Can I Call a Servlet from a JSP on Page Load Without an HTML Form?

Calling a Servlet from JSP File on Page Load without HTML Form

Question:

Is it possible to invoke a servlet from a JSP file without using an HTML form? For instance, to display database data in an HTML table upon page load.

Answer:

Yes, it is possible to call a servlet from a JSP file without an HTML form using the doGet() method of the servlet. This method allows you to preprocess a request and forward it to the JSP. You can then specify the servlet's URL instead of the JSP's in links and the browser's address bar.

Implementation:

Consider the following servlet:

And an example JSP:

Note that the JSP file is placed within the /WEB-INF folder to prevent direct access by users without calling the servlet.

Additional Notes:

• @WebServlet is available from Servlet 3.0 and above. If using an earlier version, manual servlet registration in web.xml is required.
• The servlet's URL pattern can be accessed directly (e.g., http://localhost:8080/context/products).
• If an HTML form is present within the servlet, it can post to the same URL using method="post". Add a doPost() method to the servlet for post-processing.

Related Links:

• [Servlets Wiki](https://wiki.java.net/bin/view/Javalin/servlets)
• [doGet and doPost in Servlets](https://docs.oracle.com/javase/7/docs/api/javax/servlet/http/HttpServlet.html#doGet(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse))
• [Avoiding Java Code in JSP](https://www.ibm.com/developerworks/java/tutorials/j-jsp/j-jsp-avoidjava/)
• [Servlet Returns HTTP Status 404](https://stackoverflow.com/questions/647016/java-servlet-returns-http-status-404-the-requested-resource-is-not-available-serv)

The above is the detailed content of Can I Call a Servlet from a JSP on Page Load Without an HTML Form?. For more information, please follow other related articles on the PHP Chinese website!