Question

我对JAVA很新，但我在网络编程方面有一些经验。我正在创建简单的jsp页面并使用@RequestMapping进行页面查看。但是我面临一个例外，我已经用Google搜索了但没有找到解决我问题的商品。以下是完整堆栈跟踪的例外：

严重：为servlet分配异常[WebAppGraph] java.lang.ClassNotFoundException：com.WebAppGraph.app at org.apache.catalina.loader.WebappClassLoaderBase.loadClass（WebappClassLoaderBase.java:1269）在 org.apache.catalina.loader.WebappClassLoaderBase.loadClass（WebappClassLoaderBase.java:1104）在 org.apache.catalina.core.DefaultInstanceManager.loadClass（DefaultInstanceManager.java:508）在 org.apache.catalina.core.DefaultInstanceManager.loadClassMaybePrivileged（DefaultInstanceManager.java:489）在 org.apache.catalina.core.DefaultInstanceManager.newInstance（DefaultInstanceManager.java:119）在 org.apache.catalina.core.StandardWrapper.loadServlet（StandardWrapper.java:1041）在 org.apache.catalina.core.StandardWrapper.allocate（StandardWrapper.java:770）在 org.apache.catalina.core.StandardWrapperValve.invoke（StandardWrapperValve.java:133）在 org.apache.catalina.core.StandardContextValve.invoke（StandardContextValve.java:96）在 org.apache.catalina.authenticator.AuthenticatorBase.invoke（AuthenticatorBase.java:475）在 org.apache.catalina.core.StandardHostValve.invoke（StandardHostValve.java:140）在 org.apache.catalina.valves.ErrorReportValve.invoke（ErrorReportValve.java:80）在 org.apache.catalina.valves.AbstractAccessLogValve.invoke（AbstractAccessLogValve.java:625）在 org.apache.catalina.core.StandardEngineValve.invoke（StandardEngineValve.java:87）在 org.apache.catalina.connector.CoyoteAdapter.service（CoyoteAdapter.java:342）在 org.apache.coyote.http11.Http11Processor.service（Http11Processor.java:498）在 org.apache.coyote.AbstractProcessorLight.process（AbstractProcessorLight.java:66）在 org.apache.coyote.AbstractProtocol $ ConnectionHandler.process（AbstractProtocol.java:796）在 org.apache.tomcat.util.net.NioEndpoint $ SocketProcessor.doRun（NioEndpoint.java:1372）在 org.apache.tomcat.util.net.SocketProcessorBase.run（SocketProcessorBase.java:49）在 java.util.concurrent.ThreadPoolExecutor.runWorker（ThreadPoolExecutor.java:1142）在 java.util.concurrent.ThreadPoolExecutor中的$ Worker.run（ThreadPoolExecutor.java:617）在 org.apache.tomcat.util.threads.TaskThread $ WrappingRunnable.run（TaskThread.java:61）在java.lang.Thread.run（Thread.java:745）

我的代码示例：

indexController.java

package com.WebAppGraph.app;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
public class indexController {

    @RequestMapping("/")
    public String home() {
        return "index.jsp";
    }

    @RequestMapping("/test.html")
    public String test() {
        return "test.jsp";
    }

}

Web.xml中

<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
    <display-name>Archetype Created Web Application</display-name>
    <servlet>
        <servlet-name>WebAppGraph</servlet-name>
        <servlet-class>
            com.WebAppGraph.app
        </servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>WebAppGraph</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

WebAppGraph-servlet.xml中

<?xml version="1.0" encoding="UTF-8" ?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-3.0.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">

    <context:component-scan base-package="com.WebAppGraph.app"></context:component-scan>

</beans>

的pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.WebAppGraph.app</groupId>
    <artifactId>WebAppGraph</artifactId>
    <packaging>war</packaging>
    <version>1.0</version>
    <name>WebAppGraph Maven Webapp</name>
    <url>http://maven.apache.org</url>
    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>3.8.1</version>
            <scope>test</scope>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.springframework/spring-webmvc -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>4.3.10.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.0.1</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>
    <build>
        <finalName>WebAppGraph</finalName>
    </build>
</project>

文件结构：

当我尝试运行我的程序时，会打开index.jsp页面，但是当我写localhost:9000/WebAppGraph/test.jsp时，第二页才会打开但是当我写localhost:9000/WebAppGraph/test.html时它没有显示给我test.jsp，而是显示我上面发布的异常。知道如何解决这个问题吗？

Answer 1

对于servlet映射，您可以在web.xml中执行类似的操作：

<servlet>
    <servlet-name>WebAppGraph</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/WebAppGraph-servlet.xml</param-value>
    </init-param>
</servlet>

<listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<servlet-mapping>
    <servlet-name>WebAppGraph</servlet-name>
    <url-pattern>*.html</url-pattern>
    <url-pattern>/</url-pattern>
</servlet-mapping>

Answer 2

你需要尝试一个spring-mvc hello world教程。您的班级名称为com.WebAppGraph.app.indexController而不是com.WebAppGraph.app，如果您要将其列入web.xml 需要扩展<Servlet>的{{1}}标记。你所拥有的是一个注释为spring MVC控制器而不是Servlet的spring bean。您希望将spring MVC dispatch servlet放在XML中：

javax.servlet.Servlet

然后在spring xml（你已经在做）中使用上下文扫描注入Controller注释

Answer 3

更改servlet-class文件中web.xml标记的值。您可以更改如下（因为我们大多数人使用DispatcherServlet作为servlet-class）：

<servlet>
    <servlet-name>WebAppGraph</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <load-on-startup>1</load-on-startup>
</servlet>

另外一件事，如果你使用spring的默认配置，那么你需要从返回的控制器函数字符串中删除.jsp，如下所示：

@RequestMapping("/")
public String home() {
    return "index";
}

@RequestMapping("/test.html")
public String test() {
    return "test";
}

为servlet分配异常 - JAVA中的Web编程

3 个答案: