Question

我是开发Google App Engine的初学者，因此我尝试遵循基本的Java教程。目前，我已按照“{Guestbook”应用程序的step 3 of Building and testing the app执行了所有步骤。

我在终端中执行mvn appengine:devserver，但当我在浏览器中转到localhost:8080时，会看到以下消息。

HTTP ERROR: 503

Problem accessing /. Reason:

SERVICE_UNAVAILABLE

在我启动服务器的终端中，由于此错误，我看不到任何输出。任何人都可以提供任何洞察这个问题？

修改 - localhost:8080/guestbook也会产生同样的HTTP 503错误

这是我的web.xml文件（从GAE教程页面复制）：

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE web-app PUBLIC
 "-//Oracle Corporation//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd">
<web-app xmlns="http://java.sun.com/xml/ns/javaee" version="2.5">
    <servlet>
        <servlet-name>guestbook</servlet-name>
        <servlet-class>com.google.appengine.demos.guestbook.GuestbookServlet</servlet-class>
    </servlet>
        <servlet-mapping>
        <servlet-name>guestbook</servlet-name>
        <url-pattern>/guestbook</url-pattern>
    </servlet-mapping>
    <welcome-file-list>
        <welcome-file>guestbook.jsp</welcome-file>
    </welcome-file-list>
</web-app>

这是他们提供的guestbook.jsp（如果这有帮助）：

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ page import="com.google.appengine.api.users.User" %>
<%@ page import="com.google.appengine.api.users.UserService" %>
<%@ page import="com.google.appengine.api.users.UserServiceFactory" %>
<%@ page import="java.util.List" %>
<%@ taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %>

<html>
<head>
    <link type="text/css" rel="stylesheet" href="/stylesheets/main.css"/>
</head>

<body>

<%
    String guestbookName = request.getParameter("guestbookName");
    if (guestbookName == null) {
        guestbookName = "default";
    }
    pageContext.setAttribute("guestbookName", guestbookName);
    UserService userService = UserServiceFactory.getUserService();
    User user = userService.getCurrentUser();
    if (user != null) {
        pageContext.setAttribute("user", user);
%>

<p>Hello, ${fn:escapeXml(user.nickname)}! (You can
    <a href="<%= userService.createLogoutURL(request.getRequestURI()) %>">sign out</a>.)</p>
<%
} else {
%>
<p>Hello!
    <a href="<%= userService.createLoginURL(request.getRequestURI()) %>">Sign in</a>
    to include your name with greetings you post.</p>
<%
    }
%>


<form action="/guestbook.jsp" method="get">
    <div><input type="text" name="guestbookName" value="${fn:escapeXml(guestbookName)}"/></div>
    <div><input type="submit" value="Switch Guestbook"/></div>
</form>

</body>
</html>

基本的GAE Java教程HTTP 503错误

0 个答案: