<?xml version="1.0" encoding="UTF-8"?>
<ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:noNamespaceSchemaLocation="../bin/ehcache.xsd">
	<defaultCache overflowToDisk="true" eternal="true"/>
	<diskStore path="f:/test/cache" />
</ehcache>

employee.xml
	<mapper namespace="com.test.mybatis.dao.impl">
	<cache type="org.mybatis.caches.ehcache.LoggingEhcache"/>
  
    <select id="selectAll"  resultType="com.test.entity.Employee">
        select name as username ,age from employee 
    </select>




测试代码



@Override
	public List<Employee> selectList() {
		return super.getSession(false).selectList("selectAll");
	}
	
	public static void main(String args[]) throws Exception{
		EmployeeDaoImpl emplDao = new EmployeeDaoImpl();
		emplDao.selectList();//第一次
		emplDao.selectList();//第二次，应该从缓存里面读取
	}




mybatis 源码：

    BoundSql boundSql = ms.getBoundSql(parameterObject);
   //根据规则创建缓存对应的键，因为查询相同，所以第二次这个还是这个键，没错
    CacheKey key = createCacheKey(ms, parameterObject, rowBounds, boundSql);
   //在执行查询
    return query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);




  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, key, parameterObject, boundSql);
        if (!dirty) {
          cache.getReadWriteLock().readLock().lock();
          try {
            @SuppressWarnings("unchecked")
            List<E> cachedList = (List<E>) cache.getObject(key);
            if (cachedList != null) return cachedList;
          } finally {
            cache.getReadWriteLock().readLock().unlock();
          }
        }
        List<E> list = delegate.<E> query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);
//因为第一次没有缓存，所以创建了缓存然后再把数据放入缓存里面，但是这里有个问题，这个缓存每次都是重新创建的，大家可以去debug 看看，不知是我配置错了，还是怎么的，反正进入到这个方法里面，每次都是空的，看下面代码
        tcm.putObject(cache, key, list); // issue #578. Query must be not synchronized to prevent deadlocks
        return list;
      }
    }
//这里老是空对象，每次都是从新new 
    TransactionalCache txCache = transactionalCaches.get(cache);
    if (txCache == null) {
      txCache = new TransactionalCache(cache);
      transactionalCaches.put(cache, txCache);
    }




不知道有没有人碰到过类似的问题，谢谢



源码贴的可能不怎么规范，大家注意下，我只是截取了部分代码


          
          

            

            问题补充：从贴下代码，好乱

这是 employee.xml



	<mapper namespace="com.ztiny.mybatis.dao.impl">

	<cache type="org.mybatis.caches.ehcache.LoggingEhcache"/>

  

    <select id="selectAll"  resultType="com.ztiny.test.entity.Employee">

        select name as username ,age from employee 

    </select>

===============================================================

测试java代码

@Override

	public List<Employee> selectList() {

		return super.getSession(false).selectList("selectAll");

	}

	

	public static void main(String args[]) throws Exception{

		EmployeeDaoImpl emplDao = new EmployeeDaoImpl();

		emplDao.selectList();

		emplDao.selectList();

	}



=======================================================

ehcache.xml

   <diskStore path="D:/cache" />

   <defaultCache overflowToDisk="true" eternal="true"/>



=========================================================

部分源码

  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, key, parameterObject, boundSql);

        if (!dirty) {

          cache.getReadWriteLock().readLock().lock();

          try {

            @SuppressWarnings("unchecked")

            List<E> cachedList = (List<E>) cache.getObject(key);

            if (cachedList != null) return cachedList;

          } finally {

            cache.getReadWriteLock().readLock().unlock();

          }

        }

        List<E> list = delegate.<E> query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);

        tcm.putObject(cache, key, list); // issue #578. Query must be not synchronized to prevent deadlocks

        return list;

      }

    }

    return delegate.<E>query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);

  }



  public <E> List<E> query(MappedStatement ms, Object parameterObject, RowBounds rowBounds, ResultHandler resultHandler) throws SQLException {

    BoundSql boundSql = ms.getBoundSql(parameterObject);

    CacheKey key = createCacheKey(ms, parameterObject, rowBounds, boundSql);

    return query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);

  }





 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, key, parameterObject, boundSql);

        if (!dirty) {

          cache.getReadWriteLock().readLock().lock();

          try {

            @SuppressWarnings("unchecked")

            List<E> cachedList = (List<E>) cache.getObject(key);

            if (cachedList != null) return cachedList;

          } finally {

            cache.getReadWriteLock().readLock().unlock();

          }

        }

        List<E> list = delegate.<E> query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);

        tcm.putObject(cache, key, list); // issue #578. Query must be not synchronized to prevent deadlocks

        return list;

      }

    }

    return delegate.<E>query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);

  }