/*
* $Header: /home/cvs/jakarta-struts/src/example/org/apache/struts/webapp/example/memory/MemoryDatabasePlugIn.java,v 1.8 2003/02/17 00:31:45 craigmcc Exp $
* $Revision: 1.8 $
* $Date: 2003/02/17 00:31:45 $
*
* ====================================================================
*
* The Apache Software License, Version 1.1
*
* Copyright (c) 1999-2002 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* distribution.
*
* 3. The end-user documentation included with the redistribution, if
* any, must include the following acknowlegement:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowlegement may appear in the software itself,
* if and wherever such third-party acknowlegements normally appear.
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* 4. The names "The Jakarta Project", "Struts", and "Apache Software
* Foundation" must not be used to endorse or promote products derived
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* 5. Products derived from this software may not be called "Apache"
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package org.apache.struts.webapp.example.memory;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.util.ArrayList;
import javax.servlet.ServletException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.struts.action.ActionServlet;
import org.apache.struts.action.PlugIn;
import org.apache.struts.config.ModuleConfig;
import org.apache.struts.util.LabelValueBean;
import org.apache.struts.webapp.example.Constants;
/**
* <p><strong>MemoryDatabasePlugIn</strong> initializes and finalizes the
* persistent storage of User and Subscription information for the Struts
* Demonstration Application, using an in-memory database backed by an
* XML file.</p>
*
* <p><strong>IMPLEMENTATION WARNING</strong> - If this web application is run
* from a WAR file, or in another environment where reading and writing of the
* web application resource is impossible, the initial contents will be copied
* to a file in the web application temporary directory provided by the
* container. This is for demonstration purposes only - you should
* <strong>NOT</strong> assume that files written here will survive a restart
* of your servlet container.</p>
*
* @author Craig R. McClanahan
* @version $Revision: 1.8 $ $Date: 2003/02/17 00:31:45 $
*/
public final class MemoryDatabasePlugIn implements PlugIn {
// ----------------------------------------------------- Instance Variables
/**
* The application configuration for our owning module.
*/
private ModuleConfig config = null;
/**
* 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());
/**
* The {@link ActionServlet} owning this application.
*/
private ActionServlet servlet = null;
// ------------------------------------------------------------- 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;
}
// --------------------------------------------------------- PlugIn Methods
/**
* Gracefully shut down this database, releasing any resources
* that were allocated at initialization.
*/
public void destroy() {
log.info("Finalizing memory database plug in");
if (database != null) {
try {
database.close();
} catch (Exception e) {
log.error("Closing memory database", e);
}
}
servlet.getServletContext().removeAttribute(Constants.DATABASE_KEY);
database = null;
servlet = null;
database = null;
config = null;
}
/**
* Initialize and load our initial database from persistent storage.
*
* @param servlet The ActionServlet for this web application
* @param config The ApplicationConfig for our owning module
*
* @exception ServletException if we cannot configure ourselves correctly
*/
public void init(ActionServlet servlet, ModuleConfig config)
throws ServletException {
log.info("Initializing memory database plug in from '" +
pathname + "'");
// Remember our associated configuration and servlet
this.config = config;
this.servlet = servlet;
// Construct a new database and make it available
database = new MemoryUserDatabase();
try {
String path = calculatePath();
if (log.isDebugEnabled()) {
log.debug(" Loading database from '" + path + "'");
}
database.setPathname(path);
database.open();
} catch (Exception e) {
log.error("Opening memory database", e);
throw new ServletException("Cannot load database from '" +
pathname + "'", e);
}
// Make the initialized database available
servlet.getServletContext().setAttribute(Constants.DATABASE_KEY,
database);
// Setup and cache other required data
setupCache(servlet, config);
}
// --------------------------------------------------------- Public Methods
// ------------------------------------------------------ Protected Methods
/**
* <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(ActionServlet servlet, ModuleConfig config) {
// Set up list of server types under "serverTypes"
ArrayList serverTypes = new ArrayList();
serverTypes.add(new LabelValueBean("IMAP Protocol", "imap"));
serverTypes.add(new LabelValueBean("POP3 Protocol", "pop3"));
servlet.getServletContext().setAttribute("serverTypes", serverTypes);
}
// -------------------------------------------------------- Private Methods
/**
* 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() throws Exception {
// Can we access the database via file I/O?
String path = servlet.getServletContext().getRealPath(pathname);
if (path != null) {
return (path);
}
// Does a copy of this file already exist in our temporary directory
File dir = (File)
servlet.getServletContext().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 =
servlet.getServletContext().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());
}
}
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