001 package edu.nrao.sss.webapp;
002
003 import java.io.IOException;
004
005 import org.apache.log4j.Logger;
006
007 import org.hibernate.HibernateException;
008
009 import javax.servlet.Filter;
010 import javax.servlet.FilterChain;
011 import javax.servlet.FilterConfig;
012 import javax.servlet.ServletException;
013 import javax.servlet.ServletRequest;
014 import javax.servlet.ServletResponse;
015 import javax.servlet.ServletContext;
016 import javax.servlet.http.HttpSession;
017 import javax.servlet.http.HttpServletRequest;
018
019 import java.util.List;
020 import java.util.ArrayList;
021
022 import edu.nrao.sss.dao.HibernateDao;
023
024 /**
025 * This Filter is responsible for retrieving HibernateDaos from the
026 * HttpSession and commiting any open transactions for those Daos after the
027 * response has been rendered. It finds the Dao's in the HttpSession using the
028 * attribute names configured for the filter with the
029 * <code>edu.nrao.sss.dao.DaoSessionAttrNames</code> init-parameter. The
030 * parameter value should be a comma separated list of attribute names that
031 * can be looked up with {@link HttpSession#getAttribute(String)}.
032 */
033 public class HibernateFilter implements Filter
034 {
035 private static final Logger log = Logger.getLogger(HibernateFilter.class);
036
037 protected final static String INIT_PARAM_NAME = "edu.nrao.sss.dao.DaoSessionAttrNames";
038
039 private List<String> sessionAttrNames = new ArrayList<String>();
040
041 /**
042 * See class comments.
043 */
044 public void init(FilterConfig conf)
045 {
046 ServletContext ctx = conf.getServletContext();
047 String attrNames = conf.getInitParameter(INIT_PARAM_NAME);
048 if (attrNames == null)
049 {
050 //Try to find it in the ServletContext.
051 attrNames = ctx.getInitParameter(INIT_PARAM_NAME);
052
053 //Assign a default if still not found.
054 if (attrNames == null)
055 attrNames = "";
056 }
057
058 for (String attr : attrNames.split(","))
059 {
060 if (attr.length() > 0)
061 {
062 this.sessionAttrNames.add(attr);
063 }
064 }
065 }
066
067 /**
068 * See class comments.
069 */
070 @SuppressWarnings("unchecked")
071 public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
072 throws IOException, ServletException
073 {
074 log.debug("STARTING REQUEST...");
075 HttpServletRequest req = (HttpServletRequest)request;
076 HttpSession userSession = req.getSession(true);
077
078 //get list of dao attr names from the httpsession
079 for (String daoName : this.sessionAttrNames)
080 {
081 Object dao = userSession.getAttribute(daoName);
082 if (dao != null && dao instanceof HibernateDao)
083 {
084 try
085 {
086 log.debug("beginning transaction...");
087 ((HibernateDao)dao).beginTransaction();
088 }
089 catch(HibernateException he)
090 {
091 log.error("Couldn't begin transaction from Filter.", he);
092 }
093 }
094
095 else
096 {
097 log.warn("No dao's found in the http session for name: " + daoName);
098 }
099 }
100
101 try
102 {
103 chain.doFilter(request, response);
104 }
105
106 finally
107 {
108 //get list of dao attr names from the httpsession
109 for (String daoName : this.sessionAttrNames)
110 {
111 Object dao = userSession.getAttribute(daoName);
112 if (dao != null && dao instanceof HibernateDao)
113 {
114 try
115 {
116 log.debug("About to send response, committing any open transactions...");
117 ((HibernateDao)dao).commitTransaction();
118 }
119 catch(HibernateException he)
120 {
121 log.error("Couldn't commit transactions from Filter.", he);
122 }
123 }
124
125 else
126 {
127 log.warn("No dao's found in the http session for name: " + daoName);
128 }
129 }
130 }
131
132 log.debug("FINISHED REQUEST.");
133 }
134
135 /** empty implementation */
136 public void destroy() {}
137 }