Seven tricks to improve your JSP application

Are you often complained by customers that JSP pages respond very slowly? Do you think your Web application can withstand ever-increasing amounts of traffic when the number of customer visits is soaring? This article describes some of the most useful ways to adjust the JSP and servlet to make your servlet and JSP pages respond faster and more scalable. And in the case of increasing the number of users, the system load will show a trend of smooth and long. In this article, I'll use some examples and configuration methods to make your application's performance unexpectedly elevated. Some of these tuning techniques are implemented in your programming work. Other technologies are related to the configuration of the application server. In this article, we will describe in detail how to improve the overall performance of your application by adjusting the servlet and JSP pages. Before reading this article, let's say you have basic servlet and JSP knowledge.

Method One: Caching data in the Init () method of the Servlet

After the application server initializes the servlet instance, it invokes the Init () method of the servlet before servicing the client request. In the lifecycle of a servlet, the init () method is invoked only once. System performance can be greatly improved by caching some static data in the Init () method or by completing some time-consuming operations that need to be performed only once.

For example, creating a JDBC Connection pool in the init () method is a good example, assuming that we are using the jdbc2.0 DataSource interface to get a database connection, and that, in general, we need to get a specific data source through Jndi. We can imagine that in a specific application, if a jndi query is executed every time a SQL request is performed, the performance of the system will drop dramatically. The workaround is the following code, which is cached datasource, making it possible for the next SQL call to continue to take advantage of it:

public class ControllerServlet extends HttpServlet
{
　private javax.sql.DataSource testDS = null;
　public void init(ServletConfig config) throws ServletException
　{
　　super.init(config);
　　Context ctx = null;
　　try
　　{
　　　ctx = new InitialContext();
　　　testDS = (javax.sql.DataSource)ctx.lookup("jdbc/testDS");
　　}
　　catch(NamingException ne)
　　{
　　　ne.printStackTrace();
　　}
　　catch(Exception e)
　　{
　　　e.printStackTrace();
　　}
　}
　public javax.sql.DataSource getTestDS()
　{
　　return testDS;
　}
　...
　...
}

Method 2: Disable servlet and JSP automatic overloading (auto-reloading)

SERVLET/JSP provides a practical technology, automatic overload technology, which provides developers with a good development environment, when you change the servlet and JSP pages without restarting the application server. However, this technology is a great drain on the resources of the system during the operation of the product, because it will bring a great burden to the JSP engine class loader (ClassLoader). Therefore, turning off the automatic overload feature is a great help to improve system performance.