java - servlet url 模式与参数问题

Question

当我访问“http://localhost:8080/project/Song”时，没有出现任何错误，它可以在页面中列出一些歌曲。当我点击一首歌曲时，我进入一个URL“http://localhost:8080/SongPage?name=A+Tribe&id=201”，但是这里出现404错误，可能是因为该url有参数，访问这个URL出现错误:

HTTP 状态 404 – 未找到

说明源服务器未找到目标资源的当前表示或不愿意透露该表示的存在。

你知道为什么吗？

也许是因为下面这个 urlPattern:

@WebServlet(name ="SongPage", urlPatterns = {"/SongPage"})

我有下面这个 servlet:

@WebServlet(name ="Song", urlPatterns = {"/Song"})
public class Song extends HttpServlet {

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        QueryManager qm = new QueryManager();
        ArrayList<ArrayList<String>> result = qm.Songs();
        qm.closeConnections();

        request.setAttribute("result", result.get(0));
        request.setAttribute("id", result.get(1));
        RequestDispatcher view=request.getRequestDispatcher("songList.jsp");
        view.forward(request,response);    

    }
}

在songList.jsp中我有这个:

<c:forEach items="${result}" var="item" varStatus="status">
  <a href="/SongPage?name=${result[status.index].replace(" ","+")}&id=${id[status.index]}"> ${result[status.index]} </a> <br />
</c:forEach>

SongPage.java:

@WebServlet(name ="SongPage", urlPatterns = {"/SongPage"})
public class SongPage extends HttpServlet {

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String name = request.getParameter("name").replace("+"," ");

    ...
 }

Answer 1

您的原始网址“http://localhost:8080/project/Song”将“project”作为基本路径，但另一个网址“http://localhost:8080/SongPage?name=A+Tribe&id=201”没有该路径。作为快速修复，您很可能需要更新 JSP 以将其包含在“href”标记中:

<a href="project/SongPage?name=${result[status.index].replace(" ","+")}&id=${id[status.index]}"> ${result[status.index]} </a> <br />

或者很可能它实际上是上下文路径:

<a href="${pageContext.request.contextPath}/SongPage?name=${result[status.index].replace(" ","+")}&id=${id[status.index]}"> ${result[status.index]} </a> <br />