Java Web应用程序编辑不起作用_Java_Servlets_Netbeans 8_Glassfish 4

Java Web应用程序编辑不起作用

java servlets

Java Web应用程序编辑不起作用,java,servlets,netbeans-8,glassfish-4,Java,Servlets,Netbeans 8,Glassfish 4,我正在学习Java CRUD操作。我正在尝试从sql数据库中插入、更新和删除记录。插入和显示所有记录方法正在工作，但问题是当我单击编辑和删除链接时，其抛出http 404未找到异常下面是我的HTML代码，显示所有记录 <%@page contentType="text/html" pageEncoding="UTF-8"%> <%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %> <!DOCT

我正在学习Java CRUD操作。我正在尝试从sql数据库中插入、更新和删除记录。插入和显示所有记录方法正在工作，但问题是当我单击编辑和删除链接时，其抛出http 404未找到异常

下面是我的HTML代码，显示所有记录

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE html>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>All Posts</title>
    </head>
    <body>
        <div style="width: 1200px; margin-left: auto; margin-right: auto;">
            <table cellpadding="10">
                <tr>
                    <th>Id</th>
                    <th>Title</th>
                    <th>Description</th>
                    <th>Detail</th>
                    <th>Category</th>
                    <th>Date</th>
                    <th>Image</th>
                    <th></th>
                </tr>
                <c:forEach items="${AllPost}" var="p">
                    <tr>
                        <td>${p.id}</td>
                        <td>${p.title}...</td>
                        <td>${p.description}...</td>
                        <td>${p.detail}...</td>
                        <td>${p.category}</td>
                        <td>${p.date}...</td>
                        <td>${p.image}...</td>
                        <td>
                            <a href="EditPost?id=${p.id}">Edit</a>
                            <a href="DeletePost?id=${p.id}">Delete</a>
                        </td>
                    </tr>
                </c:forEach>
            </table>
        </div>
    </body>
</html>

下面是servlet代码

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


    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
             {
        String idTemp = request.getParameter("id");
        int id = Integer.parseInt(idTemp);
        request.setAttribute("getNewsById", DataAccess.getNewById(id));
        RequestDispatcher rd = request.getRequestDispatcher("CRUD/EditPost.jsp");
        try {
            rd.forward(request, response);
        } catch (ServletException | IOException ex) {
            Logger.getLogger(EditPost.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

下面是代码web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.1" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd">
    <context-param>
        <param-name>javax.faces.PROJECT_STAGE</param-name>
        <param-value>Development</param-value>
    </context-param>
    <servlet>
        <servlet-name>Faces Servlet</servlet-name>
        <servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet>
        <servlet-name>EditPost</servlet-name>
        <servlet-class>servlet.EditPost</servlet-class>
    </servlet>
    <servlet>
        <servlet-name>DeletePost</servlet-name>
        <servlet-class>servlet.DeletePost</servlet-class>
    </servlet>
    <servlet>
        <servlet-name>AllPost</servlet-name>
        <servlet-class>servlet.AllPost</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>Faces Servlet</servlet-name>
        <url-pattern>/faces/*</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>EditPost</servlet-name>
        <url-pattern>/EditPost</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>DeletePost</servlet-name>
        <url-pattern>/DeletePost</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>AllPost</servlet-name>
        <url-pattern>/AllPost</url-pattern>
    </servlet-mapping>
    <session-config>
        <session-timeout>
            30
        </session-timeout>
    </session-config>
    <welcome-file-list>
        <welcome-file>faces/index.xhtml</welcome-file>
    </welcome-file-list>
</web-app>


javax.faces.PROJECT_阶段
发展
Facesservlet
javax.faces.webapp.FacesServlet
1.
社论
servlet.EditPost
删除邮件
servlet.DeletePost
邮政总局
servlet.AllPost
Facesservlet
/面孔/*
社论
/社论
删除邮件
/删除邮件
邮政总局
/邮政总局
30
faces/index.xhtml

这是我单击编辑和删除链接时出错的屏幕截图

以下显示了创建所需功能所需的最低限度。显然，需要添加关于真正实现的所有内容

最后，

.jsp

中的路径需要与

@WebServlet

路径匹配。虽然具体的转发取决于一点

这在Tomcat9.0中工作，但可能适用于其他类似的服务器，如glassfish等

web.xml 这提供了基本信息

<web-app>
  <welcome-file-list>
    <welcome-file>welcome.jsp</welcome-file>
  </welcome-file-list>
</web-app>

EditPost.java 这是一个带注释的servlet的快速示例

@WebServlet("/EditPost")
public class EditPost extends HttpServlet {
  private static final long serialVersionUID = 1L;

  /**
   * Default constructor. 
   */
  public EditPost() {
  }

  /**
   * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
   */
  protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    response.getWriter().append("Served at: ").append(request.getContextPath());
  }

  /**
   * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
   */
  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    doGet(request, response);
  }

}

在.html页面中，参考是

删除

和

编辑

，但URL模式是

/DeletePost

。我可能错过了某个地方的地图。但是404是指在指定路径中找不到页面/servlet。此处发布的内容太多--您需要将发布内容减少到仅包含基本内容（例如，

DataAccess

不太可能涉及404错误）。同样，在这一切的某个地方可能有一个映射。但是，乍一看，.html文件

中的这段代码需要一个名为

edit

的页面/servlet，但是您的servlet路径声明为

/EditPost

。这些路径不同。请尝试更改为

，然后查看路径是否解析。另外，请添加收到404错误时浏览器显示的完整路径。换句话说，从href中删除绝对引用。请参阅（或您可以执行

href=“EditPost”

）谢谢您，卡文。请发布您的答案。我只是删除了所有的servlet并再次添加了它。现在它可以按照您的建议工作了

<web-app>
  <welcome-file-list>
    <welcome-file>welcome.jsp</welcome-file>
  </welcome-file-list>
</web-app>

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<!DOCTYPE html>
<html>
  <head>
    <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
    <title>Insert title here</title>
  </head>
  <body>

    <h1>Hello World!</h1>
    <!-- note this can also be ./EditPost -->
    <!-- also note that not passing any query here -->
    <a href="EditPost">Edit Post</a>
  </body>
</html>

@WebServlet("/EditPost")
public class EditPost extends HttpServlet {
  private static final long serialVersionUID = 1L;

  /**
   * Default constructor. 
   */
  public EditPost() {
  }

  /**
   * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
   */
  protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    response.getWriter().append("Served at: ").append(request.getContextPath());
  }

  /**
   * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
   */
  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    doGet(request, response);
  }

}