How do I pass information from a servlet to a JSP

问题:

Is it possible to have a servlet that contains an object (an ArrayList in this case) that then does the equivalent of displaying a jsp page and passing that object to the jsp page. In this case the ArrayList contains database results an I want to iterate through and display the results on the JSP page.

I am not using any MVC framework, is it possible to do this with the basic Servlet/JSP architecture.

回答1:

Yes.

1. in the servlet call request.setAttribute("result", yourArrayList);

2. then forward to the jsp:

   getServletContext().getRequestDispatcher("your.jsp")
       .forward(request, response);
   

3. using JSTL, in the jsp:

   <c:forEach items="${result}" var="item">
     ...
   </c:forEach>
   

If you don't want to use JSTL (but I recommend using it), then you can get the value using request.getAttribute("result") in the JSP as well.

Alternatively, but not recommended, you can use request.getSession().setAttribute(..) instead, if you want to redirect() rather than forward().

回答2:

You can pass objects to jsp's by embedding them within the Request.

request.setAttribute("object", object);

and within the jsp:

request.getAttribute("object");

回答3:

You can put it using request.setAttribute("myobj", myObj); see javadoc

回答4:

If you are trying to make some kind of "component" then it's better to convert the JSP page into a custom tag. Here is excellent article about that: http://onjava.com/pub/a/onjava/2004/05/12/jsp2part4.html