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spring下hibernate多数据库解决方案,以及跨库事务的尝试(二)

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  • atianchen
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最后更新时间：2007-05-17 关键字: spring 多数据库 事务 hibernate

假设，我配置了两个sessionFatory ,一个是mitSessionFactory，一个是testSessionFactory，如下:

xml 代码
  1. <hibernatesupport>
  2. <item id="mit" bean="mitSessionFactory"/>
  3. <item id="test" bean="testSessionFactory"/>
  4. hibernatesupport>

这个我自己系统配置的一部分，系统会解析他，从而知晓究竟存在多少个sessionFactory,item's XmlNode中的id可以理解会托管客户的客户单位

编号,当然，这个配置完全可以忽略，直接从ApplicationContext中一样可以获取到这样的信息

在客户登陆的时候，系统要记录下该客户所属托管单位，然后通过上面的id找到bean's name ，最后获取这个sessionFactory,托管单位信息一般

都是个编号而已跟己方系统的托管用户管理相结合，一般是保存这个编号在session里面,也可以象asp.net一样，记录在安全凭证里,还不知道JAVA方面有没有类似实现，个人认为asp.net这个方法很值得采用,虽然MS号称安全系数+++++这个观点值得怀疑

首先建立一个类,HibernateSupport ，存放当前请求线程所需sessionFactory


java 代码
  1. public class HibernateSupport {
  2. public static final String HIBERNATE_SESSIONIDKEY = "com.mit.hibernatesupport.factory.id";
  3. private static final Logger logger = Logger.getLogger(HibernateSupport.class);
  4. private static ApplicationContext applicationContext ;
  5. private static boolean singleSession=true;
  6. private static Map factorybeanset;
  7. private static ThreadLocal switchhistory;//ÔÚÇл»²»Í¬sessionFactoryµÄʱºòÓõ½
  8. private static ThreadLocal idset;//¼Ç¼µ±Ç°Ä¬ÈϵÄÍйÜÓû§id,ÔÚʵ¼ÊʹÓÃÖУ¬Õâ¸öÊÇ¿ÉÒÔÈ¡ÏûµôµÄ
  9. private static ThreadLocal curfactory;//µ±Ç°ÕýÔÚʹÓõÄsessionFactory
  10. private static ThreadLocal trace;//Ò»¸ösessionFactory¼¯ºÏ,ÓÃÀ´¼Ç¼Õâ´ÎÏ̵߳÷ÓÃÁËÄÇЩsessionFactory
  11. static
  12. {
  13. idset = new ThreadLocal();
  14. curfactory = new ThreadLocal();
  15. trace = new ThreadLocal();
  16. switchhistory = new ThreadLocal();
  17. }
  19. /**
  20. * set current sessionfactory for the Request
  21. * @param ServletContext
  22. * @param the factory's id defined in courser.xml
  23. */
  24. public static synchronized void setCurrent(ServletContext context,Object id)
  25. {
  26. if (idset.get()==null)
  27. {
  28. idset.set(id);
  29. if (factorybeanset.containsKey(id))
  30. {
  31. if (applicationContext==null)
  32. {
  33. applicationContext =
  34. WebApplicationContextUtils
  35. .getWebApplicationContext(context);
  36. }
  37. curfactory.set((SessionFactory)applicationContext
  38. .getBean((String)factorybeanset.get(id)));
  39. putTrace(idset.get(),(SessionFactory)curfactory.get());
  40. }
  41. }
  42. }
  44. /**
  45. * put the sessionfactory to tracemap
  46. * @see COPenSessionInViewFilter release sessionfactory in tracemap
  47. * @param the factory's id defined in courser.xml
  48. * @param hibernate's sessionfactory
  49. */
  50. private static void putTrace(Object id ,SessionFactory factory)
  51. {
  52. Map tracemap = null;
  53. if (trace.get()==null)
  54. {
  55. tracemap = new HashMap();
  56. trace.set(tracemap);
  57. }
  58. else
  59. {
  60. tracemap = (Map)trace.get();
  61. }
  62. if (!tracemap.containsKey(id))
  63. {
  64. tracemap.put(id, factory);
  65. }
  66. }
  68. /**
  69. * switch current sessionfactory
  70. * @param the factory's id defined in courser.xml
  71. */
  72. public static synchronized void swtichFactory(Object id)
  73. {
  74. if (!idset.get().equals(id) )
  75. {
  76. if (factorybeanset.containsKey(id))
  77. {
  78. SessionFactory oldfactory = (SessionFactory)curfactory.get();
  79. SessionFactory newfactory = (SessionFactory)applicationContext
  80. .getBean((String)factorybeanset.get(id));
  81. curfactory.set(newfactory);
  82. pushHistory(oldfactory);
  83. putTrace(id,newfactory);
  84. bindSessionFactory(newfactory);
  85. }
  86. }
  87. }
  89. /**
  90. * restore sessionfactory from queue of switchhistory
  91. */
  92. public static synchronized void restoreFactory()
  93. {
  94. SessionFactory factory = popHistory();
  95. if (factory!=null)
  96. {
  97. curfactory.set(factory);
  98. }
  99. }
  100. /**
  101. * push old sessionfactory to swithhistory after swtichFactory
  102. * @param hibernate's sessionfactory
  103. */
  104. private static void pushHistory(SessionFactory sessionfactory)
  105. {
  106. LinkedList list = null;
  107. if (switchhistory.get()==null)
  108. {
  109. list = new LinkedList();
  110. switchhistory.set(list);
  111. }
  112. else
  113. {
  114. list = (LinkedList)switchhistory.get();
  115. }
  116. list.add(0,sessionfactory);
  118. }
  119. /**
  120. * pop sessionfactory in queue
  121. */
  122. private static SessionFactory popHistory()
  123. {
  124. if (switchhistory.get()!=null)
  125. {
  126. LinkedList list = (LinkedList)switchhistory.get();
  127. if (list.size()>0)
  128. {
  129. SessionFactory factory = (SessionFactory)list.getFirst();
  130. list.removeFirst();
  131. return factory;
  132. }
  133. }
  134. return null;
  135. }
  137. public static Map getTraceMap()
  138. {
  139. if (trace.get()!=null)
  140. {
  141. return (Map)trace.get();
  142. }
  143. return null;
  144. }
  146. public static SessionFactory getCurrentFactory()
  147. {
  148. return (SessionFactory)curfactory.get();
  149. }
  151. public static synchronized void release()
  152. {
  153. idset.set(null);
  154. curfactory.set(null);
  155. switchhistory.set(null);
  156. trace.set(null);
  157. }
  159. /**
  160. * °ó¶¨sessionFactoryµ½springµÄ×ÊÔ´¹ÜÀí
  161. * @param hibernate's sessionfactory
  162. */
  163. private static synchronized boolean bindSessionFactory(SessionFactory sessionFactory)
  164. {
  165. boolean participate=false;;
  166. if (singleSession) {
  167. // single session mode
  168. if (TransactionSynchronizationManager.hasResource(sessionFactory)) {
  169. // Do not modify the Session: just set the participate flag.
  170. participate = true;
  171. }
  172. else {
  173. logger.debug("Opening single Hibernate Session in OpenSessionInViewFilter");
  174. Session session = getSession(sessionFactory);
  175. if (!TransactionSynchronizationManager.hasResource(sessionFactory))
  176. {
  177. TransactionSynchronizationManager.bindResource(sessionFactory, new SessionHolder(session));
  178. }
  179. }
  180. }
  181. else {
  182. // deferred close mode
  183. if (SessionFactoryUtils.isDeferredCloseActive(sessionFactory)) {
  184. // Do not modify deferred close: just set the participate flag.
  185. participate = true;
  186. }
  187. else {
  188. SessionFactoryUtils.initDeferredClose(sessionFactory);
  189. }
  190. }
  191. return participate;
  192. }
  194. //see SessionFactoryUtils
  195. private static Session getSession(SessionFactory sessionFactory) throws DataAccessResourceFailureException {
  196. Session session = SessionFactoryUtils.getSession(sessionFactory, true);
  197. FlushMode flushMode = FlushMode.COMMIT;
  198. if (flushMode != null) {
  199. session.setFlushMode(flushMode);
  200. }
  201. return session;
  202. }
  204. public static synchronized void initSessionFactory(Map res,Class loadclass)
  205. {
  206. factorybeanset =res;
  207. }
  209. public static void setSingleSession(boolean singleSession) {
  210. HibernateSupport.singleSession = singleSession;
  211. }
  213. }
  216. bindSessionFactory·½·¨ºÍgetSession¶¼ÊÇ´ÓspringÖ±½ÓCOPY¹ýÀ´µÄ¡£
  217. Õâ¸öÀàÆäËû·½·¨¿ÉÒÔ²»¹Ü£¬ÔÝʱ¹Ø×¢setCurrentÕâ¸ö·½·¨
  218. if (idset.get()==null)
  219. {
  220. idset.set(id);
  221. if (factorybeanset.containsKey(id)) //factorybeanset°üº¬µÄ¾ÍÊÇÎÒ×Ô¼ºÏµÍ³ÅäÖÃÖÐÄÇÒ»²¿·Ö,key¾ÍÊÇid£¬,value¾ÍÊÇsessionFactory ÔÚspring»·¾³ÖеÄbeanName
  222. {
  223. if (applicationContext==null)
  224. {
  225. applicationContext =
  226. WebApplicationContextUtils
  227. .getWebApplicationContext(context);
  228. }
  229. curfactory.set((SessionFactory)applicationContext
  230. .getBean((String)factorybeanset.get(id)));//ÉèÖõ±Ç°µÄsessionFactory
  231. putTrace(idset.get(),(SessionFactory)curfactory.get());//putµ½µ±Ç°Ï̵߳ÄÒ»¸ö¼Ç¼¼¯
  232. }
  233. }
  234. HibernateSupportFilterÊǸöservlet filter,Ëû»á»ñÈ¡µ±Ç°ÇëÇóµÄÍйÜÓû§±àºÅÈ»ºóµ÷ÓÃsetCurrent
  236. public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
  237. HttpSession session = ((HttpServletRequest)req).getSession();
  238. if (session.getAttribute(HibernateSupport.HIBERNATE_SESSIONIDKEY)!=null)//ÎҰѱàºÅ¼Ç¼ÔÚsessionÖУ¬»ñÈ¡Õâ¸ö±àºÅ
  239. {
  240. Object id = session.getAttribute(HibernateSupport.HIBERNATE_SESSIONIDKEY);
  241. if (log.isDebugEnabled())
  242. {
  243. log.debug("Set Current SessionFactory:"+id.toString());
  244. }
  245. HibernateSupport.setCurrent(config.getServletContext(),session.getAttribute(HibernateSupport.HIBERNATE_SESSIONIDKEY));//µ÷ÓÃsetCurrent
  246. }
  247. try
  248. {
  249. chain.doFilter(req, res);
  250. }
  251. catch (Exception ex)
  252. {
  253. ex.printStackTrace();
  254. }
  255. finally
  256. {
  257. HibernateSupport.release();
  258. }
  259. }

这个类其他方法可以不管，暂时关注setCurrent这个方法


java 代码
  1. if (idset.get()==null)
  2. {
  3. idset.set(id);
  4. if (factorybeanset.containsKey(id)) //factorybeanset包含的就是我自己系统配置中那一部分,key就是id，,value就是sessionFactory 在spring环境中的beanName
  5. {
  6. if (applicationContext==null)
  7. {
  8. applicationContext =
  9. WebApplicationContextUtils
  10. .getWebApplicationContext(context);
  11. }
  12. curfactory.set((SessionFactory)applicationContext
  13. .getBean((String)factorybeanset.get(id)));//设置当前的sessionFactory
  14. putTrace(idset.get(),(SessionFactory)curfactory.get());//put到当前线程的一个记录集
  15. }
  16. }

HibernateSupportFilter是个servlet filter,他会获取当前请求的托管用户编号然后调用setCurrent

java 代码
  1. public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
  2. HttpSession session = ((HttpServletRequest)req).getSession();
  3. if (session.getAttribute(HibernateSupport.HIBERNATE_SESSIONIDKEY)!=null)//ÎҰѱàºÅ¼Ç¼ÔÚsessionÖУ¬»ñÈ¡Õâ¸ö±àºÅ
  4. {
  5. Object id = session.getAttribute(HibernateSupport.HIBERNATE_SESSIONIDKEY);
  6. if (log.isDebugEnabled())
  7. {
  8. log.debug("Set Current SessionFactory:"+id.toString());
  9. }
  10. HibernateSupport.setCurrent(config.getServletContext(),session.getAttribute(HibernateSupport.HIBERNATE_SESSIONIDKEY));//µ÷ÓÃsetCurrent
  11. }
  12. try
  13. {
  14. chain.doFilter(req, res);
  15. }
  16. catch (Exception ex)
  17. {
  18. ex.printStackTrace();
  19. }
  20. finally
  21. {
  22. HibernateSupport.release();
  23. }
  24. }

然后，就要修改spring关于hibernate的一些支持类了，当然，也可以选择重新写一套dao支持类，呵呵，不过，显然，在spring基础上做一些小修改代价更小

HibernateAccessor （HibernateTemplate的基类）以及HibernateTransactionManager都是靠注入方式获取一个sessionFactory，显然，这套不适合了，修改之
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