Java 未解决org.springframework.beans.factory.NoSuchBeanDefinitionException异常

我从Spring开始，在使用基于XML的bean factory运行这个Spring应用程序时，它给出了

NoSuchBeanDefinitionException

-

Exception in thread "main" org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'myCoach' available
at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeanDefinition(DefaultListableBeanFactory.java:816)
at org.springframework.beans.factory.support.AbstractBeanFactory.getMergedLocalBeanDefinition(AbstractBeanFactory.java:1288)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:298)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:207)
at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1115)
at com.paras.springdemo.HelloSpringApp.main(HelloSpringApp.java:14)

类-HelloSpringApp.java

package com.paras.springdemo;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class HelloSpringApp {
    public static void main(String[] args) {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("classpath*:applicationContext.xml");
        Coach theCoach = context.getBean("myCoach", Coach.class);
        System.out.println(theCoach.getDailyWorkout());
        context.close();
    }
}

applicationContext.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" 
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context.xsd">

    <bean id="myCoach"
        class="com.paras.springdemo.TrackCoach">            
    </bean>
</beans>

TrackCoach.java

package com.paras.springdemo;

public interface Coach {
    public String getDailyWorkout();
}

package com.paras.springdemo;
public class TrackCoach implements Coach {

    @Override
    public String getDailyWorkout() {
        return "run 5k";
    }

}

---

xml中缺少这一行

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

到

---

只需确保您的XML位于src/applicationContext.XML

将coach更改为ClassCoach，但作为一种良好的编码实践，coach应该是练习中的一个接口。TrackCoach在类路径上实现CoachIs上下文文件？正如@SotiriosDelimanolis所建议的那样，我能看到您得到当前错误的唯一方法是，如果Spring没有处理该

applicationContext.xml

文件，那么在此之前没有其他错误。如果正在处理该文件并且在处理时没有导致错误，那么肯定会有一个名为

mycach

的bean。Spring是否可能找到了与上面显示的不同的

applicationContext.xml

？有时我会这样做，即提取结果JAR文件的内容，以查看其中的实际内容（bean XML文件）使用

classpath:

而不是

classpath*：

。这可能会导致启动时出错，说明它无法加载

applicationContext.xml

，这意味着它不是类路径的一部分。确保它位于源目录中，并且在使用maven/gradle时，它位于

src/main/resources

而不是

src/main/java

中。

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

    <bean id="myCoach"
        class="com.paras.springdemo.TrackCoach">            
    </bean>
</beans>

ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");