解决Spring导致iBatis缓存失效问题

版本：
  Spring 3.0.4（2.x版本中也存在类似问题）
  iBatis 2.3.4.726（2.3.x版本都适用）

起因：
  使用Spring管理iBatis实例，标准方式采用SqlMapClientFactoryBean创建SqlMapClient

 

	<bean id="sqlMapClient" class="org.springframework.orm.ibatis.SqlMapClientFactoryBean">
		<property name="configLocation"
			value="classpath:/com/foo/xxx/sqlMapConfig.xml" />
		<property name="dataSource" ref="dataSource" />
		<property name="mappingLocations" value="classpath*:/**/sqlmap/*SqlMap.xml" />
	</bean>

使用mappingLocations方式定义可以让sqlmap不必添加到sqlMapConfig.xml
即避免了如下形式

 

 

<sqlMapConfig>
...
  <sqlMap url="someSqlMap" resource="com/foo/xxx/someSqlMap.xml"/>
...
</sqlMapConfig>

 

随之而来的问题是在sqlMap中的cache无法在执行预订方法时自动flush！

<cacheModel id="mycache" type ="LRU" readOnly="false" serialize="false">
  <flushInterval hours="24"/>
  <flushOnExecute statement="myobj.insert"/>
  <property name="cache-size" value="50" />
</cacheModel>

 

在myobj.insert被执行时cache不会flush，即无报错也无提醒，彻头彻尾的坑爹，不清楚Spring开发组为什么会让这问题一直存在。

产生问题的原因网上有不少分析贴（不再重复，需要的可搜索相关帖子），原因是Spring在处理mappingLocations之前，iBatis已经完成对sqlMapConfig里注册的sqlMap的cache设置（真绕口=.="），非亲生的sqlMap被无情的抛弃了。解决办法大都建议放弃mappingLocations的方式，把sqlMap写到sqlMapConfig里——还真是够简单——或者说够偷懒。

找到原因就想办法解决吧，从SqlMapClientFactoryBean下手，扩展一份

/**
* 
* @author Foxswily
*/

@SuppressWarnings("deprecation")
public class MySqlMapClientFactoryBean implements FactoryBean<SqlMapClient>,
        InitializingBean {

    private static final ThreadLocal<LobHandler> configTimeLobHandlerHolder = new ThreadLocal<LobHandler>();

    /**
     * Return the LobHandler for the currently configured iBATIS SqlMapClient,
     * to be used by TypeHandler implementations like ClobStringTypeHandler.
     * <p>
     * This instance will be set before initialization of the corresponding
     * SqlMapClient, and reset immediately afterwards. It is thus only available
     * during configuration.
     * 
     * @see #setLobHandler
     * @see org.springframework.orm.ibatis.support.ClobStringTypeHandler
     * @see org.springframework.orm.ibatis.support.BlobByteArrayTypeHandler
     * @see org.springframework.orm.ibatis.support.BlobSerializableTypeHandler
     */
    public static LobHandler getConfigTimeLobHandler() {
        return configTimeLobHandlerHolder.get();
    }

    private Resource[] configLocations;

    private Resource[] mappingLocations;

    private Properties sqlMapClientProperties;

    private DataSource dataSource;

    private boolean useTransactionAwareDataSource = true;

    @SuppressWarnings("rawtypes")
    private Class transactionConfigClass = ExternalTransactionConfig.class;

    private Properties transactionConfigProperties;

    private LobHandler lobHandler;

    private SqlMapClient sqlMapClient;

    public MySqlMapClientFactoryBean() {
        this.transactionConfigProperties = new Properties();
        this.transactionConfigProperties.setProperty("SetAutoCommitAllowed", "false");
    }

    /**
     * Set the location of the iBATIS SqlMapClient config file. A typical value
     * is "WEB-INF/sql-map-config.xml".
     * 
     * @see #setConfigLocations
     */
    public void setConfigLocation(Resource configLocation) {
        this.configLocations = (configLocation != null ? new Resource[] { configLocation }
                : null);
    }

    /**
     * Set multiple locations of iBATIS SqlMapClient config files that are going
     * to be merged into one unified configuration at runtime.
     */
    public void setConfigLocations(Resource[] configLocations) {
        this.configLocations = configLocations;
    }

    /**
     * Set locations of iBATIS sql-map mapping files that are going to be merged
     * into the SqlMapClient configuration at runtime.
     * <p>
     * This is an alternative to specifying "&lt;sqlMap&gt;" entries in a
     * sql-map-client config file. This property being based on Spring's
     * resource abstraction also allows for specifying resource patterns here:
     * e.g. "/myApp/*-map.xml".
     * <p>
     * Note that this feature requires iBATIS 2.3.2; it will not work with any
     * previous iBATIS version.
     */
    public void setMappingLocations(Resource[] mappingLocations) {
        this.mappingLocations = mappingLocations;
    }

    /**
     * Set optional properties to be passed into the SqlMapClientBuilder, as
     * alternative to a <code>&lt;properties&gt;</code> tag in the
     * sql-map-config.xml file. Will be used to resolve placeholders in the
     * config file.
     * 
     * @see #setConfigLocation
     * @see com.ibatis.sqlmap.client.SqlMapClientBuilder#buildSqlMapClient(java.io.InputStream,
     *      java.util.Properties)
     */
    public void setSqlMapClientProperties(Properties sqlMapClientProperties) {
        this.sqlMapClientProperties = sqlMapClientProperties;
    }

    /**
     * Set the DataSource to be used by iBATIS SQL Maps. This will be passed to
     * the SqlMapClient as part of a TransactionConfig instance.
     * <p>
     * If specified, this will override corresponding settings in the
     * SqlMapClient properties. Usually, you will specify DataSource and
     * transaction configuration <i>either</i> here <i>or</i> in SqlMapClient
     * properties.
     * <p>
     * Specifying a DataSource for the SqlMapClient rather than for each
     * individual DAO allows for lazy loading, for example when using
     * PaginatedList results.
     * <p>
     * With a DataSource passed in here, you don't need to specify one for each
     * DAO. Passing the SqlMapClient to the DAOs is enough, as it already
     * carries a DataSource. Thus, it's recommended to specify the DataSource at
     * this central location only.
     * <p>
     * Thanks to Brandon Goodin from the iBATIS team for the hint on how to make
     * this work with Spring's integration strategy!
     * 
     * @see #setTransactionConfigClass
     * @see #setTransactionConfigProperties
     * @see com.ibatis.sqlmap.client.SqlMapClient#getDataSource
     * @see SqlMapClientTemplate#setDataSource
     * @see SqlMapClientTemplate#queryForPaginatedList
     */
    public void setDataSource(DataSource dataSource) {
        this.dataSource = dataSource;
    }

    /**
     * Set whether to use a transaction-aware DataSource for the SqlMapClient,
     * i.e. whether to automatically wrap the passed-in DataSource with Spring's
     * TransactionAwareDataSourceProxy.
     * <p>
     * Default is "true": When the SqlMapClient performs direct database
     * operations outside of Spring's SqlMapClientTemplate (for example, lazy
     * loading or direct SqlMapClient access), it will still participate in
     * active Spring-managed transactions.
     * <p>
     * As a further effect, using a transaction-aware DataSource will apply
     * remaining transaction timeouts to all created JDBC Statements. This means
     * that all operations performed by the SqlMapClient will automatically
     * participate in Spring-managed transaction timeouts.
     * <p>
     * Turn this flag off to get raw DataSource handling, without Spring
     * transaction checks. Operations on Spring's SqlMapClientTemplate will
     * still detect Spring-managed transactions, but lazy loading or direct
     * SqlMapClient access won't.
     * 
     * @see #setDataSource
     * @see org.springframework.jdbc.datasource.TransactionAwareDataSourceProxy
     * @see org.springframework.jdbc.datasource.DataSourceTransactionManager
     * @see SqlMapClientTemplate
     * @see com.ibatis.sqlmap.client.SqlMapClient
     */
    public void setUseTransactionAwareDataSource(boolean useTransactionAwareDataSource) {
        this.useTransactionAwareDataSource = useTransactionAwareDataSource;
    }

    /**
     * Set the iBATIS TransactionConfig class to use. Default is
     * <code>com.ibatis.sqlmap.engine.transaction.external.ExternalTransactionConfig</code>
     * .
     * <p>
     * Will only get applied when using a Spring-managed DataSource. An instance
     * of this class will get populated with the given DataSource and
     * initialized with the given properties.
     * <p>
     * The default ExternalTransactionConfig is appropriate if there is external
     * transaction management that the SqlMapClient should participate in: be it
     * Spring transaction management, EJB CMT or plain JTA. This should be the
     * typical scenario. If there is no active transaction, SqlMapClient
     * operations will execute SQL statements non-transactionally.
     * <p>
     * JdbcTransactionConfig or JtaTransactionConfig is only necessary when
     * using the iBATIS SqlMapTransactionManager API instead of external
     * transactions. If there is no explicit transaction, SqlMapClient
     * operations will automatically start a transaction for their own scope (in
     * contrast to the external transaction mode, see above).
     * <p>
     * <b>It is strongly recommended to use iBATIS SQL Maps with Spring
     * transaction management (or EJB CMT).</b> In this case, the default
     * ExternalTransactionConfig is fine. Lazy loading and SQL Maps operations
     * without explicit transaction demarcation will execute
     * non-transactionally.
     * <p>
     * Even with Spring transaction management, it might be desirable to specify
     * JdbcTransactionConfig: This will still participate in existing
     * Spring-managed transactions, but lazy loading and operations without
     * explicit transaction demaration will execute in their own auto-started
     * transactions. However, this is usually not necessary.
     * 
     * @see #setDataSource
     * @see #setTransactionConfigProperties
     * @see com.ibatis.sqlmap.engine.transaction.TransactionConfig
     * @see com.ibatis.sqlmap.engine.transaction.external.ExternalTransactionConfig
     * @see com.ibatis.sqlmap.engine.transaction.jdbc.JdbcTransactionConfig
     * @see com.ibatis.sqlmap.engine.transaction.jta.JtaTransactionConfig
     * @see com.ibatis.sqlmap.client.SqlMapTransactionManager
     */
    @SuppressWarnings("rawtypes")
    public void setTransactionConfigClass(Class transactionConfigClass) {
        if (transactionConfigClass == null
                || !TransactionConfig.class.isAssignableFrom(transactionConfigClass)) {
            throw new IllegalArgumentException(
                    "Invalid transactionConfigClass: does not implement "
                            + "com.ibatis.sqlmap.engine.transaction.TransactionConfig");
        }
        this.transactionConfigClass = transactionConfigClass;
    }

    /**
     * Set properties to be passed to the TransactionConfig instance used by
     * this SqlMapClient. Supported properties depend on the concrete
     * TransactionConfig implementation used:
     * <p>
     * <ul>
     * <li><b>ExternalTransactionConfig</b> supports "DefaultAutoCommit"
     * (default: false) and "SetAutoCommitAllowed" (default: true). Note that
     * Spring uses SetAutoCommitAllowed = false as default, in contrast to the
     * iBATIS default, to always keep the original autoCommit value as provided
     * by the connection pool.
     * <li><b>JdbcTransactionConfig</b> does not supported any properties.
     * <li><b>JtaTransactionConfig</b> supports "UserTransaction" (no default),
     * specifying the JNDI location of the JTA UserTransaction (usually
     * "java:comp/UserTransaction").
     * </ul>
     * 
     * @see com.ibatis.sqlmap.engine.transaction.TransactionConfig#initialize
     * @see com.ibatis.sqlmap.engine.transaction.external.ExternalTransactionConfig
     * @see com.ibatis.sqlmap.engine.transaction.jdbc.JdbcTransactionConfig
     * @see com.ibatis.sqlmap.engine.transaction.jta.JtaTransactionConfig
     */
    public void setTransactionConfigProperties(Properties transactionConfigProperties) {
        this.transactionConfigProperties = transactionConfigProperties;
    }

    /**
     * Set the LobHandler to be used by the SqlMapClient. Will be exposed at
     * config time for TypeHandler implementations.
     * 
     * @see #getConfigTimeLobHandler
     * @see com.ibatis.sqlmap.engine.type.TypeHandler
     * @see org.springframework.orm.ibatis.support.ClobStringTypeHandler
     * @see org.springframework.orm.ibatis.support.BlobByteArrayTypeHandler
     * @see org.springframework.orm.ibatis.support.BlobSerializableTypeHandler
     */
    public void setLobHandler(LobHandler lobHandler) {
        this.lobHandler = lobHandler;
    }

    public void afterPropertiesSet() throws Exception {
        if (this.lobHandler != null) {
            // Make given LobHandler available for SqlMapClient configuration.
            // Do early because because mapping resource might refer to custom
            // types.
            configTimeLobHandlerHolder.set(this.lobHandler);
        }

        try {
            this.sqlMapClient = buildSqlMapClient(this.configLocations,
                    this.mappingLocations, this.sqlMapClientProperties);

            // Tell the SqlMapClient to use the given DataSource, if any.
            if (this.dataSource != null) {
                TransactionConfig transactionConfig = (TransactionConfig) this.transactionConfigClass
                        .newInstance();
                DataSource dataSourceToUse = this.dataSource;
                if (this.useTransactionAwareDataSource
                        && !(this.dataSource instanceof TransactionAwareDataSourceProxy)) {
                    dataSourceToUse = new TransactionAwareDataSourceProxy(this.dataSource);
                }
                transactionConfig.setDataSource(dataSourceToUse);
                transactionConfig.initialize(this.transactionConfigProperties);
                applyTransactionConfig(this.sqlMapClient, transactionConfig);
            }
        }

        finally {
            if (this.lobHandler != null) {
                // Reset LobHandler holder.
                configTimeLobHandlerHolder.set(null);
            }
        }
    }

    /**
     * Build a SqlMapClient instance based on the given standard configuration.
     * <p>
     * The default implementation uses the standard iBATIS
     * {@link SqlMapClientBuilder} API to build a SqlMapClient instance based on
     * an InputStream (if possible, on iBATIS 2.3 and higher) or on a Reader (on
     * iBATIS up to version 2.2).
     * 
     * @param configLocations
     *            the config files to load from
     * @param properties
     *            the SqlMapClient properties (if any)
     * @return the SqlMapClient instance (never <code>null</code>)
     * @throws IOException
     *             if loading the config file failed
     * @throws NoSuchFieldException
     * @throws SecurityException
     * @throws IllegalAccessException
     * @throws IllegalArgumentException
     * @throws NoSuchMethodException
     * @throws InvocationTargetException
     * @see com.ibatis.sqlmap.client.SqlMapClientBuilder#buildSqlMapClient
     */
    protected SqlMapClient buildSqlMapClient(Resource[] configLocations,
            Resource[] mappingLocations, Properties properties) throws IOException,
            SecurityException, NoSuchFieldException, IllegalArgumentException,
            IllegalAccessException, NoSuchMethodException, InvocationTargetException {

        if (ObjectUtils.isEmpty(configLocations)) {
            throw new IllegalArgumentException(
                    "At least 1 'configLocation' entry is required");
        }

        SqlMapClient client = null;
        SqlMapConfigParser configParser = new SqlMapConfigParser();
        for (Resource configLocation : configLocations) {
            InputStream is = configLocation.getInputStream();
            try {
                client = configParser.parse(is, properties);
            } catch (RuntimeException ex) {
                throw new NestedIOException("Failed to parse config resource: "
                        + configLocation, ex.getCause());
            }
        }

        if (mappingLocations != null) {
            SqlMapParser mapParser = SqlMapParserFactory.createSqlMapParser(configParser);
            for (Resource mappingLocation : mappingLocations) {
                try {
                    mapParser.parse(mappingLocation.getInputStream());
                } catch (NodeletException ex) {
                    throw new NestedIOException("Failed to parse mapping resource: "
                            + mappingLocation, ex);
                }
            }
        }
        //*************其实只改这一点而已，为了方便他人，全source贴出**************
        //为了取sqlMapConfig，反射private的field
        Field stateField = configParser.getClass().getDeclaredField("state");
        stateField.setAccessible(true);
        XmlParserState state = (XmlParserState) stateField.get(configParser);
        SqlMapConfiguration sqlMapConfig = state.getConfig();
        //反射取设置cache的方法，执行
        Method wireUpCacheModels = sqlMapConfig.getClass().getDeclaredMethod(
                "wireUpCacheModels");
        wireUpCacheModels.setAccessible(true);
        wireUpCacheModels.invoke(sqlMapConfig);
        //*************************************************************************
        return client;
    }

    /**
     * Apply the given iBATIS TransactionConfig to the SqlMapClient.
     * <p>
     * The default implementation casts to ExtendedSqlMapClient, retrieves the
     * maximum number of concurrent transactions from the
     * SqlMapExecutorDelegate, and sets an iBATIS TransactionManager with the
     * given TransactionConfig.
     * 
     * @param sqlMapClient
     *            the SqlMapClient to apply the TransactionConfig to
     * @param transactionConfig
     *            the iBATIS TransactionConfig to apply
     * @see com.ibatis.sqlmap.engine.impl.ExtendedSqlMapClient
     * @see com.ibatis.sqlmap.engine.impl.SqlMapExecutorDelegate#getMaxTransactions
     * @see com.ibatis.sqlmap.engine.impl.SqlMapExecutorDelegate#setTxManager
     */
    protected void applyTransactionConfig(SqlMapClient sqlMapClient,
            TransactionConfig transactionConfig) {
        if (!(sqlMapClient instanceof ExtendedSqlMapClient)) {
            throw new IllegalArgumentException(
                    "Cannot set TransactionConfig with DataSource for SqlMapClient if not of type "
                            + "ExtendedSqlMapClient: " + sqlMapClient);
        }
        ExtendedSqlMapClient extendedClient = (ExtendedSqlMapClient) sqlMapClient;
        transactionConfig.setMaximumConcurrentTransactions(extendedClient.getDelegate()
                .getMaxTransactions());
        extendedClient.getDelegate().setTxManager(
                new TransactionManager(transactionConfig));
    }

    public SqlMapClient getObject() {
        return this.sqlMapClient;
    }

    public Class<? extends SqlMapClient> getObjectType() {
        return (this.sqlMapClient != null ? this.sqlMapClient.getClass()
                : SqlMapClient.class);
    }

    public boolean isSingleton() {
        return true;
    }

    /**
     * Inner class to avoid hard-coded iBATIS 2.3.2 dependency (XmlParserState
     * class).
     */
    private static class SqlMapParserFactory {

        public static SqlMapParser createSqlMapParser(SqlMapConfigParser configParser) {
            // Ideally: XmlParserState state = configParser.getState();
            // Should raise an enhancement request with iBATIS...
            XmlParserState state = null;
            try {
                Field stateField = SqlMapConfigParser.class.getDeclaredField("state");
                stateField.setAccessible(true);
                state = (XmlParserState) stateField.get(configParser);
            } catch (Exception ex) {
                throw new IllegalStateException(
                        "iBATIS 2.3.2 'state' field not found in SqlMapConfigParser class - "
                                + "please upgrade to IBATIS 2.3.2 or higher in order to use the new 'mappingLocations' feature. "
                                + ex);
            }
            return new SqlMapParser(state);
        }
    }

}

 

修改Spring配置文件

<bean id="sqlMapClient" class="com.foo.xxx.MySqlMapClientFactoryBean">
  <property name="configLocation"
value="classpath:/com/foo/xxx/sqlMapConfig.xml" />
  <property name="dataSource" ref="dataSource" />
  <property name="mappingLocations" value="classpath*:/**/sqlmap/*SqlMap.xml" />
</bean>

 
至此，cache又工作如初了。
编后：
·反射会消耗，但仅仅在初始化时一次性消耗，还可以接受。
·iBatis的cache能力比较弱，但没太多要求的情况下是个省事的方案，聊胜于无。
·Mybatis3.0的cache暂时不用为好，EhCache选项本身还有bug，实在很无语。