Java Servlet:严重：为Servlet分配异常

下面的stacktrace是我在尝试访问servlet时得到的，它似乎在Tomcat manager中运行良好

11 Sep, 2012 11:50:12 AM org.apache.catalina.core.ApplicationContext log
INFO: Marking servlet LoginServlet as unavailable
11 Sep, 2012 11:50:12 AM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Allocate exception for servlet LoginServlet
java.lang.Error: Unresolved compilation problems: 
    The import javax.servlet cannot be resolved
    The import javax.servlet cannot be resolved
    The import javax.servlet cannot be resolved
    The import javax.servlet cannot be resolved
    The import javax.servlet cannot be resolved
    The import javax.servlet cannot be resolved
    HttpServlet cannot be resolved to a type
    ServletConfig cannot be resolved to a type
    ServletException cannot be resolved to a type
    HttpServlet cannot be resolved to a type
    ServletContext cannot be resolved to a type
    ServletException cannot be resolved to a type
    HttpServletRequest cannot be resolved to a type
    HttpServletResponse cannot be resolved to a type
    ServletException cannot be resolved to a type
    request cannot be resolved
    The method getLoggedin() from the type LoginHandler refers to the missing type ServletException
    The method destroy() of type LoginManager must override or implement a supertype method
    HttpServlet cannot be resolved to a type

    at com.login.servlets.LoginManager.<init>(LoginManager.java:5)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
    at java.lang.reflect.Constructor.newInstance(Unknown Source)
    at java.lang.Class.newInstance0(Unknown Source)
    at java.lang.Class.newInstance(Unknown Source)
    at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1149)
    at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:827)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:129)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
    at org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:877)
    at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:594)
    at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1675)
    at java.lang.Thread.run(Unknown Source)
11 Sep, 2012 12:05:12 PM org.apache.catalina.core.ApplicationContext log
INFO: Marking servlet Log4JInitServlet as unavailable
11 Sep, 2012 12:05:12 PM org.apache.catalina.core.StandardContext loadOnStartup
SEVERE: Servlet /logintest threw load() exception
java.lang.Error: Unresolved compilation problems: 
    The import javax.servlet cannot be resolved
    The import javax.servlet cannot be resolved
    The import javax.servlet cannot be resolved
    The import javax.servlet cannot be resolved
    The import org.apache cannot be resolved
    The import org.apache cannot be resolved
    HttpServlet cannot be resolved to a type
    ServletConfig cannot be resolved to a type
    ServletException cannot be resolved to a type
    ServletContext cannot be resolved to a type
    BasicConfigurator cannot be resolved
    PropertyConfigurator cannot be resolved
    BasicConfigurator cannot be resolved

    at com.logger.WebLogger.<init>(WebLogger.java:5)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
    at java.lang.reflect.Constructor.newInstance(Unknown Source)
    at java.lang.Class.newInstance0(Unknown Source)
    at java.lang.Class.newInstance(Unknown Source)
    at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1149)
    at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1026)
    at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4421)
    at org.apache.catalina.core.StandardContext.start(StandardContext.java:4734)
    at org.apache.catalina.core.StandardContext.reload(StandardContext.java:3461)
    at org.apache.catalina.manager.ManagerServlet.reload(ManagerServlet.java:943)
    at org.apache.catalina.manager.HTMLManagerServlet.reload(HTMLManagerServlet.java:557)
    at org.apache.catalina.manager.HTMLManagerServlet.doGet(HTMLManagerServlet.java:121)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.filters.CsrfPreventionFilter.doFilter(CsrfPreventionFilter.java:186)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:563)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
    at org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:877)
    at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:594)
    at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1675)
    at java.lang.Thread.run(Unknown Source)

我不知道为什么会这样。还有一些其他的webapp，它们几乎使用相同的libs运行良好。希望有人能帮我做这件事

---

谢谢

不知何故，您缺少了

servlet api.jar

。它应该位于

tomcat\lib

文件夹中。

“

java.lang.Error:未解决的编译问题

：”

表示应用程序未正确编译。请将

ServletAPI.jar

放在类路径中，不仅放在项目的lib文件夹中，还要将其附加到类路径中

---

请确保相同的jar也可以在

tomcat/common/lib

文件夹中使用。

在查看异常后，您发现了一些错误放置jar文件的地方

（ServletAPI.jar）。它应该在Project/WEB-INF/lib文件夹下。我想会的

---

如果您的jar文件位于上面指定的路径中，则可以正常工作。

最后，我搞错了。这是由eclipse构建引起的问题。由于构建不正确，类文件已损坏。我清理了整个项目，进行了新的构建，现在它运行良好。感谢您的回复。

我也看到了这个异常，@Resource注释导致两种技术相互冲突（tomcat servlet api 3和spring）。

如果您收到这个错误“严重：为servlet分配异常”以及“java.lang.InstanceionException”异常，确保您的servlet类具有公共无参数构造函数，因为servlet容器需要能够实例化它

---

如果servlet类没有定义显式的非零参数构造函数（通常是这种情况），那么编译器提供的默认构造函数就足够了

我也有同样的问题！花了2小时寻找解决方案！ 就在这里

WebContent（在动态Web项目下）->Web-INF->lib（它是空的- 好的）->右键单击它（lib）->构建路径->用作源 文件夹

---

完成了

我的案例是使用Java8lamda表达式和不基于java8的旧版本Rest

对我来说，这发生在我在junit测试中使用Lambda表达式时。在对测试进行注释后，服务器返回了正确的api响应。

我得到了类似的异常
从Java8迁移到Java11时，我遇到了以下错误

Servlet[health Servlet]的异常org.apache.catalina.core.ApplicationContext.log Servlet.init（）引发了异常java.lang.IllegalArgumentException

为了修复错误，我升级了pom中的版本

<jersey.version>2.23.2</jersey.version><!-- Remove this  -->
<jersey.version>2.30.1</jersey.version><!-- Add this  -->

2.23.2
2.30.1

我的web.xml中有以下条目

    <servlet>
    <servlet-name>health-servlet</servlet-name>
    <servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>
    <init-param>
        <param-name>javax.ws.rs.Application</param-name>
        <param-value>com.xyz.platform.registry.service.ServiceRegistryApplication</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
</servlet>

健康servlet
org.glassfish.jersey.servlet.ServletContainer
javax.ws.rs.Application
com.xyz.platform.registry.service.ServiceRegistryApplication
1.

转到项目属性->部署程序集->检查maven依赖项是否可见，如果它们缺少，我们也会收到相同的错误。我可以解决将maven依赖项添加到部署程序集中的问题

[将Maven依赖项添加到部署程序集中后，看起来是这样的]

---

在Eclipse或独立Tomcat中运行时会发生这种情况吗？请检查此Tomcat/common/lib是否适用于Tomcat 5.5或更早版本。由于Tomcat6，它与eclipse损坏的构建无关。真想听！

    <servlet>
    <servlet-name>health-servlet</servlet-name>
    <servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>
    <init-param>
        <param-name>javax.ws.rs.Application</param-name>
        <param-value>com.xyz.platform.registry.service.ServiceRegistryApplication</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
</servlet>