5

某种噩梦 - 无法通过使用 servlet 注释在 Apache Tomcat 9.0.22（或 Glassfish 5.0.1）和 Apache NetBeans IDE 11.0（Build incubator-netbeans-release-404-on-20190319）上启动原始 servlet。使用 JDK 1.8u221。这是代码：

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

    protected void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.getWriter().println("test");
    }
}

和web.xml文件：

<?xml version="1.0" encoding="UTF-8"?>

<web-app 
    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"
    version="3.1">

</web-app>

根本原因（注意行号，它总是1！）：

java.lang.RuntimeException: 
    com.example.NewServlet.<init>(NewServlet.java:1)
    java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:490)
    java.base/java.lang.Class.newInstance(Class.java:584)
    org.apache.openejb.core.WebContext.newWeakableInstance(WebContext.java:147)
    org.apache.openejb.core.WebContext.newInstance(WebContext.java:181)
    org.apache.tomee.catalina.JavaeeInstanceManager.newInstance(JavaeeInstanceManager.java:78)
    org.apache.tomee.catalina.JavaeeInstanceManager.newInstance(JavaeeInstanceManager.java:124)
    org.apache.tomee.catalina.JavaeeInstanceManager.newInstance(JavaeeInstanceManager.java:119)
    org.apache.tomee.catalina.OpenEJBValve.invoke(OpenEJBValve.java:45)
    org.apache.tomee.catalina.OpenEJBValve.invoke(OpenEJBValve.java:45)
    org.apache.tomee.catalina.OpenEJBValve.invoke(OpenEJBValve.java:45)
    org.apache.tomee.catalina.OpenEJBValve.invoke(OpenEJBValve.java:45)
    org.apache.tomee.catalina.OpenEJBValve.invoke(OpenEJBValve.java:45)
    org.apache.tomee.catalina.OpenEJBValve.invoke(OpenEJBValve.java:45)
    org.apache.tomee.catalina.OpenEJBValve.invoke(OpenEJBValve.java:45)
    org.apache.tomee.catalina.OpenEJBValve.invoke(OpenEJBValve.java:45)
    org.apache.tomee.catalina.OpenEJBValve.invoke(OpenEJBValve.java:45)
    org.apache.tomee.catalina.OpenEJBValve.invoke(OpenEJBValve.java:45)
    org.apache.tomee.catalina.OpenEJBValve.invoke(OpenEJBValve.java:45)
    org.apache.tomee.catalina.OpenEJBValve.invoke(OpenEJBValve.java:45)
    org.apache.tomee.catalina.OpenEJBValve.invoke(OpenEJBValve.java:45)
    org.apache.tomee.catalina.OpenEJBValve.invoke(OpenEJBValve.java:45)
    org.apache.tomee.catalina.OpenEJBValve.invoke(OpenEJBValve.java:45)
    org.apache.tomee.catalina.OpenEJBValve.invoke(OpenEJBValve.java:45)
    org.apache.tomee.catalina.OpenEJBValve.invoke(OpenEJBValve.java:45)
    org.apache.tomee.catalina.OpenEJBValve.invoke(OpenEJBValve.java:45)
    org.apache.tomee.catalina.OpenEJBValve.invoke(OpenEJBValve.java:45)
    org.apache.tomee.catalina.OpenEJBValve.invoke(OpenEJBValve.java:45)
    org.apache.tomee.catalina.OpenEJBValve.invoke(OpenEJBValve.java:45)
    org.apache.tomee.catalina.OpenEJBValve.invoke(OpenEJBValve.java:45)
    org.apache.tomee.catalina.OpenEJBValve.invoke(OpenEJBValve.java:45)
    org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490)
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
    org.apache.tomee.catalina.OpenEJBSecurityListener$RequestCapturer.invoke(OpenEJBSecurityListener.java:97)
    org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:678)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
    org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408)
    org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
    org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:836)
    org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1839)
    org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
    java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
    org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    java.base/java.lang.Thread.run(Thread.java:834)

目标是仅通过注释来声明 servlet，例如@WebServlet(name = "NewServlet", urlPatterns = {"/meow"}).

在带有 JDK1.8u221 的 NetBeans 8.2 上进行了测试 - 一切都按预期工作。我怀疑问题出在 Apache NetBeans 11 中，即使项目 JDK 设置为 8（也是源/二进制格式）。

4

2 回答 2

6

我今天在使用 OpenJDK 14 的 Netbeans 12.0 中遇到了这个问题。事实证明，通过安装 nb-javac 插件解决了这个问题。

于 2020-06-13T01:30:45.030 回答
2

问题出在 Apache NetBeans 11 中。在更高版本（仍然是非官方的）11.1 中，即使没有 web.xml 文件，Servlet 注释也可以正常工作。在 Apache NetBeans IDE 11.1 上使用 Apache Tomcat 9.0.22 和 Glassfish 5.0.1 进行了测试（可从此网页下载）。

于 2019-07-21T12:15:11.243 回答