经过velocity模板和Hibernate sql-query的实现动态hql

在开发的时候，很多时候都遇到过需要动态拼写SQL，有的是在配置文件中写SQL，有的是在Java代码中拼写SQL，以配置文件拼SQL的可以拿IBatis为代表，但是很多时候是使用Hibernate的，这个时候就想要是Hibernate能像IBatis那样写就好了。

原创不易，转载请注明出处：通过velocity模板和Hibernate sql-query的实现动态hql

代码下载：http://www.zuidaima.com/share/1723627800005632.htm

这个时候就想到了模板语言和配置文件的结合。模板引擎可以选择Velocity，简单而不失强大，配置文件可以模仿Hibernate的sql-query 的XML文件。

Sql-query的示例代码如下(SQL or HQL)：

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE dynamic-hibernate PUBLIC "-//ANYFRAME//DTD DYNAMIC-HIBERNATE//EN""http://www.anyframejava.org/dtd/anyframe-dynamic-hibernate-mapping-4.0.dtd"><dynamic-hibernate>    <query name="selectUserSQL">        <![CDATA[            SELECT  USER_ID,NAME            FROM zuidaima_com_user Where 1=1            #if($name && $name.length() > 1)             AND name =:name            #end    ]]>    </query>    <query name="selectUserHQL">    <![CDATA[         FROM zuidaima_com_users        Where 1=1            #if($name && $name.length() > 1)                AND name =:name            #end        ]]>    </query>

 package com.zuidaima.util
public class DynamicHibernateImpl implements InitializingBean, ResourceLoaderAware, ApplicationContextAware{ public void afterPropertiesSet() throws Exception { for (int i = 0; i < fileNames.size(); i++) { String fileName = ((String) fileNames.get(i)).trim(); if (resourceLoader instanceof ResourcePatternResolver) { try { Resource[] resources= ((ResourcePatternResolver) resourceLoader).getResources(fileName); buildHQLMap(resources); } catch (IOException ex) { throw new Exception("Could not resolve sql definition resource pattern [" + fileName + "]", ex); } } else { Resource resource = resourceLoader.getResource(fileName); buildHQLMap(new Resource[] { resource }); } } } protected void buildHQLMap(Resource[] resources) throws Exception { for (int i = 0; i < resources.length; i++) { buildHQLMap(resources[i]); } } private void buildHQLMap(Resource resource) throws Exception { try { InputSource inputSource = new InputSource(resource.getInputStream()); org.w3c.dom.Document doc = this.documentLoader.loadDocument(inputSource, null, null, org.springframework.util.xml.XmlValidationModeDetector.VALIDATION_NONE, false); Element root = doc.getDocumentElement(); List<Element> querys = DomUtils.getChildElements(root); for(Element query:querys){ String queryName = query.getAttribute("name"); if (StringUtils.isEmpty(queryName)) { throw new Exception("DynamicHibernate Service : name is essential attribute in a <query>."); } if(statements.containsKey(queryName)){ throw new Exception("DynamicHibernate Service : duplicated query in a <query>."+queryName); } statements.put(queryName, DomUtils.getTextValue(query)); } } catch (SAXParseException se) { throw se; } catch (IOException ioe) { throw ioe; } }