Indeed, the keyword is “Ajax”: Asynchronous JavaScript and XML. However, last years it’s more than often Asynchronous JavaScript and JSON. Basically, you let JavaScript execute an asynchronous HTTP request and update the HTML DOM tree based on the response data. Since it’s pretty tedious work to make it to work across all browsers (especially Internet … Read more
Introduction This can have a lot of causes which are broken down in following sections: Put servlet class in a package Set servlet URL in url-pattern @WebServlet works only on Servlet 3.0 or newer javax.servlet.* doesn’t work anymore in Servlet 5.0 or newer Make sure compiled *.class file is present in built WAR Test the … Read more
Introduction To browse and select a file for upload you need a HTML <input type=”file”> field in the form. As stated in the HTML specification you have to use the POST method and the enctype attribute of the form has to be set to “multipart/form-data”. <form action=”upload” method=”post” enctype=”multipart/form-data”> <input type=”text” name=”description” /> <input type=”file” … Read more
When you create servlets you do not directly access the classes. There are two ways of defining the servlet mappings either through annotations, or through web.xml. Through Annotation Servlets using the 3.0 specification have a annotation that specifies the servlet-mapping… you should check this to see which URLs are mapped to your class/servlet. Have a … Read more
You have given no HTML or any script you have tried yourself as such the below should serve as a good template for you to get started. DEMO – Cascading dropdowns, show managers for selected department Assuming the following HTML <div> <div style=”float: left;”> Select Department <br /> <select id=”departments”></select> </div> <div style=”float: left; margin-left: … Read more
Your query looks like this: “SELECT E.username FROM MyUser E” The E.username part will return a list of username Strings. It should be From MyUser to get MyUser objects. Something like: List<MyUser> p1 =sn.createQuery(“FROM MyUser”).list();