Spring/Java org.springframework.beans.factory.CannotLoadBeanClassException：找不到类 [C:\launchCodeFiles\src\main\java\RunMario.java]

Question

我正在学习 Java，并被告知要学习 Spring。我正在编写一个简单的程序并收到此错误消息（我正在使用 IntelliJ Idea IDE）：

first line of main
2015-05-06 11:37:38 INFO  ClassPathXmlApplicationContext:510 -   Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@1e717c2: startup date [Wed May 06 11:37:38 CDT 2015]; root of context hierarchy
2015-05-06 11:37:38 INFO  XmlBeanDefinitionReader:317 - Loading XML bean definitions from class path resource [ApplicationContext.xml]
2015-05-06 11:37:39 WARN  ClassPathXmlApplicationContext:487 - Exception encountered during context initialization - cancelling refresh attempt
Exception in thread "main" org.springframework.beans.factory.CannotLoadBeanClassException: Cannot find class [C:\launchCodeFiles\src\main\java\RunMario.java] for bean with name 'obstacle1' defined in class path resource [ApplicationContext.xml]; nested exception is java.lang.ClassNotFoundException: C:\launchCodeFiles\src\main\java\RunMario.java
org.springframework.beans.factory.CannotLoadBeanClassException: Cannot find class [C:\launchCodeFiles\src\main\java\RunMario.java] for bean with name 'obstacle1' defined in class path resource [ApplicationContext.xml]; nested exception is java.lang.ClassNotFoundException: C:\launchCodeFiles\src\main\java\RunMario.java
at org.springframework.beans.factory.support.AbstractBeanFactory.resolveBeanClass(AbstractBeanFactory.java:1328)
at org.springframework.beans.factory.support.AbstractBeanFactory.resolveBeanClass(AbstractBeanFactory.java:1328)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.determineTargetType(AbstractAutowireCapableBeanFactory.java:622)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.determineTargetType(AbstractAutowireCapableBeanFactory.java:622)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.predictBeanType(AbstractAutowireCapableBeanFactory.java:591)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.predictBeanType(AbstractAutowireCapableBeanFactory.java:591)
at org.springframework.beans.factory.support.AbstractBeanFactory.isFactoryBean(AbstractBeanFactory.java:1397)
at org.springframework.beans.factory.support.AbstractBeanFactory.isFactoryBean(AbstractBeanFactory.java:1397)
at org.springframework.beans.factory.support.AbstractBeanFactory.isFactoryBean(AbstractBeanFactory.java:968)
at org.springframework.beans.factory.support.AbstractBeanFactory.isFactoryBean(AbstractBeanFactory.java:968)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:735)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:757)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:735)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:480)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:757)
at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:480)
at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139)
at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:83)
at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:83)
at RunMario.main(RunMario.java:17)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at RunMario.main(RunMario.java:17)
at java.lang.reflect.Method.invoke(Method.java:497)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:140)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
Caused by: java.lang.ClassNotFoundException: C:\launchCodeFiles\src\main\java\RunMario.java
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
at java.lang.reflect.Method.invoke(Method.java:497)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:140)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
Caused by: java.lang.ClassNotFoundException: C:\launchCodeFiles\src\main\java\RunMario.java
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
at org.springframework.util.ClassUtils.forName(ClassUtils.java:249)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at org.springframework.beans.factory.support.AbstractBeanDefinition.resolveBeanClass(AbstractBeanDefinition.java:395)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
at org.springframework.beans.factory.support.AbstractBeanFactory.doResolveBeanClass(AbstractBeanFactory.java:1349)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at org.springframework.beans.factory.support.AbstractBeanFactory.resolveBeanClass(AbstractBeanFactory.java:1320)
at org.springframework.util.ClassUtils.forName(ClassUtils.java:249)
... 15 more
at org.springframework.beans.factory.support.AbstractBeanDefinition.resolveBeanClass(AbstractBeanDefinition.java:395)
at org.springframework.beans.factory.support.AbstractBeanFactory.doResolveBeanClass(AbstractBeanFactory.java:1349)
at org.springframework.beans.factory.support.AbstractBeanFactory.resolveBeanClass(AbstractBeanFactory.java:1320)
... 15 more

Process finished with exit code 1

我的ApplicationContext.xml文件如下。

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

<beans xmlns="http://www.springframework.org/schema/beans"
   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">

    <bean id="obstacle1" class="C:\launchCodeFiles\src\main\java\RunMario.java">
    <constructor-arg name= "marioObstacles" ref="obstacle"/>
    </bean>

    <bean id="obstacle" class="C:\launchCodeFiles\src\main\java\MarioObstacles.java">
    <constructor-arg name="obstacle" value="0"/>
    </bean>

</beans>

我从项目面板复制并粘贴了 RunMario 类文件路径，因此它应该是完全限定的路径。这是 RunMario.java 文件：

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import java.util.Scanner;

public class RunMario {

    private MarioObstacles marioObstacles;

    public RunMario(MarioObstacles marioObstacles) {
    this.marioObstacles = marioObstacles;
    }
    public static void main(String[] arguments) {
   //        RunMario runMario1 = new    RunMario(MarioObstacles.getInstance());
        System.out.println("first line of main");

        ApplicationContext context = new ClassPathXmlApplicationContext("ApplicationContext.xml");
        System.out.println("just out of context");

        RunMario obj = (RunMario) context.getBean("obstacle1");
        obj.start();
    }

    public void start() {
        System.out.println("first line of start");
        BuildOstacles pyramid = marioObstacles.pyramid();
        pyramid.setHeight(runMario());
        pyramid.buildPyramid();
        System.out.println(pyramid);
        System.out.println("exiting start");
    }

    public static int runMario() {
        System.out.println("entering runMario");
        int height;
        do {
            Scanner scan = new Scanner(System.in);
            System.out.println("Please enter a whole number between 1 and 10");
            height = scan.nextInt();
        } while (height < 1 || height > 10);
        return height;
    }
}

我花了 2 天时间寻找答案。我似乎无法弄清楚。

有什么建议吗？

Answer 1

您是对的，您需要完全限定的类名，但在这种情况下，这意味着 包位置，例如 com.yourapp.RunMario，而不是文件路径。

根据您的代码，您没有定义任何包（也就是说，您的 RunMario 类的顶部没有 package）。定义包是最佳实践，但在您这样做之前，您的完全限定类只是 RunMario。

换句话说，你在哪里拥有

<bean id="obstacle1" class="C:\launchCodeFiles\src\main\java\RunMario.java">
    <constructor-arg name= "marioObstacles" ref="obstacle"/>
</bean>

<bean id="obstacle" class="C:\launchCodeFiles\src\main\java\MarioObstacles.java">
    <constructor-arg name="obstacle" value="0"/>
</bean>

应该是

<bean id="obstacle1" class="RunMario">
    <constructor-arg name= "marioObstacles" ref="obstacle"/>
</bean>

<bean id="obstacle" class="MarioObstacles">
    <constructor-arg name="obstacle" value="0"/>
</bean>

Answer 2

问题出在您的应用程序上下文文件中；你指出了java源代码而不是你的类的编译 你应该这样写你的application-context.xml

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

<beans xmlns="http://www.springframework.org/schema/beans"
   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">

    <bean id="obstacle1" class="RunMario">
    <constructor-arg name= "marioObstacles" ref="obstacle"/>
    </bean>

    <bean id="obstacle" class="MarioObstacles">
    <constructor-arg name="obstacle" value="0"/>
    </bean>
</beans>

注意类必须是全限定的（包+类名）

Answer 3

我没有看到 RunMario.java 类的任何包。可以看到java类在父目录下。

所以不要声明

<bean id="obstacle" class="C:\launchCodeFiles\src\main\java\MarioObstacles.java">

声明为

<bean id="obstacle" class="MarioObstacles">

Answer 4

如果你不遵循包结构，那么使用下面的一个

<bean id="obstacle" class="MarioObstacles">