我正在使用其 URL 地址调用 Servlet
。这是我输入的 URL
http://localhost:7001/ryan/olympics?action=selectCatalog&id=1
这肯定是 Servlet 的 URL;如果我更改我得到的地址
page not found
这是 Servlet 的代码。
public class Servlet extends javax.servlet.http.HttpServlet
implements javax.servlet.Servlet {
private static final long serialVersionUID = 1L;
public Servlet() {
super();
}
public void init(ServletConfig config) throws ServletException {
System.out.println("*** initializing controller servlet.");
super.init(config);
}
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
String action = request.getParameter("action");
if (action.equals("selectCatalog")) {
String categoryId = request.getParameter("id");
ProductModelDAO dao4 = new ProductModelDAOImpl("jpac");
if (categoryId != null && !categoryId.trim().equals("")) {
CategoryDAO dao1 = new CategoryDAOImpl("jpac");
try {
Category category = dao1.getCategoryName(categoryId);
request.setAttribute("category", category);
} catch (Exception e) {
e.printStackTrace();
}
}
try {
@SuppressWarnings("unchecked")
List<Product> products = dao4
.getProductsByCategory(categoryId);
request.setAttribute("products", products);
} catch (Exception e) {
e.printStackTrace();
}
url = "SelectCatalog.jsp";
RequestDispatcher requestDispatcher =
getServletContext().getRequestDispatcher(url);
requestDispatcher.forward(request, response);
我得到指向 RequestDispatcher
行的 NullPointerException
。有帮助吗?
最佳答案
尝试将 "SelectCatalog.jsp"
更改为 "/SelectCatalog.jsp"
,因为据我了解,您想使用 绝对路径
.
关于java - Servlet 的 NullPointerException,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/13220553/