviction = context.getStringAttribute("eviction", "LRU");
		Class<? extends Cache> evictionClass = typeAliasRegistry
				.resolveAlias(eviction);
		Long flushInterval = context.getLongAttribute("flushInterval");
		Integer size = context.getIntAttribute("size");
		boolean readWrite = !context.getBooleanAttribute("readOnly", false);
		Properties props = context.getChildrenAsProperties();
		builderAssistant.useNewCache(typeClass, evictionClass,
				flushInterval, size, readWrite, props);
	}
}
 

import org.apache.ibatis.cache.Cache; //导入依赖的package包/类
@Override
public boolean equals(Object o) {
  //只要id相等就认为两个cache相同
  if (getId() == null) {
    throw new CacheException("Cache instances require an ID.");
  }
  if (this == o) {
    return true;
  }
  if (!(o instanceof Cache)) {
    return false;
  }

  Cache otherCache = (Cache) o;
  return getId().equals(otherCache.getId());
}
 

import org.apache.ibatis.cache.Cache; //导入依赖的package包/类
public Cache useNewCache(Class<? extends Cache> typeClass,
    Class<? extends Cache> evictionClass,
    Long flushInterval,
    Integer size,
    boolean readWrite,
    boolean blocking,
    Properties props) {
    //这里面又判断了一下是否为null就用默认值，有点和XMLMapperBuilder.cacheElement逻辑重复了
  typeClass = valueOrDefault(typeClass, PerpetualCache.class);
  evictionClass = valueOrDefault(evictionClass, LruCache.class);
  //调用CacheBuilder构建cache,id=currentNamespace
  Cache cache = new CacheBuilder(currentNamespace)
      .implementation(typeClass)
      .addDecorator(evictionClass)
      .clearInterval(flushInterval)
      .size(size)
      .readWrite(readWrite)
      .blocking(blocking)
      .properties(props)
      .build();
  //加入缓存
  configuration.addCache(cache);
  //当前的缓存
  currentCache = cache;
  return cache;
}
 

import org.apache.ibatis.cache.Cache; //导入依赖的package包/类
private void cacheElement(XNode context) throws Exception {
    if (context != null) {
      String type = context.getStringAttribute("type", "PERPETUAL");
      Class<? extends Cache> typeClass = typeAliasRegistry.resolveAlias(type);
      String eviction = context.getStringAttribute("eviction", "LRU");
      Class<? extends Cache> evictionClass = typeAliasRegistry.resolveAlias(eviction);
      Long flushInterval = context.getLongAttribute("flushInterval");
      Integer size = context.getIntAttribute("size");
      boolean readWrite = !context.getBooleanAttribute("readOnly", false);
      boolean blocking = context.getBooleanAttribute("blocking", false);
      //读入额外的配置信息，易于第三方的缓存扩展,例:
//    <cache type="com.domain.something.MyCustomCache">
//      <property name="cacheFile" value="/tmp/my-custom-cache.tmp"/>
//    </cache>
      Properties props = context.getChildrenAsProperties();
      //调用builderAssistant.useNewCache
      builderAssistant.useNewCache(typeClass, evictionClass, flushInterval, size, readWrite, blocking, props);
    }
  }
 

import org.apache.ibatis.cache.Cache; //导入依赖的package包/类
@Override
public <E> List<E> query(MappedStatement ms, Object parameterObject, RowBounds rowBounds, ResultHandler resultHandler, CacheKey key, BoundSql boundSql)
    throws SQLException {
  Cache cache = ms.getCache();
  //默认情况下是没有开启缓存的(二级缓存).要开启二级缓存,你需要在你的 SQL 映射文件中添加一行: <cache/>
  //简单的说，就是先查CacheKey，查不到再委托给实际的执行器去查
  if (cache != null) {
    flushCacheIfRequired(ms);
    if (ms.isUseCache() && resultHandler == null) {
      ensureNoOutParams(ms, parameterObject, boundSql);
      @SuppressWarnings("unchecked")
      List<E> list = (List<E>) tcm.getObject(cache, key);
      if (list == null) {
        list = delegate.<E> query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);
        tcm.putObject(cache, key, list); // issue #578 and #116
      }
      return list;
    }
  }
  return delegate.<E> query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);
}
 

import org.apache.ibatis.cache.Cache; //导入依赖的package包/类
/**
 * {@inheritDoc}
 */
@Override
public boolean equals(Object obj) {
  if (this == obj) {
    return true;
  }
  if (obj == null) {
    return false;
  }
  if (!(obj instanceof Cache)) {
    return false;
  }

  Cache otherCache = (Cache) obj;
  return id.equals(otherCache.getId());
}
 

import org.apache.ibatis.cache.Cache; //导入依赖的package包/类
@Override
public Cache getCache(String id) {
  if (id == null) {
    throw new IllegalArgumentException("Cache instances require an ID");
  }

  if (!cacheManager.cacheExists(id)) {
    CacheConfiguration temp = null;
    if (cacheConfiguration != null) {
      temp = cacheConfiguration.clone();
    } else {
      // based on defaultCache
      temp = cacheManager.getConfiguration().getDefaultCacheConfiguration().clone();
    }
    temp.setName(id);
    net.sf.ehcache.Cache cache = new net.sf.ehcache.Cache(temp);
    cacheManager.addCache(cache);
  }

  return new EhcacheCache(id, cacheManager.getEhcache(id));
}
 

import org.apache.ibatis.cache.Cache; //导入依赖的package包/类
@Override
public Cache getCache(String id) {
  if (id == null) {
    throw new IllegalArgumentException("Cache instances require an ID");
  }

  if (!cacheManager.cacheExists(id)) {
    CacheConfiguration temp = null;
    if (cacheConfiguration != null) {
      temp = cacheConfiguration.clone();
    } else {
      // based on defaultCache
      temp = cacheManager.getConfiguration().getDefaultCacheConfiguration().clone();
    }
    temp.setName(id);
    net.sf.ehcache.Cache cache = new net.sf.ehcache.Cache(temp);
    Ehcache instrumentCache = InstrumentedEhcache.instrument(registry, cache);
    cacheManager.addCache(instrumentCache);
  }
  return new EhcacheCache(id, cacheManager.getEhcache(id));
}
 

import org.apache.ibatis.cache.Cache; //导入依赖的package包/类
public Cache useNewCache(Class<? extends Cache> typeClass,
    Class<? extends Cache> evictionClass,
    Long flushInterval,
    Integer size,
    boolean readWrite,
    boolean blocking,
    Properties props) {
  typeClass = valueOrDefault(typeClass, PerpetualCache.class);
  evictionClass = valueOrDefault(evictionClass, LruCache.class);
  Cache cache = new CacheBuilder(currentNamespace)
      .implementation(typeClass)
      .addDecorator(evictionClass)
      .clearInterval(flushInterval)
      .size(size)
      .readWrite(readWrite)
      .blocking(blocking)
      .properties(props)
      .build();
  configuration.addCache(cache);
  currentCache = cache;
  return cache;
}