Question

我正在学习Spring并编写一个简单的程序来将属性注入到POJO中。以下是主要类 -

public class test {
    public static void main (String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("Beans.xml");
        MySpring sm = (MySpring)context.getBean("myspring");
        System.out.println(sm);
    }

}

POJO低于 -

  public class MySpring {
    public String count;
    void setcount(String val){
        this.count = val;
    }
    String getcount(){
        return count;
    }

}

配置文件位于 -

之下

   <?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="myspring" class="MySpring" >
   <property name="count" value="PowerShell" />
   </bean>
</beans>

但是，当我运行test.java类时，我收到以下错误 -

 Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'myspring' defined in class path resource [Beans.xml]: Error setting property values; nested exception is org.springframework.beans.NotWritablePropertyException: Invalid property 'count' of bean class [MySpring]: Bean property 'count' is not writable or has an invalid setter method. Does the parameter type of the setter match the return type of the getter?
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1396)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1118)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:517)
    at 
.....
    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139)
    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:83)
    at test.main(test.java:7)
Caused by: org.springframework.beans.NotWritablePropertyException: Invalid property 'count' of bean class [MySpring]: Bean property 'count' is not writable or has an invalid setter method. Does the parameter type of the setter match the return type of the getter?
    at org.springframework.beans.BeanWrapperImpl.setPropertyValue(BeanWrapperImpl.java:1064)
    at org.springframework.beans.BeanWrapperImpl.setPropertyValue(BeanWrapperImpl.java:924)

我知道这是一个常见错误，但由于一切似乎都没有找到根本原因。关于可能存在问题的任何指示都受到高度赞赏。

Answer 1

Bean属性'count'不可写或具有无效的setter方法

您需要为count属性

设置一个setter

Answer 2

设置者应该是setCount()，而不是setcount()

Answer 3

代码void setcount(String val){应在Caps

中更改为“C”

void setCount(String val)

获取/设置后的起始字母应为CAPS。同样适用于getter方法。

Answer 4

在命名setter / getters时需要遵循Javabeans命名约定。这是BeanIntrospection框架的要求。以下应该工作：

void setCount(String val){
  this.count = val;
}

String getCount(){
  return count;
}

Answer 5

我猜，Spring严格遵循naming convention bean'属性来注入。 Properties始终为accessed via method calls on their owning object。对于readable属性，将有一个getter method来读取该值，对于writable属性，将有一个setter method来写值。

因此，在您的情况下，Spring's IOC container implementation ApplicationContext尝试实例化bean（MySpring）和inject MySpring类的属性count，{ {1}}，但injecting purpose container try to finding out the getCount() getter method inside your MySpring class中没有此类方法可归class。

修改了你的bean

Exception

Answer 6

Spring IoC容器支持JavaBeans规范（http://www.oracle.com/technetwork/java/javase/documentation/spec-136004.html）中描述的setter injection。

它搜索类似“setCamelVarName（）”的内容，并在方法名称中将“set”后面的第一个字母缩小，并按原样使用方法名称的其余部分来推断属性名称。因此，要在班级中设置“count”属性，您应该声明公共方法public void setCount(int count)而不是public void setcount(int count)。无论如何，最后一个也是反对良好的Java开发实践。

依赖注入期间的Spring错误

6 个答案: