protected boolean removeEldestEntry(java.util.Map.Entry eldest) {
        
            System.out.println(this.containsKey(eldest.getKey())); //此处返回false

             if (size() > maxSize){
                          return true;
             }
            
 }

不能移除多于的缓存实例的问题,

百般调试无效,改用 org.apache.commons.collections.map.LRUMap 后问题解决.

应对需求的变化才是OO方法最好的用武之地,如果没有需求的变化那么OO方法的优势就很难体现了,对于

很多程序员使用C++,java,C#等等 很多支持OO方法的语言环境编程时都不能(貌似也不必)熟练地使用OO

方法.所以我觉得有必要把一些更具体的场景写出来,说明典型的OO设计.
例如:使用Decorator而不是参数.
具体场景如下:
    已有一个接口,包含一个方法 execute(),由于需求变化,该接口的实现有些需要加入一种能力

–需要异步执行,有两种典型的处理方法:
    1.将execute()加入一个参数:签名将被改为 execute(boolean asynchronous)
    2.新写一个 AsynDecorator 的新接口实现,实现execute()方法的异步调用.
显然,第二中方法是典型的OO方法.

名称 Decorator
意图 动态地给一个对象添加一些额外的职责。就增加功能来说，D e c o r a t o r 模式相比生成子

类更为灵活。
适用性 在不影响其他对象的情况下，以动态、透明的方式给单个对象添加职责。
处理那些可以撤消的职责。
当不能采用生成子类的方法进行扩充时。一种情况是，可能有大量独立的扩展，为支持每一种组合将产

生大量的子类，使得子类数目呈爆炸性增长。另一种情况可能是因为类定义被隐藏，或类定义不能用于

生成子类。 

    <settings cacheModelsEnabled="true" enhancementEnabled="true"
        lazyLoadingEnabled="true" errorTracingEnabled="true" maxRequests="32"
        maxSessions="10" maxTransactions="5" useStatementNamespaces="true" />

    <!–sqlMap resource="includes:mapping*.xml" /–>
    <sqlMap resource="mapping-table_meta.xml" />
    <sqlMap resource="mapping-task.xml" />
    <sqlMap resource="mapping-table_status.xml" />
    <sqlMap resource="mapping-auth_menu_info.xml" />
    <sqlMap resource="mapping-auth_user_group.xml" />
    <sqlMap resource="mapping-auth_bank_group.xml" />
    <sqlMap resource="mapping-auth_curr_group.xml" />
    <sqlMap resource="mapping-auth_table_group.xml" />
    <sqlMap resource="mapping-auth_oper_group.xml" />
    <sqlMap resource="mapping-auth_menu_subject.xml" />
    <sqlMap resource="mapping-auth_admin_subject.xml" />
    <sqlMap resource="mapping-auth_user_menu.xml" />
    <sqlMap resource="mapping-auth_user_data.xml" />
    <sqlMap resource="mapping-message_info.xml" />

</sqlMapConfig>

IncludesSqlMapClientFactoryBean: 通过重写 afterPropertiesSet() 实现了简化配置文件的目的.
现在的配置文件像这样:
<sqlMapConfig>

    <settings cacheModelsEnabled="true" enhancementEnabled="true"
        lazyLoadingEnabled="true" errorTracingEnabled="true" maxRequests="32"
        maxSessions="10" maxTransactions="5" useStatementNamespaces="true" />

    <sqlMap resource="includes:mapping*.xml" />
<sqlMapConfig>

import org.apache.log4j.Logger;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.StringWriter;
import java.io.UnsupportedEncodingException;
import java.util.Iterator;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.Node;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;
import org.springframework.core.io.ByteArrayResource;
import org.springframework.core.io.Resource;
import org.springframework.core.io.ResourceLoader;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.core.io.support.ResourcePatternResolver;
import org.springframework.orm.ibatis.SqlMapClientFactoryBean;

import com.ibatis.sqlmap.engine.builder.xml.SqlMapClasspathEntityResolver;

public class IncludesSqlMapClientFactoryBean extends SqlMapClientFactoryBean {
   
    /** Logger for this class */
    private static final Logger log = Logger
            .getLogger(IncludesSqlMapClientFactoryBean.class);
   
    public static String INCLUDES_PREFIX = "includes:";

    private Resource configLocation;

    public void setConfigLocation(Resource configLocation) {
        super.setConfigLocation(configLocation);
        this.configLocation = configLocation;
    }

    public void afterPropertiesSet() throws Exception {
        Document source = buildDocument(configLocation.getInputStream());
        Document target = generateSqlMapConfig(source);
        setConfigLocation(toResources(target));

        //System.out.println(format(out.toByteArray()));
        super.afterPropertiesSet();
    }

    private Resource toResources(Document target)
            throws UnsupportedEncodingException, IOException {
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        XMLWriter writer = new XMLWriter(out);
        writer.write(target);

        Resource resource = new ByteArrayResource(out.toByteArray());
        return resource;
    }

    private Document generateSqlMapConfig(Document source)
            throws IOException {
        Document target = (Document) source.clone();
        Element targetRoot = (Element) target.node(0);
        targetRoot.clearContent();
        ResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
        Element sourceRoot = (Element) source.node(0);
        for (Iterator iter = sourceRoot.nodeIterator(); iter.hasNext();) {
            Node node = (Node) iter.next();
            if(node.getNodeType() == Node.ELEMENT_NODE) {
                Element element = (Element) node;
                if("sqlMap".equals(element.getName())) {
                    String resourcePath = element.attributeValue("resource");
                    if(resourcePath == null) {
                        continue;
                    }
                    if(resourcePath.startsWith(INCLUDES_PREFIX)) {
                        String pattern = ResourceLoader.CLASSPATH_URL_PREFIX + resourcePath.substring(INCLUDES_PREFIX.length());
                        Resource[] resources = resolver.getResources(pattern);
                        for (int i = 0; i < resources.length; i++) {
                            Resource resource = resources[i];

                            Element sqlmap = targetRoot.addElement("sqlMap");
                           
                            log.info(">>> iBatis includes sqlMap: " + resource.getURL().toString());
                           
                            sqlmap.addAttribute("url", resource.getURL().toString());
                        }
                        continue;
                    }
                }
            }
            targetRoot.add((Node) node.clone());
        }
        return target;
    }

    private Document buildDocument(InputStream in) throws DocumentException, IOException {
        SAXReader reader = new SAXReader();
        reader.setEntityResolver(new SqlMapClasspathEntityResolver());
        return reader.read(in);
    }

    protected String format(byte[] data) throws Exception {
        Document document = buildDocument(new ByteArrayInputStream(data));
        StringWriter formatWriter = new StringWriter();
        XMLWriter writer = new XMLWriter(formatWriter, new OutputFormat("  ", true));
        writer.write(document);
        return formatWriter.toString();
    }
}