Question

Servlet无法在Eclipse Juno for Java EE中新创建的Dynamic Web Project中工作。以下是从头开始的方式：

我下载了Eclipse EE（Juno），没有更改任何默认配置
我下载了最新的Tomcat（7.0.30）
在偏好设置＆gt;服务器＆gt;运行时环境我添加了新的Apache Tomcat v7.0
我创建了名为UniBudget的新动态Web项目（上下文根：budget）
我添加了新文件（index.jps与“它有效！”在里面）

在将项目添加到服务器并运行它之后，我可以在屏幕上看到“it works！”。因此，部署可行。

接下来我添加了servlet文件（control.Controller.java）：

package control;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet({ "/Controller", "*.do" })
public class Controller extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public Controller() {
        super();
    }

    protected void doGet(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        System.out.println("doGet()");
    }

    protected void doPost(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        System.out.println("doPost()");
    }

}

我将index.jsp更改为这样，仅此而已：
```
<jsp:forward page="/departments.do"/>
```

当然还有web.xml：

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
id="WebApp_ID" version="3.0">
    <display-name>UniBudget</display-name>
    <welcome-file-list>
        <welcome-file>index.html</welcome-file>
        <welcome-file>index.htm</welcome-file>
        <welcome-file>index.jsp</welcome-file>
            <welcome-file>default.html</welcome-file>
            <welcome-file>default.htm</welcome-file>
        <welcome-file>default.jsp</welcome-file>
    </welcome-file-list>

    <!-- servlet definition -->
    <servlet>
        <servlet-name>Do</servlet-name>
        <servlet-class>control.Controller</servlet-class>
    </servlet>
    <!-- servlet mapping -->
    <servlet-mapping>
        <servlet-name>Do</servlet-name>
        <url-pattern>*.do</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>Do</servlet-name>
        <url-pattern>/Controller</url-pattern>
    </servlet-mapping>
</web-app>

生成的.class个文件必须在WEB-INF/classes对吗？这就是我读到的。所以：Configure Build Path > Source tab > Browse >我在classes创建了WEB-INF文件夹（Advanced我链接到文件系统中的文件夹：... /UniBudget/build/classes）
这是项目中的文件层次结构：

file hierarchy in project

我清理并构建了UniBudget项目并重新发布到服务器。清理服务器。

我以为我现在会工作（我的意思是在控制台中显示“doGet（）”或“doPost（）”。但是在Console中我没有打印输出，而是出现了这个错误：

HTTP Status 404 - /budget/departments.do

--------------------------------------------------------------------------------

type: Status report

message: /budget/departments.do

description: The requested resource is not available.

当我尝试直接访问http://localhost:8080/budget/Controller时（同时没有从index.jsp重定向）

看起来Eclipse根本看不到servlet！你能指出我犯错的地方吗？我现在无法解决这个问题。

修改

删除多余注释（@WebServlet）后，会发生另一个错误：

HTTP Status 503 - Servlet Do is currently unavailable

--------------------------------------------------------------------------------

type Status report

message Servlet Do is currently unavailable

description The requested service is not currently available.

控制台出错：

wrz 24, 2012 9:34:15 PM org.apache.catalina.core.ApplicationDispatcher invoke
WARNING: Servlet Do is currently unavailable

不多。但就是这样。

修改

我发现此处发生了另一个错误。我甚至不确定如何重新创建它，但至少这一个提供了更多的日志信息：

HTTP Status 500 - An exception occurred processing JSP page /index.jsp at line 3

--------------------------------------------------------------------------------

type: Exception report

message: An exception occurred processing JSP page /index.jsp at line 3

description: The server encountered an internal error that prevented it from fulfilling this request.

exception: 

org.apache.jasper.JasperException: An exception occurred processing JSP page /index.jsp at line 3

1: <%@ page language="java" contentType="text/html; charset=UTF-8"
2:     pageEncoding="UTF-8"%>
3: <jsp:forward page="/departments.do"/>


Stacktrace:
    org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:568)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:455)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:722)


root cause: 

javax.servlet.ServletException: Error instantiating servlet class control.Controller
    org.apache.jasper.runtime.PageContextImpl.doForward(PageContextImpl.java:746)
    org.apache.jasper.runtime.PageContextImpl.forward(PageContextImpl.java:716)
    org.apache.jsp.index_jsp._jspService(index_jsp.java:65)
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:722)


root cause: 

java.lang.ClassNotFoundException: control.Controller
    org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1714)
    org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1559)
    org.apache.jasper.runtime.PageContextImpl.doForward(PageContextImpl.java:746)
    org.apache.jasper.runtime.PageContextImpl.forward(PageContextImpl.java:716)
    org.apache.jsp.index_jsp._jspService(index_jsp.java:65)
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:722)

修改

project right click > Export > WAR file期间的错误：

java.lang.NoClassDefFoundError: org/eclipse/wst/web/internal/deployables/IFlatDeployable
    at org.eclipse.jst.j2ee.internal.archive.operations.JavaEEComponentExportOperation.getModuleParticipants(JavaEEComponentExportOperation.java:77)
    at org.eclipse.jst.j2ee.internal.archive.operations.JavaEEComponentExportOperation.getParticipants(JavaEEComponentExportOperation.java:43)
    at org.eclipse.jst.j2ee.internal.archive.operations.JavaEEComponentExportOperation.createFlatComponentArchiver(JavaEEComponentExportOperation.java:91)
    at org.eclipse.jst.j2ee.internal.archive.operations.ComponentExportOperation.export(ComponentExportOperation.java:191)
    at org.eclipse.jst.j2ee.internal.archive.operations.ComponentExportOperation.execute(ComponentExportOperation.java:136)
    at org.eclipse.wst.common.frameworks.internal.datamodel.DataModelPausibleOperationImpl$1.run(DataModelPausibleOperationImpl.java:385)
    at org.eclipse.core.internal.resources.Workspace.run(Workspace.java:2344)
    at org.eclipse.wst.common.frameworks.internal.datamodel.DataModelPausibleOperationImpl.runOperation(DataModelPausibleOperationImpl.java:410)
    at org.eclipse.wst.common.frameworks.internal.datamodel.DataModelPausibleOperationImpl.runOperation(DataModelPausibleOperationImpl.java:360)
    at org.eclipse.wst.common.frameworks.internal.datamodel.DataModelPausibleOperationImpl.doExecute(DataModelPausibleOperationImpl.java:247)
    at org.eclipse.wst.common.frameworks.internal.datamodel.DataModelPausibleOperationImpl.executeImpl(DataModelPausibleOperationImpl.java:219)
    at org.eclipse.wst.common.frameworks.internal.datamodel.DataModelPausibleOperationImpl.cacheThreadAndContinue(DataModelPausibleOperationImpl.java:89)
    at org.eclipse.wst.common.frameworks.internal.datamodel.DataModelPausibleOperationImpl.execute(DataModelPausibleOperationImpl.java:207)
    at org.eclipse.wst.common.frameworks.internal.datamodel.ui.DataModelWizard$1CatchThrowableRunnableWithProgress.run(DataModelWizard.java:220)
    at org.eclipse.jface.operation.ModalContext$ModalContextThread.run(ModalContext.java:121)

Answer 1

java.lang.NoClassDefFoundError: org/eclipse/wst/web/internal/deployables/IFlatDeployable

糟糕。这是一个非常严重的错误，这个类就是Eclipse的内部。这已被报告为Eclipse issue 388698，但不幸的是，这被关闭为WORKSFORME。毕竟这似乎是一个环境/平台/配置特定的问题。我会考虑重新发布相同的问题以及有关所用环境的详细信息（OS make / version，JRE / JDK make / version，hardware specs等）。

我个人还没有尝试过Juno（我通常会等待一个SR1在冬天发布，以便涵盖所有主要的出牙问题），但如果完全删除Eclipse安装并重新解压缩它不起作用，那么我建议尝试回到之前的Eclipse版本Indigo SR2。确保为您的平台下载了正确的版本（32位对64位）。

Answer 2

对我来说

java.lang.NoClassDefFoundError: org/eclipse/wst/web/internal/deployables/IFlatDeployable

错误是由以下插件引起的：

WTP Patches for org.eclipse.jst.web_core.feature 3.4.0.v201207092049-20F8O7w312318212711

在插件被禁用后，我能够使用Eclipse打包并部署它。

（此解决方案来自BalusC提及的网址Bug 388698 - Error exporting WAR file）

java.lang.NoClassDefFoundError：org / eclipse / wst / web / internal / deployables / IFlatDeployable

2 个答案: