编辑:
当前代码是有效的解决方案,它不会阻止应用程序,它包含在批准的答案中提出的建议。
我想要一个后台线程连续下载 MS Access 数据库,而我的 tomcat 7 Web 应用程序正在运行,该线程确实下载了数据库,但是它似乎阻止了我的应用程序的启动,因为我无法从该服务访问任何页面,这是我正在使用的代码:
public class DatabaseUpdater implements ServletContextListener {
private Thread thread = null;
private final Runnable updater = new Runnable() {
private boolean hasExpired(File mdbFile) throws IOException {
if (!mdbFile.exists())
return true;
Long ttl = Long.parseLong(Configuration.getValueForOS("db.http-expiration"));
Date now = new Date();
Date fileDate = new Date(mdbFile.lastModified());
return (now.getTime() - fileDate.getTime()) > ttl;
}
@Override
public void run() {
while (true) {
if (Thread.currentThread().isInterrupted())
throw new RuntimeException("Application Shutdown");
try {
String databases[] = new String[]{"database1", "database2"};
for (String database : databases) {
String fileName = database + "." + StringUtil.randomString(8) + ".mdb";
String fileLocation = Configuration.getValueForOS("db.path");
File mdbFile = new File(fileLocation, fileName);
File currentDatabaseFile = new File(fileLocation, database + ".mdb");
if (hasExpired(currentDatabaseFile)) {
URL url = new URL(Configuration.getValueForOS("db.url." + database));
InputStream in = url.openConnection().getInputStream();
OutputStream out = new FileOutputStream(mdbFile);
FileUtil.streamBridge(in, out);
FileUtil.close(in, out);
while (currentDatabaseFile.exists() && !currentDatabaseFile.delete()) ;
while (!mdbFile.renameTo(currentDatabaseFile)) ;
}
}
// Put the thread to sleep so the other threads do not starve
Thread.sleep(Long.parseLong(
Configuration.getValueForOS("db.http-expiration"));
} catch (IOException ioe) {
ioe.printStackTrace();
} catch (InterruptedException ie) {
ie.printStackTrace();
}
}
}
};
@Override
public void contextInitialized(ServletContextEvent servletContextEvent) {
this.thread = new Thread(updater);
thread.start();
}
@Override
public void contextDestroyed(ServletContextEvent servletContextEvent) {
if (this.thread.isAlive())
this.thread.interrupt();
}
}
可能是什么原因造成的?
我的实现基于这个问题:Background Thread for a Tomcat servlet app