@Autowired注解春天给我的NullPointerException

我想通过一个简单的程序来使用@Autowired注释Spring中的依赖注入但我给我下面的错误@Autowired注解春天给我的NullPointerException

Exception in thread "main" java.lang.NullPointerException 
    at Customer.d(Customer.java:8) 
    at Main.main(Main.java:12)

通过xml配置它给我正确的结果。

我的XML文件

<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-2.5.xsd"> 
    <bean class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor"/> 
    <bean id="person" class="Person"> 
    <property name="name" value="khan"/> 
    </bean> 
    <bean id="cust" class="Customer"></bean> 
</beans>

Customer类

public class Customer { 
@Autowired 
private Person p; 
public void display(){ 
    System.out.println(p.getName()); 
} 
}

Person类

public class Person { 

    public String getName() { 
     return name; 
    } 

    public void setName(String name) { 
     this.name = name; 
    } 

    private String name; 

}

主类

public class Main { 
    public static void main(String[] a) { 

     Resource r=new ClassPathResource("SpringXml.xml"); 
     BeanFactory factory=new XmlBeanFactory(r); 
     Customer c=(Customer)factory.getBean("cust"); 
     c.display(); 
    } 

}

来源

2017-08-23 junaid Khan

而不是只提 “客户” 或 “人”，将其更改为CLASS = “complete-package-path.Customer”如果上面的类没有默认包 – Afridi

谢谢上面的类都是默认包 –

尝试在创建客户对象时使用ApplicationContext – Balasubramanian

尝试这样

public static void main(String[] args) throws Exception { 
    ApplicationContext context= new ClassPathXmlApplicationContext("SpringXml.xml"); 
    Customer c = (Customer) context.getBean("cust"); 
    c.display(); 
}

来源

2017-08-23 11:11:55

BeanFac tory和ApplicationContext在[documentation]中描述（http://docs.spring.io/spring/docs/2.5.x/reference/beans.html#context-introduction-ctx-vs-beanfactory） – VitalyZ

试试这个：

<bean id="person" class="com.yourpackage.Person"> 
    <property name="name" value="khan"/> 
</bean> 
<bean id="cust" class="com.yourpackage.Customer"> 
    <property name="p" ref="person"/> 
</bean>

不要忘记添加FULLPATH类包

来源

2017-08-23 11:10:13

@Autowired注解春天给我的NullPointerException

回答

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