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What is the difference between JSF, Servlet and JSP?

How are JSP and Servlet related to each other? Is JSP some kind of Servlet? How are JSP and JSF related to each other? Is JSF some kind of prebuild UI based JSP like ASP.NET-MVC?

How do I import the javax.servlet API in my Eclipse project?

I want to develop with Servlets in Eclipse, but it says that the package javax.servlet cannot be resolved. How can I add javax.servlet package to my Eclipse project?

How to use Servlets and Ajax?

I'm very new to web apps and Servlets and I have the following question:

Whenever I print something inside the servlet and call it by the webbrowser, it returns a new page containing that text. Is there a way to print the text in the current page using Ajax?

Get JSF managed bean by name in any Servlet related class

I'm trying to write a custom servlet (for AJAX/JSON) in which I would like to reference my @ManagedBeans by name. I'm hoping to map:

http://host/app/myBean/myProperty

to:

@ManagedBean(name="myBean")
public class MyBean {
    public String getMyProperty();
}

Is it possible to load a bean by name from a regular servlet? Is there a JSF servlet or helper I could use for it?

I seem to be spoilt by Spring in which all this is too obvious.

How do servlets work? Instantiation, shared variables and multithreading

Suppose, I have a webserver which holds numerous Servlets. For information passing among those Servlets I am getting the Servlets context and setting session variables.

Now, if 2 or more users send request to this server then what happens to the session variables? Will they all be common for all the users or they will be different for each user. If they are different, then how was the server able to differentiate between different users?

One more similar question, if there are *n* users accessing a particular Servlets, then this Servlets gets instantiated only the first time the first user accessed it or does it get instantiated for all the users separately?

Design Patterns web based applications

I am designing a simple web based application. I am new to this web based domain.I needed your advice regarding the design patterns like how responsibility should be distributed among Servlets, criteria to make new Servlet, etc.

Actually I have few entities on my home page and corresponding to each one of them we have few options like add, edit and delete. Earlier I was using one Servlet per options like Servlet1 for add entity1, Servlet2 for edit entity1 and so on and in this way we ended up having a large number of servlets.

Now we are changing our design. My question is how you exactly choose how you choose the responsibility of a servlet. Should we have one Servlet per entity which will process all it's options and forward request to service layer.Or should we have one servlet for the whole page which will process the whole page request and then forward it to corresponding service layer.Also should the request object forwarded to service layer or not.

Please you guide us in choosing the best design.Also any pointer to a good design pattern material will be welcome.

HttpServletRequest to complete URL

I have an HttpServletRequest object.

How do I get the complete and exact URL that caused this call to arrive at my servlet?

Or at least as accurately as possible, as there are perhaps things that can be regenerated (the order of the parameters, perhaps).

Tomcat VS Jetty [closed]

I'm wondering about the downsides of each servers in respect to a production environement. Did anyone have big problems with one of the features? Performance, etc. I also quicky took a look at the new Glassfish, does it match up the simple servlet containers (it seems to have a good management interface at least)?

Where to place and how to read configuration resource files in servlet based application?

In my web application I have to send email to set of predefined users like finance@xyz.com, so I wish to add that to a .properties file and access it when required. Is this a correct procedure, if so then where should I place this file? I am using Netbeans IDE which is having two separate folders for source and JSP files.

How to upload files to server using JSP/Servlet?

How can I upload files to server using JSP/Servlet? I tried this:

<form action="upload" method="post">
    <input type="text" name="description" />
    <input type="file" name="file" />
    <input type="submit" />
</form>

However, I only get the file name, not the file content. When I add enctype="multipart/form-data" to the <form>, then request.getParameter() returns null.

During research I stumbled upon Apache Common FileUpload. I tried this:

FileItemFactory factory = new DiskFileItemFactory();
ServletFileUpload upload = new ServletFileUpload(factory);
List items = upload.parseRequest(request); // This line is where it died.

Unfortunately, the servlet threw an exception without a clear message and cause. Here is the stacktrace:

SEVERE: Servlet.service() for servlet UploadServlet threw exception
javax.servlet.ServletException: Servlet execution threw an exception
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:313)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
    at java.lang.Thread.run(Thread.java:637)

Maven dependency for Servlet 3.0 API?

How can I tell Maven 2 to load the Servlet 3.0 API?

I tried:

<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>servlet-api</artifactId>
    <version>3.0</version>
    <scope>provided</scope>
</dependency>

I use http://repository.jboss.com/maven2/ but what repository would be correct?

Addendum:

It works with a dependency for the entire Java EE 6 API and the following settings:

<repository>
    <id>java.net</id>
    <url>http://download.java.net/maven/2</url>
</repository>

<dependency>
    <groupId>javax</groupId>
    <artifactId>javaee-api</artifactId>
    <version>6.0</version>
    <scope>provided</scope>
</dependency>

I'd prefer to only add the Servlet API as dependency, but "Brabster" may be right that separate dependencies have been replaced by Java EE 6 Profiles. Is there a source that confirms this assumption?

Java web development, what skills do I need? [closed]

I want to learn, at least at a basic level, how to build Java web applications (coming from a .NET background).

Meaning, I would like to be able to build, deploy a simple CMS type application from the ground up.

What exactly do I need to learn?

Tomcat seems to be a good web server for Java.

What options are there for the web? I know there is Hibernate for an ORM.

Does Java have MVC? What about JSP? Can MVC and JSP be together? NetBeans?

Maybe a book that covers all of these?

How to define servlet filter order of execution using annotations in WAR

If we define webapp specific servlet filters in WAR's own web.xml, then the order of execution of the filters will be the same as the order in which they are defined in the web.xml.

But, if we define those filters using @WebFilter annotation, what is the order of execution of filters, and how can we determine the order of execution?

What does the servlet value signify

I am getting a bit confused here. In our application we are having a few servlets defined. Here is the excerpt from the web.xml for one of the servlets:

<servlet>
    <servlet-name>AxisServlet</servlet-name>
    <display-name>Apache-Axis Servlet</display-name>
    <servlet-class>com.foo.framework.axis2.http.FrameworkServlet</servlet-class>
    <load-on-startup>0</load-on-startup>
</servlet> 

As per my understanding the value for the <load-on-startup> has to be a positive integer in order for it to get loaded automatically. I looked up on google but the responses I came across only added to my confusion.

How to use a servlet filter in Java to change an incoming servlet request url?

How can I use a servlet filter to change an incoming servlet request url from

http://nm-java.appspot.com/Check_License/Dir_My_App/Dir_ABC/My_Obj_123

to

http://nm-java.appspot.com/Check_License?Contact_Id=My_Obj_123

?

Update: according to BalusC's steps below, I came up with the following code:

public class UrlRewriteFilter implements Filter {

    @Override
    public void init(FilterConfig config) throws ServletException {
        //
    }

    @Override
    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws ServletException, IOException {
        HttpServletRequest request = (HttpServletRequest) req;
        String requestURI = request.getRequestURI();

        if (requestURI.startsWith("/Check_License/Dir_My_App/")) {
            String toReplace = requestURI.substring(requestURI.indexOf("/Dir_My_App"), requestURI.lastIndexOf("/") + 1);
            String newURI = requestURI.replace(toReplace, "?Contact_Id=");
            req.getRequestDispatcher(newURI).forward(req, res);
        } else {
            chain.doFilter(req, res);
        }
    }

    @Override
    public void destroy() {
        //
    }
}

The relevant entry in web.xml look like this:

<filter>
    <filter-name>urlRewriteFilter</filter-name>
    <filter-class>com.example.UrlRewriteFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>urlRewriteFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

I tried both server-side and client-side redirect with the expected results. It worked, thanks BalusC!