context：xml中的property-placeholder

Question

I am new to spring framework. When I am trying to load properties files in my xml file it is showing the following error.

log4j:WARN No appenders could be found for logger (org.springframework.context.support.ClassPathXmlApplicationContext). log4j:WARN Please initialize the log4j system properly. Exception in thread "main" Exception in thread "main" org.springframework.beans.factory.xml.XmlBeanDefinitionStoreException: Line 10 in XML document from class path resource [byConstructor.xml] is invalid; nested exception is org.xml.sax.SAXParseException; lineNumber: 10; columnNumber: 70; The prefix "context" for element "context:property-placeholder" is not bound.

Here is my my .xml file:

<?xml version="1.0" encoding="UTF-8"?>
<context:property-placeholder location="classpath:from.properties"/>
<bean id="u" class="dependenceInjection.ByConstructor">
    <constructor-arg value="101" type="int"></constructor-arg>
    <constructor-arg value="java"></constructor-arg>
</bean>
<bean id="impleCoach" class="dependenceInjection.ImpleCaoch">
    <property name="name" value="${value}" />
</bean>

from.properties

value=value from properties

thanks in advance

Answer 1

The proper xml file :

<?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"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    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
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc.xsd">

    <context:property-placeholder location="classpath:from.properties"/>

    <bean id="u" class="dependenceInjection.ByConstructor">
        <constructor-arg value="101" type="int"></constructor-arg>
        <constructor-arg value="java"></constructor-arg>
    </bean>
    <bean id="impleCoach" class="dependenceInjection.ImpleCaoch">
        <property name="name" value="${value}" />
    </bean>
</beans>

Note : This xml will work. But I recommend checking your beans in the xml that you have written.

Please follow this convention for creating beans :

Example : Class : Team , package: com.demo , id = firstletter of the class is small , ie, team

<bean id ="team" class="com.demo.Team">
</bean>

Answer 2

byConstructor.xml我认为我的xml代码是正确的，您可以在下一张图片中检出，但是eclipse将<context:property-placeholder location="classpath:from.properties"/> as an error