spring set注入-null和空字符串

举例说明：

Cat类

public class Cat {
    private String name;

    private int age;

    @Override
    public String toString() {
        return "Cat{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }

    public String getName() {
        return name;
    }

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

    public void setAge(int age) {
        this.age = age;
    }
}

配置文件set-di.xml

<bean id="catBean" class="per.sxhzs.spring6.bean.Cat">
        <!--不给属性注入，属性的默认值就是null-->
        <!--<property name="name" value="hxh"/>-->

        <!--这不是注入null，这只是注入了一个“null“字符串-->
        <!--<property name="name" value="null"/>-->

        <!--这种方式是手动注入null-->
        <!--<property name="name">
            <null/>
        </property>-->

        <!--注入空字符串第一种方式-->
        <!--<property name="name" value=""/>-->
        <!--注入空字符串第二种方式-->
        <property name="name">
            <value/>
        </property>
        <property name="age" value="20"/>
    </bean>

测试类

@Test
    public void testNull() {
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("set-di.xml");
        Cat catBean = applicationContext.getBean("catBean", Cat.class);
        System.out.println(catBean);
    }

@Test
    public void testNull() {
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("set-di.xml");
        Cat catBean = applicationContext.getBean("catBean", Cat.class);
        System.out.println(catBean.getName());
    }

运行结果

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