spring property value 引用properties文件和直接设置的区别

当我们使用spring的setter对bean的引用对象注入时会这样用

	<bean id="testBean" class="TestBean">
		<property name="hello1" value="${hello}"></property>
		<property name="hello2" value="hello &amp; world!"></property>
	</bean>

但是你知道引用properties文件的设置和直接设置的区别吗

区别在于:

引用properties文件中key所对应的value时　spring不会做任何处理直接注入值

直接注入时spring会作转义处理

我们来看下以下示例:

创建一个bean,有hello1和hello2两个属性　通过setter注入

public class TestBean {
	private String hello1;
	private String hello2;

	public String getHello1() {
		return hello1;
	}

	public void setHello1(String hello1) {
		this.hello1 = hello1;
	}

	public String getHello2() {
		return hello2;
	}

	public void setHello2(String hello2) {
		this.hello2 = hello2;
	}

}

xml中配置bean ,hello1引用config.properties文件中key为hello的值

<?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:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx"
	xsi:schemaLocation="http://www.springframework.org/schema/beans
           http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
           http://www.springframework.org/schema/context
           http://www.springframework.org/schema/context/spring-context-3.2.xsd
           http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.2.xsd
           http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd ">
	<context:property-placeholder location="classpath:test-config.properties" />
	<bean id="testBean" class="TestBean">
		<property name="hello1" value="${hello}"></property>
		<property name="hello2" value="hello &amp; world!"></property>
	</bean>
</beans>  

config.properies:

hello = hello & world!

测试类:

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class TestSpring {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		TestBean testBean = (TestBean) new ClassPathXmlApplicationContext("test-spring.xml").getBean("testBean");
		System.out.println(testBean.getHello1());
		System.out.println(testBean.getHello2());
	}

}

输出结果如下:

hello & world!
hello & world!

可以看到同样的值输出了不同的结果　证实我们开头所说:

引用properties文件中key所对应的value时　spring不会做任何处理直接注入值

直接注入时spring会作转义处理