zk简单实例（适合初学者）

/* * Created on May 9, 2006 * * To change the template for this generated file go to * Window&gt;Preferences&gt;Java&gt;Code Generation&gt;Code and Comments */ package sample.zk; import javax.servlet.ServletContextEvent; import javax.servlet.ServletContextListener; import java.io.BufferedInputStream; import java.io.BufferedOutputStream; import java.io.File; import java.io.FileOutputStream; import java.io.InputStream; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.struts.webapp.example.memory.*; import javax.servlet.ServletContext; import java.util.HashMap; /** * @author michael lee it * * To change the template for this generated type comment go to * Window&gt;Preferences&gt;Java&gt;Code Generation&gt;Code and Comments */ public final class MemoryDatabasePlugIn implements ServletContextListener { /** * The {@link MemoryUserDatabase} object we construct and make available. */ private MemoryUserDatabase database = null; /** * Logging output for this plug in instance. */ private Log log = LogFactory.getLog(this.getClass()); // ------------------------------------------------------------- Properties /** * The web application resource path of our persistent database * storage file. */ private String pathname = "/WEB-INF/database.xml"; public String getPathname() { return (this.pathname); } public void setPathname(String pathname) { this.pathname = pathname; } /* (non-Javadoc) * @see javax.servlet.ServletContextListener#contextInitialized(javax.servlet.ServletContextEvent) */ public void contextInitialized(ServletContextEvent sce) { // TODO Auto-generated method stub log.info("Initializing memory database plug in from '" + pathname + "'"); // Remember our associated configuration and servlet // Construct a new database and make it available database = new MemoryUserDatabase(); try { setPathname(sce.getServletContext().getInitParameter("pathname")); String path = calculatePath(sce.getServletContext()); if (log.isDebugEnabled()) { log.debug(" Loading database from '" + path + "'"); } database.setPathname(path); database.open(); } catch (Exception e) { log.error("Opening memory database", e); } // Make the initialized database available sce.getServletContext().setAttribute("database",database); // Setup and cache other required data //setupCache(servlet, config); setupCache(sce.getServletContext()); } /* (non-Javadoc) * @see javax.servlet.ServletContextListener#contextDestroyed(javax.servlet.ServletContextEvent) */ public void contextDestroyed(ServletContextEvent sec) { // TODO Auto-generated method stub log.info("Finalizing memory database plug in"); if (database != null) { try { database.close(); } catch (Exception e) { log.error("Closing memory database", e); } } sec.getServletContext().removeAttribute("database"); database = null; database = null; } /** * Calculate and return an absolute pathname to the XML file to contain * our persistent storage information. * * @exception Exception if an input/output error occurs */ private String calculatePath(ServletContext sc) throws Exception { // Can we access the database via file I/O? String path = sc.getRealPath(pathname); if (path != null) { return (path); } // Does a copy of this file already exist in our temporary directory File dir = (File) sc.getAttribute("javax.servlet.context.tempdir"); File file = new File(dir, "struts-example-database.xml"); if (file.exists()) { return (file.getAbsolutePath()); } // Copy the static resource to a temporary file and return its path InputStream is = sc.getResourceAsStream(pathname); BufferedInputStream bis = new BufferedInputStream(is, 1024); FileOutputStream os = new FileOutputStream(file); BufferedOutputStream bos = new BufferedOutputStream(os, 1024); byte buffer[] = new byte[1024]; while (true) { int n = bis.read(buffer); if (n <= 0) { break; } bos.write(buffer, 0, n); } bos.close(); bis.close(); return (file.getAbsolutePath()); } /** * <p>Cache commonly required data as servlet context attributes.</p> * * @param servlet The <code>ActionServlet</code> instance running * this webapp * @param config The <code>ModuleConfig</code> for this application module */ protected void setupCache(ServletContext sc) { // Set up list of server types under "serverTypes" HashMap serverTypes = new HashMap(); serverTypes.put("imap","IMAP Protocol"); serverTypes.put("pop3","POP3 Protocol"); sc.setAttribute("serverTypes", serverTypes); } }