Spring 自动装配 byName 未按预期工作

Question

Spring 自动装配 byName 未按预期工作。

public class SpellChecker {
    public SpellChecker() {
        System.out.println("Inside SpellChecker constructor." );
    }

    public void checkSpelling() {
        System.out.println("Inside checkSpelling." );
    }
}

public class TextEditor {

       private SpellChecker spellChecker1;
       private String name;

       public void setSpellChecker( SpellChecker spellChecker1 ){
          this.spellChecker1 = spellChecker1;
       }
       public SpellChecker getSpellChecker() {
          return spellChecker1;
       }
       public void setName(String name) {
          this.name = name;
       }
       public String getName() {
          return name;
       }

   public void spellCheck() {
       System.out.println(" TextEditor name is " +name);
      spellChecker1.checkSpelling();
   }
}

public class TextEditorMain {

    public static void main(String args[]) throws InterruptedException{

        ApplicationContext context = new 
        ClassPathXmlApplicationContext("Beans.xml"); 
        TextEditor tEditor = (TextEditor) context.getBean("textEditor");
        tEditor.spellCheck();   
    }
}

Spring beans 配置：

<bean id = "spellChecker1" class = "com.spring.beans.SpellChecker">
</bean>

<bean id = "textEditor" class = "com.spring.beans.TextEditor" autowire="byName">
   <property name = "name" value = "text1"/>
</bean>

当我将 spellChecker1 作为 bean id 时，它不起作用。下面是控制台 o/p,

Inside SpellChecker constructor.
 TextEditor name is text1
Exception in thread "main" java.lang.NullPointerException
    at com.spring.beans.TextEditor.spellCheck(TextEditor.java:26)
    at com.spring.main.TextEditorMain.main(TextEditorMain.java:15)

Bean id 和引用名称都相同 spellChecker1 但仍然无法正常工作。但奇怪的是，如果我将 xml 中的 bean id 从 spellChecker1 更改为 spellChecker 代码正在运行并在 o/p,

以下给出

Inside SpellChecker constructor.
 TextEditor name is text1
Inside checkSpelling.

那么为什么我使用 spellChecker1 时没有添加依赖项？

Answer 1

它实际上按设计工作。您的属性被命名为 spellChecker 而不是 spellChecker1。您有一个名为 spellChecker1.

的字段

字段的名称与属性的名称不同。属性的名称由 class 上可用的 get 和 set 方法定义。因为你有一个 setSpellChecker（和相应的 getter）所以有一个名为 spellChecker.

的属性

所有这些都写在 JavaBeans Specification 中（写于 1998 年的某个地方！）

Basically properties are named attributes associated with a bean that can be read or written by calling appropriate methods on the bean. Thus for example, a bean might have a foreground property that represents its foreground color. This property might be read by calling a Color getForeground() method and updated by calling a void setForeground(Color c) method.

Source the JavaBeans Specification.

Spring 自动装配 byName 未按预期工作

Spring autowire byName not working as expected

java

spring

autowired